Copyright: (c) Copyright Agilent Technologies, 2000, 2001


About 89600 Optional Software
About 89600 Optional Measurement Software

The following options are available for the 89600-Series VSA software.

•	Option 105 Dynamic Link to EEsof/ADS allows you to connect your 89600-Series VSA software to Agilent's EEsof Advanced Design System.

•	Option AYA Vector Signal Modulation Analysis (Digital Demodulation): Vector Modulation Analysis (also called Digital Demodulation) adds digital demodulation analysis capability.

•	Option B7N 3G Modulation Analysis adds the following demodulation capabilities:

−	1xEV-DO Modulation Analysis: Adds 1xEV-DO First Evolution - Data Only vector modulation analysis

−	cdma2000 Modulation Analysis: Code Domain Multiple Access 2000 vector modulation analysis.

−	TD-SCDMA Modulation Analysis: Adds TSM "TD-SCDMA System for Mobile" and N-TDD "ULTRA TDD - Low Chip Rate (or Narrow TDD)" vector modulation analysis.

−	W-CDMA (3GPP) Modulation Analysis: Wideband Code Domain Multiple Access (3GPP) vector modulation analysis.

•	Option B7R WLAN Modulation Analysis adds the following wireless LAN demodulation capabilities:

−	WLAN-OFDM 802.11a and HIPERLAN/2 Modulation Analysis: Orthogonal Frequency Division Multiplexing (OFDM) vector modulation analysis for OFDM 802.11a and HIPERLAN/2 standard signals.

−	WLAN-DSSS 802.11b and 802.11g Modulation Analysis: Direct Spread Sequence Spectrum (DSSS) vector modulation analysis for IEEE Std 802.11b and for IEEE Std 802.11g standard signals.

−	Agilent 89600 WLAN Test: Agilent 89600 WLAN Test is a software application that provides a set of automated tests that validate conformance to the IEEE 802.11a-1999 TX specification.  The WLAN Test application is installed separately from the Agilent 89600 VSA application.


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Acknowledgements

The following products are mentioned in one or more places in the Agilent 89600-series documentation.

Product	Acknowledgement
Adobe® and Acrobat®	These products are trademarks of Adobe Systems Incorporated.
Microsoft®, Windows NT®, Windows®, and MS Windows®	These products are U.S. registered trademarks of Microsoft Corporation.
MS Excel, MS Word, MS Office, VBScript	These products are products of Microsoft Corporation.
MATLAB	MATLAB is a product of The MathWorks, Inc.


The Documentation Roadmap is not installed on your system.


1999-2002, Agilent Technologies


This documentation is not installed on your system.


This document was not available for inclusion in the online help. You can download the PDF from the 89600 [image] Web page .


This document was not available for inclusion in the online help. You can download the PDF from the 89600 [image] Web page .


This document was not available for inclusion in the online help. You can download the PDF from the 89600 [image] Web page .


About Option 105 (Advanced Design System Connectivity)

Option 105: Dynamic Link to EEsof/ADS, allows you to integrate your 89600-Series VSA software to Agilent EEsof Advanced Design System (ADS). This option is available for Agilent 89601A, 89610A, 89640A, and 89641.


Vector Signal Analysis for ADS

This application is available as option 105 for the Agilent 89600-series products.

VSA for ADS integrates the 89600-series analyzer with Agilent's EEsof Advanced Design System EDA software (ADS).  When the option 105 software is enabled, a vector signal analyzer block appears in the ADS software, and the two programs are seamlessly integrated--you access the analyzer directly from the ADS interface.

To find out more about ADS, visit their [image] Web page

For help on how to use the 89600 components in ADS, you can access help in the ADS window.  Click Help, Topics and Index, Manuals, Components, Signal Processing Components, Instruments, then the component for which you want help: VSA89600, VSA89600_1, VSA89600_2, or VSA89600Source.  To go directly to help for an individual 89600 VSA component, double click on the component, then click Help in the lower right corner of the resulting dialog box.

VSA for ADS adds a stream interface to 89600-Series VSA software.  The stream interface lets you input digitized waveforms directly from ADS to 89600-series VSA software without using 89600-series hardware. The full functionality of the 89600 analyzer is available to analyze and display the ADS signal.

89600 for ADS also provides a source component. You can use your 89600 analyzer to make real-world measurements with hardware, then use the measurement results as a signal input in your ADS circuit. (Available only with ADS version 1.7 or later and 89601 revision 3.00 or later.)

You can start the 89600 analyzer from the ADS interface by simply starting a simulation that includes a VSA89600 component.

Some 89600 ADS example designs are available. To open the example designs, use the "View Example Directory" toolbar button on the Main ADS window.  Under that, explore the agilent89600 directory for various example designs.

The ADS screen below shows the schematic for one of the example designs. On the left in the schematic is an 89600VSA Source component. On the upper right in the schematic is a single-channel VSA 89600 component.

See also:

89601 VSA Software


Troubleshooting Advanced Design System (ADS)

This topic contains information to help you troubleshoot measurements when using the 89600 software with Agilent's Advanced Design System (ADS).  We recommend that you review Vector Signal Analysis with ADS to learn more about using ADS with the 89600 VSA application.  You can also visit the Agilent's EEsof Advanced Design System EDA software (ADS) [image] Web page for current software information and updates.

PROBLEM	POSSIBLE CAUSE	SOLUTION
Known problems using ADS cdma2000 Library, (version 1.5.1), with the 89600-VSA cdma2000 Demodulation (Opt B7N).	1)  For both Forward and Reverse links, the baseband RF frequency spectrums are the complex conjugate of actual cdma2000 signals.	Un-flip the displayed frequency spectrum to produce the correct display.  Select the Mirror Frequency Spectrum check box (Click MeasSetup, Demod Properties, Format tab). You can also fix this in the simulation by inverting the final "Q" signal or inverting the "LO" phase in the up conversion modulator.
	2)  The initial phase decimator (D2) in the ADS Reverse link modulator, (the CDMA2K_RevHPSK component), is incorrect which leads to a completely different "I" channel spreading sequence.	Select the modulator, pushing down to its schematic, and changing the Phase property from 0 to 1.  Unfortunately, this library component cannot be saved, so it must be modified each time ADS is entered.
	3)  In the CDMA2K_RevHPSK component, the phase of the length 2 Walsh cover sequence generator (C4) is inverted.    This could be a none issue:  Because all channels are only "I" and "Q" channels, this results in either complex conjugation of the final output ("I" Channels) or both inversion and complex conjugation ("Q" Channels), so leaving this in place effectively fixes problem (1) above.	This can be corrected by inserting a Gain block in series with the output of the Walsh generator (C4) with the Gain property set to -1.
	4)  The 89600 VSA can only demodulate Reverse link signals with a long code mask of 0.	Because binary 0 maps to +1.0 Float, a Const component with Level set to 1.0 should be substituted for the long code generator in Reverse link simulations.
	5)  The Example Forward link simulations do not include the phase equalization filter described in 3.1.3.1.14.2 of cdma2000 specification. This results in excessive 89600 EVM measurement results.	Enable external IF Calibration using a calibration file which applies the necessary phase correction data.  Procedure: 1) Copy this calibration file "C:\Program Files\Agilent\89600\VSA\Files\CDMA2kPhaseDist.cal" to a convenient place, such as your project file data directory;  2) Load and apply the cal data:  Click Utilities > Calibration > Amplitude > IF Calibration check box, and locate the cal file. Note: If an "IQ" measurement is being performed, Apply the calibration File to both channels.
See also

Troubleshooting cdma2000 Measurements

VSA Troubleshooting

About Option 105 Advanced Design System (ADS)


Demod Errors and ADS

To use the Demod Errors output type, configure the 89600 demodulator and trace data as indicated in the demod error tables. To see the individual demod error tables, click on the appropriate Demodulation Mode in the following list. Note that the number of output error Indexs depends on the configuration.

	Demodulation  Mode	Trace Data	Total Number of Error Indexes
	Digital Demod	Syms/Errs	21
	W-CDMA (3GPP) or cdma2000	Chan Syms/Errs Comp Error Summary	12 18
	WLAN-OFDM	Syms/Errs	22
	WLAN-DSSS/CCK/PBCC	Syms/Errs	21
	TD-SCDMA	Overall Error Summary Comp Error Summary Channel Error Summary	37 16 10
	1xEV-DO	Fwd Overall Error Summary Fwd Comp Error Summary Rev Comp Error Summary Rev Chan Error Summary	12 16 25 11
Availability of specific demod types depends on 89600 licensing.

The easiest way to get individual error values is to place DownSample components in parallel at the VSA89600Source output.

For example, consider the example "source_demodErrors.dsn" in the VSA89600_demos.prj project. We want to determine the EVM for a Digital Demod measurement. The total number of error indexes for Digital Demod is 21. The error index for EVM is 1. Set the DownSample Factor parameter to the total number of error indexes (21 for Digital Demod) and the Phase parameter to 20 (the total number of error indexes minus the EVM error index, or 21 minus 1).

Note

When OutputType is Integer Scalar and trace data is configured to one of the above types (Syms/Errs, for example), the module will source demodulation symbols.


Digital Demod Errors

Digital Demod Error Summary

For information on how to use the entries in this table, see Demod Errors and ADS.

For details on specific errors, see Available Error Summary Data for digital demodulation. Note that error items vary with demod type (QPSK, QAM, FSK, etc.)

	Error Index	Description
	1	error vector magnitude (EVM) in %rms,  or FSK error in [FSK] %rms
	2	magnitude error in %rms
	3	phase error in degrees-rms
	4	frequency error in Hz,  or carrier offset in [FSK] Hz
	5	amplitude droop in dB/symbol,  or estimated RHO
	6	pilot level in [VSB] linear units
	7	IQ gain Imbalance in dB
	8	quadrature error in degree
	9	peak error vector magnitude in %pk,  or peak FSK Error in [FSK] %pk
	10	symbol number at which the peak error vector magnitude occurred,  or peak FSK error symbol number
	11	peak magnitude error in %pk
	12	symbol number at which the peak magnitude error occurred,  or symbol offset
	13	peak phase error in degrees-pk
	14	symbol number at which the peak phase error occurred
	15	clock alignment (unused)
	16	main frequency error (unused)
	17	amplitude error (unused)
	18	signal to noise ratio (SNR) in dB
	19	waveform quality factor (RHO)
	20	peak error vector magnitude in %
	21	EVM (in %) below which 95% of the individual symbol EVM's occur


W-CDMA (3GPP) or cdma2000 Demod Errors

This topic includes 2 tables: channel error summary and composite error summary.

W-CDMA (3GPP) or cdma2000 Channel Error Summary

For information on how to use the entries in this table, see Demod Errors and ADS.

For details on specific errors, see Available Channel  Error Summary Data for W-CDMA  or Available Channel Error Summary Data for cdma2000.

	Error Index	Description
	1	error vector magnitude (EVM) in %rms
	2	peak error vector magnitude in %pk
	3	peak error vector symbol
	4	channel magnitude error in rms
	5	channel magnitude error pk
	6	symbol with peak magnitude error
	7	phase error rms
	8	peak phase error
	9	symbol with peak phase error
	10	channel pilot bits
	11	slot
	12	tDCPH
W-CDMA (3GPP) or cdma2000 Syms/Errs Composite Error Summary

For information on how to use the entries in this table, see Demod Errors and ADS.

For details on specific errors, see Available Composite  Error Data for W-CDMA or Available Composite  Error Data for cdma2000.

	Error Index	Description
	1	error vector magnitude (EVM) in %rms
	2	peak error vector magnitude in %pk
	3	peak error vector magnitude chip
	4	rms composite magnitude error
	5	peak composite magnitude error
	6	chip number with peak magnitude error
	7	rms composite phase error
	8	peak composite phase error
	9	chip with peak composite phase error
	10	composite frequency error
	11	composite IQ offset
	12	composite IQ gain imbalance
	13	composite IQ quadrature error
	14	composite Rho
	15	composite peak active CDE
	16	composite peak CDE
	17	composite Slot
	18	composite t-trigger


WLAN-OFDM Errors

OFDM error summary

For information on how to use the entries in this table, see Demod Errors and ADS.

For details on specific errors, see Available Error Summary Data for OFDM.

	Error Index	Description
	1	error vector magnitude (EVM) in %rms
	2	peak error vector magnitude in %pk
	3	peak error vector magnitude symbol
	4	rms magnitude error
	5	peak magnitude error
	6	symbol with peak magnitude error
	7	rms phase error
	8	peak magnitude error
	9	symbol with peak magnitude error
	10	frequency error
	11	IQ offset
	12	sync corr
	13	not used
	14	pilot error vector magnitude
	15	rms common pilot error
	16	octets
	17	number of symbols
	18	coding rate numerator
	19	coding rate denominator
	20	bits per sym
	21	bit rate
	22	symbol clock error (ppm)


WLAN-DSSS Demod Errors

WLAN-DSSS Error Summary

For information on how to use the entries in this table, see Demod Errors and ADS.

For details on specific errors, see Available Error Summary Data.

	Error Index	Description
	1	error vector magnitude (EVM) in %rms
	2	peak error vector magnitude in %pk
	3	peak error vector magnitude chip
	4	rms magnitude error
	5	peak magnitude error
	6	chip with peak magnitude error
	7	rms phase error
	8	peak phase error in degrees
	9	chip with peak phase error
	10	frequency error in Hz
	11	IQ offset
	12	IQ quadrature error in degrees
	13	IQ gain imbalance in dB
	14	sync corr
	15	80211b Peak Evm in %
	16	HdrStat (Status result - PLCP Header Status) †
	17	MacStat (Status result - PSDU MAC status) †
	18	burst type
	19	bit rate in bps
	20	octets
	21	data length in seconds

† This is the Status line summary information, which is composed of two parts, the HdrStat (PLCP Header status) and MacStat (PSDU MAC status) status information.  This table provides the HdrStat and MacStat values and meaning:

	HdrStat Value	Meaning
	0	No SFD found - the Preamble Start Frame Delimiter was not found.
	1	Invalid header bits - some of the bits in the PLCP Header were incorrect, but the analyzer was able to determine the data length and data modulation format.
	2	Header CRC failed - the header looked correct except for the CRC, which did not match the rest of the header data.
	3	Invalid header phase shift - an extra (incorrect) 90 degree phase shift was detected at the start of the header.
	4	Invalid Barker1/short - the detected burst type is 1MB/sec Barker with a short preamble, which is an invalid format.
	5	Unknown - the result length was not long enough to capture all of the header data, so the status can not be determined.
	6	OK - the header appears correct and the CRC passed.
	MacStat Value	Meaning
	0	Unknown - the result length was not long enough to capture all of the data, so  the MAC status can not be determined.
	1	MAC FCS failed - the MAC frame checksum failed.
	2	OK - the MAC frame checksum passed.


TD-SCDMA Demod Errors

This topic includes 3 tables: overall error summary, channel error summary, and composite error summary.

TD-SCDMA Overall Error Summary

For information on how to use the entries in this table, see Demod Errors and ADS.

For details on specific errors, see Available Overall Error Summary Data.

	Error Index	Description
	1	DwPhCoding
	2	TmErrTS0 in chips
	3	TotPwrTS0 dBm
	4	MidambPwrTS0 dBm
	5	DataPwrTS0 dBm
	6	TmErrDwPTS in chips
	7	TotPwrDwPTS dBm
	8	MidambPwrDwPTS dBm
	9	DataPwrDwPTS dBm
	10	TmErrUpPTS in chips
	11	TotPwrUpPTS dBm
	12	MidambPwrUpPTS dBm
	13	DataPwrUpPTS dBm
	14	TmErrTS1 in chips
	15	TotPwrTS1 dBm
	16	MidambPwrTS1 dBm
	17	DataPwrTS1 dBm
	18	TmErrTS2 in chips
	19	TotPwrTS2 dBm
	20	MidambPwrTS2 dBm
	21	DataPwrTS2 dBm
	22	TmErrTS3 in chips
	23	TotPwrTS3 dBm
	24	MidambPwrTS3 dBm
	25	DataPwrTS3 dBm
	26	TmErrTS4 in chips
	27	TotPwrTS4 dBm
	28	MidambPwrTS4 dBm
	29	DataPwrTS4 dBm
	30	TmErrTS5 in chips
	31	TotPwrTS5 dBm
	32	MidambPwrTS5 dBm
	33	DataPwrTS5 dBm
	34	TmErrTS6 in chips
	35	TotPwrTS6 dBm
	36	MidambPwrTS6 dBm
	37	DataPwrTS6 dBm
TD-SCDMA Comp Error Summary

For information on how to use the entries in this table, see Demod Errors and ADS.

For details on specific errors, see Available Composite Error Summary Data.

	Error Index	Description
	1	rho
	2	error vector magnitude (EVM) in %rms
	3	peak error vector magnitude in %pk
	4	chip with peak error vector magnitude
	5	magnitude error in %rms
	6	peak magnitude error in %
	7	chip with peak magnitude error
	8	rms phase error
	9	peak phase error in degrees
	10	chip with peak phase error
	11	frequency error in Hz
	12	IQ offset in watts/watts
	13	IQ skew in degres
	14	IQ gain imbalance in dB
	15	peak active CDE in watts/watts
	16	peak CDE in watts/watts
TD-SCDMA Chan Error Summary

For information on how to use the entries in this table, see Demod Errors and ADS.

For details on specific errors, see Available Chan Error Summary Data.

	Error Index	Description
	1	error vector magnitude (EVM) in %rms
	2	peak error vector magnitude in %pk
	3	symbol with peak error vector magnitude
	4	magnitude error in %rms
	5	peak magnitude error in %
	6	symbol with peak magnitude error
	7	rms phase error
	8	peak phase error in degrees
	9	symbol with peak phase error
	10	code phase in degrees


1xEV-DO Demod Errors

This topic includes 4 tables: fwd overall error summary, fwd composite error summary, rev composite error summary, and  rev channel error summary.

1xEV-DO Fwd Overall Error Summary

For information on how to use the entries in this table, see Demod Errors and ADS.

For details on specific errors, see Available Overall Error Summary Data.

	Error Index	Description
	1	overall rho 1
	2	overall rho 2
	3	overall error vector magnitude (EVM) 1 in %rms
	4	overall error vector magnitude (EVM) 1 in %rms
	5	overall magnitude error 1 in %rms
	6	overall magnitude error 1 in %rms
	6	peak magnitude error in %
	7	overall phase error 1 in degrees
	8	overall phase error 2 in degrees
	9	overall frequency error 1 in Hz
	10	overall frequency error 1 in Hz
	11	overall IQ offset 1
	12	overall IQ offset 2
1xEV-DO Fwd Comp Error Summary

For information on how to use the entries in this table, see Demod Errors and ADS.

For details on specific errors,see Available Composite Error Summary Data.

	Error Index	Description
	1	analysis channel
	2	rho
	3	error vector magnitude (EVM) in %rms
	4	peak error vector magnitude in %pk
	5	chip with peak error vector magnitude
	6	magnitude error in %rms
	7	peak magnitude error in %
	8	chip with peak magnitude error
	9	rms phase error
	10	peak phase error in degrees
	11	chip with peak phase error
	12	frequency error in Hz
	13	IQ origin offset
	14	preamble length
	15	analyzed slot number
	16	timing offset
1xEV-DO Rev Comp Error Summary

For information on how to use the entries in this table, see Demod Errors and ADS.

For details on specific errors, see Available Composite Error Summary Data.

	Error Index	Description
	1	rho
	2	error vector magnitude (EVM) in %rms
	3	peak error vector magnitude in %pk
	4	peak error vector magnitude chip
	5	peak CDE
	6	peak CDE code
	7	rms magnitude error
	8	peak magnitude error
	9	chip with peak magnitude error
	10	rms phase error
	11	peak phase error in degrees
	12	chip with peak phase error
	13	frequency error in Hz
	14	IQ Origin Offset
	15	analyzed slot number
	16	TimingOffset
	17	PilotPwr
	18	RRIPower
	19	RRIPilotRatio
	20	ACKPower
	21	ACKPilotRatio
	22	DRCPower
	23	DRCPilotRatio
	24	DataPower
	25	DataPilotRatio
1xEV-DO Rev Chan Error Summary

For information on how to use the entries in this table, see Demod Errors and ADS.

For details on specific errors, see Available Channel Error Summary Data.

	Error Index	Description
	1	error vector magnitude (EVM) in %rms
	2	peak error vector magnitude in %pk
	3	chip with peak error vector magnitude
	4	magnitude error in %rms
	5	peak magnitude error in %
	6	chip with peak magnitude error
	7	rms phase error
	8	peak phase error in degrees
	9	chip with peak phase error
	10	analysis start slot
	11	analysis end slot


About Option AYA: Digital Demodulation

(Vector Signal Analyzer application only)

Option AYA (Vector Modulation Analysis) adds Digital Demodulation capability to your 89600-Series application software. Digital Demodulation lets you perform measurements on digitally modulated signals. Measurements are possible on continuous or pulsed (burst) carriers (such as TDMA). In addition, you can specify a sync pattern and an offset to look at selected segments of demodulated data.

You can extend option AYA to include Wideband CDMA and cdma2000 analysis by ordering option B7N, and OFDM analysis by ordering option B7R.

Digital Demodulation provides various analysis techniques for several standard and non-standard digital modulation formats. Analysis capabilities include several display formats as well as numeric error measurements. Flexible scaling and markers enhance these capabilities.

Digital Demodulation requires no external filters, coherent carriers, or symbol clock timing signals. The analyzer allows you to demodulate pulsed or continuous carriers, and it locks to the carrier and to a defined symbol rate.

The digital demodulator used in this analyzer incorporates advanced technology that does not require external filtering, coherent carrier signals, or symbol-clock timing signals. The analyzer has built-in Gaussian, raised-cosine, and user-definable matching filters (with adjustable alpha).

The digital demodulator uses your signal to generate an ideal signal (called I/Q reference or FSK reference). You can compare the measured signal to the reference signal to quantify and locate errors in your signal.

Digital demodulation has built-in filters which may be applied to the measured signal as well as to the reference signal. This allows you maximum flexibility in comparing your signal to an ideal signal. Additionally, this allows complete flexibility to probe any analog point in a communication system.

If you have an 89610 Vector Signal Analyzer, an optional second baseband channel allows IQ baseband measurement capability. You can also perform IQ baseband measurements on data from a file or Agilent's Advanced Design System.

See also

Digital Demodulation Block Diagram

Digital Demodulator Block Diagram

Tutorials for Digital Demodulation

About 89600 Optional Measurement Software


Digital Demodulation Block Diagram

The following block diagram shows how the analyzer performs digital, demodulated measurements. This block diagram applies to all demodulation formats. For a detailed block diagram of the digital demodulator (the block below labeled Digital Demodulator, see Digital Demodulator Block Diagram).

Note

If your analyzer has two input channels, you can remove the quadrature mixer from the following block diagram. This lets you connect your I (In-phase) signal directly to Channel 1 and your Q (Quadrature-phase) signal directly to Channel 2. For details, see Connecting Your Signal to the Analyzer.

As shown in the block diagram, the analyzer uses the demodulated signal to generate an ideal reference signal. The reference signal is the signal that would result after demodulating your signal if your signal were ideal (contained no errors). You can compare the measured signal to the reference signal to quantify and locate errors in your signal.


Digital Demodulator Block Diagram

The following block diagram shows the digital demodulator used to demodulate all formats except FSK. To see how the digital demodulator fits into the overall instrument block diagram, see Digital Demodulation Block Diagram.

Notes

For systems that use matched filtering, use full filtering for the reference filter and root-filtering for the measured filter.

For MSK, the measured filter is applied before carrier lock.


Available Features (Digital Demodulation)

The standard set of analyzer features are applicable to Digital Demodulation with the following exceptions:

•	Time gating is not available

•	Averaging is not available for any demodulated trace data in digital demod but is applied to numeric error data in the symbol table, as follows:

−	rms (video)—computes an average of each rms error update in the table.

−	rms exponential—is like rms (video) except that averaging continues past the average count with an exponential weighting.

−	continuous peak hold—keeps track of the peak rms error of each update in the table.

−	Time and time exponential averaging—like rms averaging, computes an average of each rms error update in the table.

•	Average Types applicable to the pre-demodulated spectrum trace data results.

−	rms (video)

−	rms exponential

−	continuous peak hold)

Note

Time averaging is not applied to time data, but is applied to the rms error information in the symbol table.

See also

Digital Demodulation Available Trace Data

About Opt AYA: Digital Demodulation

89600-Series VSA Application Standard Features


Setting up a Digital Demodulation Measurement

(Vector Signal Analyzer application only.)

When setting up a digital demodulation measurement, there are several things you need to consider. This topic tells you how to connect your signal to an 89600-series analyzer and successfully demodulate digital signals.

•	Connecting Your Signal to the Analyzer

•	Carrier locking (all except VSB)

•	Carrier locking and pilot search: VSB

•	Input Range

•	Tips When Using Digital Demodulation

Connecting Your Signal to the Analyzer

The analyzer lets you connect your carrier signal or, if your 89600-series analyzer has two input channels, the raw I (In-phase) and Q (Quadrature-phase) signals.

For all receiver configurations except I + jQ, connect your signal to Channel 1. In this case, the analyzer assumes that your signal contains both the I and Q components (the carrier signal). If your analyzer has two input channels, the analyzer ignores the second input channel.

If your analyzer has a second input channel, you can also connect the raw I (In-phase) and Q (Quadrature- phase) signals. To do this, select Input, Channels, I + jQ. With this configuration, the analyzer removes the quadrature mixer from the demodulator's block diagram, which lets you connect the I component of your signal to Channel 1; the Q component to Channel 2.

Notes

•	Selecting I+jQ turns on DC coupling.

•	When using I+jQ, use external calibration to correct for any offset or gain imbalance between the I and Q signals.

•	Ranges for Channel 1 and Channel 2 are set independently.

Carrier locking (all except VSB)

For QAM signals, the analyzer's center frequency must be close to the transmitted carrier frequency to achieve carrier lock. The required proximity of the center frequency to the carrier frequency varies depending on the signal type, symbol rate, and system noise. If symbol locking appears poor, you may achieve better carrier locking by observing the Freq Err value in the symbol table of any successfully locked measurement and adding that amount to the center frequency.

To obtain reliable carrier locking, the difference between the analyzer's center frequency and carrier frequency should be within 10% of the symbol rate.

For QAM signals, the result length also affects the analyzer's ability to achieve reliable carrier lock, as shown in the following table. Result lengths less than those shown may result in unreliable carrier lock. Optimal carrier locking occurs when the result length is 1000 or greater.

If the modulation  type is:	The minimum result length  for reliable carrier lock is:
16 QAM or 16 DVB QAM	50 symbols
32 QAM or 32 DVB QAM	75 symbols
64 QAM or 64 DVB QAM	150 symbols
128 QAM	250 symbols
256 QAM	400 symbols

The following may also affect carrier locking:

•	A frequency span that is too narrow.

•	An incorrect range setting.

•	Using the wrong measured or reference filter.

Carrier locking and pilot search: VSB

The same parameters that affect carrier locking for QAM signals also affect carrier locking for VSB signals. For VSB signals, the analyzer must also find the pilot signal to achieve carrier lock.

If your VSB signal uses a high-side pilot, you must configure the analyzer to demodulate a high-side pilot by selecting mirror frequency spectrum. If you don't do this, the analyzer cannot find the pilot signal and cannot lock to your signal.

If the analyzer cannot lock to your signal, it displays CARRIER LOCK?. There are several conditions that may cause loss of carrier lock, one of which is an unsuccessful pilot search. If carrier lock is not obtained after several measurements, the analyzer assumes the pilot search failed and repeats the pilot search.

CARRIER LOCK? may appear even when the data appears to be locked. If this occurs, the results may be inaccurate. Normally, this condition clears in a few measurements as the instrument obtains better estimates of the carrier frequency.

The following paragraphs describe other conditions that may cause loss of carrier lock. The analyzer always assumes pilot search failed if there are carrier lock problems, even if the cause is one of the conditions below.

Like QAM signals, the analyzer's center frequency must be close to the transmitted carrier frequency to achieve carrier lock for VSB signals. The following formulas show you how to calculate the ideal center frequency. Use the formula for low-side pilot if your pilot is on the left (low) side of your spectrum; use high-side pilot if your pilot is on the right (high) side of your spectrum.

Center Frequency (Low Side Pilot) = Pilot Frequency − (Symbol Rate / 4)

Center Frequency (High Side Pilot) = (Symbol Rate / 4) + Pilot Frequency

The result length also affects the analyzer's carrier locking. For VSB measurements, the result length should be at least 800 symbols. Smaller result lengths may cause unreliable carrier locking. The following may also cause loss of carrier lock:

•	A frequency span that is too narrow.

•	An incorrect range setting.

•	Using the wrong measured or reference filter.

•	Not using mirror frequency spectrum.

•	A pilot that is not in phase with the transmitted data. You may be able to compensate for pilot-phase problems by using clock adjust to change when the analyzer samples the I/Q trajectory.

Input Range

The input range must be set correctly to obtain accurate measurements. Input ranges that are too low overload the analyzer's ADC. Input ranges that are too high increase noise, which increases errors reported in error summary data, such as EVM.

Tips When Using Digital Demodulation

The following summarizes the major points from the previous paragraphs and contains additional information you should know when using Digital Demodulation:

•	I/Q Reference or FSK Reference: the analyzer does not need an ideal signal to generate the reference signal. The analyzer uses your signal to internally generate the ideal, reference signal.

•	Carrier Lock and Detection: the analyzer does not need a sync word to perform carrier locking or detection. See also the next paragraph on "Center Frequency."

•	Center Frequency: the analyzer's center frequency must be close to the transmitted carrier frequency to achieve carrier lock. The required proximity of the center frequency to the carrier frequency varies depending on the signal type, symbol rate, and system noise. If symbol locking appears poor, you may achieve better carrier locking by observing the "Freq Err" value in the symbol table (for QAM, PSK, and MSK formats) of any successfully locked measurement and add that amount to the center frequency. As a general rule, the carrier-frequency-to-center-frequency error should be within 3% of the symbol rate.

•	Symbol Clock: the analyzer does not need an external symbol clock; the analyzer internally generates the symbol clock.

•	Maximum Symbol Rate: The maximum symbol rate depends on the alpha of your system and on the span (information bandwidth). See symbol rate for details.

•	Span: The minimum span (information bandwidth) depends on the alpha of your system and on the symbol rate. The maximum span is limited by the symbol rate. See span for details.

•	Time Gating: time gating is not available for digital demodulation.

•	Averaging: averaging is not available for demodulated trace data in digital demodulation but may be applied to numeric error data in the symbol table. For details, see Available Features.

•	Accuracy: To meet specifications, your signal and its modulation must be fully contained in the selected measurement span.

Troubleshooting

The Tips listed above should help you successfully set up your digital demodulation measurement. If you encounter problems, see Troubleshooting .

See also

Tutorials for Digital Demodulation

Troubleshooting


Speed and Resolution Considerations

The following information can help maximize the measurement speed and increase the display quality.

Maximize speed - Measurement and Display

•	Use cardinal spans.

•	Use fewer points per symbol.

•	Use fewer symbols.

•	Decrease span.

•	Decrease search length, if applicable.

Maximize resolution

•	Use more points per symbol


Selecting Digital Demodulation

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demodulator > Digital Demod

Digital Demod sets the analyzer to demodulate digitally modulated signals such as QAM or QPSK.

See also:

About Option AYA (Digital Demodulation)

Digital Demod Standard Presets

Tutorials for Digital Demodulation


Using Standard Setups (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Preset to Standard button

There are two ways to configure the analyzer for digital demodulation measurements—you can manually enter values for all demodulation parameters, or you can specify the standard of your digital communications system and let the analyzer automatically set the parameters.

The following standard presets are available, click on the standard to view the default settings:

Preset to Standard

Cellular	Wireless Networking	Digital Video	Other
CDMABASE	Bluetooth	DTV8	APCO 25
CDMA MOBILE	HIPERLAN/1 (HBR)	DTV16	DECT
CDPD	HIPERLAN/1 (LBR)	DVB16	TETRA
EDGE	WLAN (802.11b)	DVB32	VDL Mode 3
GSM		DVB64
NADC
PDC
PHP (PHS)
W-CDMA
Tip

In the following tables, to convert symbols to seconds, divide by the symbol rate.

Parameter	NADC	PDC	PHP(PHS)
Demod Format	pi/4 DQPSK	pi/4 DQPSK	pi/4 DQPSK
Frequency Span	75 kHz	75 kHz	625 kHz
Symbol Rate	24.3 kHz	21 kHz	192 kHz
Filtering
- Measured	root cosine	root cosine	root cosine
- Reference	cosine	cosine	cosine
Alpha/BT	0.35	0.5	0.5
Points/Symbol	5	5	5
Result Length	157 symbols	135 symbols	111 symbols
Search Length	1175 symbols	1000 symbols	1100 symbols
Pulse Search	ON	ON	ON
Sync Search	OFF	OFF	OFF
Normalize	ON	ON	ON
Clock Delay Adj	0.0	0.0	0.0
Back to Preset to Standard Table.

Parameter	GSM	CDPD	DECT
Demod Format	MSK Type 1	MSK Type 2	FSK 2
Frequency Span	1.0 MHz	75 kHz	5 MHz
Symbol Rate	270.83 kHz	19.2 kHz	1.152 MHz
Filtering
- Measured	off	off	off
- Reference	Gaussian	Gaussian	Gaussian
Alpha/BT	0.3	0.5	0.5
Points/Symbol	5	5	4
Result Length	148 symbols	378 symbols	480 symbols
Search Length	1434 symbols	400 symbols	11,200 symbols
Pulse Search	ON	OFF	ON
Sync Search	OFF	OFF	OFF
Normalize	ON	ON	ON
Clock Delay Adj	0.0	0.0	0.0
Back to Preset to Standard Table.

Parameter	CDMA BASE	CDMA MOBILE	W-CDMA
Demod Format	QPSK	OQPSK	QPSK
Frequency Span	2.6 MHz	2.6 MHz	5 MHz
Symbol Rate	1.2288 MHz	1.2288 MHz	3.84 MHz
Filtering
- Measured	IS-95 base	OFF	Root Cosine
	base EQ
- Reference	IS-95	IS-95	Cosine
	baseband	baseband
Alpha/BT	---	---	0.22
Points/Symbol	4	4	5
Result Length	200 symbols	200 symbols	200 symbols
Search Length	---	---	2560 Syms
Pulse Search	OFF	OFF	OFF
Sync Search	OFF	OFF	OFF
Normalize	ON	ON	ON
Clock Delay Adj	0.0	0.0	0.0
Bit Definitions	defined by IS-95	defined by IS-95	---
Back to Preset to Standard Table.

Parameter	APCO 25	DTV 8	DTV 16
Demod Format	4 FSK	8 VSB	16VSB
Frequency Span	40 kHz	7 MHz	7 MHz
Symbol Rate	4.8 kHz	10.762 MHz	10.762 MHz
Filtering
- Measured	rect	root cosine	root cosine
- Reference	cosine	cosine	cosine
Alpha/BT	0.2	0.1152	0.1152
Points/Symbol	5	2	2
Result Length	200 symbols	800	800
Search Length	400 symbols	---	---
Pulse Search	OFF	OFF	OFF
Sync Search	OFF	OFF	OFF
Normalize	ON	ON	ON
Clock Delay Adj	0.0	0.0	0.0
Back to Preset to Standard Table.

Parameter	DVB 16	DVB 32	DVB 64
Demod Format	16 DVB QAM	32 DVB QAM	64 DVB QAM
Frequency Span	8 MHz	8 MHz	8 MHz
Symbol Rate	6.9 MHz	6.9 MHz	6.9 MHz
Filtering
- Measured	root cosine	root cosine	root cosine
- Reference	cosine	cosine	cosine
Alpha/BT	0.15	0.15	0.15
Points/Symbol	2	2	2
Result Length	800	800	800
Search Length	---	---	---
Pulse Search	OFF	OFF	OFF
Sync Search	OFF	OFF	OFF
Normalize	ON	ON	ON
Clock Delay Adj	0.0	0.0	0.0
Back to Preset to Standard Table.

Parameter	EDGE	Bluetooth	WLAN (802.11b)
Demod Format	EDGE (3π/8 8PSK)	FSK 2	QPSK
Frequency Span	625 kHz	2.5 MHz	18.7 MHz
Symbol Rate	270.83 kHz	1 MHz	11 MHz
Filtering
- Measured	EDGE(Windowed RC)	Off	Off
- Reference	EDGE	Gaussian	Gaussian
Alpha/BT	0.25	0.5	0.5
Points/Symbol	1	2	4
Result Length	142 symbols	320 symbols	1000 Syms
Search Length	1434 Syms	1650 Syms	1434 Syms
Pulse Search	ON	Off	Off
Sync Search	OFF	Off	Off
Normalize	ON	On	On
Clock Delay Adj	0.0	0.0	0.0
Equalization	OFF	—	—
Back to Preset to Standard Table.

Parameter	HIPERLAN/1 (LBR)	HIPERLAN/1 (HBR)	TETRA
Demod Format	FSK 2	MSK Type 1	pi/4 DQPSK
Frequency Span	18.7 MHz	36 MHz	40 kHz
Symbol Rate	1.4705875 MHz	23.5294 MHz	18 kHz
Filtering
- Measured	Off	Off	root cosine
- Reference	Rect	Gaussian	cosine
Alpha/BT	--	0.3	0.35
Points/Symbol	20	5	4
Result Length	1000 symbols	1000 symbols	231 symbols
Search Length	1434 Syms	1434 Syms	1300 symbols
Pulse Search	Off	Off	ON
Sync Search	Off	Off	OFF
Normalize	On	On	ON
Clock Delay Adj	0.0	0.0	0.0
Equalization	--	--	-
Back to Preset to Standard Table.

Parameter	VDL Mode 3
Demod Format	D8PSK
Frequency Span	25 kHz
Symbol Rate	10.5 kHz
Filtering
- Measured	Off
- Reference	raised cosine
Alpha/BT	0.6
Points/Symbol	5
Result Length	315 symbols
Search Length	120 msec
Pulse Search	ON
Sync Search	OFF
Normalize	ON
Clock Delay Adj	0.0
Back to Preset to Standard Table.

See also

Digital Demod Properties Dialog Box - Format tab

Selecting Digital Demodulator

Setting up a Digital Demod Measurement

Troubleshooting Digital Demodulation

Tutorials for Digital Demodulation


Troubleshooting (Digital Demodulation)

(Vector Signal Analyzer application only.)

This topic contains information to help you troubleshoot measurements when using Digital Demodulation. You should also see Setting up a Digital Demodulation Measurement for additional measurement information.

PROBLEM	POSSIBLE CAUSE	SOLUTION
Demodulation fails to lock on signal	Signal not present	Check connections
	Carrier too far from center frequency	Adjust center frequency
	Input is over-loaded or under ranged	Adjust input range
	Frequency span is too narrow	Increase frequency span
	Signal is pulsed	Set pulse search ON
	Signal is pulsed and result length is longer than pulse	Decrease result length.
	Wrong symbol rate	Enter correct symbol rate (not bit rate)
	Wrong filter selections	Select proper meas and ref filters, & correct setting for alpha/BT.
	Wrong modulation format	Select correct modulation format
	I/Q offset too large	Reduce LO feedthrough (or DC offset for I+jQ receiver)
	I/Q misaligned using I+jQ receiver	Ensure that ch1 and ch2 trigger delays are correct
Spectrum Disappears	Spectrum not present or digital demodulation not configured correctly.	View the spectrum trace (Trace > Data, Spectrum). If pulse search is on, also examine the time and search time traces (Trace >  Data >  Time or Trace, Data, Search Time). Use these traces to determine if the spectrum is present or if the digital demodulator isn't configured properly.
Eye diagrams show incorrect symbol timing	Signal path has phase distortion	Adjust clock delay to minimize EVM
	Clock delay is incorrect	Adjust clock delay to minimize EVM
	I and Q are misaligned using I+jQ receiver	Check trigger delay and cable length
		Adjust for delay using external calibration.
	Signal path limits amplitude fluctuations for non-MSK signals	Remove non-linearity, or compensate with clock delay
SYNC NOT FOUND	Search length too short or search offset incorrect	Increase search length, adjust search offset
	Incorrect sync word	Check and correct sync word
	Incorrect state definitions	Change state definitions or sync word
	Wrong MSK demodulator	Select correct MSK demodulator
PULSE NOT FOUND	Signal not pulsed	Turn off pulse search
	Search length too short	Increase search length or adjust triggering to ensure that leading and trailing edges of pulse are fully within search length
Pulse found but incorrectly aligned	Poor signal-to noise ratio or on/off ratio	Check input range setting
		Reduce span to eliminate excess noise and interfering signals.
	Pulse is asymmetrical	Use sync search to align result length
	Span is too narrow	Increase span to prevent degradation of pulse edges
Error Vector Time shows large error between symbols	Wrong filter alpha	Adjust filter's alpha
Error Vector Time shows regions of large errors	Distortion or a poor signal to-noise ratio causing bit errors	Check input range
	Large frequency errors interfering with carrier lock	Adjust center frequency
	Large I/Q offsets causing bit errors	Reduce LO feedthrough (or DC offset if using I+jQ receiver)
EVM larger than expected and Error Vector Time shows errors that increase towards beginning and end of result length	Wrong symbol rate	Make fine adjustments to the symbol rate
	Result length larger than pulse	Decrease result length
EVM larger than expected and Error Vector Time shows a uniform distribution of errors	Frequency span too narrow	Increase span
	Input is overloaded or under ranged	Adjust input range
	Result length is too short	Increase result length
	Wrong filter selections	Check that filter selections allow the filtered measured signal to match the reference signal
	Channel conditions have biased symbol timing recovery	Observe eye diagrams and adjust clock delay to compensate symbol timing recovery.
	Time corrections disabled	Enable time corrections
	Signal too close to DC	Increase carrier frequency
	I and Q misaligned using I+jQ receiver	Check trigger delay settings and cable lengths
	AC coupling when using I+jQ receiver	Select DC coupling on both input channels
	I and Q imbalance	Ensure impedance is identical for both inputs
	Sync enabled and sync word not unique. Result incorrectly positioned with respect to signal	Ensure that sync word is unique
	For MSK type 1, signal contains I/Q offset	Select MSK Type 2 to remove I/Q offset term from result
See also

Parameter Interactions

Setting up a Digital Demodulation Measurement

VSA error and status messages

VSA Troubleshooting Topics


About Digital Demodulation Dialog Box

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties

The Digital Demodulation dialog box contains parameters that let you configure the analyzer's digital demodulator.

Note

In the MeasSetup menu, Demod Properties is greyed (unavailable) if the digital demodulator is not enabled. To enable the digital demodulator, click MeasSetup > Demodulator > Digital Demod.

The dialog box contains four tabs:

•	Format tab: lets you select the demodulation format, symbol rate, result length, and Points/Symbol. From here, you can also select a standard setup to automatically configure the analyzer to demodulate a known signal. For example, selecting the NADC standard setup configures the analyzer to demodulate an NADC signal.

•	Filter tab: lets you select the filtering used by the analyzer to demodulate your signal.

•	Search tab: lets you enable and set up pulse search or sync search.

•	Compensate tab: lets you adjust the analyzer's digital demodulator with parameters such as clock adjust, IQ normalize, and mirror frequency spectrum. In addition, this tab lets you enable and configure adaptive equalization.

See also

Setting up Digital Demod Measurement

Selecting Digital Demodulation

Troubleshooting Digital Demodulation

About Option AYA: Digital Demodulation


Compensate Tab (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > compensate tab

The digital demodulation Compensate tab lets you adjust the analyzer's digital demodulator to compensate for nonstandard or imperfect modulated signals.

The Compensate tab lets you configure these parameters:

•	Equalization Filter

•	Filter Length

•	Convergence

•	Adaptive Equalization

•	Reset Equalizer

•	Clock Adjust

•	IQ Normalize

•	Mirror Frequency Spectrum (Digital Demodulation)

•	Rotation

See also

About Adaptive Equalization

Digital Demod Properties dialog box


Filter Tab (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup, Demod Properties, Filter tab

The digital demodulation Filter tab lets you configure the filters used by the analyzer's digital demodulator. This includes both a measurement filter and reference filter. You can select from a list of standard predefined filters or create you own custom filters and use the data register feature.

The Filter tab lets you configure these parameters:

•	Alpha/BT

•	Measurement Filter

•	Reference Filter

•	Data Register

Available predefined Filters

•	EDGE

•	EDGE(WindowedRC)

•	Rect Filter

•	Gaussian Filter

•	IS-95 Filters

•	Low Pass Filter (for FSK)

•	Raised Cosine Filter

•	Root Raised Cosine Filter

•	User-defined Filters

See also

About Filters (Digital Demodulation)

Digital Demod Properties dialog box


Format Tab (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup, Demod Properties, Format tab

The Digital Demodulation Format tab lets you configure the analyzers Digital Demodulator. These are the parameters necessary to lock-on to and demodulate the test signal.

Note

Some hardware configurations, such as the E4406, may not support a span that is wide enough for the selected demod standard.

Digital Demod Format parameters:

•	Format

•	Points/Symbol

•	Preset to Standard

•	Result length

•	Symbol Rate

•	View State Definitions

See also

About Option AYA (Digital Demodulation)

Digital Demod Properties dialog box

Couple to Gain Imb. /Quad Skew

Setting up a Digital Demodulation Measurement


Search Tab (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup, Demod Properties, Search tab

The digital demodulation Search tab lets you enable and set up pulse search or sync search. Pulse Search lets you demodulate pulsed (burst) transmissions. Sync search lets you use a synchronization pattern to isolate a segment of your signal for display and analysis.

Digital Demod Search parameters:

•	Pulse Search

•	Search Length

•	Search Offset

•	Search Pattern

•	Sync Search

See also

About Option AYA (Digital Demodulation)

Digital Demod Properties dialog box


Digital Demod Tab (Trace Properties)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Digital Demod

The Digital Demod tab lets you adjust parameters that affect how demodulated data is displayed. You can adjust the following trace parameters:

•	Code Order: lets you select Bit Reversed or Hadamard code order for the W-CDMA or cdma2000 Code Domain Power display.

•	Copy Digital Demod to: lets you apply the current Trace Digital Demod Property settings to one of the other trace data displays.

•	Eye Length: determines the length of eye or trellis diagrams.

•	Frequency Unit: lets you select either carrier or Hz as the frequency unit.

•	Ideal State: lets you select a circle or cross (or none) to indicate the location of ideal states. You can adjust state size to change the size of the ideal states (in % EVM).

•	Symbol Table Format: lets you select binary or hexadecimal data for the symbol table.

•	Symbol Shape: lets you select a bars or dots (or none) to indicate symbol locations.

•	Time Unit: lets you select symbols or seconds as the time unit.

See also

Trace Properties - Format tab

Trace Properties - X -Scale tab

Trace Properties - Y Scale tab

Trace Properties - Spectrogram


Setting Measurement Parameters (Digital Demodulation)

(Vector Signal Analyzer application only.)

The following table shows how measurement parameters affect digital demodulation.

Digital Demodulation Parameters

Time Sequence	Parameters Involved	Effect	Result	Notes
Signal setup	Range Trigger Frequency/span Input Time Corrections	Sets up basic signal parameters required for digital demodulation	Raw data	Any changes made in the signal setup parameters later in the time sequence require that a new measurement be performed
Pre-demodulation	Pulse search Search length Result length	Determines what signal enters the demodulator by trimming the raw data	Input to demodulator	This signal is the maximum possible length, limited only by memory constraints.
Demodulation	Setup parameters Clock adjust Filter  Format Result length Rotation Symbol rate Sync search Points/Symbol	Determines the type of demodulation performed on the input time data	Demodulated, symbol-locked data in the default display format	Result length determines the amount of data that is demodulated and can be up to 4096 symbols long.
Post-demodulation	Trace data Trace format X and Y Scale Marker Normalize	Formats the data for display	Formatted, demodulated data	Changes may be made in the display parameters without acquiring a new measurement


Parameter Interactions (Digital Demodulation)

(Vector Signal Analyzer application only.)

When using digital demodulation, changing one parameter may necessitate changes in other parameters to achieve the desired measurement. For example,

•	Symbol rate limits frequency span.

•	Frequency span limits search length.

•	Search length limits number of symbols.

•	Number of symbols limits search offset and the length of the equalization filter.

•	Minimum frequency span may limit the symbol rate (this may occur when playing back a recording or analyzing data from the stream interface).

TIP

The following topics may help you optimize your measurements and explain the reasons for changes made automatically by the analyzer:

Display Limitations

IQ Gain Imbalance and Quadrature Skew Error

Resolution Bandwidth

Span considerations


Display limitations (Digital Demodulation)

Points per symbol affects the resolution of all displayed demodulation results. For example, increasing the points per symbol improves the resolution of the vector diagram, but there is still only one point at the symbol clock.


IQ Gain Imbalance and Quadrature Skew Error Data Interaction

IQ Gain Imbalance and Quadrature Error are defined and evaluated relative to a chosen I/Q reference axis. Often the reference is obvious, such as for 64 QAM. For other formats such as 8 PSK, the reference must be established manually, or by synchronizing to known data patterns.

A factor in IQ Gain Imbalance and Quadrature Error evaluation is the symbol mapping of a modulator. For example the VSA chooses an "off-axis" mapping of the symbols for QPSK, yielding points at (0.707, 0.707), (0.707, -0.707), (-0.707, -0.707), and (-0.707, 0.707). Some modulators may implement QPSK using an "on-axis" mapping of symbols, yielding points at (1.0, 0.0), (0.0, -1.0), (-1.0, 0.0), (0.0, 1.0). In this second case, the symbols—though estimated correctly—have a different IQ axis relative to the modulator symbol mapping upon demodulation in the VSA. This is apparent because the constellation diagram has symbol decision points in the "off-axis" locations instead of in the locations used in the modulator mapping as shown in figure 1. This 45° shift of reference affects only the IQ Gain Imbalance Error and Quadrature Error data of the Symbols/Errors table in the VSA.

Figure 1: Two possible constellation mappings for QPSK.

When a signal contains Quadrature skew, the error could be reported as IQ Gain Imbalance if the signal generator has a mapping that is different from the VSA receiver. The reverse is also true. IQ Gain Imbalance is characterized by a gain difference between I and Q channels. This equates to a rectangular stretch along the ideal I/Q axes, once DC offset, phase and amplitude errors have been minimized, as shown in figure 2. Likewise, Quadrature Error is created when the I/Q axes are not exactly 90° apart, leading to a rectangular stretch along a 45° line, as shown in figure 4. When the constellation mapping is incorrect, a 45° rotation is added to the symbols. With a Quadrature Error, the rectangular off-axis stretch is rotated onto the ideal I/Q axes yielding IQ Gain Imbalance. Likewise, the same 45° rotation converts an on-axis rectangular stretch into an off-axis stretch interpreted as Quadrature Error. These results are shown graphically in the differences between figures 4 and 5.

The VSA Digital Demodulation software allows the constellation to be rotated, changing the skew and imbalance calculations. For the example above, a value of 45° will cause the error data to be calculated relative to the "on-axis" mappings. Note the symbol detection locations are rotated with the data, but the bit state definitions are relative to the 0° case, so bit data output will not change with rotation.

Figure 2: QPSK with IQ Gain Imbalance.

Figure 3: QPSK with Quadrature Error.

Figure 4: QPSK with Quadrature Error, corrected for DC offset, phase, and amplitude errors.

Figure 5: QPSK with Quadrature Error corrected for DC offset, phase, and amplitude errors, but with incorrect state mapping.

For coherent modulation formats, synchronization search should be enabled to create a consistent phase reference relative to the I/Q modulator mapping. If this cannot be accommodated, or the modulation format cannot provide such information (As for Pi/4 DQPSK and EDGE), it is recommended to use the rotation parameter with single sweep mode to analyze IQ Gain Imbalance and Quadrature Skew. Averaging does not provide reliable results for IQ Gain Imbalance and Quadrature Error in cases without a consistent phase reference1. This analysis can give information regarding the extent of the problem, but if the problem includes both IQ Gain Imbalance and Quadrature Skew, isolation of the two error data results is not possible without extended information.

Also Note that slight variations in measurement results occur depending on points chosen to be included in the IQ Gain Imbalance and Quadrature Skew algorithms. By default, the VSA software calculates IQ Gain Imbalance and Quadrature Skew using the same point selection as the other measurements. This includes choosing only the symbol decision points for most formats, with the notable exceptions of OQPSK and MSK. OQPSK requires an even number of points for accurate results, and MSK results depend heavily upon trajectory points between the sample locations. The "Couple to Gain Imb. / Quad. Skew" parameter of the Digital Demodulation properties, controls how the calculations are performed. Selecting this box forces the calculations to be performed using the requested number of points per symbol. Leaving the box cleared results in sending only symbol decision points to the calculation. The default values are typically correct, but increased sensitivity to effects occurring between symbol decision points may be more apparent by choosing to couple the measurements to points per symbol.

Special considerations for EDGE demod format

With EDGE, the modulation scheme is 3Pi/8 8PSK. The 3Pi/8 rotation per symbol interval makes IQ Gain Imbalance and Quadrature Error measurements ambiguous, as the phase relative to the midamble may be arbitrary. If the particular modulator has known data characteristics for when the rotation is started (i.e. at the beginning of the frame or with a particular training sequence), these can be used with markers to determine the correct rotation to obtain the correctly decoupled IQ Gain Imbalance and Quadrature Error data results. In addition, the ISI compensation provided by the VSA software makes it advisable to take IQ Gain Imbalance and Quadrature Skew measurements with the measurement filter turned off and with points per symbol set to a value greater than one2. This will make the vector plot a "doughnut with sprinkles". This is not a clean plot, but it is still correct, and is a result of the EDGE modulation format.

Notes

•	This does not apply to Pi/4 DQPSK when sync search is enabled, as the phase ambiguity is ±90°. This known ambiguity leads exclusively to changes in sign for IQ Gain Imbalance and Quadrature Skew. This is taken into account in the VSA software by averaging only magnitude values of IQ Gain Imbalance and Quadrature Skew.

•	One point-per-symbol is the preset default for EDGE. This provides a "clean" constellation plot and provides measurement ISI cancellation.

See also

Couple to Gain Imb./Quad Skew

IQ Gain Imbalance symbol error

IQ Gain Imbalance and Quadrature Skew Error data Interaction

IQ Meas Time and IQ Ref Time

Quadrature Skew Symbol Error

Rotation parameter


Resolution bandwidth (Digital Demodulation)

Resolution bandwidth (ResBW) in digital demodulation is determined automatically by the analyzer, and cannot be set independently. Resolution bandwidth is determined by the time record length as usual, according to the following formula:

However, in Digital Demodulation the time record length is determined as follows (result length is in symbols):


Span considerations (Digital Demodulation)

When selecting a frequency span, select the narrowest span that includes all of your signal components (select a span that is larger than the bandwidth of your signal). If you select a span that is too narrow, your measurement may have excessive errors or the analyzer may lose carrier lock. If you select a span that is too wide, your measurement may be affected by excessive noise and slower speed. You may want to set the span while viewing the spectrum of your signal.

The analyzer displays a warning message if the frequency span is (a is the filter alpha):

Frequency span < (1 + a) × (symbol rate)

If you see this warning message, increase the frequency span until it includes all components of your signal.

For digital demodulation, the symbol rate determines the maximum frequency span that you can select, as follows:

This formula can be rewritten to obtain the maximum span-to-symbol-rate ratio, as follows (for FSK demodulation formats, the maximum span-to-symbol-rate ratio is 100):

You may notice that the frequency span for digitally demodulated spectrums (the IQ measured spectrum, IQ reference spectrum, and error vector spectrum) is different than that set for the analyzer. The reason is that the digital demodulation process derives its own frequency span and sample rate, as follows:

When viewing digitally demodulated spectrums, aliasing may occur if the frequency span is too large. Aliasing only affects the validity of the spectral displays, not the accuracy of the demodulation. The analyzer displays DATA? if it suspects aliasing in digitally demodulated spectrums. To prevent aliasing, be sure that:


Clock Adjust (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Compensate tab

Clock Adjust determines when the analyzer's digital demodulator samples the I/Q trajectory.

 Minimum value: -0.5 symbols
 Maximum value: +0.5 symbols

The digital demodulator used in this analyzer does not require symbol-clock timing signals to determine the location of symbols (detection decision points). Instead, the digital demodulator uses an algorithm to determine symbol locations.

Some digital communications systems contain non- linearity's that can bias the digital demodulator's estimation of the symbol clock position. You can use clock adjust to compensate for this "offset" and obtain a lower EVM (Error Vector Magnitude).

The clock adjust, or offset, is entered in symbols. By default, the offset is zero (0) symbols. You can specify an offset from −0.5 to +0.5 symbols.

You can see the effects of changing clock adjust by displaying a constellation diagram or eye diagram. Increasing (or decreasing) clock adjust:

•	Shifts the detection-decision points in the constellation diagram.

•	Slides the eye diagram right or left (remember that in the eye diagram, the symbol locations remain in a fixed location on the display; therefore, changing the location of symbols has the effect of horizontally shifting the eye diagram).

Additional Tips

Here are some additional Tips that may help you use clock adjust:

•	Specifying a clock adjust only affects the I/Q measured trace. It does not affect the I/Q reference trace.

•	Use the eye diagram with an eye length of one (1) to observe the accuracy of the symbol clock timing. You may also want to monitor the EVM (Error Vector Magnitude) in the symbol table summary while adjusting clock adjust to obtain the optimum symbol timing.

•	Clock adjust is reset to 0.0 on power-up or when you select Preset.


Couple to Gain Imb./Quad Skew
Couple to Gain Imb./Quad Skew (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Format tab

The Couple to Gain Imb. / Quad Skew parameter controls what measurement data is included in the Quadrature Skew Error and IQ Gain Imbalance error data calculations.

Cleared:	Calculations use one Point per Symbol.
Selected:	Calculations use the value shown in the Points per Symbol parameter box.
See also

IQ Gain Imbalance symbol error

IQ Gain Imbalance and Quadrature Skew Error

IQ Meas Time and IQ Ref Time

Points/Symbol

Quadrature Skew Symbol Error


IQ Normalize
IQ Normalize (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Compensate tab

IQ normalize turns normalization on or off. Selecting the IQ normalize check box turns on normalization; clearing the check box turns off normalization.

When normalization is ON, the analyzer normalizes or scales the demodulated trace data results to a nominal value of 1. Normalization is performed on these traces:

•	IQ measured time for Digital, WLAN-OFDM, WLAN-DSSS/CCK/PBSS, WCDMA, cdma2000, TD-SCDMA and 1xEV-DO demodulation.

•	IQ reference time for Digital, WLAN-OFDM, WLAN-DSSS/CCK/PBSS, WCDMA, cdma2000, TD-SCDMA and 1xEV-DO demodulation.

•	Error vector time

•	FSK measured time (FSK measurements)

•	FSK measured reference (FSK measurements)

•	Carrier error magnitude (FSK measurements)

•	FSK error (FSK measurements)

•	CDP and CDE measurements for W-CDMA, cdma2000 1xEV-DO and TD-SCDMA demodulation)

How Normalization Works for Digital Demodulation
(except FSK, W-CDMA, cdma2000, 1xEV-DO, TD-SCDMA, WLAN-OFDM and WLAN-DSSS/CCK/PBCC demodulation)

For all demodulation formats except FSK, normalization uses the outermost state of the ideal (I/Q reference) constellation diagram, which is given a magnitude of one (1), to map the constellation diagram onto the unit circle. Thus, for QAM formats, normalization sets the magnitude of the ideal, outermost state to one (as shown below); for formats such as 8 PSK where the ideal states occur on a circle, the magnitude of all ideal states is one.

Demodulated data is mapped onto this unit circle by selecting a scaling factor that minimizes the error over all states. In other words, the analyzer examines all states, chooses a scaling factor that minimizes the overall error, and rescales the demodulated data.

Note

A 32 QAM constellation diagram does not have corner states. Therefore, for 32 QAM, the analyzer normalizes the constellation diagram to the corner state of an ideal, 36 QAM constellation diagram. In other words, when normalization is ON for 32 QAM, a value of one (1) corresponds to the corner state of an ideal 36 QAM constellation diagram.

128 QAM is normalized to 144 QAM.

Hint

When you turn on normalization and the display is a vector or constellation diagram, the analyzer displays cross-hairs or circles at the ideal constellation locations.

How Normalization Works with FSK

For FSK, normalization scales the demodulated data as follows:

This FSK trace:	Is scaled by this:
FSK measured time	Deviation
FSK reference time	Deviation
Carrier magnitude error	rms magnitude
FSK error time	Deviation
For further details about normalizing and FSK, see online help for each type of trace in the above table.

How Normalization Works for OFDM demodulation

For OFDM normalization, each subcarrier is normalized so that the RMS level of the ideal constellation is one,

How Normalization works with Composite Trace Data for W-CDMA, cdma2000, 1xEV-DO and TD-SCDMA demodulation

For composite time data in W-CDMA and cdma2000 measurements, the ideal state positions vary depending on the CDMA channel configuration. Instead of normalizing the outermost state to have a magnitude of one, the data is normalized so that the signal RMS level is one.

•	Code domain trace data results

Code domain results (CDP Composite, CDP Layer, CDE Composite, and CDE Layer) are normalized to the total measured signal power.  This means that the sum of all the values in a CDP Layer trace will be one.

•	Composite time trace data results

Composite time results (Composite Error Vector Time, Composite IQ Meas Time, Composite IQ Ref Time, and so on) are normalized to the composite reference signal power.  This means that the RMS level of the Composite IQ Ref Time trace will be one.

•	Channel time trace data results

Channel time results (Channel Error Vector Time, Channel IQ Meas Time, Channel IQ Ref Time, and so on) are normalized to the Channel IQ Ref Time power.  This means that the RMS level of the Channel IQ Ref Time trace will be one.

How Normalization Affects the Trace Measurement Units

For most configurations, the measurement data determines the units of the normalized trace. With normalization on, the y-axis units (for rectangular traces) or polar units (for polar traces) become unitless or are converted to a percentage. If the Log Mag trace format is selected, the units are decibels.

As mentioned previously, normalization scales the demodulated data onto the unit circle. This process of scaling yields a unitless scalar (number). For some traces, such as error vector time, the number is multiplied by 100 to display the percentage error. Thus an error vector of 0.10 is 10%.

See also

Compensate Tab

Format Tab - W-CDMA

Format Tab - cdma2000


Mirror Frequency Spectrum (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Compensate tab

Default: Cleared

Lets you correctly demodulate frequency spectrums that are mirrored (flipped) about the center frequency. The default frequency spectrum is assumed not mirrored. This parameter does not change the displayed spectrum trace data.

Cleared:  Does not mirror the frequency spectrum.

Selected:  Mirrors the frequency spectrum about the analyzer center frequency.

Note

The display of the spectrum data will not change with this parameter. To mirror the display, clear the Mirror Frequency Spectrum check box, and select the MeasSetup Properties dialog box, Frequency tab, Mirror Frequency check box.

External Down Converter

If you are using an external down converter, clear this Mirror Frequency check box and use the Mirror Frequency parameter in the External Frequency Calibration dialog box instead.

Mirror Frequency Concepts

Often, when a signal is mixed down from a higher frequency, the spectrum is flipped or mirrored about the center frequency. This occurs as a result of the mixing scheme used. A mirrored spectrum occurs when the frequency of the mixer's LO is higher than the frequency of the signal being measured.

Many RF and microwave spectrum analyzers perform their first frequency conversion in bands. The mixing scheme for each band may be different—the spectrum may be mirrored in some bands but not in others.

See Also

Compensate Tab - Digital Demodulation Properties

Digital Demodulation Properties dialog box


Result Length (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Format tab

Result length determines the number of symbols that the analyzer displays. For example, if you set the result length to 10, the analyzer displays 10 symbols in time-domain traces (such as vector, eye, and constellation diagrams).

Result Length and Carrier Lock

The result length for some demodulation formats affects carrier lock. The following table shows the minimum result length needed to obtain reliable carrier lock:

If the modulation type is:	The minimum result length  for reliable carrier lock is:
16 QAM or 16 DVB QAM	50 symbols
32 QAM or 32 DVB QAM	75 symbols
64 QAM or 64 DVB QAM	150 symbols
128 QAM	250 symbols
256 QAM	400 symbols
Result Length for Pre-Demodulated Time Data

The result length for pre-demodulated data (such as the Time, Spectrum, and Inst Spectrum trace data) is 20% larger than the result length for demodulated data.


Rotation (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Compensate tab

The rotation parameter rotates the Meas/Ref Time data and corresponding ideal state positions by a user defined amount ranging from -360 degrees to 360 degrees.

The rotation parameter affects the IQ Gain Imbalance and Quadrature Skew error data results.

For more information, see IQ Gain Imbalance and Quadrature Skew Error data interaction .

See also

IQ Gain Imbalance symbol error

IQ Gain Imbalance and Quadrature Skew Error

IQ Meas Time and IQ Ref Time

Quadrature Skew Symbol Error


Symbol Rate (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Format tab

The symbol rate parameter sets the symbol rate for the analyzer's digital demodulator. Set this parameter to match the symbol rate of your system.

In digital modulation, the symbol rate determines the rate (frequency) at which symbols occur. A symbol may consist of one or more bits as determined by the modulation format. For example, in a BPSK system, each symbol represents 1 bit; in a QPSK system, each symbol represents 2 bits.

Symbols are valid only at the timing instant when the receiver interprets the signal. This timing instant is called the detection-decision point.

The analyzer's demodulator uses the symbol rate determine the frequency of your detection-decision points. It is important that you set the symbol rate to match exactly the symbol rate of your system, because the symbol clock frequency is not estimated.

Note

The more complex your modulation format, the more critical it is that the symbol rate be exact. Specifying an incorrect symbol rate introduces errors into the demodulation process.

Maximum Symbol Rate

The analyzer can accurately measure symbol rates that are less than the maximum span of the analyzer.

Note

There may be instances where you want to set the symbol rate beyond what can be measured. The analyzer lets you do this, but accuracy is not specified.

Hint

If you enter a symbol rate that is slightly different than the symbol rate of your signal, the EVM (error vector magnitude) is typically small at the center of the result length and increases linearly towards the ends of the result length.

Symbol Rate and Frequency Span

The symbol rate determines the maximum frequency span (information bandwidth) that you can measure. For QAM and PSK signals, the symbol rate also determines the minimum frequency span that meets published specifications.

The following formulas show how the symbol rate determines the maximum frequency span that you can measure:

The next formulas show, for some signals, how you can use the symbol rate to determine the minimum frequency span that meets published specifications. The first formula is valid only for QAM and PSK signals that use raised cosine or root raised-cosine filtering at the transmitter. The second formula is valid only for VSB signals.

where: alpha is the roll-off factor set with Alpha/BT

For all other signals, there is no "easy" formula to help you determine the minimum span that meets published specifications. However, you can ensure that the span meets published specifications by selecting a span that contains all energy of your transmitted signal.

Hint

To see if your signal falls within the current frequency span, view the spectrum of your signal. If necessary, modify the frequency span until it includes all of your signal's energy.

Note

To meet published specifications, all of the signal's energy must fall within the span. If you select a frequency span or symbol rate that causes the frequency span to be narrower than (symbol rate) × (1 + alpha), the analyzer displays DATA?.


About State Definitions (Digital Demodulation)

(Vector Signal Analyzer application only.)

A state definitions file is used to define state definitions for Digital Demodulation.

The state definitions file is an ASCII file. This file contains definitions for several variables that are used when Digital Demodulation is selected. These variables let you define the bit mapping for each state in all demodulation formats except pi/4 DQPSK, MSK, and DVB QAM.

Note

You can also recall a state definitions file created with an 89400-series analyzer. Definitions unique to 89400-series analyzers (such as sync patterns) are ignored.

Modifying the State Definitions File

A sample state definitions file (Program Files\Agilent\89600 VSA\Vector\data\default.csd) is installed on your system when you install the 89600-series software. You can modify this file with any ASCII editor.

Examples

The default.csd file contains all state definition variables. The file contains comments that describe the format you must use for each variable. The following examples are from default.csd.

!# Example: State definitions for 16 QAM
!#
! "S_16QAM_1","0011","0010","0001","0000"
! "S_16QAM_2","0111","0110","0101","0100"
! "S_16QAM_3","1011","1010","1001","1000"
! "S_16QAM_4","1111","1110","1101","1100"

!# Example: State definitions for 4-level FSK
!#
! "S_4FSK_1","00"
! "S_4FSK_2","01"
! "S_4FSK_3","11"
! "S_4FSK_4","10"

The first example defines each state for the 16 QAM modulation format. The rows and columns correspond to the rows and columns in the 16 QAM constellation diagram.

The second example defines each state for the 4-level FSK modulation format. Note that S_4FSK_1 corresponds to the right-most point in the constellation diagram and S_4FSK_4 to the left-most point.

Defining Selected Variables

You can create a state definitions file that defines all variables or only selected variables.

Loading the State Definitions File

You load your state definitions file by clicking File, Recall, Recall State Defs. Simply click Recall State Defs and enter the name of your state definitions file to load it from disk.

Displaying the Current State Definitions

To view the state definitions for the currently selected modulation format, open the Digital Demodulation dialog box, click the Format tab, then click the View State Definitions button. For additional information, see View State Definitions.


View State Definitions

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Format tab

For most demodulation formats, the "state definitions" table represents the constellation diagram, and shows the bit definitions for each symbol in the constellation diagram.

For example, if the current demodulation format is QPSK, View State Definitions displays a table similar to the following, which shows the bit definitions for each state in the QPSK constellation diagram.

   QPSK
  01 00
  11 10

FSK State Definitions

State definitions for the FSK modulation format are mapped to the eye diagram instead of the constellation diagram. In other words, the top entry corresponds to the top of the eye diagram; the bottom entry to the bottom of the eye diagram.

The following table shows a sample FSK state-definitions table and how to map the table to the constellation diagram:

State Definitions Table 4-level FSK	Corresponding Constellation Diagram
01 00 10 11	11    10    00    01 -----|-----|-----|-----|-----
DVB QAM, Pi/4 DQPSK, and MSK State Definitions

You cannot change or display the state definitions for DVB QAM, pi/4 DQPSK, or MSK. To see the state definitions for these formats, display two traces with the constellation diagram in one trace and the symbol table in the other. Then turn markers on for both traces, couple the markers, and step through the constellation diagram to view the bit definitions.


Pulse Search (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Search tab

Pulse Search lets you demodulate pulsed (burst) transmissions. Selecting the Pulse Search check box turns on pulse search, clearing it disables pulse search.

Digital communication systems that use pulsed transmissions send and receive information in bursts (such as those in mobile units). In other words, carrier power is switched on and off. The carrier turns on when the transmitter transmits data; it turns off when the transmitter finishes transmitting data. If pulse search is on, the analyzer searches within the defined search length to locate the first complete pulse, which can occur anywhere in the search length. Pulses beyond the first complete pulse are disregarded and are not demodulated. In order for the pulse search algorithm to detect a pulse edge, the pulse must be at least 15 dB above the noise floor. The resultant pulse is then demodulated. If sync search is selected in addition to pulse search, the analyzer performs pulse search first then performs sync search on the resultant demodulated pulse as illustrated below.

The result length, which includes both the offset and the sync word, must not violate the boundaries of the demodulated pulse.

Using Pulse Search

There are two ways to use pulse search:

•	Pulse search with sync search OFF

•	Pulse search with sync search ON

Pulse Search with Sync Search OFF

When you use pulse search and no sync search (sync search is OFF), these parameters determine how the analyzer searches for the pulse, and the data that is demodulated:

•	Search length

•	Trigger signal

•	Result length

Search length determines the length of time over which the analyzer searches for a complete pulse (off-on-off).

The trigger signal determines when the analyzer begins its search.

Result length determines how much information is demodulated. Only the first pulse detected in the search region is demodulated.

The analyzer automatically centers the result length with respect to the pulse. In other words, the analyzer positions the result length around the center of the pulse, as shown below.

Pulse Search With Sync Search ON

When you use pulse search with sync search (sync search is ON), these parameters determine how the analyzer searches for the pulse, and the data that is demodulated:

•	Search length

•	Trigger signal

•	Result length

•	Sync pattern

•	Search offset

The operation of pulse search differs when sync search is ON. With sync search ON, the analyzer searches for a pulse within the search length. The analyzer demodulates the entire pulse to locate the synchronization pattern (also called sync pattern or sync word). If there are multiple pulses within the search length, the analyzer demodulates only the first pulse.

The analyzer uses the sync pattern and the search offset to position the result length—the result length is NOT centered around the center of the pulse.

The following example shows the operation of pulse search when sync search is ON. The example uses a positive (+) offset (for details about offset, see Search offset).

Tips When Using Pulse Search

Here are some additional Tips for using pulse search:

•	If a single measurement contains more than one pulse, the analyzer examines only the first pulse. The analyzer ignores all other pulses in the measurement—even when sync search is used and the first pulse does not contain the sync word. This situation can occur for large search lengths. For example, if your pulse consists of 100 symbols and the search length is 500 symbols, a single measurement may contain up to 4 pulses. Use external triggering to align the desired pulse near the beginning of the search record.

•	Increasing the span may improve pulse-position repeatability. Narrow spans may distort the pulse shape, whereas wider spans offer better time resolution in the pulse detector. For spans below twice the symbol rate, you'll see about 1 symbol of jitter. For more stable results, set the span equal to or larger than three times the symbol rate.

•	It's often helpful to view the Search Time and Time trace data when setting up or troubleshooting pulsed measurements. The Search Time trace data shows data before applying pulse search; the Time trace data shows data after applying pulse search.


Search Length (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Search tab

Search Length determines the amount of data over which a search is performed when pulse search or sync search is on. You can specify search length in number of symbols or units of time.

See also

Sync search

Pulse Search


Search Offset (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Search tab

The analyzer lets you specify an offset, in symbols, when you use sync search. The offset determines the location of result length within search length, as shown below:

You can specify a positive or negative offset. If the SYNC pattern occurs before the start of result length, specify a negative offset. If it occurs after the start of result length, specify a positive offset.

The following illustration shows a SYNC pattern surrounded by several fields of data. The SYNC pattern is 14 symbols in length; each field is 10 symbols in length. The illustration shows you how you can use different offsets to view different fields.

Tip

The analyzer lets you change the offset after your signal is demodulated.

Minimum and Maximum Offset

The minimum and maximum offsets you can enter depend on these parameters:

•	Search Length

•	Result Length

•	Sync Pattern

Basically, you can enter any offset such that the result length falls within the search length. Increasing any of these parameters affects the maximum positive or negative offset that you can enter as follows:

•	Increasing search length increases the maximum positive or negative offset that you can enter.

•	Increasing result length decreases the maximum negative offset that you can enter but has no effect on the maximum positive offset.

•	Increasing the length of the sync pattern decreases the maximum positive offset that you can enter but has no effect on the maximum negative offset.


Search Pattern (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Search tab

Search Pattern sets the synchronization (sync) pattern that the analyzer uses when Sync Search is enabled.

 Minimum length: 1 Symbol
 Maximum length: 32 symbols

Tip

For details about sync search, see Sync Search

Edit, Add, Delete Search Patterns

To edit a search pattern, click MeasSetup > Demod Properties > Search tab > Edit button. Highlight the desired pattern and click the edit button. Make your changes and click OK.

To add a pattern, click MeasSetup > Demod Properties > Search tab > Edit button > New button. This opens the New Sync Pattern dialog box that lets you add your new search pattern. The search pattern must be entered as binary data. The analyzer ignores all characters except ones (1) and zeroes (0).

To delete a search pattern, click MeasSetup > Demod Properties > Search tab > Edit button. Highlight the desired pattern and click the delete button.

Default Search Patterns

The analyzer remembers the search patterns that you enter. These search patterns are preserved and loaded each time you start the Vector Signal Analyzer application. To display a list of remembered search patterns, click MeasSetup > Demod Properties > the Search tab > and the Patterns… button.

Symbols and Search Pattern

The maximum search pattern that you can enter is 32 symbols and depends on the current modulation format. If your modulation format is 16 QAM, 32 symbols represents 128 bits (4 bits/symbol x 32 symbols); if your modulation format is QPSK, 32 symbols represents 64 bits (2 bits/symbol x 32 symbols).

Note

The analyzer can search only for search patterns that are a multiple of the number of bits-per-symbol (see below).

The analyzer can only search for search patterns that are a multiple of the number of bits-per-symbol. Internally, the analyzer assembles the search pattern into an integer number of symbols. When the analyzer assembles the final bits in the search pattern, if there are not enough bits to form a symbol, the analyzer ignores the final bits.

For example, if the number of bits-per-symbol is 4 (as with 16 QAM), the number of bits in your search pattern should be a multiple of four. If your search pattern contains 18 bits, the analyzer ignores the last two bits. In other words, the analyzer uses only the first 16 bits during sync search.


Sync Search (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Search tab

Synchronization words (or patterns) are often used to resolve carrier phase ambiguity on non-differential modulation formats. It is important to realize that synchronization words are optional and are not necessary in order to achieve carrier locking.

Sync search lets you use a synchronization pattern to isolate a segment of your signal for display and analysis. The analyzer searches through demodulated data to find your sync pattern, and then uses the Result Length to determine how much data to display and the Search Offset to display data relative to the sync pattern.

Note

The sync pattern must be a multiple of the number of bits-per-symbol. For example, if the number of bits-per-symbol is 4 (as with 16 QAM), the number of bits in the sync pattern must be a multiple of four. Sync search lets you specify any number of bits for the sync pattern, however, bits that are not a multiple of the bits-per-symbol are truncated. In this example, if you entered 6 bits for the sync pattern, sync search would only use the first four bits.

With pulse search off, triggering determines when the analyzer starts demodulating data and search length determines when the analyzer stops demodulating data. Sync search locates only the first match and ignores any subsequent matches within the search length. The sync pattern and the search offset must fit within the search length.

You can use sync search with or without pulse search, although many measurements require both features.

Sync search uses the following parameters:

•	Search Length determines how much data the analyzer searches through to find your sync pattern.

•	Result Length determines what data is displayed.

•	Search Pattern specifies the sync pattern.

•	Search Offset and the sync pattern determine the location of Result Length within Search Length.

Using Sync Search

There are two ways to use sync search:

•	Sync search with pulse search OFF

•	Sync search with pulse search ON

Note

The following paragraphs describe sync search with pulse search OFF. To learn how sync search works with pulse search ON, see pulse search.

Sync Search With Pulse Search OFF

The following illustration shows how sync search works when pulse search is OFF. The illustration shows a positive (+) offset.

Trigger determines the start of search length.

Offset determines the position of result length with respect to the start of the sync pattern.

Result length determines how much data is displayed.

Search length determines how much data is demodulated.

Triggering

Selecting an appropriate trigger is critical when using sync search. Basically, you must trigger the analyzer such that the Sync pattern and Result Length fit within Search Length.

Note

If you set the Search Length less than the result length, the analyzer sets the result length equal to the Search Length .

Your trigger signal determines when the analyzer begins accumulating data for Search Length. The analyzer begins to demodulate your signal when it receives a valid trigger, and continues to demodulate your signal for the duration of Search Length. If Search Length does not contain your Sync pattern, the analyzer displays SYNC NOT FOUND.

The location of the Sync pattern and the value of Search Offset determine the location of Result Length within Search Length. Because the Sync pattern can occur anywhere within Search Length, it is possible to specify a Search Offset such that the Result Length doesn't fit within the Search Length . If this situation occurs, the analyzer displays SYNC NOT FOUND.

Note

If the analyzer finds two or more Sync patterns in the Search Length, the analyzer ignores all but the first Sync pattern.

You may want to select external trigger and connect a signal to the analyzer's EXT TRIGGER BNC. In this case, a valid external-trigger signal causes the analyzer to capture the amount of data specified by Search Length.

Hints

If you use free run trigger for continuous transmissions, you must be careful when setting the Search Length. For best results, set Search Length large enough to include at least two result lengths.

For additional information for troubleshooting digital demodulated measurements, see Troubleshooting, Digital Demodulation.


About Filters (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Filter tab

The following topics will help you understand and the digital demodulation filters and configuration parameters:

•	Digital Demod Filter Overview

•	Selecting the Correct Filter

•	Selecting the Alpha or BT for a Filter

•	Special consideration for MSK

•	List of Available Digital Demod Filters

Digital Demod Filter Overview

Data filtering is used in digital demodulation to limit bandwidth and reduce intersymbol interference. This analyzer includes several commonly used filter types and has the ability to apply user-defined filters. All filters are computed to 20 symbols in length. If the filter alpha is < 0.2, the analyzer uses 40 symbols to compute filter length (for most formats).

The shape and width of a filter is defined by the alpha (for cosine filters) or the BT (for Gaussian filters). The alpha or BT indicates the filter roll-off (or excess bandwidth) of the selected filter which occurs due to the practical inability of filter technology to build a perfectly square (brick-wall) filter which would have an alpha of 0 (no excess bandwidth). For example, a typical filter with an alpha of 0.3 has a bandwidth 30% greater than the theoretical minimum.

The analyzer's digital demodulator produces two signals: a measured and a reference signal. These signals are called I/Q Measured and I/Q Reference or, for FSK measurements, FSK Measured and FSK Reference.

You can select different filters for the measured and reference signals, as shown in the following, generic block diagram.

Note

For FSK signals, filtering is baseband and occurs after the FM demodulator.

The measured signal is the signal that results after demodulating your waveform. The reference signal is the signal that would result after demodulating your signal if your signal were ideal (contained no errors).

Notice that there are separate filters for the measured and reference signals. You MUST select the correct filter for both signals.

Selecting the Correct Filter

Filtering for various communication systems may occur either at the transmitter or the receiver; or the filtering may be distributed between the transmitter and the receiver. This is an important concept which affects your filter selection for the measured and reference signals. The analyzer's measured filter represents filtering in the system's receiver while the reference filter represents filtering in the entire system. Both filters share the same alpha/BT.

As an example, if the communication system under test filters the signal partially at the transmitter and partially at the receiver (as with NADC signals), you choose a root-raised-cosine filter for the measured signal to simulate receiver filtering in a system which includes a similar filter at the transmitter. However, the reference signal is a calculated ideal signal which is derived from the detected symbols. Therefore, you must choose raised-cosine filtering for the reference in order to represent all the filtering included throughout the simulated system. The following table shows some examples of filter selection:

If the transmitter  filter is:	The measure filter  should be:	The reference filter  should be:
root raised cosine	root raised cosine	raised cosine
raised cosine	none	raised cosine
Gaussian	none	Gaussian
any type	user defined	any type
Selecting the Alpha or BT for a Filter

You can modify the shape and width of Gaussian and Nyquist (cosine) filters. The shape and width is defined by the alpha (for cosine filters) or the BT (for Gaussian filters). All filters are computed to 20 symbols in length. If the filter alpha is < 0.2, the analyzer uses 40 symbols to compute filter length (for most formats).

For further details, see Alpha/BT.

Special consideration for MSK

Matched filtering of a demodulated signal is not available with the MSK demodulators. The measured filter is normally off. A user defined filter can be selected. Its primary use is for additional band-limiting and channel equalization.

List of Available Digital Demod Filters

•	Alpha/BT

•	Rect Filter

•	Gaussian Filter

•	IS-95 Filters

•	Low Pass Filter (for FSK)

•	Raised Cosine Filter

•	Root Raised Cosine Filter

•	User-defined Filters

See also

Digital Demodulation Properties dialog box - Filter tab


Alpha/BT

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup, Demod Properties, Filter tab

Determines the filter characteristics of the Nyquist and Gaussian filters used by the analyzer's digital demodulator.

 Allowable values, non-Gaussian filters: .05 to 1
 Allowable values, Gaussian filters: .05 to 100
 Minimum increment: .01
 Increment using arrow keys or mouse wheel: .05

If you select one of the analyzer's Nyquist (cosine) or Gaussian filters, you must specify the filter's characteristics. For Nyquist filters, you must specify the "alpha" of the filter; for Gaussian filters, you must specify the "BT" of the filter.

The alpha parameter determines the alpha (or BT) of these filters:

Measured Filter	Reference Filter
Root-raised cosine (alpha)	Raised cosine (alpha)
Gaussian (BT)	Root-raised cosine (alpha)
	Gaussian (BT)

The value that you specify for Alpha/BT is used by both the measured filter and the reference filter. For example, if you enter a value of .35, the analyzer sets the alpha of the measured and reference cosine filters to .35 and the BT of the measured and reference Gaussian filters to .35.

Your communications system should specify the "alpha" or "BT" for filters in the system. You should set the value of Alpha/BT to match that of your communications system.

Because the filter alpha/BT can easily be changed with a minimum amount of delay, you can manually adjust the filters to achieve a minimum EVM (Error Vector Magnitude).

Alpha

Alpha describes the shape of a Nyquist (cosine) filter. Alpha is also called the roll-off or the excess bandwidth factor. A higher value for alpha increases the bandwidth that is used in excess of the theoretical minimum.

Modulation theory states that the minimum bandwidth needed to transmit a signal is equal to half of the symbol rate. However, to realize this system would require a perfect brick-wall filter. This filter is equivalent to an alpha of 0. This would give the best possible spectral efficiency. Unfortunately, this filter is unrealizable.

In practice, radios typically use a filter alpha of about 0.3. This means that they take up 30% more bandwidth than the theoretical minimum.

BT

BT (Bandwidth Time Product) describes the shape of a Gaussian filter. BT indicates the filter roll-off (or excess bandwidth) of the Gaussian filter.


EDGE Filter

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Filter tab > Reference Filter box

Click EDGE to select the EDGE filter as the reference filter. The state of the EDGE measured filter (on or off) determines which EDGE reference filter the analyzer implements.

If the measured filter is OFF, the analyzer uses a linearized Gaussian filter for the EDGE reference filter, as defined by the European Telecommunication Standards Institute, standard ETSI 300 959 (GSM 05.04 Version 5.0.1):May 1997.

If the measured filter is EDGE(Windowed RC), the analyzer uses an EDGE convolved filter for the EDGE reference filter. The convolved filter is the EDGE GSM 5.04filter (described above) convolved with the EDGE(Windowed RC) filter (GSM 5.05).


EDGE(Windowed RC) Filter

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup, Demod Properties, Filter tab, Measurement Filter: selection

The EDGE(Windowed RC) filter is a windowed, raised cosine filter used to demodulate EDGE signals. It has a 180kHz, 6 dB bandwidth (as defined by the European Telecommunication Standards Institute, GSM 05.05 standard).

Note

The Alpha/BT setting does not affect this filter.


Gaussian Filter

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Filter tab

Gaussian filters are typically used for MSK and FSK signals. Typically MSK transmission performs all filtering in the transmitter (where T is the symbol interval).


IS-95 Filters

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Filter tab

The analyzer includes two filters that conform to US CDMA digital cellular standard IS-95:

•	IS-95 Base EQ filter.

•	IS-95 Baseband (Chebyshev) filter.

These filters let you measure base stations or mobile phones that conform to US CDMA digital cellular standard IS-95. The IS-95 base-phase EQ filter is the inverse of the forward all-pass phase-compensation filter that is specified for IS-95 base-station transmission. The IS-95 Chebyshev filter is the filter specified in IS-95 that provides overall channel filtering for both base-to-mobile and mobile-to-base links.

The IS-95 base-phase EQ filter is applied to the I/Q measured signal. The IS-95 Chebyshev filter is applied to the I/Q reference signal.

Hint

To automatically configure the analyzer for base-station or mobile measurements, display the Digital Demodulation dialog box, then click Preset to Standard and select CDMA BASE or CDMA MOBILE.

IS-95 Base EQ filter

This filter is the inverse of the forward all-pass phase-compensation filter that is specified for IS-95 base-station transmission. IS-95 base-station transmit filters include a baseband filter followed by an all-pass phase-compensation filter which compensates for typical IF phase-distortion in a mobile phone.

The inverse all-pass phase-compensation filter selected with IS-95 base-phase EQ is an ideal digital implementation. While actual IF characteristics in mobile phones may vary, base- station filtering is a fixed standard in IS-95. Therefore, selecting IS-95 base-phase EQ configures the analyzer to behave as an ideal measuring receiver for determining base-station compliance to IS-95 filtering.

The following illustration shows filtering for base stations as defined in IS-95. The illustration also shows how to use the analyzer's IS-95 base-phase EQ and IS-95 baseband filters to measure base-station transmissions.

Note

Mobile transmitters do not use an all- pass phase filter. Therefore, when measuring mobile transmissions, set the analyzer's measurement filter to OFF.

Hint

Select CDMA BASE or CDMA MOBILE to automatically configure the analyzer to measure CDMA base stations or mobile phones.

IS-95 Baseband (Chebyshev) filter

The IS-95 Chebyshev (baseband) filter is the filter specified in IS-95 that provides overall channel filtering for both base-to-mobile, and mobile-to-base links.

If you are demodulating a base station or mobile, select this filter for the reference filter.


Low Pass Filter (for FSK)

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Filter tab

FSK measurements often require spans which are much larger than the symbol rate because of large deviations inherent in many FSK signals. The wide span may result in a noisy demodulated signal. The low pass filter is a type of narrow, Gaussian filter with a cutoff frequency greater than the symbol rate. Applying the low pass filter to the measured signal may smooth the result.


Root Raised Cosine Filter

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Filter tab

Many communication systems use distributed filtering, that is, filtering is performed partially in the transmitter, to limit bandwidth, and partially in the receiver, to limit interference. To achieve the overall desired frequency response each filter's transfer function is based on the square root of the desired response. For these systems matched square-root raised cosine filters are used in the transmitter and the receiver sections of the system to achieve optimum signal to noise ratio. This implies that you must select similar filter characteristics in the analyzer (which simulates the receiver) to the filter characteristics of the transmitter. The standard NADC demodulation type offered in this analyzer provides this type of filter.

The equation for the square-root raised cosine (root Nyquist) filter follows (where T is the symbol interval):


Raised Cosine Filter

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup, Demod Properties, Filter tab

Raised cosine filters are used in systems which perform all the filtering in the transmitter. This is typical of some mobile communication systems.

The equation for the raised cosine (Nyquist) filter follows (where T is the symbol interval):


Rect Filter

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Filter tab

The rectangular filter has an impulse response that is a rectangular pulse, 1 symbol wide, centered at T = 0 (as shown below). This filter has an effect similar to an integrate and dump filter.


User-defined Filters

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Filter tab

The analyzer lets you use a filter of your design for the I/Q measured filter or the I/Q reference filter. Typical applications for user defined filters include:

•	Custom filters other than those provided. In this case both measured and reference filters are user defined.

•	Modified filters which are based on the raised cosine filter but add channel equalization. In this case the measure filter is a user defined filter and the reference filter is standard.

To use a user-defined filter, create a trace file containing the impulse response of the desired filter. The trace must:

•	Be real.

•	Be ≤ 20 symbols in overall length (401 samples). If filter alpha is < 0.2, the trace must be ≤ 40 symbols in overall length (802 samples).

•	Contain 20 samples-per-symbol. For example, 401 samples = 20 symbols at 20 points-per-symbol.

•	The impulse response must have 20 points per symbol and have an overall length ≤ 20 symbols (401 points). For filter alphas < 0.2, overall length must be ≤ 40 symbols (802 samples).

•	Have an odd number of points so that the center of the impulse is on a symbol. The middle sample (201st point in a 401 point trace) is assumed to be at t=0.

After you create the trace file, store it in a data register and select the data register to be used for the filter.

Note

Accuracy of user-defined filters is undefined. In addition, the value of Alpha/BT has no effect on user-defined filters.


Available Digital Demodulation Formats (Digital Demod)

The following Digital Demodulation format types are available from the Digital Demodulation Properties dialog box - Format tab:

•	8 PSK: 8 Phase-Shift Keying

•	BPSK: Binary Phase-Shift Keying

•	DQPSK: Differential Quadrature Phase-Shift Keying

•	D8PSK: Differential 8 Phase-Shift Keying

•	DVB QAM: Digital Video Broadcast for QAM signals

•	EDGE: Enhanced Data for Global Evolution

•	FSK: Frequency-Shift Keying

•	MSK: Minimum-Shift Keying

•	Offset QPSK: Offset Quadrature Phase-Shift Keying

•	QAM: Quadrature Amplitude Modulation

•	QPSK: Quadrature Phase-Shift Keying

•	VSB: Vestigial Side Band

See also

Digital Demodulation Properties Dialog Box

Setting up a Digital Demod Measurement


DVB QAM Signals

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Format tab > Format: box

Select the 16 DVB QAM, 32 DVB QAM, or 64 DVB QAM demodulation format to demodulate 16, 32, or 64 QAM signals that conform to the Digital Video Broadcast (DVB) standard. This standard defines the bits that represent each state as follows:

•	The first two bits are differentially encoded so that pi/2 rotations in the QAM constellation do not affect detection of the two MSB's.

•	The LSB's are positioned to be rotation- invariant, as follows (as defined in prETS 300 429):

I/Q Origin Offset Compensation

Unlike QAM, DVB QAM does not compensate for I/Q origin offset. When the demodulation format is DVB QAM, the analyzer reports I/Q origin offset in the symbol table, but doesn't remove it from the measurement. When the demodulation format is QAM, the analyzer reports I/Q origin offset in the symbol table AND removes it from the measurement.

To see the effects of I/Q origin offset on your DVB QAM signal, change the demodulation format to QAM. For example, if your signal is 16 DVB QAM, select 16 QAM to see the effects of I/Q origin offset on your signal.

Hint

The Error Vector Magnitude (EVM) for DVB QAM will be higher than QAM because DVB QAM includes IQ origin offset in the measurement.

See also

Digital Demodulation Properties Dialog Box


EDGE Signals

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Format tab > Format: box

This selection sets the instrument to the EDGE(3π/8 8PSK) "Enhanced Data for Global Evolution" digital demodulation format. You use the same process to demodulate EDGE as you do other digital demodulation formats.

EDGE adds a new measurement filter "EDGE(Windowed RC)" and reference filter "EDGE". Also two new digital demod error data results were added to the symbol table: Pk EVM and 95% EVM.

Hint

You can use the analyzers standard preset feature to automatically configure the measurement parameters: Select the MeasSetup menu option, Digital Demodulation Properties > Format Tab > Preset to Standard button > EDGE > OK.

When using EDGE, Note the following:

•	Set the points per symbol to 1 point/symbol

Because EDGE signals incorporate rotation and the EDGE filter introduces ISI (inter-symbol interference), symbol locations in the vector and constellation diagrams should appear random. However, at one point/symbol (the value set by the EDGE standard setup) the analyzer removes the effects of ISI so you can view a clean vector diagram. Above one point/symbol, the analyzer does not remove the effects of ISI.

•	EDGE reference filter "EDGE":

The "EDGE" filter is available as the reference filter and is used for demodulating EDGE PSK signals. One of two filters may be used depending on the selection of the measured filter.

a.	If the measured filter is OFF and you select the "EDGE" reference filter, the EDGE reference filter is a linearized Gaussian filter as defined by ETSI (European Telecommunications Standard Institute) GSM 05.04.

b.	If the measured filter is "EDGE(Windowed RC)" and you select the "EDGE" reference filter, the EDGE reference filter is the GSM 05.04 filter described above convolved with the "EDGE(Windowed RC)" filter.

The BT (Bandwidth Time Product) of the EDGE reference filter is fixed. The value of BT does not affect this filter.

•	EDGE measurement filter "EDGE(Windowed RC)":

The "EDGE(Windowed RC)" filter is available as the measured filter and is used for demodulating EDGE PSK signals. This filter is a windowed, raised-cosine filter that has an approximate 180 kHz, 6 dB bandwidth, as defined by ETSI (European Telecommunications Standard Institute) GSM 05.05.

The BT (Bandwidth Time Product) of the "EDGE(Windowed RC)" filter is fixed. The value of BT does not affect this filter.

•	Pk EVM and 95% EVM error data results

The EDGE demodulation format adds two new error data results to the symbol table: "Pk EVM" and "95% EVM". Pk EVM is the mean (average) of the peak EVMs - one per measurement (it is a mean of the peaks, not a peak of the peaks). 95% EVM is the error-vector-magnitude (EVM) below which 95% of the individual symbol EVMs occur.

•	Adaptive Equalization

The Equalization Filter is only available when the Measurement Filter is set to OFF.

Additional Details

To learn how the analyzer demodulates EDGE signals, see Digital Demodulation.

See also

Tutorials for EDGE Signals

Digital Demodulation Properties Dialog Box


FSK Signals

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Format tab > Format: box

You can demodulate 2-state, 4-state, 8-state and 16-state FSK (Frequency-Shift Keyed) signals. The following FSK demodulation formats are available from the Format box on the Format tab:

Format Box Selection	FSK Format
FSK 2	2-state FSK signals
FSK 4	4-state FSK signals
FSK 8	8-state FSK signals
FSK 16	16-state FSK signals
FSK is the process of shifting (modulating) an analog carrier frequency at a digital rate. FSK closely resembles standard FM (Frequency Modulation). With FSK, the modulating signal is not a sinusoidal signal but a series of dc pulses that vary between two discrete voltage levels.

FSK is often used in modems. For example, a modem may use a 1700 Hz carrier that is shifted up 500 Hz for a logic 1 (mark), and down 500 Hz for a logic 0 (space). Thus, as the digital signal alternates between 1 and 0, the carrier is shifted back and forth between 1200 and 2200 Hz.

The following block diagram shows how the analyzer demodulates FSK signals when FSK demodulation is selected.

See also

Digital Demodulation Properties Dialog Box


MSK Signals

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Format tab > Format: box

The analyzer offers two methods of demodulating MSK signals: type 1 and type 2. Both methods demodulate MSK modulated waveforms, but they differ in the compensation used and in the way they detect bits, as shown in the following table.

Features	Type 1	Type 2
Carrier lock
- Frequency correction	Yes	Yes
- Phase correction	Yes	Yes
Symbol lock	Yes	Yes
Burst amplitude droop	No	Yes
I/Q origin offset	No*	Yes
Differential detection	Yes	No
* MSK Type 1 does not compensate for I/Q origin offset (in other words, it doesn't remove I/Q origin offset), but it does report it in the symbol table.

MSK Type 1

MSK type 1 demodulation is done with carrier lock and symbol lock, and uses differential data decoding.

Hint

MSK type 1 does not compensate for I/Q origin offset and burst amplitude-droop. Therefore, I/Q origin offset and burst amplitude-droop affect the IQ measured trace.

The data is assumed to have been differentially encoded using:

dOut(i) = not[dIn(i) XOR dIn(i-1)]
where:	dOut(i) is the data bit that is output.
dIn(i) is the current data bit in.
dIn(i-1) is the previous data bit in.
XOR is the exclusive-OR operation.
not is the negation operation.

Note

When sync search is OFF, dIn(i-1) is assumed to be one (1).

MSK Type 2

MSK type 2 demodulation is done with carrier lock and symbol lock, but does not use differential detection. Furthermore, MSK type 2 compensates (removes) any I/Q origin offset or burst amplitude-droop.

Hint

With MSK type 2, I/Q origin offset and burst amplitude-droop do not affect the IQ measured trace. However, the analyzer reports these errors in the symbol table.

Additional Details

For additional details, see Digital Demodulation.

See also

Digital Demodulation Properties Dialog Box


Offset QPSK Signals

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Format tab > Format: box

You demodulate OQPSK (Offset QPSK) as you do other demodulation formats. With OQPSK, two additional IS-95 filters are available to measure signals that conform to US CDMA digital cellular standard IS-95. To learn about these filters, see IS-95 base phase EQ and IS-95 baseband measured and reference filters.

Hint

To automatically configure the analyzer for base-station or mobile measurements, display the Digital Demodulation dialog box, then click Preset to Standard and select CDMA Base (for base-station measurements) or CDMA Mobile (for mobile measurements).

When using OQPSK, Note the following:

•	You must specify an even number for Points/Symbol.

•	OQPSK displays error data in the symbol table and uses the same computations as other demodulation formats, with the following exceptions:

−	Amplitude droop is not computed for OQPSK.

−	The analyzer uses two points-per-symbol (instead of one point-per-symbol) to compute the following:

•	EVM

•	peak EVM

•	phase error

•	magnitude error

•	The symbol rate is the frequency of the I (or Q) clock, not the 2x frequency sometimes associated with the I to Q clock frequency.

•	Demodulated traces show a symbol at every I and Q detection (decision) point. Therefore, all demodulated traces (except the symbol table) show twice as many symbols as the result length, at twice the symbol rate. Therefore, the result length (in seconds) is correct.

See also

Digital Demodulation System Block Diagrams.

Tutorials for QPSK signals

Digital Demodulation Properties Dialog Box


QAM Signals

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Format tab > Format: box

Select the 16 QAM, 32 QAM, 64 QAM, 128 QAM or 256 QAM (Quadrature Amplitude Modulation) demodulation format to demodulate 16, 32, 64, 128 or 256 QAM (Quadrature Amplitude Modulated) signals.

Reliable Carrier Lock:

•	For reliable carrier lock, the analyzers center frequency must be within 10% of the carrier frequency of your signal.

•	The minimum result length for reliable carrier lock:

If the modulation type is:	The minimum result length  for reliable carrier lock is:
16 QAM or 16 DVB QAM	50 symbols
32 QAM or 32 DVB QAM	75 symbols
64 QAM or 64 DVB QAM	150 symbols
128 QAM	250 symbols
256 QAM	400 symbols
See also

Setting up a Digital Demod Measurement

Digital Demodulation Properties Dialog Box


VSB Signals

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Format tab > Format: box

Select the VSB 8, VSB 16 demodulation format to demodulate 8 VSB or16 VSB (Vestigial Side Band) modulated signals.

The following topics provide additional information that is unique to VSB signals that will help you successfully analyze VSB signals:

•	Carrier locking and pilot search: VSB

•	Symbol Rate

•	Standard Presets using VSB

•	Available Error Data Results

•	Pilot Level error data results

•	SNR Measurements

See also

Setting up a Digital Demod Measurement


About the Symbol Table (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Syms/Errs

When Digital Demodulation is enabled, selecting the Syms/Errs trace data displays the symbol table. The symbol table shows the error summary data and the symbol data (binary bits) for each symbol.

Symbol Data

The bottom half of the symbol table shows the raw data symbol bits for each demodulated symbol. The first bit in the table corresponds to the first bit of the first symbol in the digital data stream.

When the symbol table marker is enabled, the trace marker highlights the data symbol bits for the selected symbol and the marker readout provides the symbol number and its value in decimal.

To make the table easier to read, the data bits are shown in groupings of eight characters followed by a space. The characters can represent a binary digit or a hexadecimal digit as specified by the Symbol Table Format parameter. The number to the left of each row indicate either the bit or symbol offset position depending the symbol table format as described below:

Binary Format: The symbol data bit format is binary and each character represents a binary digit. The number to the left of each row indicates the bit offset of the first bit in the row.

Hexadecimal Format: The symbol data bit format is hexadecimal and each character represents a hexadecimal digit. The number to the left of each row indicate the symbol offset of the first symbol in the row.

Note

There must be at least 4 bits/symbol to use the hexadecimal format, that is, symbols that have less than 4 bits/symbol will only be displayed in binary format regardless of the Symbol Table Format setting.

For example, if the symbol table format is binary and 192 is displayed to the left of third row, the first bit in the third row is the 192nd bit in the digital data stream.

Note

For 2-level FSK, a 1 (one) corresponds to a positive frequency deviation (frequency greater than the carrier).

The following Tips will help you to use the Symbol Table:

•	You can chose to show the symbol data bits in either binary or hexadecimal format, see the "Symbol Table Format" topic.

•	The Result Length parameter specifies the number of symbols shown in the table.

•	Here's an easy way to identify symbol bits and their corresponding symbol points in the constellation diagram: Display the constellation diagram in one grid and the symbol table in another. Then turn on the markers for both displays and enable marker coupling. When you place the marker on a point in the constellation diagram, the analyzer highlights the corresponding symbol bits in the symbol table.

•	Marker Movement: You can use the keyboard arrow keys or the mouse wheel to move the marker from one symbol to the next. You can use the Marker Position - X Position parameter to move the marker to a specific symbol location.

Error Summary Data

The top half of this display shows the Error Summary data. The digital demodulation type determines which error summary data are shown. See Symbol Table Error Summary Data (Digital Demod) for information about Digital Demodulation Error Summary data.

See also

Symbol Table Format

Symbol Table Error Summary Data

Alphabetical Listing: Symbol Table Error Summary Data


Symbol Table Format
Symbol Table Format (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Format > Digital Demod tab > Symbol Table Format box

The Symbol Table Format allows you to specify the format used to display the symbol binary bit data in the Symbol Table. The available format choices are binary or hexadecimal formats:

Binary Format: The symbol data bit format is binary and each character represents a binary digit. The number to the left of each row indicates the bit offset of the first bit in the row.

Hexadecimal Format: The symbol data bit format is hexadecimal and each character represents a hexadecimal digit. The number to the left of each row indicate the symbol offset of the first symbol in the row.

Note

Their must be at least 4 bits/symbol to use the hexadecimal format, that is, symbols that have less than 4 bits/symbol will only be displayed in binary format regardless of the Symbol Table Format setting

This parameter is valid only when:

1.	The active trace is a symbol table, and

2.	The current demodulation format supports hexadecimal, the demodulation format's bits/symbol is equal to or greater than four.

See also

Digital Demod Trace Data Property dialog box


About Error Summary Data (Digital Demodulation)
Error Summary Data (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Syms/Errs

At the top of the symbol table are several error data results. The demodulation type determines which error summary data results are displayed in the symbol table (see: Available Symbol Table Error Summary Data).

Averaging and Error Summary Data

When averaging is on, averaging is applied to the numeric error data in the symbol/errors table with the following exception. Averaging only applies to peak EVM, peak magnitude and peak phase error data for the Continuous Peak Hold averaging type.

Error data from the current scan is not included in the average if any of these conditions exist:

•	Pulse Not Found

•	Sync Not Found

•	Carrier Unlock.

•	DATA?

Error Information at Symbol Times

Error summary data in the symbol table are computed only at the symbol times (the instant in time when symbols are detected). The analyzer does not use points taken between symbols when computing these data results (there are some MSK error data that use all points in their derivation, for details, see Alphabetical Listing: Symbol Table Error Summary Data).

In contrast, error traces (such as error vector magnitude (EVM), IQ error, FSK error, Carrier error magnitude) display the error at the symbol times and at ALL points between symbols. Changing the value of Points/Symbol DOES NOT affect the error summary data shown in the symbol table, but does affect error traces.

Using Band Power markers to limit Error Information

If you want error information for all points over a selected region, you can use the band-power markers with an error trace.

For example, here's how you could compute the phase error for all points within a region. Click Trace > Data > IQ Phase Error to display the IQ phase-error trace, then click Markers > Calculation and select the Band Power check box to turn on the band-power markers.

Now position the band-power markers to select the region of interest, and select RMS Sqrt (Pwr) to display the phase error for the selected region.

Hint

At this point, you could simply click Trace, Data, IQ Mag Error to display the magnitude error for the same region.

How EVM and Magnitude Error Data is calculated (%RMS)

In the symbol table, the analyzer displays the error-vector magnitude, magnitude error, and phase error, as a percentage. Before computing this percentage, the analyzer normalizes the constellation diagram such that the outer-most, ideal states have a magnitude of one.

Note

A 32 QAM constellation diagram does not have corner states. Therefore, for 32 QAM, the analyzer normalizes the constellation diagram to the corner state of an ideal, 36 QAM constellation diagram.

128 QAM is normalized to 144 QAM.

The analyzer computes the overall, percent error by first computing the error-vector magnitude, magnitude error, and phase error at each symbol time.

Note

The overall, percent error is computed only at the detection decision-points (symbol locations). Other points are not included in the calculation.

Next, the analyzer derives the rms average for each parameter. For example, to compute the rms average for the magnitude error, the analyzer takes the square root of the sum of the squares of the individual magnitude-error values at each symbol time.

Because the magnitude of the constellation diagram's outer-most state has been normalized to one, the rms average is the overall, percent error.

EDGE Demodulation

For `EDGE` demodulation format the EVM, Phase and Magnitude Error data results may vary for different points/symbol settings.  When points/symbol is set to 1 (default), the trace data results are compensated for ISI (inter-symbol interference). For points/symbol greater than one, the trace data results are not compensated for the effects of ISI.

See also

About the Symbol Table

Alphabetical Listing: Symbol Table Error Summary Data


Alphabetical List of Symbol Table Error Summary Data (Digital Demod)

(Vector Signal Analyzer application only.)

The Digital Demodulation Type determines which error summary data are displayed in the symbol table, as shown in the following table (Yes indicates the error data result is shown for that demodulation type). A description of all error summary data, in alphabetical order, follows the table.

For information about using error summary data with ADS, see Demod Errors and ADS.

Tip

See About the Symbol Table for an overview of the symbol table. See Symbol Table Error Summary Data for an overview of the symbol-table error summary data.

	Modulation Format Type
Error Summary  Data	All Others	QPSK OQPSK	8/16 VSB	8PSK D8PSK pi/4DQPSK BPSK DQPSK MSK2	EDGE QAM DVB QAM	FSK
95% EVM	—	—	—	—	EDGE	—
Amplitude Droop	—	—	—	Yes	—	—
Carrier Offset	---	---	---	---	---	Yes
Deviation	—	—	—	—	—	Yes
EVM	Yes	Yes	Yes	Yes	Yes	—
Frequency Error	Yes	Yes	Yes	Yes	Yes	—
FSK Error	—	—	—	—	—	Yes
IQ Gain Imbalance	Yes	Yes	—	Yes	Yes	—
IQ Offset	Yes	Yes	Yes	Yes	Yes	---
Magnitude Error	Yes	Yes	Yes	Yes	Yes	Yes
Phase Error	Yes	Yes	Yes	Yes	Yes	—
Pilot Level	—	—	Yes	—	—	—
Pk EVM	---	—	—	—	EDGE	---
Quadrature Skew	Yes	Yes	—	Yes	QAM DVB QAM	—
Rho	---	Yes	—	—	—	—
SNR(MER)	—	QPSK	Yes	—	QAM DVB QAM	—


95% EVM (Digital Demodulation)

The 95% EVM error data exists only for the EDGE demodulation format. 95% EVM is the error-vector-magnitude (EVM) below which 95% of the individual symbol EVMs occur.

For example; At 200 averages, with each measurement containing 142 symbols, there would be symbol EVMs for a total of 200 × 142 symbols. The 95% EVM is the EVM for which 200 × 142 × 0.95 symbols have lower EVMs, or 200 × 142 × 0.05 have higher EVMs.


Amp Droop (Digital Demodulation)

Amplitude droop (also called burst amplitude droop) is a measure of the change in the magnitude of the signal over the measured burst in units of dB per symbol.

Note

Amplitude droop is not computed for OQPSK, QPSK, QAM, DVB QAM, and VSB formats.

This data result is most significant for pulsed signals. A high number most likely indicates a problem with the pulse modulation process.

The amplitude droop shown in the symbol table is computed only at the symbol times (the instant in time when symbols are detected). The computation does not include points between symbols. Therefore, the value of Points/Symbol has no effect on this error data.

Note

For the MSK demodulation format, the analyzer uses ALL points to compute this parameter. Therefore, changing the value of Points/Symbol affects this data result when MSK is selected.


Carr Ofst (Digital Demodulation)

This error data shows the carrier frequency-error relative to the analyzer's center frequency. This error data is displayed in Hertz and is the amount of frequency shift, from the analyzer's center frequency, that the analyzer must perform to achieve carrier lock.

Errors in RF frequency, or LO frequency could all appear as carrier offset.


Deviation (Digital Demodulation)

Deviation is derived at the symbol locations, as shown in the following diagram. Points between symbols are not used to compute the deviation.

Note

The analyzer uses the outermost symbol locations to compute deviation for 4-level FSK.


Error Vector Magnitude (Digital Demodulation)

EVM is the Root Mean Square (RMS) of the error vectors computed and expressed as a percentage of the square root of the mean power of the ideal signal.

The error vector is the magnitude of the vector, at the detected symbol location, which connects the I/Q reference-signal phasor to the I/Q measured-signal phasor, and is computed as follows (refer to the phasor diagram show below):

The symbol table also shows the symbol that has the largest EVM called the Peak EVM.

Notes

OQPSK uses two points-per-symbol (symbols and midpoints between symbols) to compute EVM and peak EVM due to the offset between I and Q.

For `EDGE` demodulation format, the EVM, Phase and Magnitude Error data results may vary for different points/symbol settings.  When points/symbol is set to 1 (default), the trace data results are compensated for ISI (inter-symbol interference). For points/symbol greater than one, the trace data results are not compensated for the effects of ISI.

Hint

If the EVM is larger than expected, see the troubleshooting Tips in Troubleshooting, Digital Demodulation.

EVM is calculated only at the symbol times (the instant in time when symbols are detected). The computation does not include points between symbols. Therefore points/symbol does not effect the value.


Freq Err (Digital Demodulation)

This error data shows the carrier frequency-error relative to the analyzer's center frequency. This error data is displayed in Hertz and is the amount of frequency shift, from the analyzer's center frequency, that the analyzer must perform to achieve carrier lock.

Errors in RF frequency, LO frequency, or digitizer clock rate could all appear as carrier frequency error.


FSK Err (Digital Demodulation)

The FSK Error is computed by comparing the FSK reference signal with the FSK measured signal at the symbol locations—points between symbols are not used, as follows:

The FSK error in the symbol table is shown as a percentage of the deviation. To derive this percentage, the analyzer computes the rms average of the FSK error at all symbol locations, divides by the deviation, and mulTiplies by 100:

The symbol table also shows the symbol that has the largest (peak) FSK error.


Gain Imb (Digital Demodulation)
IQ Gain Imb (Digital Demodulation)

IQ Gain Imbalance compares the gain of the I signal with the gain of the Q signal, as follows:

The effects of IQ gain imbalance are best viewed in constellation diagrams, where the width of the constellation diagram is different than its height.

Because gain imbalance is expressed as a logarithmic value, it may be a positive or negative value. The gain imbalance is always positive if averaging is ON and Sync Search is OFF.

For non-rectangular formats (such as 8 PSK or pi/4 DQPSK), IQ Gain Imbalance may look like Quadrature Skew, and vice-versa. This occurs when the analyzer is phase locked to an orientation that is different than that of the modulator. To ensure the same phase orientation, use Sync Search. You can also use the digital demod Rotation compensate parameter to swap the IQ Gain Imbalance and Quadrature Skew data results.

Note

IQ Gain Imbalance is unavailable when demodulating FSK or VSB signals.

See also

Couple to Gain Imb./Quad Skew

IQ Gain Imbalance and Quadrature Skew Parameter Interaction

Quadrature Skew


IQ Offset (Digital Demodulation)

IQ Offset (also called I/Q origin offset) indicates the magnitude of the carrier feedthrough signal. When there is no carrier feedthrough, IQ offset is zero (-infinity dB).

IQ origin offset is easily seen in the constellation diagram, as shown below:

In the above illustration, "x" is the center of the constellation diagram. When "x" occurs at the origin, the IQ offset is zero. When "x" is not at the origin, the IQ offset is the magnitude of the vector (in dB) between "x" and the origin.

The carrier feedthrough shown in the symbol table is computed only at the symbol times (the instant in time when symbols are detected). The computation does not include points between symbols. Therefore, the value of Points/Symbol has no effect on this error data.

Notes

DVB QAM and MSK type 1 do not compensate for I/Q origin offset, but they do report it in the error summary table.

Unlike other demodulation formats, MSK uses all points to compute I/Q origin offset.


Mag Err (Digital Demodulation)

For all signals except FSK, magnitude error is the difference in amplitude between the I/Q measured signal and the I/Q reference signal (for FSK, see Magnitude Error: FSK below).

Magnitude error is an indicator of the quality of the amplitude component of the modulated signal. For example: a very high magnitude error might indicate high incidental AM modulation on the signal.

The magnitude error shown in the symbol table is computed only at the symbol times (the instant in time when symbols are detected). The computation does not include points between symbols. Therefore, the value of Points/Symbol has no effect on this error data.

The symbol table also shows the symbol that has the largest magnitude error (peak magnitude error).

Notes

OQPSK uses two points-per-symbol (symbols and midpoints between symbols) to compute magnitude error and the peak magnitude error due to the offset between I and Q.

For the MSK demodulation format, the analyzer uses ALL points to compute this error data. Therefore, changing the value of Points/Symbol affects this error data when MSK is selected.

For `EDGE` demodulation format the EVM, Phase and Magnitude Error data results may vary for different points/symbol settings.  When points/symbol is set to 1 (default), the trace data results are compensated for ISI (inter-symbol interference). For points/symbol greater than one, the trace data results are not compensated for the effects of ISI.


FSK (Mag Err) (Digital Demodulation)

The magnitude error (also called carrier magnitude error) shows the magnitude error of the carrier over all symbols—points between symbols are not used to compute the magnitude error. The magnitude error shown in the symbol table is shown as a percentage, and is the rms average of the magnitude errors at all symbol locations divided by the average magnitude, as follows:

The symbol table also shows the symbol that has the largest (peak) carrier magnitude error.


Phase Err (Digital Demodulation)

Phase Err is the phase difference between the I/Q reference signal and the I/Q measured signal measured at the symbol time.

The magnitude of this error data is an indicator of the quality of the phase component of the modulated signal. For example, a very high phase error might indicate high incidental FM modulation on the signal.

The phase error shown in the symbol table is computed only at the symbol times (the instant in time when symbols are detected). The computation does not include points between symbols. Therefore, the value of Points/Symbol has no effect on this error data.

The symbol table also shows the symbol that has the largest phase error (the peak phase error).

Notes

OQPSK uses two points-per-symbol (symbols and midpoints between symbols) to compute phase error and the peak phase error due to the offset between I and Q.

For the MSK demodulation format, the analyzer uses ALL points to compute phase error. Therefore, changing the value of Points/Symbol affects phase error when MSK is selected.

For `EDGE` demodulation format the EVM, Phase and Magnitude Error data results may vary for different points/symbol settings.  When points/symbol is set to 1 (default), the trace data results are compensated for ISI (inter-symbol interference). For points/symbol greater than one, the trace data results are not compensated for the effects of ISI.


Pilot Lvl (Digital Demodulation)

Pilot Lvl is reported for the VSB demodulation format. The result is in dB. A number greater than zero indicates a pilot with an amplitude that is larger than nominal.

Note

The VSB demodulator removes the pilot from IQ measured signal.


Pk EVM (Digital Demodulation)

The Pk EVM (Peak EVM) error data exists only for the EDGE demodulation format. Pk EVM equals the mean (average) of the peak EVMs − one per measurement. That is, it is a mean of the peaks, not a peak of the peaks.


Quad Err (Digital Demodulation)

Quad Err (Quadrature Skew Error) indicates the orthogonal error between the I and Q signals. Ideally, I and Q should be orthogonal (90 degrees apart). A quadrature skew error of 3 degrees means I and Q are 87 degrees (or 93 degrees) apart.

For non-rectangular formats (such as 8 PSK or pi/4 DQPSK), IQ gain imbalance may show up as Quadrature Skew Error, and vice-versa. This occurs when the analyzer is phase locked to an orientation that is different than that of the modulator. To ensure the same phase orientation, use Sync Search. You can also use the digital demod Rotation compensate parameter to swap the IQ Gain Imbalance and Quadrature Skew Error data results.

Note

Quad Err is not available for FSK or VSB Signals.

See also

Couple to Gain Imb./Quad Skew

IQ Gain Imbalance and Quadrature Skew Parameter Interaction


Rho (Digital Demodulation)

Rho is reported for QPSK and OQPSK formats. It is similar to error vector magnitude (EVM) and is a measure of the quality of digital modulation. Rho is computed by comparing the normalized correlated power between the measured signal and the reference signal and is designated as the waveform quality factor. The maximum value of Rho is 1.0 (which means the measured signal and reference signal are 100% identical).

A Rho value of 1.0 indicates that all of the transmitted power correlates with the ideal signal as determined by the detected sequence.

For Digital demodulation, Rho is the correlated power of a single channel (for example, the pilot channel in IS-97).


SNR (Digital Demodulation)

SNR (MER) - Signal to Noise Ratio (Message Error Rate) is reported for QAM, DVB QAM, QPSK and VSB demodulation formats. It is the signal-to-noise ratio, where signal is the average symbol power of the transmitted waveform, and noise power includes any term that causes the symbol to deviate from its ideal state position, such as additive noise, distortion, and ISI (inter-symbol-interference). The following formula shows how SNR is computed:

Another way of looking at SNR is:

Note

VSB uses only REAL data to compute SNR, as shown in the equation below.


Trace Data (Digital Demodulation)
Available Trace Data (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data

Measurement trace data available with Digital Demodulation.

                                       Digital Demodulation
                                Available Measurement Trace Data

Carrier Magnitude Error (FSK only)	IQ Mag Error
Ch Frequency Response	IQ Meas Spec
Eq Impulse Response	IQ Meas Time
Error Vector Spec	IQ Phase Error
Error Vector Time	IQ Ref Spec
FSK Error Time (FSK only)	IQ Ref Time
FSK Error Spectrum (FSK only)	Raw Main Time
FSK Measured and FSK Reference Signals (FSK only)	Search Time (pre-demodulated time data)
Inst Err Vect Spec	Spectrum (pre-demodulated time data)
Inst IQ Meas Spec	Syms/Errs
Inst IQ Ref Spec	Time (pre-demodulated time data)
Inst Spectrum (pre-demodulated time data)
Note

Data for the Time trace data is 20% larger than demodulated data.

You can also display data from a math function or data register. If you select No Data, the active trace is empty.

See also

89600-Series VSA Application Standard Trace Data

Option AYA: Digital Demodulation Available Features


Carrier Magnitude Error - FSK signals (Digital Demodulation)

(Vector Signal Analyzer application only.)
(Available only when the digital-demodulation format is FSK.)

Menu Path: Trace > Data > Carrier Mag Error

The analyzer AM demodulates your FSK signal to obtain its AM envelope. The analyzer then compares the carrier magnitude at each point to the average carrier-magnitude, and displays the difference, as follows:

Mag Err[n] =	envelope[n] - (avg. envelope)
avg Err =	Carrier Magnitude Error
envelope[n] =	Magnitude of AM envelope at current point in the FSK signal.
avg. envelope =	rms magnitude of AM envelope over all points.

If normalization is ON, the carrier magnitude-error is shown as a percentage of the average envelope:

Additional Tips

Here's some additional information you may need to know:

•	The Result Length determines the number of symbols in the carrier magnitude-error trace. The Points/Symbol determines the number of points between symbols.

•	The analyzer uses all points in your FSK signal. To compare only those points at the symbol times, set Points/Symbol to one (1).

•	The band-power markers compute the carrier magnitude-error over all points in your FSK signal. Again, to compute the error only at the symbol times, set Points/Symbol to one (1).

•	For a block diagram that shows how carrier-error magnitude is derived, see FSK demodulation


Ch Frequency Response (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Ch Frequency Response

When Digital Demodulation is enabled and the equalizer is ON, the Ch Frequency Response trace shows the frequency response channel for which the equalizer is correcting. Ch Frequency Response is computed as the inverse of the equalization filter's frequency response. The data is complex and is normally displayed in units of magnitude, phase, or group delay.

Note

The analyzer applies the equalization filter to your measurement when you select the Equalization Filter check box. When you clear the check box, the filter still exists, but is not used. The filter may be turned on and off without resetting the filter coefficients.

Frequency Span

The frequency span of Ch Frequency Response is determined by the symbol rate and points-per-symbol, as follows:

The segment of the displayed span that is valid is determined by the bandwidth of the input signal with the measurement filter applied. For example, a signal with a 1 MHz symbol rate and root cosine filter with an alpha of 0.2 would have a bandwidth of 1.2 MHz. The valid segment of the channel frequency response would be less than 1.2 MHz.

For further details, see Using the Equalization Filter.


Correction (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Correction

Displays the correction trace derived by the analyzer from the calibration data. The correction trace is applied to the acquired data to compensate for phase and magnitude anomalies in the analyzer's hardware and software signal processing.

See Also

About Calibration


Eq Impulse Response (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Eq Impulse Response

When Digital Demodulation is enabled and the equalizer is ON, the Eq Impulse Response trace shows the impulse response of the equalization filter.

Note

The analyzer applies the equalization filter to your measurement when you select the Equalization Filter check box. When you clear the check box, the filter still exists, but is not used. The filter may be turned on and off without resetting the filter coefficients.

For complete details, see Using the Equalization Filter.


Error Vector Spec (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Error Vector Spec

When Digital Demodulation is enabled, the Error Vector Spec trace shows the spectrum of the Error Vector Time trace. In other words, the analyzer derives the Error Vector Time trace, and then windows and FFTs this trace to produce the Error Vector Spectrum trace.

The analyzer's digital demodulator removes carrier-frequency error. Therefore, in the error vector spectrum display, you must add the carrier-frequency error to marker readouts to obtain exact frequency information. The carrier-frequency error (Freq Err) is shown in the symbol table.

Note

The center frequency and span for error vector spectrum is identical to IQ measured spectrum. For details, see IQ Measured Time.


Error Vector Time (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Error Vector Time

When Digital Demodulation is enabled, the Error Vector Time trace shows the time-domain error vector trace data results. This trace is the computed error vector between corresponding symbol points in the I/Q measured and I/Q reference signals.   You can view the data results as Error Vector Magnitude, Error Vector Phase, only the I component or only the Q component (see Trace Data Formats below).

Hint

To increase the resolution, increase the number of symbols (increase result length).

If normalization is OFF, the analyzer displays the instantaneous magnitude for each point. If normalization is ON, the analyzer displays the error vector as a percentage ( IQ normalize explains how this percentage is derived).

Trace Data Formats

It is important to remember that the Error Vector Time trace is a time record made up of complex, time-domain data. Each point in the time record has two components: I and Q. To make sense of the data, you must select an appropriate trace data format (Trace > Format > Format: drop--down list).

•	Linear Mag :  Displays the EVM (Error Vector Magnitude).

•	Real(I) :  Displays the I component of the error vector.

•	Imag(Q) :  Displays the Q component of the error vector.

•	Wrap Phase:  Displays the Error Vector Phase error.

For example, to see the error-vector magnitude, select the Linear Mag trace format (Trace > Format > Format: Linear Mag). Selecting Linear Mag computes the square root of the sum of the squares for each complex pair of points in the time record, which is the error-vector magnitude (EVM):

Hint

If the Error Vector Time is different than expected, see the troubleshooting Tips in Troubleshooting, Digital Demodulation.


FSK Error Time (Digital Demodulation)

(Vector Signal Analyzer application only.)
(Available only when the digital-demodulation format is FSK.)

Menu Path: Trace > Data > FSK Error Time

When you select FSK error time, the analyzer displays the FSK error, time-domain trace. This trace is the result of computing the error from corresponding points in the FSK measured and FSK reference signals, as follows:

Because the FSK measured and FSK reference traces contain REAL data, not complex data, the FSK error trace is REAL, not complex.

If normalization is ON, the FSK error trace is normalized to the deviation. In other words, the FSK error is shown as a percentage of the deviation, as follows:

The analyzer uses the first point in the FSK measured and FSK reference signals to compute the first point in the FSK error trace. Then the analyzer uses the second point in each signal to compute the second point in the FSK error trace, and so forth.

Hint

To increase the resolution, increase the number of symbols (increase Result Length ).

It is important to remember that the FSK error time trace is a time record made up of REAL time-domain data. To make sense of the data, you must select an appropriate data format. For example, to see the FSK- error trace, select the Real(I) trace format.

Note

By default, normalization is ON and the y-axis units are displayed as a percentage. To see the instantaneous frequency, turn normalization OFF. For further details, see IQ normalize.


FSK Error Spectrum (Digital Demodulation)

(Vector Signal Analyzer application only.)
(Available only when the digital-demodulation format is FSK.)

Menu Path: Trace > Data > FSK Error Spec

When you select FSK error spectrum, the analyzer displays the spectrum of FSK error time. In other words, the analyzer derives the FSK error time trace, and then windows and FFTs this trace to produce the FSK error spectrum trace.

Additional Tips

Here's some additional information you may need to know:

•	The Result length determines the number of symbols in the FSK error trace. The Points/Symbol determines the number of points between symbols.

•	The analyzer compares all points in the FSK measured and FSK reference signals. To compare only those points at the symbol times, set Points/Symbol to one (1).

•	The band-power markers compute the error over all points in the FSK error trace. Again, to compute the error only at the symbol times, set Points/Symbol to one (1).


FSK Measured and FSK Reference Signals (Digital Demodulation)

(Vector Signal Analyzer application only.)
(Available only when the digital-demodulation format is FSK.)

Menu Path: Trace > Data > FSK Meas or FSK Ref

When FSK is selected, the analyzer's digital demodulator produces two signals:

•	FSK Measured

•	FSK Reference

The FSK measured signal is the measured signal that has been FM demodulated, filtered, carrier locked, and symbol locked.

The FSK reference signal is the signal that would result after demodulating your signal if your signal were ideal (contained no errors). It is the ideal signal against which the FSK measured signal is compared. The analyzer creates this signal from the detected bits (symbols).

Online help for FSK includes a block diagram that shows how FSK measured and FSK reference are generated.

Filtering

You can select different filters for the FSK measured and FSK reference signals. Use Measured Filter to select filtering for the FSK measured signal; use Reference Filter to select filtering for the FSK reference signal.

Time-Domain Displays

The FSK digital demodulator produces REAL time- domain data. If you select FSK measured time, the analyzer displays the FSK measured signal in the time domain. Likewise, if you select FSK reference time, the analyzer displays the FSK reference signal in the time domain.

If normalization is OFF, the analyzer displays the instantaneous frequency. If normalization is ON, the analyzer normalizes the FSK measured and reference traces to the deviation, which yields a unitless y-axis. For example, if normalization is ON, each point in the FSK measured trace is derived as follows:

The following parameters affect how the analyzer displays the FSK measured and FSK reference signals:

•	Result Length determines the number of symbols, which determines the length of the displayed trace.

•	Points/Symbol determines the number of points between symbols. Increase Points/Symbol to increase the resolution; decrease it to decrease the resolution.

Hint

The FSK demodulator produces real data; not complex data. Therefore, IQ diagrams display a horizontal line Because the imaginary part is zero. Likewise, selecting a trace format of Imag (Q) or Q-Eye also displays a horizontal line (zero).

Frequency-Domain Displays

If you select FSK measured spectrum, the analyzer displays the spectrum of the FSK measured signal. Likewise, if you select FSK reference spectrum, the analyzer displays the spectrum of the FSK reference signal. The analyzer produces the spectrum by windowing and FFTing the FSK measured or FSK reference signal.

If a measured filter is selected, the spectrum represents the signal AFTER filtering.

Hint

By default, the analyzer displays the log(dB) magnitude when you select FSK measured spectrum. The same is true for FSK reference.

The span for the displayed spectrum is a function of two parameters: the symbol rate and Points/Symbol, as follows:

Span-Demod is the span displayed when you select FSK measured spectrum or FSK reference spectrum.

It is possible to set the symbol rate and the Points/Symbol such that Span-Demod exceeds the information bandwidth (frequency span) of the analyzer. The following illustration shows the case where Span-Demod exceeds the frequency span.

The illustration shows an "x" in the region where Span-Demod exceeds the frequency span. Because the analyzer essentially filters out all information outside of the frequency span, the analyzer will not show information that may exist in this region.

Frequency-Domain Displays and Aliasing

It is important to know that the analyzer uses one sample rate to take data, and another (Sample_rate_demod) to display the demodulated data, as follows:

As shown, Frequency Span determines the sample rate used to take data, whereas the symbol rate and Points/Symbol determine the sample rate used to display demodulated data.

If the sample rate of the demodulator is less than that used to take data, the analyzer displays DATA? to inform you that the FSK measured and FSK reference spectrums may contain alias by-products.

Note

In summary, to avoid aliasing in the spectrum display, always set the frequency span, symbol rate, and Points/Symbol such that the sample rate of the demodulator equals or exceeds that used to acquire data.


Inst Err Vect Spec (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Inst Err Vect Spec

When Digital Demodulation is enabled, the Inst Err Vector Spec trace shows the instantaneous spectrum of the Error Vector Time trace. This is the non-averaged Error Vector Spec trace data.

The analyzer's digital demodulator removes carrier-frequency error. Therefore, in the error vector spectrum display, you must add the carrier-frequency error to marker readouts to obtain exact frequency information. The carrier-frequency error (Freq Err) is shown in the symbol table.

Note

The center frequency and span for error vector spectrum is identical to IQ measured spectrum. For details, see IQ Measured Time.


Inst IQ Meas Spec and Inst IQ Ref Spec (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path:	Trace > Data > Inst IQ Meas Spec

or Trace > Data > Inst IQ Ref Spec

When Digital Demodulation is enabled, the Inst IQ Meas Spec and Inst IQ Ref Spec traces are the instantaneous spectrum of the IQ Meas Time or IQ Ref Time signals. It is the non-averaged IQ Meas Spec and IQ Ref Spec trace data.

Note

The analyzer's digital demodulator removes carrier-frequency error. Therefore, in the error vector spectrum display, you must add the carrier-frequency error to marker readouts to obtain input signals frequency information. The carrier-frequency error (Freq Err) is shown in the symbol table.

See also

IQ Meas Time and IQ Ref Time


Inst Spectrum (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Inst Spectrum

When Digital Demodulation is enabled, the Instantaneous Spectrum trace is the frequency spectrum of the pre-demodulated time data. The time data is windowed and FFTed to create the Instantaneous Spectrum display.

If Pulse search is ON, spectrum trace data is the results of the pulse search.  If averaging is on, the Instantaneous Spectrum does not show the effects of averaging. To see the effects of averaging, use the Spectrum trace data.

The following block diagram is part of the Digital Demodulation Block Diagram and shows how the Instantaneous Spectrum is created.

Note

The Inst Spectrum trace is derived from pre-demodulated time data, which is 20% longer than the result length.


IQ Mag and IQ Phase Error (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > IQ Mag Error or IQ Phase Error

When Digital Demodulation is enabled, the IQ Mag Error and IQ Phase Error traces show the error between the I/Q measured and the I/Q reference signals. IQ Mag Error displays the magnitude error and IQ Phase Error displays the phase error.

If you select IQ Mag Error, the analyzer compares the magnitude, at the sampled symbol times, of the I/Q measured signal with the magnitude of the I/Q reference signal. The analyzer then displays the difference, in magnitude, between the two signals.

If normalization is OFF, the analyzer displays the instantaneous magnitude error. If normalization is ON, the analyzer displays the magnitude error as a percentage ( IQ Normalize on/off explains how this percentage is derived).

If you select IQ Phase Error, the analyzer compares the unwrapped phase, point-by-point, of the I/Q measured signal with the unwrapped phase of the I/Q reference signal. The analyzer then displays the phase difference between the two signals.

Note

IQ Mag Error and IQ Phase Error compare all points in the I/Q measured and I/Q reference signals. Likewise, if you are using band-power markers, the analyzer computes the error over all points in the I/Q error trace.

Note

For `EDGE` demodulation format the Magnitude/Phase Error data results may vary for different points/symbol settings.  When points/symbol is set to 1 (default), the trace data results are compensated for ISI (inter-symbol interference). For points/symbol greater than one, the trace data results are not compensated for the effects of ISI.


IQ Meas Spec and IQ Ref Spec (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > IQ Meas Spec or IQ Ref Spec

When Digital Demodulation is enabled, the IQ Meas Spec and IQ Ref Spec trace data is the frequency spectrum of the IQ Meas Time and IQ Ref Time trace data respectively. The analyzer produces the spectrum by windowing and FFTing the I/Q measured or I/Q reference data..

Note

The analyzer's digital demodulator removes carrier-frequency error. Therefore, in the error vector spectrum display, you must add the carrier-frequency error to marker readouts to obtain input signals frequency information. The carrier-frequency error (Freq Err) is shown in the symbol table.

If a measured filter is selected, the spectrum represents the signal AFTER filtering.

Tip

By default, the analyzer displays the data in log(dB) magnitude format. You can change the format in the Trace Properties dialog box [click Trace >.Format > Format select box]

The frequency span for the displayed spectrum is a function of two parameters: the symbol rate and Points/Symbol, as follows:

where: Span-Demod is the span displayed when you select IQ measured spectrum or IQ reference spectrum.

It is possible to set the symbol rate and the Points/Symbol such that Span-Demod exceeds the information bandwidth of the analyzer. The information bandwidth of the analyzer is set with frequency span.

The following illustration shows the case where Span-Demod exceeds analyzer measurement span.

The illustration shows an "x" in the region where Span-Demod exceeds the measurement span. Because the analyzer essentially filters out all information outside of span, the analyzer will not show information that may exist in this region.

Aliasing

It is important to know that the analyzer uses one sample rate to acquire data, and another sample rate (Sample_rate_demod) to display the demodulated data, as follows:

Sample Rate = 1.28 x [span]
Sample_rate_demod = (symbol rate) x (Points/Symbol)

As shown, the frequency span determines the sample rate used to acquire data, whereas the symbol rate and Points/Symbol determine the sample rate used to display demodulated data.

If the sample rate, of the demodulator, is less than that used to acquire data the analyzer displays DATA? to inform you that the I/Q measured and I/Q reference spectrums may contain alias by-products.

Note

In summary, to avoid aliasing in the spectrum display, always set the frequency span, symbol rate, and Points/Symbol such that the sample rate of the demodulator equals or exceeds that used to acquire data.

See also

IQ Meas Time and IQ Ref Time


IQ Meas Time and IQ Ref Time (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > IQ Meas Time or IQ Ref Time

When Digital Demodulation is enabled, the IQ Meas Time and IQ Ref Time trace data are the time data results of digital demodulation.  IQ Meas Time is the data results for the measured input signal.  IQ Ref Time trace data is the data results that would be derived from an ideal input signal (reference signal).

Concepts

For all demodulation formats except FSK, the analyzer's digital demodulator produces two signals: I/Q Measured and I/Q Reference.

I-Q measured signal

The IQ measured signal is the result of resampling the data to an integer number of points per symbol and applying carrier/symbol locking, IQ origin offset and amplitude droop compensation, system gain normalization, and filtering to the input signal. The filtering is user-selectable.

Note

DVB QAM does not compensate for IQ origin offset. FSK and MSK type 1 do not compensate for IQ origin offset or amplitude droop.

I-Q reference signal

A powerful analysis technique involves comparing a demodulated signal with an ideal signal generated from detected bits. The analyzer detects bits from the measured IQ signal and reconstructs a sequence of ideal I and Q states. These are then treated as ideal impulses and are baseband filtered according to a reference filter selected by the user. The resultant IQ reference can be overlaid or compared side-by-side with the IQ measured signal.

The reference filter can be selected independently from the measured signal (although the alpha/BT is the same for both filters). Therefore, you can apply different filters to the measured and reference signals to accommodate special test requirements.

Tip

Online help for Digital Demodulation includes a block diagram that shows how I/Q measured and I/Q reference are generated.

Special considerations for FSK demodulation

Separate I and Q signals do not exist for FSK demodulated signals. There is no phase information (the imaginary data is zero) because FSK demodulation performs FM demodulation on the input signal. Consequently, the FSK demodulator produces real rather than complex data. The display result is a baseband, single-sided spectrum and a time display representing frequency versus time.

Filtering

You can select different filters for the I/Q measured and I/Q reference signals. To do this, display the Digital Demodulation dialog box and choose a filter under Measurement Filter for the I/Q measured signal; choose a filter under Reference Filter for the I/Q reference signal.

Compensation

All demodulation schemes are performed with carrier lock, symbol lock, and filtering (if filtering is selected). In addition, all schemes (except those listed in the following Note) compensate for I/Q origin offset and burst amplitude-droop.

Note

DVB QAM does not compensate for IQ origin offset. FSK and MSK type 1 do not compensate for IQ origin offset or amplitude droop.

Compensation removes the effects of an error on the I/Q measured signal. For example, BPSK compensates for both I/Q origin offset and burst amplitude-droop, which means I/Q origin offset and burst amplitude- droop do not affect the I/Q measured signal.

Time-Domain Displays

The analyzer's digital demodulator produces time-domain data. If you select IQ measured time, the analyzer displays the I/Q measured signal in the time domain. Likewise, if you select IQ reference time, the analyzer displays the I/Q reference signal in the time domain.

The data can be displayed in a variety of trace data formats, including I-Q, Constellation, Q-Eye, I-Eye, and Trellis-Eye formats (see Trace Formats (Digital Demodulation)) topic.

If normalization is OFF, the analyzer displays the instantaneous magnitude. If normalization is ON, the analyzer scales the IQ measured and IQ reference traces to map them onto the unit circle, which yields a unitless y-axis.

Hint

For further details about normalization, see IQ Normalize.

The following parameters affect how the analyzer displays the I/Q measured and I/Q reference signals:

•	Result Length determines the number of symbols, which determines the length of the displayed trace.

•	Points/Symbol determines the number of points between symbols. Increase Points/Symbol to increase the resolution; decrease it to decrease the resolution.

Note

For `EDGE` demodulation format the IQ Meas Time, Magnitude/Phase Error and Summary Table data results may vary for different points/symbol settings.  When Points/Symbol is set to 1 (default), the trace data results are compensated for ISI (inter-symbol interference). For points/symbol greater than one, the trace data results are not compensated for the effects of ISI.

See also

IQ Meas Spec and IQ Ref Spec


Raw Main Time
Raw Main Time (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Ch1 > Raw Main Time

Raw Main Time is the raw data read from the input hardware or playback file. It is similar to Time data with the following exceptions:

•	This data has not had time corrections applied, so it displays a "CAL?" trace LED.

•	The data has not gone through the analyzer's software resampling filters, so is generally not sampled at the specified sample rate.

•	The data has a wider bandwidth than the measurement span would indicate.

Raw Main Time data is useful in the following situations:

•	When you use Channel, IF Magnitude, or Magnitude trigger types, the input hardware detects the trigger, so Raw Main Time sometimes gives a better indication of what caused the trigger.

•	When you play back a recording, the Raw Main Time measurement data allows you to see exactly the samples that are saved in the recording, with no filtering applied or settling removed.


Search Time (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Search Time

When Digital Demodulation is enabled and Pulse Search or Sync Search is ON, the Search Time trace shows time-data before pulse search and digital demodulation, as shown in the following block diagram. This trace is only available when pulse or sync search is on. This is the acquired input time data which we search in for a burst. The value of Search Length determines the length of the Search Time trace

Note

The following block diagram is part of the Digital Demodulation Block Diagram.


Spectrum (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Spectrum

When Digital Demodulation is enabled, the Spectrum trace is the averaged, Instantaneous Spectrum display, as shown in the following block diagram (the block diagram is part of the Digital Demodulation Block Diagram). If averaging is OFF, the Spectrum and Instantaneous Spectrum displays are identical.

The Spectrum trace has the following characteristics:

•	It is derived from pre-demodulated time data, which is 20% larger than the result length.

•	It is averaged if averaging is ON and the average type is RMS(Video), RMS(Video) Exponential, Time, Time Exponential or Continuous Peak Hold averaging.

Note

If averaging is ON, a scan is not included in the average if any of these conditions exist: Pulse Not Found, Sync Not Found, Carrier Unlock, or certain DATA? conditions.


Syms/Errs (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Syms/Errs

When Digital Demodulation is enabled, selecting the Syms/Errs trace data displays the symbol table. The symbol table shows you error information and the binary bits for each symbol. The first bit in the table corresponds to the first bit of the first symbol.

Go to the About the Symbol Table for more information.

See also

Symbol Table Error Summary Data

Alphabetical Listing: Symbol Table Error Summary Data


Time (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Time

When Digital Demodulation is enabled, the Time trace shows the time record before digital demodulation and after pulse search, as shown in the following block diagram. (The block diagram is part of the Digital Demodulation Block Diagram).

The Time trace has the following characteristics:

•	It is pre-demodulated time data. Because of this, it is 20% longer than the result length.

•	It is unaffected by time averaging.

•	It shows 10% of the result length before the demodulated segment and 10% after. Therefore, only the section between the first and last grid lines (x-axis) is demodulated, as shown in the following illustration.


IQ (Polar) Diagrams

(Vector Signal Analyzer application only.)

Menu Path: Trace > Format > Format box

Selecting the IQ trace format displays demodulated data using an IQ diagram (also called a polar or vector diagram). With an IQ diagram, the analyzer displays the in-phase signal (I) on the x-axis versus the quadrature-phase signal (Q) on the y-axis. The following information is provided:

•	How Vector Magnitude is determined

•	Interpreting Marker Information

•	Number of Display Points and viewing the IQ Diagram

•	Dots In the IQ Diagram

•	Modifying Colors

How Vector Magnitude is determined

Each point is represented as a vector: its magnitude is determined by its displacement from the origin; its phase is determined by its angle counterclockwise from the positive x- axis, as shown below.

Interpreting Marker Information

Marker readouts show magnitude and phase or real and imaginary values. Markers hold their frequency (or time) position when you change between IQ and other trace formats (except constellation diagrams that do not include sub-symbol samples).

Note

To substitute real and imaginary values for magnitude and phase values in the marker readout, click Markers, Position, and select Real & Imag for the Polar Format.

For IQ diagrams, the first marker readout is the magnitude, the next readout is the phase. If the marker's Polar Format is Real & Imag, the first marker readout is the x (or I) value, the next readout is the y (or Q) value.

Number of Display Points and viewing the IQ Diagram

Note

Number of Display Points does not apply to W-CDMA(3GPP) or cdma2000 demodulation.

For IQ diagrams, the number of display points per symbol is determined by the value of Points/Symbol. For example, if the value of Points/Symbol is 1, each display point corresponds to a symbol. If the value is 5, the 5th display point corresponds to a symbol—in this case, the IQ diagram would show 4 display points between each symbol.

You can see the effect of Points/Symbol by displaying the IQ diagram and pressing an arrow key or turning the mouse wheel to move the marker between symbols. If the number of points per symbol is 5, moving the marker would reveal four distinct display points between symbols.

Dots In the IQ Diagram

In an IQ diagram, you can highlight or unhighlight the symbols (detection decision-points). Toggle symbol to dots or bars to highlight the symbols (display them in a different color). Or, toggle symbol to none to unhighlight the symbols (display them in the same color as the trace).

Hint

The number of symbols in the IQ diagram is set by the Result Length (Digital Demod).or the Measurement Interval (W-CDMA(3GPP)/cdma2000)

Modifying Colors

You can modify the colors used to represent symbols. To do this, click Display, Appearance, and click the Color tab. Then select the appropriate color-element and select the desired color.

To change this color:	Modify this color element:
Symbol Color, Trace A	Symbol A
Symbol Color, Trace B	Symbol B
Symbol Color, Trace C	Symbol C
Symbol Color, Trace D	Symbol D


Constellation Diagrams

(Vector Signal Analyzer application only.)

Menu Path: Trace > Format > Format box

A constellation diagram is like an IQ diagram, but information is shown only at specified time intervals. The constellation diagram shows the IQ diagram only at points that correspond to the symbol clock times. These points are commonly referred to as detection decision-points, and are called symbols. Constellation diagrams help identify such things as amplitude imbalance, quadrature error, or phase noise.

Note

The constellation diagram is a time-domain display. If you select the constellation diagram for frequency-domain data, the analyzer displays the IQ diagram.

For Digital demodulation, you can define the bits that correspond to each symbol location. For details, see sync and state definitions.

In the constellation diagram, you can show the location of ideal states using crosshairs or circles. For details, see ideal state.

Note

Ideal States do not apply to composite time trace data for W-CDMA(3GPP) or cdma2000 demodulation.


Eye Diagrams (I-Eye or Q-Eye)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Format > Format box

Eye diagrams are commonly used in digital communication systems. Eye diagrams help identify problems such as ISI (Inter-symbol interference) and jitter. The following eye diagram information is provided:

•	General Information

•	Positioning of Eye Diagram

•	Eye Diagrams and Frequency-Domain Data

•	Width of Eye Diagrams

•	Eye Diagrams and Incorrect Symbol Timing

Note

W-CDMA and cdma2000 Composite Time trace data use chips and not symbols. So, for these trace data types, the following information still applies except that the you need to replace symbols with chips.

General Information

An eye diagram is simply the display of the I (real) or Q (imaginary) signal versus time that is triggered by the symbol clock.

The eye diagram is a superimposed display. For example, the analyzer draws the first trace, then overlays the second trace, the third trace, and so on until the number of symbols specified by Result Length (Digital Demod) (or by Meas Interval (W-CDMA/cdma2000) is displayed.

The second trace is a continuation of the first trace; the third trace is a continuation of the second trace, and so forth. In other words, the analyzer draws one trace to the end of the display, and then wraps it back to the beginning of the display to start the next trace.

To create a complete eye diagram, the I or Q signal must alternate between all states. The number of eyes (vertically) in the eye diagram indicates the number of states.

For example, if there are two states, one at 1 volt, and another at -1 volt, the eye diagram would have 1 eye: the top of the eye corresponds to the state at 1 volt, the bottom of the eye corresponds to the state at -1 volt. It is the degree to which the two signal levels are discernible at the clock instant that determines the clarity of the data in the eye diagram.

As is evident, there are m-1 eyes in an m-level system; where m is the number of states. In other words, if a vector modulation system has 4 states, its complete eye diagram would have 3 eyes—one above the other.

Positioning of Eye Diagram

The analyzer centers the eye diagram on the display such that the eye is in the center of the display. For example, if the length of the eye diagram is one symbol, the eye diagram is positioned on the x-axis between -1/2 symbol and +1/2 symbol.

In the eye diagram, the analyzer displays vertical lines at the symbol positions. Symbol positions are at the location where the maximum eye opening should occur, and correspond to the symbol clock.

Hints

For closer examination, set the eye length less than one (1).
The eye diagram for some modulation formats, such as MSK, look better when the eye length is odd (1, 3, etc.).

For Q-Eye on OQPSK signals, the symbol positions are offset from the display's center by 0.5 symbol. This looks best when the eye-length is an even number of symbols.

Eye Diagrams and Frequency-Domain Data

Eye diagrams are relevant only for time-domain data. If you select the eye diagram for frequency-domain data, the analyzer displays I versus time without superimposing the trace segments.

Width of Eye Diagrams

You can vary the width of the eye diagram by varying the Eye Length parameter (click Trace, Digital Demod). The width, in time, of the eye diagram is calculated as:

Note

Replace symbol rate with chip rate for W-CDMA and cdma2000 demodulation composite time trace data.

Eye Diagrams and Incorrect Symbol Timing

If the eye diagram shows incorrect symbol timing, see this topic for details: Troubleshooting, Digital Demodulation.


Trellis-Eye Diagrams

(Vector Signal Analyzer application only.)

Menu Path: Trace, Format, Format box

Trellis-eye diagrams are typically used to analyze the Minimum Shift Keyed (MSK) modulation format. The trellis diagram shows time on the x axis and unwrapped phase on the y axis. The following eye diagram information is provided:

•	General Information

•	Trellis Diagrams and MSK

•	Tips When Using Trellis Diagrams

•	Width of Trellis Diagrams

Note

W-CDMA and cdma2000 Composite Time trace data use chips and not symbols. So, for these trace data types, the following information still applies except that the you need to replace symbols with chips.

General Information

The trellis diagram is similar to an eye diagram in that it consists of superimposed traces. For example, the analyzer draws the first trace, then overlays the second trace, the third trace, and so on until the number of symbols specified by Result Length (Digital Demod) (or by Meas Interval (W-CDMA/cdma2000) is displayed.

The second trace is a continuation of the first trace; the third trace is a continuation of the second trace, and so forth. In other words, the analyzer draws one trace to the end of the display, and then wraps it back to the beginning of the display to start the next trace.

Here's some additional information you should know:

•	Most trellis diagrams seen in text books start midway between symbols. In this analyzer, trellis diagrams start at the first symbol. Furthermore, the analyzer wraps traces such that the trellis diagram begins within +/- 90 degrees.

•	For best results, set the eye length greater than or equal to four (4).

•	The vertical trace grid lines are located at the detection decision points (at the symbol positions).

Trellis Diagrams and MSK

The trellis diagram is especially useful for analyzing the Minimum Shift Keyed (MSK) modulation format.

With MSK, the symbols occur in 90 degree intervals, at 45 degrees, 135 degrees, 225 degrees, and 315 degrees. Each symbol represents one bit—a one (1) or zero (0). A positive, 90-degree phase change represents a one (1); a negative, 90-degree phase change represents a zero (0).

Therefore, with MSK, the trellis diagram shows a rising phase ramp if the bit is a one; it shows a negative phase ramp if the bit is a zero.

Tips When Using Trellis Diagrams

Here are some additional Tips to help you use and interpret trellis diagrams:

•	You can use Time Units to set the x-axis units in seconds or in symbols (W-CDMA and cdma2000 composite time trace data use chips).

•	You can use the arrow keys on the keyboard or the mouse wheel to examine transitions between symbols. Pressing the right-arrow key moves the marker forward in time (from one symbol to the next symbol). Pressing the left-arrow key moves it backward in time (from one symbol to the previous symbol).

•	Use the Offset marker to easily place the marker on any part of the trellis diagram. First turn on the offset marker and position it on the point of interest. Then select Move Offset to Mkr to quickly move the marker to the point nearest the offset marker.

Width of Trellis Diagrams

As with eye diagrams, you can vary the width of the trellis diagram. You vary the width of the trellis diagram the same way you do with an eye diagram—with Eye Length.

The Eye Length determines the width, in symbols, of the trellis diagram. If the value of Eye Length is 5, the trellis diagram is 5 symbols in width, and the width, in time, is calculated as:

Note

For W-CDMA and cdma2000 composite time trace data replace symbol rate with chip rate


Eye Length

(Vector Signal Analyzer application only.)

Menu Path: Trace, Digital Demod tab, Eye Length

The Eye Length parameter determines the length of eye diagrams and trellis diagrams when Digital Demodulation is selected. For details, see these topics:

•	Eye Diagrams

•	Trellis-Eye Diagrams

See also

Digital Demod Trace Data Property dialog box


Frequency Unit

(Vector Signal Analyzer application only.)

Menu Path: Trace > Digital Demod tab > Frequency Unit

Lets you select the x- or z-axis Frequency units that are applied to marker readouts for trace data results that use carrier information. The available measurement units are carrier or Hz.

For example, z-axis marker readouts for OFDM demodulation "Ch1 OFDM Err Vect Time" trace data can be viewed in units of carrier or Hz.

See also

Digital Demod Trace Data Property dialog box


Ideal State

(Vector Signal Analyzer application only.)

Menu Path: Trace > Digital Demod tab

Digital Demodulation shows you the location of all ideal states in an IQ or constellation diagram. The analyzer lets you choose between a cross, circle, or none to represent the ideal state on the trace.

Note

Ideal States are not shown for Composite Time trace data for W-CDMA or cdma2000 demodulation.

If you choose a cross, the ideal state occurs at the center of the cross. If you choose a circle, the ideal state occurs at the center of the circle.

The ideal state is where symbols occur if your signal is without error. Showing the ideal states gives a visual indication of the quality of your signal.

You can adjust the size of the ideal states. You can specify an ideal-state EVM (Error Vector Magnitude) from 0.1% to 50%. The value you enter determines the radius of the ideal-state circle or ideal-state crosshair.

You can use this feature to determine if symbols have an EVM above a specified value. For example, to see if any symbols have an EVM greater than 10%, set the state size to 10% and display the ideal state as a circle. Any symbols that fall outside of the circle (other than SYNC or PILOT symbols) have an EVM greater than 10%.

See also

Digital Demod Trace Data Property dialog box


Symbol Shape

(Vector Signal Analyzer application only.)

Menu Path: Trace > Digital Demod tab

Symbol Shape lets you display dots, bars, or nothing for symbol locations on the active trace (if the trace contains demodulated time-domain data).

For all time-domain displays except IQ diagrams, Symbol Shape lets you display dots, bars, or nothing (none) at symbol locations. If you select bars, vertical lines (bars) are drawn from the baseline to the symbol location on the trace. The baseline is 0 for all traces that have coordinates other than log (dB). The baseline is the bottom of the trace box for traces that have log (dB) coordinates.

With IQ diagrams, displaying vertical bars is meaningless. Therefore, selecting bars displays dots in IQ diagrams.

With constellation diagrams, selecting none is the same as selecting bars—you cannot turn off the dots in a constellation diagram.

Tip

To change the colors of the bars or dots at symbol locations, click Display, Appearance, and the Color tab. Then change the color for Symbol A, Symbol B, Symbol C, or Symbol D (Symbol A corresponds to symbols in trace A, Symbol B to symbols in trace B, and so forth).

See also

Digital Demod Trace Data Property dialog box


Points/Symbol

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Format tab

Points/Symbol determines the number of points displayed between symbols for digitally demodulated data.

Note

Points/Symbol do not apply to W-CDMA(3GPP) or cdma2000 demodulation.

• Minimum (except OQPSK):	1 point per symbol
• Minimum (OQPSK):	2 points per symbol
• Maximum:	20 points per symbol
• EDGE default (see below):	1 point per symbol
For example, if the value of Points/Symbol is 1, each display point corresponds to a symbol. If the value is 5, the 5th display point corresponds to a symbol—in this case, an IQ diagram would show 4 display points between each symbol, as shown in the following illustration.

	Points/Symbol = 5
	|     *         *         *         *       |    . .       . .       . .       . . V     |   .   .     .   .     .   .     .   .         |  .     .   .     .   .     .   .     .        | .       . .       . .       . .       .       |*         *         *         *         *       +-----------------------------------------                     Time
	* = Symbol locations    . = Points between symbols

You can see the effect of Points/Symbol by displaying the IQ diagram and pressing an arrow key (on the keyboard) or turning the mouse wheel to move the marker between symbols. If the number of points per symbol is 5, moving the marker would reveal four distinct display points between symbols.

Note

For details about IQ diagrams, see IQ (Polar) Diagrams.

Additional Details

Here are some additional details you may need to know:

•	Measurement Effects: For details about how Points/Symbol affects measurement data, see IQ measured Time.

•	Saving Points/Symbol: When you save a digitally, demodulated trace, the Points/Symbol used to create the trace is saved with the trace. When you recall the trace, the analyzer displays the trace with the Points/Symbol used to create the trace—the analyzer DOES NOT use the current value of Points/Symbol.

•	MSK Demodulation: For the MSK demodulation format, changing Points/Symbol affects the error data displayed in the Alphabetical Listing of Error Summary Data. This occurs because the analyzer uses all points to compute Error data results for MSK, whereas the analyzer uses only the points that occur at the symbol times to compute error data results for other demodulation formats.

•	OQPSK Demodulation: For OQPSK, an even number of Points/Symbol are required due to the offset between I and Q. If you specify an odd value for Points/Symbol, the analyzer chooses the next, lower, even value.

•	EDGE demodulation: For `EDGE` demodulation format and the Points/Symbol is set to 1 (default), the IQ Meas Time, IQ Magnitude Error, IQ Phase Error and Error Summary Table trace data results are the ISI (inter-symbol interference) compensated values. That is, when the points/symbol is set to 1 (default), the analyzer removes the effects of ISI (inter-symbol interference), which provides a "clean" IQ Meas Time constellation diagram. For points/symbol greater than one, the trace data results are not compensated for the effects of ISI. For values greater than 1 point/symbol, the symbols in EDGE constellation diagrams may appear randomly placed due to the effects of ISI.

•	Couple to Gain Imb./Quad Skew: This measurement parameter selection controls the number of points per symbol used to calculate the IQ Gain Imbalance and Quadrature Skew symbol error data results. See these topics for further information: Couple to Gain Imb./Quad Skew, IQ Gain Imbalance, and Quadrature Skew.


Time Unit

(Vector Signal Analyzer application only.)

Menu Path: Trace > Digital Demod tab

Lets you select the x- or z-axis Time units that are applied to marker readouts for trace data results that use symbol information. The available measurement units are sym (symbols) or sec (seconds).

For example, you can view the Meas Time trace data symbol locations for an EDGE demodulated signal in units of symbols or time.

Exception

For W-CDMA(3GPP) and cdma2000 demodulation the x-axis symbol unit is replaced with chip for marker readouts using the composite time trace data.

See also

Digital Demod Trace Data Property dialog box


About Adaptive Equalization
About Adaptive Equalization  (Digital Demodulation)

(Vector Signal Analyzer application only.)

Menu Path:  MeasSetup, Digital Demod, Compensate tab

Adaptive equalization removes linear errors from modulated signals by dynamically creating and applying a FIR (feed-forward) compensating filter. Linear errors can come from filters in a transmitter or receiver's IF, or from the presence of multiple paths in the transmission path, such as reflections in a cable system. These types of problems appear as group-delay distortion, frequency-response errors (tilt, ripple), and reflections or multipath distortion.

Equalization allows measurement of some impaired channels and can be used to isolate linear from non- linear error mechanisms. Equalization does not require symbol lock or prior knowledge of the signal (such as a training sequence) and is compatible with recorded data.

Filter Coefficients

By default, the equalization filter has a unit impulse response which yields a flat frequency response (only one tap in the filter has a non-zero value and data simply passes through the filter).  The position of the unit impulse is a function of the filter length and is positioned to provide the most optimum efficiency for most situations.  The position cannot be adjusted.

The equalization filter has a unit impulse response when you:

•	first run the application

•	reset the equalizer filter

•	change points/symbol.

•	change the measured or reference filter

•	change the symbol rate

•	change the clock delay adjustment

•	change the equalizer filter length

•	preset the application

Aside from the above conditions, the application uses the last computed coefficients when you enable equalization.  For example, if you used equalization in a previous measurement, the application uses the coefficients from the previous measurement unless you select reset the equalization filter or change [points/symbol].  Therefore, it is good practice to reset the equalization filter to initialize the filter coefficients before you start a measurement.

Important Concepts

The following paragraphs highlight important concepts about adaptive equalization:

•	Equalization is available most Digital Demodulation formats with the following exceptions:

−	Not available for FSK signals.

−	Not available for EDGE signals when the Measured Filter is set to EDGE(Windowed RC).  You can use the Equalization Filter when the Measured Filter is set to OFF.

•	The primary application of the equalizer's impulse-response display is for evaluating multi-path environments. Multi-path environments usually require longer filter lengths.

•	The primary application of the equalizer's frequency-response display is for evaluating the transmitter or receiver signal-path for errors such as passband ripple and group-delay distortion.  Short filter lengths usually work well for these types of measurements.

•	The analyzer estimates new filter coefficients with each measurement, and then uses the new coefficients to adapt the filter for the next measurement.

•	Generally, there is no advantage to using more than 2 points/symbol when using equalization.  You may want to use more than 2 points/symbol for better resolution of such displays as eye diagrams, but the tradeoff is slower measurement speed.

•	To see the channel frequency-response over the entire bandwidth of your signal, use 2 points/symbol or greater.  You cannot see the channel frequency-response over the entire bandwidth of your signal if you use 1 point/symbol.

See also

Using the Equalization Filter


Using the Equalization Filter

(Vector Signal Analyzer application only.)

Menu Path:  MeasSetup, Demod Properties, Compensate tab

Check the Equalization Filter checkbox to apply the analyzer's equalization filter to your measurement.

Note

Adaptive equalization uses the measured signal to determine the coefficients of the equalization filter.

When equalization is reset (see About Adaptive Equalization for conditions that reset the equalization filter), the equalization filter has a unit impulse response. The length of the filter determines the position of the unit impulse response in the filter. The impulse is located in the center of the filter for short filter lengths. As the filter length increases, the impulse moves, proportionally, towards the start of the filter to handle channels with large delay-spread.

If Adaptive is set to run, the analyzer uses the results of the current measurement to update the filter coefficients for the next measurement. The analyzer chooses coefficients that produce a modulation quality metric that is less impacted by the presence of linear distortion.

If Adaptive is set to hold, the analyzer does not update the filter coefficients. Instead, the analyzer uses the last updated coefficients before selecting hold.

You can select run or hold at any time to continue or stop updating filter coefficients.

Note that the analyzer does not redefine the equalization filter to have a unit impulse response when you select run or when you turn the equalization filter off and then on--instead, the analyzer uses the last updated filter coefficients.

Notes

You can select Reset Equalizer at any time to redefine the equalization filter to have a unit impulse response.

Equalization is applied to time-domain data. To see where equalization is applied, see the block diagram for [Digital Demodulation]--in this block diagram, equalization is applied in the time-domain corrections block.

Selecting a Frequency Span

For best results, make sure you select a frequency span that contains all energy of your signal. If significant energy from your signal falls outside of the displayed frequency span, equalization will not work on your signal.

Equalization Parameters

You can define the length of the equalization filter (in symbols) and set the convergence (convergence determines the size of the steps used to reshape the equalization filter). For additional details about these parameters, see online help for convergence and filter length.

Viewing Impulse Response or Frequency Response

You can view the impulse response or the frequency response of the equalized channel by clicking Trace, Data, and selecting [EQ Impulse Response] or [Ch Frequency Response].

Note

The analyzer applies the equalization filter to your measurement when you check the Equalization Filter checkbox. When you uncheck the checkbox, the filter still exists, and may be viewed, but is not used. The filter may be turned on and off without resetting the filter coefficients.

Equalization With Pulse and Sync Search (Digital Demodulation)

You can use equalization with pulse search and sync search. Note, however, that the adaptive equalizer does not update the filter coefficients when a "Pulse Not Found" condition exists. In other words, if pulse search is on and the measurement results in a "pulse not found" message, the results of that measurement will not affect the equalization filter coefficients.  The same is true if sync search is on and the measurement results in a "SYNC NOT FOUND" message.

Equalization and Measurement Speed

The following parameters affect measurement speed when using adaptive equalization:

•	result length

•	filter length (for the equalization filter)

•	points/symbol

See also

About Adaptive Equalization


Adaptive (equalization)

(Vector Signal Analyzer application only.)

Menu Path:  MeasSetup, Digital Demod, Compensate tab

Set Adaptive: to run to update the equalization filter with each measurement (the default). Set it to hold to stop updating the equalization filter.

Note

This parameter is available only when the Equalization Filter checkbox is checked.

The analyzer combines the previous measurement with the previous equalization filter coefficients to compute new filter coefficients. For the first measurement after the equalizatinon filter is reset, the analyzer defines the equalization filter to have a unit impulse response.

See also

About Adaptive Equalization.

Using the Equalization Filter


Filter Length (equalization)

(Vector Signal Analyzer application only.)

Menu Path:  MeasSetup, Digital Demod, Compensate tab

Default:	3 to 99 symbols, odd values only.

Range:	With first use, 21 symbols, otherwise, previous value.

The Filter Length parameter sets the filter length for the analyzer's equalization filter.

Note

This parameter is available only when the Equalization Filter checkbox is checked.

Selecting a Filter Length

In general, the best filter length is the smallest that meets your measurement requirements. For measurements at the transmitter, the filter length may only need to be a few symbols in length. Longer filter lengths may be needed to measure multi-path environments.

The number of symbols determines the maximum filter length that you can enter, as follows:

Filter Length ≤ [result length] − 2

For example, if the result length is 50 symbols, the maximum filter length is 47.

Filter Design

The filter length and points-per-symbol) determine the number of taps in the equalization filter, as follows:

Taps = [(filter length − 1) × (points per symbol)] + 1

The filter length also determines the placement of the impulse response in the equalization filter. For longer filter lengths, the analyzer puts the initial, unit impulse response closer to the beginning of the time record to accommodate multi-path measurements, as follows:

Filter Length	Unit Impulse Response Position
(symbol)	(symbol)
3 to 31	(length - 1)/2
31 to 75	15
75 to 99	(length)/5
For example, if the filter length is 11, the unit impulse response is positioned at symbol 5. If the filter length is 35, the unit impulse response is positioned at symbol 15.

Note

The analyzer places the unit impulse response at the position shown when you reset the equalization filter (About Adaptive Equalization tells you the conditions that reset equalization filter).

See also

About Adaptive Equalization

Using the Equalization Filter


Convergence (equalization)

(Vector Signal Analyzer application only.)

Menu Path:  MeasSetup, Digital Demod, Compensate tab

Nominal value:	1e-07
Step size (using arrow keys or mouse wheel): 1-2-5 sequence

Convergence determines the rate at which the equalization filter converges.

Note

This parameter is available only when the Equalization Filter checkbox is checked.

Convergence determines how quickly the equalization- filter coefficients converge to the estimated values for each measurement. Larger values converge faster. Values that are too large can cause the adaptation algorithm to become unstable or may cause the algorithm to fluctuate from stable to unstable--limiting the minimum EVM or SNR.

You can adjust the convergence while the adaptation algorithm is running. For example, the convergence may be increased to obtain faster convergence, and then decreased to obtain better results.

Hint

At the start of your measurement, set the convergence high to quickly shape the filter.  Then decrease the convergence to fine-tune the filter to the optimum shape.

The best value for convergence is affected by the following parameters:

•	Equalization filter length

•	Points-per-symbol

•	Modulation format

•	Result length

Normally, convergence values between 1e-7 and 1e-6 yield good results.

Hint

If the adaptation algorithm becomes unstable, reduce the convergence value and then reset the equalization filter. You can use the up/down arrow keys or mouse wheel to change the convergence in a 1-2-5 sequence.

See also

About Adaptive Equalization

Using the Equalization Filter


Reset Equalizer

(Vector Signal Analyzer application only.)

Menu Path:  MeasSetup, Digital Demod, Compensate tab

The analyzer defines the equalization filter to have a unit impulse response when you first turn-on equalization. If run is selected, the analyzer then reshapes the equalization filter after each subsequent measurement. You can click the Reset Equalizer button at any time to reset the equalization filter to a unit impulse response.  There are several conditions that automatically reset the equalization filter.  For details, see "Filter Coefficients" in About Adaptive Equalization.

Note

This button is available only when the Equalization Filter checkbox is checked.

Hint

Large convergence values may cause the adaptation algorithm to become unstable. If this happens, reduce the convergence, click Reset Equalizer to reset the filter, then resume your measurement.

See also

About Adaptive Equalization

Using the Equalization Filter


About Opt B7N: W-CDMA (3GPP) Demodulation

Option B7N: W-CDMA (3GPP) adds W-CDMA (Wideband Code Domain Multiple Access) demodulation capability to your 89600-Series application software. W-CDMA (3GPP) lets you measure W-CDMA modulated signals that are compliant to the following 3GPP Technical Specifications:

•	downlink (base station) TS 25.101 V3.2.2 (2000-04)

•	uplink (mobile station) TS 25.141 V3.2.0 (2000-04)

With W-CDMA you can descramble, despread and demodulate W-CDMA uplink and downlink signals. The analyzer will automatically identify all active channels regardless of the Symbol Rate or Spread Code Length.

W-CDMA (3GPP) provides various signal analysis capabilities including composite code domain power, composite time and channel specific analysis. Measurement results may be shown in several trace display formats as well as numeric error data formats. Flexible display scaling and marker functionality enhance these measurement capabilities.

The digital demodulator used in this analyzer incorporates advanced technology that does not require coherent carrier signals or symbol-clock timing signals. The analyzer has a built-in root raised-cosine filter, with user definable alpha (defines roll-off factor for chip shaping). Signal locking requires the carrier frequency, chip rate, uplink/downlink direction, sync type (CPICH/SCH) and scramble code to be set.

The digital demodulator uses the measured signal (called I/Q Meas Time) to generate an ideal signal (called IQ Ref Time). You can compare the measured signal to the reference signal to quantify and locate errors in your signal.

If you have an 89610 Vector Signal Analyzer, an optional second baseband channel allows IQ baseband measurement capability. You can also perform IQ baseband measurements on data that is from a file or the stream interface.

See also

W-CDMA(3GPP) Available features

Setting up a W-CDMA (3GPP) measurement

About 89600 Optional Measurement Software

Tutorials for WCDMA(3GPP)


Available Features (W-CDMA)

Features applicable to W-CDMA(3GPP) demodulation:

•	Standard presets for

−	W-CDMA (3GPP) Uplink (Mobile Station or User Equipment)

−	W-CDMA (3GPP) Downlink (Mobile Station)

•	3.84 MHz variable (user definable) chip rate

•	Single code domain layer or composite code-domain power and code-domain error displays (the composite display shows all code layers simultaneously). You can normalize code-domain power to display the code-domain power relative to the total signal power in the code domain.

•	Single channel time-domain displays, such as IQ measured, IQ reference, IQ magnitude/phase error, and error vector traces.

•	Composite time-domain displays, such as IQ measured time, IQ magnitude or phase error, and error Vector time traces.

•	Adjustable filter Alpha (default 0.22)

•	Mirrored (flipped) frequency spectrums can be used to remove the effects of high-side mixing.

•	Measurement offset and interval (similar to time gating) used to select specific data slots for analysis

•	Time gating is not available (does offer measurement offset/interval feature)

•	Averaging is available only for code domain trace data and is only applied to the numeric error summary data in the symbol table, as follows:

−	rms (video) - computes an average of each rms error update in the table.

−	rms exponential - is like rms (video) except that averaging continues past the average count with an exponential weighting.

−	continuous peak hold - keeps track of the peak rms error of each update in the table.

−	Time and time exponential averaging are not available.

•	Average types available for the pre-demodulated spectrum, code domain power and code domain error trace data results.

−	rms (video)

−	rms exponential

−	continuous peak hold)

•	Features that are applicable to Digital Demod but not available with W-CDMA demodulation:

−	Measurement/Reference filter

−	Pulse and Sync search

−	Equalization Filter

See also

89600-Series VSA Standard Features

About Opt B7N: W-CDMA(3GPP) Demodulation

Setting up a W-CDMA (3GPP) measurement

About VSA Optional Features


Setting up a W-CDMA(3GPP) Measurement

(Vector Signal Analyzer application only)

When setting up a digital demodulation measurement, there are several things you need to consider. This topic tells you how to connect your signal to an 89600-series analyzer and successfully demodulate digital signals. The information is provided in this order:

•	Connecting Your Signal to the Analyzer

•	Center Frequency

•	Frequency Span

•	Input 	Range:

•	Scramble Code

•	Uplink/Downlink Direction

•	Chip Rates, Symbol Rates and Spread Code Length

•	Result Length

•	Filtering

•	Mirrored Spectrum

•	Tutorials for WCDMA(3GPP)

Connecting Your Signal to the Analyzer

The analyzer lets you connect your carrier signal or, if your 89600-series analyzer has two input channels, the raw I (In-phase) and Q (Quadrature-phase) signals.

For all receiver configurations except I + jQ, connect your signal to Channel 1. In this case, the analyzer assumes that your signal contains both the I and Q components (the carrier signal). If your analyzer has two input channels, the analyzer ignores the second input channel.

If your analyzer has a second input channel, you can also connect the raw I (In-phase) and Q (Quadrature- phase) signals. To do this, select Input, Channels, I + jQ. With this configuration, the analyzer removes the quadrature mixer from the demodulator's signal flow, which lets you connect the I component of your signal to Channel 1; the Q component to Channel 2.

Notes

1) Selecting I+jQ turns on DC coupling.

2) When using I+jQ, use external calibration to correct for any offset or gain imbalance between the I and Q signals.

3) 	Range: for Channel 1 and Channel 2 are set independently.

Center Frequency

The analyzer's center frequency must be set within approximately ±500 Hz of the carrier frequency of the W-CDMA ((3GPP) signal, otherwise the analyzer may not be able to lock onto your signal.

For W-CDMA downlink with the "SCH" sync type, the center frequency may need to be within ±300 Hz of the carrier frequency.

Frequency Span

When selecting a frequency span, select the narrowest span that includes all of your signal components (select a span that is slightly larger than the bandwidth of your signal). If you select a span that is too narrow, your measurement may have excessive errors or the analyzer may lose carrier lock. If the span is less than the chip rate * (1+filter alpha), the analyzer shows "DATA?" to indicate that the results may not be accurate.

For best results, the frequency span should be set according to the following formula (filter alpha is the filter characteristic of the Nyquist filter used to demodulate the W-CDMA signal):

Frequency Span ≥ (1 + Filter alpha) × Chip Rate

If you select a span that is too wide, your measurement may be affected by excessive noise and slower speed.

Using the "Preset to Default" configuration settings will select a default span that should work well.

Input 	Range:

The input range must be set correctly to obtain accurate measurements. Input ranges that are too low overload the analyzer's ADC. Input ranges that are too high increase noise, which increases errors reported in error summary data, such as EVM.

Scramble Code

You must enter the scramble code to demodulate your W-CDMA signal.

Uplink/Downlink channel direction

The analyzer can demodulate both uplink and downlink W-CDMA signals. Therefore you must select the desired uplink or downlink direction. Downlink refers to the Base Station (or base station transceiver) and uplink refers to the mobile station (or User Equipment)

Chip Rates, Symbol Rates and Spread Code Length

To successfully demodulate W-CDMA signals, the analyzer chip rate must match the chip rate of your W-CDMA signal. The Spread Code Length determines the Symbol Rate per the following equation.

Symbol Rate = Chip Rate/Spread Code Length

CHIP RATE: 3.84 MHz

Spread Code Length (Symbol Rate)

(Downlink)	(Uplink)
4 (960 ksym/s)	4 (960 ksym/s)
8 (480 ksym/s)	8 (480 ksym/s)
16 (240 ksym/s)	16 (240 ksym/s)
32 (120 ksym/s)	32 (120 ksym/s)
64 (60 ksym/s)	64 (60 ksym/s)
128 (30 ksym/s)	128 (30 ksym/s)
256 (15 ksym/s)	256 (15 ksym/s)
512 (7.5 ksym/s)	-
Result Length

Result Length determines the amount of signal the analyzer demodulates in terms of the number of slots (or equivalent slot time). Make sure that the result length is long enough to capture all the desired data.

Result Length may be entered as an integer number of slots, frames or time. If you choose to enter seconds, the analyzer will automatically increment your entry as necessary to obtain an integer number of slots.

Filtering

For W-CDMA demod, the measurement filter is a root-raised cosine filter with user definable alpha capability (default alpha value = 0.22). This differs from the filtering capabilities available with either digital demod or Video demodulation. With those two demod types you had the option of selecting a measurement and reference filter, which is not available for W-CDMA demodulation (See the Digital Demod "About Filters topic).

Mirrored Spectrum

Wideband CDMA demodulation provides a feature that lets you configure the analyzer's demodulator to conjugate the complex time-domain waveform. This has the effect of flipping the spectrum around the analyzer's center frequency. This feature is useful when the W-CDMA signal is inverted, or flipped due to an IF down conversion.

See also

Measurement speed and resolution considerations

Selecting W-CDMA(3GPP) Demodulation

About Opt B7N: W-CDMA(3GPP) Demodulation

Troubleshooting W-CDMA

Tutorials for WCDMA(3GPP)


Measurement Speed Considerations

The primary factor in the measurement speed for W-CDMA(3GPP) measurements is the amount of input data that must be processed. Reducing the result length, by decreasing the number of slots, is the best way to increase speed. However, if the result length is too short, the data results may not be accurate. If the result length is less than 6 Slots the analyzer shows the "DATA?" error message.

See also

Setting up a W-CDMA(3GPP) Measurement

Troubleshooting W-CDMA


Selecting W-CDMA (3GPP) Demodulation

(Vector Signal Analyzer application with option B7N only)

Menu Path: MeasSetup, Demodulator, Cellular, W-CDMA (3GPP)

Sets analyzer to demodulate W-CDMA (3GPP) modulated signals (uplink and downlink) that are compliant to 3GPP Technical Specifications.

After selecting the demodulator you need to set the configuration parameters. You select one of the available Standard Presets or you can manually set them from the Demod Properties dialog box.

It's also recommended that you review the Setting up a W-CDMA(3GPP) Measurement topic before setting these parameters.

See also

Using Standard Presets

Setting up a W-CDMA(3GPP) Measurement

Tutorial for WCDMA(3GPP)


Using W-CDMA (3GPP) Standard Setup

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Format tab > Preset to Default button

Click Preset to Default to select a W-CDMA(3GPP) standard preset configuration. When you select a standard preset, the analyzer automatically sets the parameters shown in the following table:

•	Downlink: W-CDMA(3GPP) downlink signal (Base Station Transceiver)

•	Uplink: W-CDMA(3GPP) uplink signal (Mobile Station or User Equipment)

Note

The W-CDMA(3GPP) demodulator must be selected before these Standard Presets are available.

W-CDMA (3GPP) Standard Presets

Parameter	Downlink	Uplink
Chip Rate	3.84 MHz	3.84 MHz
Scramble Code	0	0
Scramble Code Offset	0	-
Scramble Code Type	Std	-
Sync Type	CPICH	-
Alpha	0.22	0.22
Mirror Frequency Spectrum	OFF	OFF
IQ Normalization	ON	ON
Spread Code Length/ Channel Symbol Rate	256/15 kHz	256/15 kHz
Code Channel	0	0
Result Length	15 slots (1 frames)	15 slots (1 frames)
Measurement Offset	0 slots	0 slots
Measurement Interval	1 slot	1 slot
I/Q Branch	-	Q
Code Order	Bit Reversed	Bit Reversed

Note: The dash "-" means the parameter does not apply.

See also

Setting up a W-CDMA(3GPP) Measurement

Troubleshooting W-CDMA(3GPP)


Troubleshooting (W-CDMA)

(Vector Signal Analyzer application only)

This topic contains information to help you troubleshoot measurements when using W-CDMA Demodulation. You should also review the "Setting up a measurement" topic for additional measurement information.

PROBLEM	POSSIBLE CAUSE	SOLUTION
Demodulation fails to lock-on signal	Signal not present.	Check test setup connections
	Carrier too far from center frequency.	1) Adjust center frequency to ± 500 Hz of the carrier frequency 2) For downlink measurements using the SCH SYNC type, adjust the center frequency to ± 250 Hz of the carrier frequency
	Input is over-loaded or under ranged.	Adjust input range
	Frequency span is too narrow.	Increase frequency span
	Incorrect chip rate.	Enter correct chip rate (not symbol rate or bit rate)
	Incorrect Scramble Code, Scramble Code Type or Scramble Code Offset.	Make sure that the VSA settings match the input signal parameters (MeasSetup > Demod Properties > Format tab).
	W-CDMA (3GPP) downlink SCH or CPICH channel is missing or the signal level is to low.	Verify that the signal includes either a SCH and CPICH channel and that the Sync Type parameter setting matches the channel type. Adjust the signal level as necessary
	W-CDMA (3GPP) uplink DPCCH channel is missing or power level to low.	Verify that the signal includes the DPCCH channel and that the power level is high enough.
	W-CDMA signal is inverted	Check the Mirror Frequency Spectrum setting (MeasSetup > Demod Properties > Format tab).
	I/Q offset too large	Reduce LO feedthrough (or DC offset for I+jQ receiver)
	Agilent ESG firmware needs to be upgraded. (Cause only applies if this ESG is used to generate the input signal).	Use firmware revision B.03.50 or newer to generate W-CDMA(3GPP) modulated signals.
	I/Q misaligned using I+jQ receiver	Ensure that ch1 and ch2 trigger delays are correct
Noise Floor increases at channel turn on.	The channel that you are turning on uses a different scramble code than that set in analyzer.	Change the scramble code used to transmit the channel to match that used by the PSCH/SSCH or CPICH channels.
Wrong channel marked as active	Poor SNR (signal to noise ratio).	Increase signal power or remove cause of noise/distortion.
	All bits not transmitted within a physical channel.	Transmit all bits within a physical channel, or select code-domain power for the layer associated with the physical channel of interest (single-layer code-domain power displays are accurate even if the analyzer is unable to identify active channels in the composite code-domain power display).
	Data pattern induces large disparity in power between slower channels overlaid by the channel of interest.	Verify that your transmitter is transmitting properly.
Tslot and Tframe or tDPCH is incorrect (DATA? error message is displayed in the symbol table).	Measurement Interval is less than 6 slots (fewer slots introduce a higher degree of false correlation on pilot and sync channels)	Select 6 or more Measurement Interval slots (MeasSetup > Demod Properties > Time tab)
See also

Setting Up a W-CDMA(3GPP) Measurement

Measurement speed and resolution considerations

About Opt B7N: W-CDMA(3GPP) Demodulation

VSA error and status messages

VSA Troubleshooting Topics


About Dialog Box and Tabs (W-CDMA(3GPP))

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties

The W-CDMA (3GPP) Demodulation dialog box contains parameters that let you configure the analyzer to descramble, despread and demodulate W-CDMA (3GPP) modulated signals.

Note

The W-CDMA(3GPP) demodulator must be selected before this dialog box is available To enable the demodulator, click MeasSetup, Demodulator, W-CDMA (3GPP).

The W-CDMA(3GPP) Demodulation Properties dialog box contains tab headings that group similar configuration parameters as follows:

•	Format tab: Lets you access the W-CDMA(3GPP) demod configuration parameters. These are the parameters necessary for the analyzer to lock on to and demodulate the test signal.

•	Channel/Layer tab: Lets you specify the measurement despread channel and CDP (code domain power) code layer.

•	Time tab: Lets you access the signal capture configuration parameters. You use these parameters to isolate a segment of the time record for further viewing and data analysis.

See also

Selecting W-CDMA(3GPP) demodulator

Setting up a W-CDMA(3GPP) Measurement

Troubleshooting W-CDMA(3GPP)

Tutorials for WCDMA(3GPP)


Channel/Layer tab (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties

The Channel/Layer tab parameters let you specify the measurement despread channel and CDP (code domain power) code Layer.

•	Despread Channel parameters: Despread Channel parameters specify the channel used for the channel measurement data results which include: Chan Error Vector, Chan IQ Meas Time, Chan IQ Ref Time, Chan Mag Error, Chan Phase Error and Chan Syms/Errs trace data (Click on the parameter name for further information):

−	Spread Code Length (Despread Channel)

−	Code Channel (Despread Channel)

−	IQ Branch.

•	CDP Layer parameters: CDP Layer parameters are used to specify the active (displayed) code domain layer for the Code Domain Power (CDP) Layer and Code Domain Error (CDE) Layer trace data (Click on the parameter name for further information):

−	Spread Code Length (CDP Layer)

See also

Format tab (W-CDMA(3GPP) Demodulation Properties)

Time tab (W-CDMA(3GPP) Demodulation Properties)

W-CDMA(3GPP) Demodulation Properties


Format Tab (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties

The Format tab of the W-CDMA(3GPP) Demodulation Properties dialog box lets you configure the analyzers W-CDMA(3GPP) demodulator. These are the parameters necessary for the analyzer to lock on to and demodulate the test signal:

The Format tab dialog box lets you configure these parameters (Click on the parameter for more information;

•	Alpha

•	Chip Rate

•	Direction

•	IQ Normalize

•	Mirror Frequency Spectrum

•	Preset to Default

•	Scramble Code

•	Scramble Code Offset

•	Scramble Code Type

•	Sync Type

See also

Channel/Layer tab (W-CDMA(3GPP) Demodulation Properties)

Time tab (W-CDMA(3GPP) Demodulation Properties)

W-CDMA(3GPP) Demodulation Properties


Time Tab (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup. Demod Properties

The Time tab of the W-CDMA Demodulation Properties dialog box lets you access the signal capture configuration parameters. You use these parameters to isolate a segment of the time record (captured input signal) for further viewing and data analysis.

The Time tab dialog box lets you configure these parameters (Click on the parameter name for further information):

•	Measurement Interval

•	Measurement Offset

•	Result Length

See also

About Measurement Interval

Format tab (W-CDMA(3GPP) Demodulation Properties)

Channel/Layer tab (W-CDMA(3GPP) Demodulation Properties)

W-CDMA(3GPP) Demodulation Properties


Parameter Interactions (W-CDMA)

(Vector Signal Analyzer application only)

When using W-CDMA (3GPP) demodulation, changing one parameter may necessitate changes in other parameters to achieve the desired measurement. For example,

•	Chip rate limits frequency span.

•	Minimum frequency span may limit the chip rate (this may occur when playing back a recording or analyzing data from the stream interface).

•	Measurement Interval and Measurement Offset are limited by the Result Length

•	Changing link direction changes the valid limits for many parameters

The following table shows how measurement parameters affect W-CDMA (3GPP) demodulation.

W-CDMA (3GPP) Demodulation Parameters

Time Sequence	Parameters Involved	Effect	Result	Notes
Signal setup	Range: Trigger Frequency/span Input Time Corrections	Sets up basic signal parameters required for digital demodulation	Raw data	Any changes made in the signal setup parameters later in the time sequence require that a new measurement be performed
Demodulation	Setup parameters: Chip Rate, Direction-Link, Scramble-Code, Scramble-Code-Offset, Scramble-Code-Type, Sync-Type.	Determines the type of demodulation performed on the input time data	Demodulated, symbol-locked data in the default display format	Result length determines the amount of data that is demodulated.
Post-demodulation	Meas Offset, Meas Interval, Channel Code, Channel Spread-Code-Length, CDP-Layer Spread-Code-Length.	Specifies channel and determines how much data is used for the trace data results.	Demodulated data in the default display format.	Changes may be made in the display parameters without acquiring a new measurement
Display Formatting	Trace data Trace format X and Y Scale Marker IQ Normalize	Formats the data for display	Formatted, demodulated data	Changes may be made in the display parameters without acquiring a new measurement
TIP

The following topics may help you optimize your measurements and explain the reasons for changes made automatically by the analyzer.

Display Limitations

Resolution Bandwidth

Span Considerations

Measurement Speed Considerations

See also

Setting up a W-CDMA(3GPP) Measurement

About Measurement interval and Offset


Display limitations (W-CDMA)

All W-CDMA Channel trace data is displayed at one Point-per-Symbol and all Composite trace data is displayed at one Point-per-Chip. This causes the bandwidth displayed for the Composite IQ Meas Spectrum, the Composite IQ Ref Spectrum and the Composite Error Vector Spectrum to be less than the analyzers span setting.

The following topics may help you optimize your measurements and explain the reasons for changes made automatically by the analyzer:

•	Resolution Bandwidth

•	Span Considerations

•	Measurement Speed and Resolution considerations

See also

Setting up a W-CDMA(3GPP) Measurement


Resolution Bandwidth (W-CDMA)

Resolution bandwidth (ResBW) in W-CDMA(3GPP) demodulation is determined automatically by the analyzer, and cannot be set independently. Resolution bandwidth is determined by the time record length as usual, according to the following formula:

However, in W-CDMA(3GPP) Demodulation the time record length is determined as follows (result length is in symbols):

The following topics may help you optimize your measurements and explain the reasons for changes made automatically by the analyzer:

•	Parameter Interactions

•	Display Limitations

•	Span Considerations

•	Measurement Speed Considerations

See also

About Resolution Bandwidth

Setting up a W-CDMA(3GPP) Measurement


Span Considerations (W-CDMA)

When selecting a frequency span, select the narrowest span that includes all of your signal components (select a span that is slightly larger than the bandwidth of your signal). If you select a span that is too narrow, your measurement may have excessive errors or the analyzer may lose carrier lock. If the span is less than (1+filter alpha)*chip rate, the analyzer shows "NO DATA?" to indicate that the results may not be accurate.

For best results, the frequency span should be set according to the following formula (filter alpha is the filter characteristic of the Nyquist filter used to demodulate the W-CDMA signal):

Frequency Span ≥ (1 + Filter alpha) * Chip Rate

If you select a span that is too wide, your measurement may be affected by excessive noise and slower speed. You may want to turn the demodulator OFF (MeasSetup, Demodulator, Demod OFF) and set the span while Viewing the spectrum of your signal.

Using the "Preset to Default" configuration settings will select a default span that should work well.

The following topics may help you optimize your measurements and explain the reasons for changes made automatically by the analyzer:

•	Parameter Interactions

•	Display Limitations

•	Span Considerations

•	Measurement Speed Considerations

See also

Setting Measurement Parameters

Setting up a W-CDMA(3GPP) Measurement

About Measurement interval and Offset


Chip Rate (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Format tab

Default: See W-CDMA(3GPP) Standard Presets Table

Range:: minimum span to (10 * maximum span)

Lets you set the Chip Rate for the analyzer's demodulator. This allows you the freedom to enter nonstandard chip rates for test and analysis purposes.

Note

To demodulate a signal, the chip rate must match the chip rate of your system.

The chip rate determines the symbol rate for each Spread Code Length per the following equation (See Chip Rate, Symbol Rate and Spread Code Table):

Symbol Rate = Chip Rate/(Spread Code Length)

The chip rate also limits the resolution bandwidth (See Resolution Bandwidth)

See also

Using a Standard Setup

Format tab - (W-CDMA(3GPP) Demodulation Properties)


Despread Channel Code Channel (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Channel/Layer tab.

Default: See W-CDMA(3GPP) Standard Presets Table

Range:: 0 to (Spread Code Length -1)

Lets you set the Code Channel. The Despread-Channel Code-Channel is used (along with the Despread-Channel Spread-Code-Length) to specify the channel used for the Chan Error Vector, Chan IQ Meas Time, Chan IQ Ref Time, Chan Mag Error, Chan Phase Error and Chan Syms/Errs trace data results (See Ch1 Chan Trace Data).

Tip

You can use the Copy Mkr To Despread Channel marker feature to automatically enter the Spread Code Length, Code Channel and IQ Branch setting.

See also

Ch1 Chan Trace Data

Available Chip Rates, Symbol Rates and Spread Code Length

Channel/Layer tab - W-CDMA(3GPP) Demodulation Properties


Direction (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Format tab

Default: See W-CDMA(3GPP) Standard Presets Table

Lets you select the signal direction. W-CDMA(3GPP) provides Downlink and Uplink demodulation capabilities:

•	Downlink (Base Station)

•	Uplink (Mobile Station)

See also

Format tab - (W-CDMA(3GPP) Demodulation Properties)

W-CDMA(3GPP) Demodulation Properties


IQ Branch (WCDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Channel/Layer tab

Default: See W-CDMA(3GPP) Standard Presets Table

The "I" and "Q" options control which IQ branch data bits are shown in the Channel Symbol/Errors trace data results.  The Uplink "I" and "Q" branches of each code channel are logically separate channels.

"I" option:   Selects I branch data results

"Q" option:  Selects Q branch data results

Note

This selection is available only for Uplink.

Tip

You can use the Copy Mkr To Despread Channel marker feature to automatically enter the Spread Code Length, Code Channel and IQ Branch setting.

See also

Channel/Layer tab - (W-CDMA(3GPP) Demodulation Properties)


Measurement Interval (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Time tab

Default: See W-CDMA(3GPP) Standard Presets Table

Lets you specify how much of the Result Length data is used for trace data results. Measurement Interval is entered as an integer number of time Slots. One time Slot is equal to 2560 chips and is equal to 666.7 µs at the default chip rate.

Measurement Interval and Measurement Offset parameters are used to specify what segment of the Result Length data is used for data analysis, See About Measurement Interval and Offset.

See also

Result Length

Measurement Offset

About Measurement Interval and Offset

Time tab - (W-CDMA(3GPP) Demodulation Properties)


Measurement Offset (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Time tab

Default: See W-CDMA(3GPP) Standard Presets Table

Lets you to set the number of Measurement Offsets in time slots. Measurement Offset determines the start position of the Measurement Interval with respect to first Slot within the Result Length. One time Slot is equal to 2560 chips and is equal to 666.7 µs at the default chip rate.

Measurement Interval and Measurement Offset parameters are used to specify what segment of the Result Length data is used for data analysis, See About Measurement Interval and Offset.

See also

Measurement Interval

Result Length

About Measurement Interval and Offset

Time tab - (W-CDMA(3GPP) Demodulation Properties)


Result Length (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Time tab

Default: See W-CDMA(3GPP) Standard Presets Table

Range: 1 to 64

Lets you specify the total amount of acquired and demodulated data in integer number of time slots.  One time Slot is equal to 2560 chips (666.7 µs at the default chip rate) and one frame is equal to 15 slots (10 ms at the default chip rate).

Result Length must be specified for an integer number of slots in units of slots, frames or time. The analyzer will adjust measurement time as necessary to obtain a Result Length that contains an integer number of slots including the specified time.

Tip

Result length is a primary factor determining measurement speed. Smaller result lengths increase measurement speed, but result lengths less than 6 Slots may cause inaccurate measurement results.

For more about this parameter, See About Measurement Interval and Offset.

See also

Measurement Offset

Measurement Interval

About Measurement Interval and Offset

Time tab - (W-CDMA(3GPP) Demodulation Properties)


Scramble Code (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Format tab

Default: See W-CDMA(3GPP) Standard Presets Table

Range::: Downlink: 0-511, Uplink: 0-16777215

Lets you specify the Scramble Code. The Scramble Code must match the test signal Scramble Code in order for the analyzer to lock to the signal.

See also

Format tab - (W-CDMA(3GPP) Demodulation Properties)

W-CDMA(3GPP) Demodulation Properties


Scramble Code Offset (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Format tab.

Default: See W-CDMA(3GPP) Standard Presets Table

Range:: 0-15 (downlink only)

Lets you specify the number of scramble code Offsets. The scramble code Offset must match the test signal scramble code Offset in order for the analyzer to lock to the signal. Only used for downlink signals.

See also

Scramble Code

Scramble Code Type

Format tab - (W-CDMA(3GPP) Demodulation Properties)

W-CDMA(3GPP) Demodulation Properties


Scramble Code Type (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Format tab.

Default: See W-CDMA(3GPP) Standard Presets Table

Lets you set the scramble code Type to either Std (standard), Left, or Right. The scramble code Type must match the test signal scramble code Type in order for the analyzer to lock to the signal. Only used for downlink signals.

See also

Scramble Code

Scramble Code Offset

Format tab - (W-CDMA(3GPP) Demodulation Properties)

W-CDMA(3GPP) Demodulation Properties


Despread Channel Spread Code Length (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Channel/Layer tab.

Default: See W-CDMA(3GPP) Standard Presets Table

Range:: 4 to 512 (Downlink) and 4 to 256 (Uplink) (See Chip Rate, Symbol Rate and Code Channel Table))

Lets you set the Despread Channel Spread Code Length. This code is also known as the Orthogonal Variable Spreading Factor (OVSF). The Despread Channel Spread Code Length is used (along with the Despread Channel Code Channel) to specify the channel used for the Chan Error Vector, Chan IQ Meas Time, Chan IQ Ref Time, Chan Mag Error, Chan Phase Error and Chan Syms/Errs trace data results (See Ch1 Chan trace data).

Note

The text box shows both the Spread Code Length (and the correlate Symbol Rate).

Selecting Despread Channel Spread Code Length

The drop-down list provides a list of available W-CDMA (3GPP) compliant Spread Code Lengths that you can select from. To set the Spread Code Length, click the text box down arrow, then click desired Spread Code Length.

Tip

You can use the Copy Mkr To Despread Channel marker feature to automatically enter the Despread-Channel Spread Code Length, Code Channel and IQ Branch settings.

Chip Rate, Symbol Rates, and Spread Code Lengths

The chip rate determines the symbol rate for each Spread Code Length, See Chip Rate, Symbol Rate and Spread Code Table) for more information.

See also

Ch1 Chan trace data

Using a Standard Setup

Channel/Layer tab - W-CDMA(3GPP) Demodulation Properties


CDP Layer Spread Code Length (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Channel/Layer tab.

Default: See W-CDMA(3GPP) Standard Presets Table

Range:: 4 to 512 (Downlink) and 4 to 256 (Uplink) (See Chip Rate, Symbol Rate and Spread Code Table))

CDP Layer Spread Code Length selects the active code domain layer (Spread Code Length) for the code domain power CDP Layer trace data (See Ch1 CDP Trace Data). This parameter has no other effect except for the display of the CDP Layer and CDE Layer trace data.

Note

The text box shows both the Spread Code Length and the correlate Symbol Rate (shown within the parenthesis).

Selecting a Spread Code Length

The drop-down menu provides a list of available W-CDMA (3GPP) compliant Spread Code Lengths that you can select from. To set the CDP Layer Spread Code Length, click the text box down arrow and click the desired spread code length.

Note

The Copy Mkr To Despread Channel marker does not automatically enter the CDP Layer Spread Code Length.

See also

CDP Layer Trace Data

Available Ch1 Chan trace data

Using a Standard Setup

Available Chip Rates, Symbol Rates and Spread Code Length

Channel/Layer tab - (W-CDMA(3GPP) Demodulation Properties)


Sync Type (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Format tab.

Default: See W-CDMA(3GPP) Standard Presets Table

Lets you set the downlink synchronization channel. The uplink synchronization channel is automatically set to the DPCCH channel.

•	CPICH (default): Common Pilot Channel (downlink only)

•	SCH: Synchronization Channel (downlink only)

See also

Format tab - (W-CDMA(3GPP) Demodulation Properties)

W-CDMA(3GPP) Demodulation Properties


About Measurement Interval and Offset
(W-CDMA, cdma2000 and 1xEV-DO demodulations)

Measurement Interval and Measurement Offset parameters are used to specify what segment of the Result Length data is used for data analysis.  This feature is applicable to W-CDMA(3GPP), cdma2000 and 1xEV-DO demodulation.

When the Measurement Interval or Offset parameters are changed, the analyzer computes the new trace data results from the current measurement data (Result Length data) and does not require a new measurement cycle.

Modulation Frame Structure

•	Result Length: Result Length specifies the total amount of acquired and demodulated data. Result Length can be entered as the number time Slots (W-CDMA and 1xEV-DO) or PCGs (cdma2000), the number of frames or the equivalent time. The Result Length must be entered as an integer number of slots (or PCGs) or frames. If you enter the result length in units of time, the analyzer will adjust time as necessary to obtain an integer number of slots (or PCGs).

Tip

Result length is a primary factor determining measurement speed. Smaller result lengths will increase the measurement speed, but result lengths less than 6 slots (or 6 PCGs) may cause inaccurate measurement results.

•	Measurement Interval: The Measurement Interval determines how much of Result Length data is used for trace data results.

•	Measurement Offset: The Measurement Offset determines the start position of the Measurement Interval within the Result Length.

•	Slot (W-CDMA): One W-CDMA(3GPP) time Slot is equal to 2560 chips (666.7 µs at the default chip rate) and one frame is 15 slots (10 ms at the default chip rate).

•	Slot (1xEV-DO)): One 1xEV-DO time Slot is equal to 2048 chips (1.667 ms) at the default chip rate and one frame is 16 slots (26.667ms).

•	PCG (cdma2000): One cdma2000 PCG ( Power Control Group) is equal to 1536 chips (1.25 ms at the default chip rate) and one frame is equal to 16 PCGs (20 ms at the default chip rate).

Not all trace data results use the measurement interval and offset parameters for computing and displaying measurement results. The following trace data results ignore these parameters and use only the first slot (or PCG) of measured data:

•	CDE Composite and CDE Layer trace data (See Ch1 CDP trace data (W-CDMA), Ch1 CDP trace data (cdma2000)) and Ch1 CDP trace data (1xEV-DO))

•	All Composite Time trace data (See Ch1 Comp trace data(W-CDMA)) , Comp trace data ( cdma2000) and Comp trace data (1xEV-DO)).

•	Composite Error Summary trace data (See About Comp Error Summary data (W-CDMA). About Comp Error Summary data (cdma2000) and Composite Error summary data (1xEV-DO)).

W-CDMA (3GPP) Parameter Links

•	Result Length (W-CDMA 3GPP)

•	Measurement Interval (W-CDMA 3GPP)

•	Measurement Offset (W-CDMA 3GPP)

cdma2000 Parameter Links

•	Result Length (cdma2000)

•	Measurement Interval (cdma2000)

•	Measurement Offset (cdma2000)

1xEV-DO Parameter Links

•	Result Length (1xEV-DO)

•	Measurement Interval (1xEV-DO)

•	Measurement Offset (1xEV-DO)

See also

Time tab - (W-CDMA(3GPP) Demodulation Properties)

Time tab - cdma2000 Demodulation Properties


About the Channel Symbol Table (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan > Syms/Errs

When W-CDMA (3GPP) Demodulation is enabled, selecting Ch1 Chan Syms/Errs trace data shows the symbol table and error summary trace data for the specified Code Channel and Spread Code Length. The bottom section of the display shows the symbol table data and the upper section shows the error summary data. This topic discusses the Symbol Table trace data, the Error Summary trace data is discussed in the About the Channel Error Summary trace data topic

The Ch1 Chan Symbol table shows the binary bits for each measured symbol in the specified Code Channel and Spread Code Length. These parameters are selected in the Despread-Channel Code-Channel and Spread-Code-Length text boxes, located in the W-CDMA (3GPP) Demodulation Properties dialog box (MeasSetup, Demod Properties, Channel/Layer tab).

The first bit in the table corresponds to the first bit of the first symbol. To make the table easier to read, the analyzer shows a fixed number of bits (eight), followed by a space.

For downlink signals, the symbol table has two bits per symbol containing both the "I" and "Q" data.

However, for Uplink signals, "I" and "Q" data channels are logically separate signals. All trace data contains both the "I" and the "Q" branches of the signal, except the symbol table data. For uplink signals, the symbol table has one bit per symbol. The bit is either from the "I" branch or the "Q" branch of the channel, as specified by the "IQ" Branch parameter (MeasSetup > Demod Properties > Channel/Layer tab).

In addition, the analyzer shows numbers to the left of each row. These numbers indicate the bit position of the first bit in the row. For example, if 192 is displayed by the third row, the first bit in the row is the 192nd bit in the digital data stream.

Hints

Here's an easy way to see the bits that correspond to a point in the channel constellation diagram: display the constellation diagram in one grid, the symbol table in another, and turn on the marker and marker coupling. When you place the marker on a point in the constellation diagram, the analyzer highlights the corresponding bits in the symbol table.

Use the arrow keys on the keyboard or the mouse wheel to move the marker from one symbol to the next. Or you can use the marker X Position to move to any symbol.

Error Summary Data Information

You can find more about the error summary data in About the Channel Error Summary Data.

See also

About the Channel Error Summary Data

About the Composite Error Summary Data


About Channel Error Summary Data (W-CDMA)

(Vector Signal Analyzer application only)

When W-CDMA (3GPP) Demodulation is enabled, selecting Ch1 Chan Syms/Errs trace data, shows the symbol table and error summary trace data for the specified Code Channel and Spread Code Length. The upper section shows the error summary data results and the lower section shows the symbol table. This topic discusses the Channel Error Summary data results, the Symbol table trace data is discussed in the About the Channel Symbol Table topic. The following Error Data topics are discussed and presented as listed:

•	Available Channel Error Summary Data (W-CDMA)

•	Selecting the Code Channel and Layer

•	Averaging and Error Data Results

•	Using Band Power markers to limit Error Information

•	How EVM and Magnitude Error data results are calculated (%RMS)

Available Channel Error Summary Data

See Alphabetical list of Channel Error Summary Data

Selecting Chan Error Trace Data

The Ch1 Chan Error Summary display shows the error data results for the specified Code Channel and Spread Code Length. These parameters are entered in the "W-CDMA (3GPP) Demodulation Properties" dialog box (MeasSetup > Demod Properties > Channel/Layer tab), Despread-Channel "Code Channel" and "Spread Code Length" text boxes.

Tip

You can use the Copy Mkr To Despread Channel marker feature to automatically enter the Despread-Channel Spread Code Length, Code Channel and IQ Branch settings.

Averaging and Error data results

If averaging is on, averaging is applied to most numeric error data in the error summary table with the following exceptions. The peak data values, such as peak EVM, peak Magnitude and peak Phase error are averaged only for the Continuous Peak Hold averaging type. The Slot number is never averaged.

Error data from the current scan is not included in the average if any of these conditions occur:

•	CARRIER LOCK?.

•	DATA? (if caused by a temporary condition like partial data record)

Using Band Power markers to limit Error Information

If you want error information for all points over a selected region, you can use the band-power markers with an error trace.

For example, here's how you could compute the phase error for all points within a region. Click Trace > Data > Chan IQ Phase Error to display the IQ phase-error trace, then click Markers > Calculation and select the Band Power check box to turn on the band-power markers.

Now position the band-power markers to select the region of interest, and select RMS Sqrt (Pwr) to display the phase error for the selected region.

Hint

At this point, you could simply click Trace > Data > Chan IQ Mag Error to display the magnitude error for the same region.

How EVM (%rms)and Magnitude Error (%rms) data results are calculated (%RMS)

In the channel error summary table, the analyzer shows the error-vector magnitude and magnitude error as a percentage. Before computing this percentage, the analyzer normalizes the constellation diagram such that the outer-most, ideal states have a magnitude of one.

The analyzer computes the overall, percent error by first computing the error-vector magnitude and magnitude error at each symbol time.

Next, the analyzer derives the rms average for each parameter. For example, to compute the rms average for the magnitude error, the analyzer takes the square root of the sum of the squares of the individual magnitude-error values at each symbol time.

Because the magnitude of the constellation diagram's outer-most state has been normalized to one, the rms average is the overall, percent error.

See also

About the Channel Symbol Table

About the Composite Error Summary Data

Ch1 Chan trace data


Alphabetical list of Channel Error Data (W-CDMA(3GPP))

(Vector Signal Analyzer application only)

The following is an alphabetical list of available Channel Error Summary data results (Trace, Data, Ch1 Chan Syms/Errs):

•	Chan EVM (Error Vector Magnitude)

•	Chan Magnitude Error (MagErr)

•	Chan Phase Error (Phase Err)

•	Chan Pilot Bits

•	Chan Slot

•	Chan tDPCH

For information about using error summary data with ADS, see Demod Errors and ADS.

See also

About Channel W-CDMA(3GPP) Error Summary Data


Chan EVM (W-CDMA(3GPP))

Chan EVM is the Error Vector Magnitude for the specified Code Channel and Spread Code Length. The display shows these EVM values; the RMS (root mean square in percent) EVM, the Peak (largest) EVM, and the symbol number with the Peak EVM.

Chan EVM is similar to digital demod EVM. See Digital Demod Error Vector Magnitude (EVM) for further information about this trace data.

See also

Digital Demod Error-vector magnitude (EVM)

About Channel W-CDMA(3GPP) Error Summary Data


Chan Magnitude Error (W-CDMA(3GPP))

Chan Magnitude Error (MagErr) is the difference in amplitude between the I/Q measured signal and the I/Q reference signal for the specified Code Channel and Spread Code Length.

Magnitude error is an indicator of the quality of the amplitude component of the modulated signal. For example: a very high magnitude error might indicate high incidental AM modulation on the signal.

The display shows these Magnitude error values; the RMS (root mean square) Magnitude Error, the Peak (largest) Magnitude Error, and the symbol number with the Peak Magnitude Error.

Hint

The description of Error-vector magnitude (EVM) includes a pictorial diagram that shows how Magnitude Error is derived.

See also

Digital Demod Error-vector magnitude (EVM)

About Channel W-CDMA(3GPP) Error Summary Data


Chan Phase Error ( W-CDMA (3GPP))

Chan Phase error is the difference, in phase, between the I/Q reference signal and the I/Q measured signal for the specified Code Channel and Spread Code Length.

The magnitude of this parameter is an indicator of the quality of the phase component of the modulated signal. For example, a very high phase error might indicate high incidental FM modulation on the signal.

The display shows these Phase error values; the RMS (root mean square) Phase Error, the Peak (largest) Phase Error, and the symbol number with the Peak Phase Error.

Hint

The description of Digital Demod Error-vector magnitude (EVM) includes a pictorial diagram that shows how Phase Error is derived.

See also

Digital Demod Error-vector magnitude (EVM)

About Channel W-CDMA(3GPP) Error Summary Data


Chan Pilot Bits (W-CDMA(3GPP))

Chan Pilot Bits (PilotBits) shows the number of Pilot Bits detected in the DPCH channel for the specified Code Channel and Spread Code Length. Pilot Bits only apply to Downlink signals, there are no pilot bits for Uplink,

See also

About Channel W-CDMA(3GPP) Error Summary Data


Chan Slot (W-CDMA(3GPP))

Identifies the first time Slot used in the measurement for the specified Code Channel and Spread Code Length. The channel slot is offset from the Composite slot by the Measurement Offset parameter.

See About Measurement Interval and Offset for more information about Slot, Result Length, Measurement Interval and Measurement Offset interaction.

See also

Comp Slot (Power Control Group) Error Data

Time tab - (W-CDMA(3GPP) Demodulation Properties)

About Channel W-CDMA(3GPP) Error Summary Data


Channel tDPCH for W-CDMA(3GPP)

This is the timing value for the DPCH channel for the specified Code Channel and Spread Code Length. tDPCH only applies to Downlink signals

The tDPCH value is the time offset between the CPICH and the selected DPCH channel. The value is in units of 256 chips. The maximum offset is one frame, so tDPCH can have values between 0 to 149.

See also

About Channel W-CDMA(3GPP) Error Summary Data


About the Composite Error Summary Data (W-CDMA)

(Vector Signal Analyzer application only)

When W-CDMA(3GPP) Demodulation is enabled, selecting the Ch1 Comp, Error Summary trace data shows the composite error summary data. The error summary display shows you error information for the composite signal. See Alphabetical list of Composite Error Summary Data.

Composite error summary data is always computed from the first Slot in the measurement and ignores the measurement-offset parameter.

There is also channel error summary trace data (Ch1 Chan, Syms/Errs), which provides the error information for a specific code channel and code layer (See About Channel Error Summary Data).

See also

About Channel Error Summary Data

Ch1 Comp trace data

About Measurement Interval and Offset


Alphabetical list of Composite Error Data

(Vector Signal Analyzer application only)

The following is an alphabetical list of available Composite Error Summary data results (Trace, Data, Ch1 Comp, Error Summary):

•	Comp EVM (Error Vector Magnitude)

•	Comp Frequency Error (Freq Err)

•	Comp IQ Offset

•	Comp Magnitude Error (MagErr)

•	Comp Peak Active CDE

•	Comp Peak CDE

•	Comp Phase Error (Phase Err)

•	Comp Rho

•	Comp Slot

•	Comp T trigger

For information about using error summary data with ADS, see Demod Errors and ADS.

See also

About composite Error Summary Table


Composite Error Vector Magnitude (W-CDMA(3GPP))

Composite EVM is the Error Vector Magnitude for the composite signal. The display shows these EVM values; the RMS (root mean square) EVM, the Peak (largest) EVM, and the symbol number with the Peak EVM.

A perfect ideal signal is synthesized at the chip level and identified as the reference signal. The reference signal is subtracted from the measured signal to produce a time record of error phasors. The square root of the ratio of the mean power of the error signal to the mean power of the reference signal is computed and expressed as a percentage EVM.

This parameter is similar to digital demodulation EVM except that it is computed at the chip rate instead of the symbol rate. See Digital Demodulation Error-Vector Magnitude (EVM) for further information about this parameter.

See also

Digital Demodulation Error-Vector Magnitude (EVM)

About Composite Error Summary Table


Composite Frequency Error (W-CDMA(3GPP))

Composite Frequency Error (Freq Err) shows the composite signal carrier frequency-error relative to the analyzer's center frequency. This parameter is displayed in Hertz and is the amount of frequency shift, from the analyzer's center frequency, that the analyzer must perform to achieve carrier lock.

Errors in RF frequency, LO frequency, or digitizer clock rate could all appear as carrier frequency error.

See also

About Frequency

About composite Error Summary Table


Composite IQ Offset (W-CDMA(3GPP))

Composite IQ Offset (also called I/Q origin offset) indicates the magnitude of the carrier feedthrough signal. When there is no carrier feedthrough, IQ offset is zero (-infinity dB).

This parameter is the same as the digital demod IQ Offset except that the source data is the composite signal. See digital demod IQ Offset for further information about this parameter.

See also

Digital Demod IQ Offset

About composite Error Summary Table


Composite Magnitude Error (W-CDMA(3GPP))

Composite Magnitude Error (MagErr) is the difference in amplitude between the I/Q measured signal and the I/Q reference signal for the composite signal.

The display shows these Magnitude error values; the RMS (root mean square) Magnitude Error, the Peak (largest) Magnitude Error, and the chip number with the Peak Magnitude Error.

This error data is the same as the channel Magnitude Error except that the source data is the composite signal. See Channel Magnitude Error for further information about this parameter.

See also

Channel Magnitude Error

About composite Error Summary Table


Composite Peak Active CDE ( W-CDMA(3GPP))

Composite Peak Active CDE is the largest active code channel - Code Domain Error. This is the largest measured CDE for all active code channels in the composite signal.

Note

Code channel is the W-CDMA - Code Channel and code layer is the Spread Code length (or symbol rate).

See also

CDE Composite trace data

CDE Layer trace data

About Composite Error Summary Table


Composite Peak CDE (W-CDMA(3GPP))

Composite Peak CDE is the largest measured code channel - Code Domain Error.

Downlink Direction: This is the largest measured CDE for all code channels (active and inactive) in code layer S256 (15.0 ksym/sec symbol rate) in the composite signal.

Uplink Direction: This is the largest measured CDE for all code channels (active and inactive) in code layer S4 (960.0 ksym/sec symbol rate) in the composite signal.

Note

Code channel is the W-CDMA - Code Channel and code layer is the Spread Code length (or symbol rate).

See also

CDE Composite trace data

CDE Layer trace data

About Composite Error Summary Table


Composite Phase Error (W-CDMA(3GPP))

Composite Phase error is the difference, in phase, between the I/Q reference signal and the I/Q measured signal for composite signal.

The display shows these Phase error values; the RMS (root mean square) Phase Error, the Peak (largest) Phase Error, and the chip number with the Peak Phase Error.

Note

Composite denotes trace data results for the composite signal (includes all Spread Code Lengths (Symbol Rate) and Code Channels).

This parameter is the same as channel Phase error except that the source data is the composite signal. See Channel Phase error for further information about this parameter.

See also

Channel Phase error

About Composite Error Summary Table


Composite Rho (W-CDMA)

Rho is the normalized correlation coefficient between the measured and ideal reference signals. Rho is computed by comparing the normalized correlated power between the measured signal and the reference signal and is designated as the waveform quality factor. The maximum value of Rho is 1.0 (which means the measured signal and reference signal are 100% identical).

A Rho value of 1.0 indicates that all of the transmitted power correlates with the ideal signal as determined by the detected sequence.

Rho is the correlated power for all active code channels (as seen in the composite CDP trace data display).

If the signal errors are uniformly distributed, then Rho approximately equals:

See also

About Composite Error Summary Table


Composite Slot for W-CDMA(3GPP)

This parameter identifies the first time Slot used in the measurement for the composite signal. The composite Slot ignores the measurement offset, which is different than Channel Slot, which uses the measurement offset.

Go to the About Measurement Interval and Offset topic for more information about Slot, Result Length, Measurement Interval and Measurement Offset interaction.

See also

Time tab - (W-CDMA(3GPP) Demodulation Properties)

About Channel W-CDMA(3GPP) Error Summary Data

About Composite Error Summary Table


T trigger

T-trigger shows the amount of time, in chips, from the trigger to the start of the frame. If you select a trigger that starts measuring at the beginning of a frame, T trigger would be 0 chips.

See also

About Measurement Interval topic

Comp Slot trace data

About Composite Error Summary Table


About Trace Data (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data

This application provides trace data in the Time Domain, Frequency Domain and Code Domain.  You can view code domain power (CDP) trace data for the composite signal or for a specific CDP layer (Symbol Rate). Time domain trace data may be viewed for the composite signal or for a specific code channel. Time and spectrum trace data is also provided for the pre-demodulated and the demodulated input signal.

Composite Trace Data

Composite (or Comp) trace data are measurement results derived from the total signal. This includes the combined data from all code Layers (Spread Code Lengths (Symbol Rates)) and code channels (Code Channel)s).

Chan Trace Data

Channel (or Chan) trace data are measurement results derived from a single code channel (Code Channel) within the measured code layer (Spread Code Length (Symbol Rate)).

CDP Trace Data

CDP (code domain power) trace data is provided for both Layer specific data and Composite data.   CDP Layer trace data results include data from all code channels within one specified code layer (Spread Code Length (Symbol Rate)).  CDP Composite trace data results are for the total signal, includes data from all code channels and code layers.

Trace Data Menu

To accommodate all the available measurement results and display formats; trace data results are grouped into trace data sub-menu categories. These sub-menu categories are grouped together by common measurement types as described below:

Ch1 trace data:	Time and frequency trace data results derived from the pre-demodulated data.
Ch1: CDP trace data:	CDP (Code Domain Power) and CDE (Code Domain Error) trace data results for either the composite signal or for a specified code layer.
Ch1: Chan trace data:	Time domain trace data results for a single code channel.  "Chan" (Channel) trace data results are derived from data for a single code channel (Code Channel) within a specified code layer (Spread Code Length/Symbol Rate).
Ch1 Comp trace data:	Time domain and frequency domain trace data results for the Composite signal.  Composite trace data results are derived from data for the total signal. This includes the combined data from all Spread Code Lengths (or Symbol Rates) and Code Channel)s.
Math	Trace data results derived from a math function
Register	Trace data results derived from Data Register data
No Data	Active trace as empty.
See also

89600-Series VSA Standard Measurement Data

About Channel Error Summary data

About Composite Error Summary data


Ch1 Trace Data (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1

Time and frequency trace data results derived from the pre-demodulated channel 1 input data (Time Record data).

Available Ch1 Trace Data

Correction
Inst spectrum
Raw Main Time
Spectrum
Time
See also

Ch1: CDP trace data

Ch1 Chan trace data

Ch1 Comp trace data

About Trace Data (W-CDMA)


Ch1 CDP Trace Data (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP

CDP (Code Domain Power) and CDE (Code Domain Error) trace data results for either the composite signal or for a specified code layer.  Code Domain Power (CDP) is an analysis of the distribution of signal power across the set of code channels normalized to the total signal power.

•	CDP Composite Trace Data:    This is the CDP (Code Domain Power) and CDE (Code Domain Error) trace data results for the composite signal.  Composite trace data results are derived from data for the total signal. This includes the combined data from all Spread Code Lengths (or Symbol Rates) and Code Numbers.

•	CDP Layer Trace Data:    This is the CDP (Code Domain Power) and CDE (Code Domain Error) trace data results for a specified code layer.  You use the CDP Layer Spread Code Length drop-down list to specify the code layer (MeasSetup > Demod Properties… >  Channel/Layer tab).

Note

You can view CDP as absolute power by clearing the IQ Normalize check box (MeasSetup > Demod Properties > Format tab).

Display Format

Note

For CDP and CDE trace data displays with separate I/Q channel trace bars, to position the Marker to the desired Code Layer/Channel bar, you must click in close proximity to the horizontal bar that indicates the value of the code channel being measured.

The data is shown in a multi-color format that assigns a unique color to each code layer and related active code channels. This makes it easy to visually identify and distinguish the active Code Channels for a given code layer (Spread Code Length). The colors are also user definable (See Display Appearance).

Available Ch1 CDP Trace Data

CDE Composite	Inst CDE Composite
CDE Layer	Inst CDP Composite
CDP Composite	Inst CDE Layer
CDP Layer	Inst CDP Layer
See also

About Trace Data (W-CDMA(3GPP))

Ch1 trace data

Ch1 Chan trace data

Ch1 Comp trace data


Ch1 Chan Trace Data (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan

Time domain trace data results for a single code channel (Code Channel) within a specified code layer (Spread Code Length/Symbol Rate). This includes both time domain IQ trace data and Symbol/Error table data.

For W-CDMA(3GPP) reverse link, the "I" and "Q" branches are logically separate signals. All channel trace data results contain both I and Q branch data, except symbol table trace data. The symbol table shows either the "I" symbol bits or the "Q" symbol bits as determined by the I/Q branch setting.

Selecting a Code Channel

You specify the code channel in the Despread Channel Code Channel) drop-down list and the code layer in the Despread Channel Spread Code Length drop-down list. (click MeasSetup > Demod Properties > Channel/Layer tab).

Tip

You can use the Copy Mkr To Despread Chan marker feature to automatically enter the Spread Code Length and Code Channel information for you.

Available Ch1 Chan Trace Data

Chan Error Vector Time	Chan IQ Phase Error
Chan IQ Mag Error	Chan IQ Ref Time
Chan IQ Meas Time	Chan Syms/Errs
See also

About Trace Data (W-CDMA(3GPP))

Ch1 trace data

Ch1: CDP trace data

Ch1 Comp trace data


Ch1 Comp Trace Data (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp

Time domain and frequency domain trace data results for the Composite signal.  The Composite signal includes data for the total signal, that is, the combined data from all code channels and layers. All composite trace data results are computed from the first time slot. The Measurement Interval and Measurement offset parameters are ignored for composite trace data results.

Available Ch1 Comp Trace Data

Comp Error summary	Comp IQ Phase Error
Comp Error Vector Spec	Comp IQ Ref Spec
Comp Error Vector Time	Comp IQ Ref Time
Comp IQ Mag Error	Comp Inst Error Vector Spec
Comp IQ Meas Spec	Comp Inst IQ Meas Spec
Comp IQ Meas Time	Comp Inst IQ Ref Time
See also

About Trace Data (W-CDMA(3GPP))

Ch1 trace data

Ch1: CDP trace data

Ch1 Chan trace data


CDE Composite (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP > CDE Composite

Shows the Code Domain Error (CDE) value for each active code channel for all code layers (Spread Code Lengths), along with the CDE value for each inactive code channel at the lowest code layer.  The CDE of a particular code channel is a measure of the error power in a code channel relative to the total signal power.

Note

CDE Composite trace data results are computed only from the first measured slot. This is different than CDP Composite trace data results, which can include more than the first slot in the measurement results.

Display Format

The data is shown in a multi-color format that assigns a unique color to each code layer and then fills each related active code channels with the same color. This makes it easy to visually identify and distinguish the active code channels for a given code layer (Spread Code Length). The colors are also user definable (See Display Appearance).

Note

For CDP and CDE trace data displays with separate I/Q channel trace bars, to position the Marker to the desired Code Layer/Channel bar, you must click in close proximity to the horizontal bar that indicates the value of the code channel being measured.

Tip

You can use the CDE Layer trace datamnu_TrDataCh1CDP_CDELayer_WCDMA display to view only one code layer (Spread Code Length or Symbol Rate) at a time.

See also

CDE Layer trace data

CDP Composite trace data

Available Ch1 CDP trace data

About W-CDMA(3GPP) trace data


CDE Layer (W-CDMA(3GPP))

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP > CDE Layer

Shows the Code Domain Error (CDE) value for each code channel within the specified code layer (Spread Code Length).  The CDE of a particular code channel is a measure of the error power in a code channel relative to the total signal power.

Note

CDE Layer trace data results are computed only from the first measured slot. This is different than CDP Layer trace data results, which can include more than the first slot in the measurement results.

Display Format

The data is shown in a multi-color format that assigns a unique color to each code layer and related active code channels. This makes it easy to visually identify and distinguish the active code channels (Code Channel) for a given code layer (Spread Code Length). The colors are also user definable (See Display Appearance).

Note

For CDP and CDE trace data displays with separate I/Q channel trace bars, to position the Marker to the desired Code Layer/Channel bar, you must click in close proximity to the horizontal bar that indicates the value of the code channel being measured.

Selecting a Code Layer

You select the desired code layer by selecting a Spread Code Length from the CDP Layer Spread Code Length drop-down list (MeasSetup > Demod Properties.. > Channel/Layer tab).

See also

CDE Composite trace data

CDP Layer trace data

Available Ch1 CDP trace data

About W-CDMA(3GPP) trace data


CDP Composite (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP > CDP Composite

Shows the Code Domain Power trace data for the composite signal.  Code Domain Power (CDP) is an analysis of the distribution of signal power across the set of code channels normalized to the total signal power. If the Measurement Interval is greater than one, all Slots within the Measurement Interval are averaged together to produce the CDP Composite results.

TIP

You can view CDP trace data as absolute power by clearing the IQ Normalize check box (MeasSetup, Demod Properties, Format tab).

Display Format

The data is shown in a multi-color format that assigns a unique color to each code layer and related active code channels. This makes it easy to visually identify and distinguish the active code channels (Code Channel) for a given code layer (Spread Code Length). The colors are also user definable (See Display Appearance).

Note

For CDP and CDE trace data displays with separate I/Q channel trace bars, to position the Marker to the desired Code Layer/Channel bar, you must click in close proximity to the horizontal bar that indicates the value of the code channel being measured.

The y-axis shows the power level and the x-axis shows the Code channel. The x-axis annotation and marker location are based on the lowest symbol rate (ksym/sec), or equivalently, the highest spread code length. You can also use the code order format parameter to rearrange the placement the displayed Code Channels (See Code Order)

This example Ch1 Composite CDP display Trace A Marker shows the following:

Symbol Rate:	30 Ksym/s
Spread Code Length:	128
Code Channel:	9
Power Level:	-6.028 dB
Asterisk *:	The asterisk (*) indicates that the marker is positioned on an active channel.
Tip

You can use the CDP Layer trace data display to view only one code layer (Spread Code Length) at a time.

See also

CDP Layer trace data

Code Order trace data

About Measurement Interval and Offset

Available Ch1 CDP trace data

About W-CDMA(3GPP) trace data


CDP Layer (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP > CDP Layer

Shows the Code Domain Power trace data for all code Channels within the specified code layer (Spread Code Length). If the Measurement Interval is greater than one, all slots within the Measurement Interval are averaged together to produce the CDP Layer results.

Display Format

The data is shown in a multi-color format that assigns a unique color to each code layer and related active code channels. This makes it easy to visually identify and distinguish the active code channels (Code Channel) for a given code layer (Spread Code Length). The colors are also user definable (See Display Appearance).

Note

For CDP and CDE trace data displays with separate I/Q channel trace bars, to position the Marker to the desired Code Layer/Channel bar, you must click in close proximity to the horizontal bar that indicates the value of the code channel being measured.

Selecting a Code Layer

You select the desired code layer by selecting a Spread Code Length in the CDP Layer Spread Code Length drop-down list (MeasSetup, Demod Properties.., Channel/Layer tab).

See also

CDP Composite trace data

About Measurement Interval and Offset

Available Ch1 CDP trace data

About W-CDMA(3GPP) trace data


Channel Error Vector Time (W-CDMA(3GPP))

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan > Error Vector Time

When W-CDMA(3GPP) Demodulation is enabled, the Error Vector Time trace data shows the time-domain error vector trace data results for the specified code channel and code layer (Spread Code Length).  Error Vector Time trace data is the computed error vector between corresponding symbol points in the I/Q measured and I/Q reference signals.  You can view the data results as Error Vector Magnitude, Error Vector Phase, only the I component or only the Q component (see Trace Data Formats below).

Note

Available only for Reverse link direction channels.

Hint

You can increase the number of symbol points by increasing the Measurement Interval(see Measurement Interval).

If normalization is OFF, the analyzer shows the instantaneous magnitude for each point. If normalization is ON, the analyzer shows the error vector as a percentage (see IQ normalize for an explanation of how this percentage is derived).

Trace Data Formats

It is important to remember that the Error Vector Time trace is a time record made up of complex, time-domain data. Each point in the time record has two components: I and Q. To make sense of the data, you must select an appropriate trace data format (Trace > Format > Format: drop--down list).

•	Linear Mag :  Shows the EVM (Error Vector Magnitude).

•	Real(I) :  Shows the I component of the error vector.

•	Imag(Q) :  Shows the Q component of the error vector.

•	Wrap Phase:  Shows the Error Vector Phase error.

For example, to see the error-vector magnitude, select the Linear Mag trace format (Trace > Format > Format: Linear Mag). Selecting Linear Mag computes the square root of the sum of the squares for each complex pair of points in the time record, which is the error-vector magnitude (EVM):

See also

Ch1 Chan trace data

About Trace Data (W-CDMA(3GPP))


Channel IQ Mag Error and IQ Phase Error (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path:	Trace > Data > Ch1 Chan > IQ Mag Error

or	Trace > Data > Ch1 Chan > IQ Phase Error

When W-CDMA(3GPP) Demodulation is selected, the Chan  IQ Mag Error and Chan IQ Phase Error trace data show the vector error between the I/Q measured and the I/Q reference trace data at the sampled chip times for the specified code channel and code layer (Spread Code Length).

Chan  IQ Mag Error trace data shows the magnitude error and Chan IQ Phase Error trace data shows the phase error for the specified code channel.

Selecting the Code Channel and Code Layer

Select the code channel with the Despread Channel - Code Channel text box  (MeasSetup > Demod Properties > Channel/Layer tab).  Select the code layer with the Despread Channel - Spread Code Length drop-down list (MeasSetup > Demod Properties > Channel/Layer tab).

Concepts

This trace data is determined just like it is for the IQ Mag Error and IQ Phase Error trace data for Digital Demodulation, see IQ Mag Error and IQ Phase Error (Digital Demod) trace data topic.

See also

Ch1 Chan trace data

About Trace Data (W-CDMA(3GPP))


Channel IQ Meas Time and IQ Ref Time (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path:	Trace > Data > Ch1 Chan > IQ Meas Time

or	Trace > Data > Ch1 Chan > IQ Ref Time

When W-CDMA(3GPP) Demodulation is enabled, the IQ Meas Time and IQ Ref Time traces are the demodulated time data results, sampled at the chip times, for the specified code channel (Code Channel) and code layer (Spread Code Length).  IQ Meas Time is the data results for the measured input signal.  IQ Ref Time trace data is the data results that would be derived from an ideal input signal (reference signal).

Concepts

The analyzer's demodulator produces two signals: I/Q Measured and I/Q Reference.

IQ measured signal

The IQ measured signal is the result of resampling the data to one point per chip and applying carrier locking, symbol locking, IQ origin offset and burst amplitude-droop compensation, filtering and system gain normalization to the incoming signal.

IQ reference signal

IQ reference signal is the ideal signal that the analyzer generates from the IQ measured signal demodulated data bits.  The analyzer detects bits from the measured IQ signal and reconstructs a sequence of ideal I and Q states. These are then treated as ideal impulses and are baseband filtered according to the reference filter and added together to form the IQ reference signal. The resultant IQ reference signal is then used compare and analyze against the IQ measured signal.

Tip

Online help for Digital Demodulation includes a block diagram that shows how I/Q measured and I/Q reference data are generated.

Compensation

Demodulation is performed with carrier lock and chip lock. In addition, the analyzer compensates for I/Q origin offset and burst amplitude-droop.

Time-Domain Displays

The analyzer's demodulator produces time-domain data. If you select IQ Meas Time, the analyzer shows the I/Q measured signal in the time domain. Likewise, if you select IQ Ref Time, the analyzer shows the I/Q reference signal in the time domain.

The data can be displayed in a variety of trace data formats, including I-Q, Constellation, Q-Eye, I-Eye, and Trellis-Eye formats (see Trace Formats (Digital Demodulation)) topic.

If normalization is OFF, the analyzer shows the instantaneous magnitude. If normalization is ON, the analyzer scales the IQ measured and IQ reference traces to map them onto the unit circle, which yields a unitless y-axis.

Hint

For further details about normalization, see online help for IQ Normalize.

Parameter Interaction

The following parameters affect how the analyzer shows the I/Q measured and I/Q reference signals:

•	Result Length determines the number of slots in the measurement.

•	Measurement Interval and Measurement Offset determine which slots will be displayed

See also

Ch1 Chan trace data

About Trace Data (W-CDMA(3GPP))


Channel Syms/Errs (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan > Syms/Errs

When W-CDMA (3GPP) Demodulation is enabled, selecting Ch1 Chan Syms/Errs trace data shows the channel symbol table. The symbol table provides the signal quality error information and the binary bits for each symbol for the specified code channel and code layer. The bottom half of the display shows the symbol data bits and the upper half shows the error summary data.

For more information see the following topics:

•	About the Channel Symbol Table

•	About Channel Error Summary Data

•	Alphabetical list of Channel Error Summary Data

There is also composite error summary trace data (Trace > Data > Ch1 Comp > Error Summary), which provides the signal quality error summary information for the composite signal (See About Composite Error Summary Data)

Selecting Reverse link IQ Symbol Bit data

For Reverse link signals, the "I" and "Q" data channels are logically separate signals. All trace data results contain both the "I" and the "Q" branches of the signal, except the symbol binary bit data. The symbol data shows either the "I" or the "Q" symbol bits as specified by the I/Q channel parameter (MeasSetup > DemodProperties > Channel/Layer tab).

See also

Ch1 Chan trace data

About Trace Data (W-CDMA(3GPP))


Composite Error Summary (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

When W-CDMA(3GPP) Demodulation is enabled, selecting the Ch1 Comp > Error Summary trace data shows the composite error summary data.  This is the signal quality error summary information for the composite signal.

For more information see the following topics:

•	About Composite Error Summary Trace Data.

•	Alphabetical list of Composite Error Summary Data

Composite error summary data is always computed from the first Slot in the measurement and ignores the measurement-offset parameter.

There is also channel error summary trace data (Trace > Data > Ch1 Chan > Syms/Errs), which provides the error information for a specific code channel and code layer (See About Channel Error Summary Data)

See also

Ch1 Comp trace data

About Trace Data (W-CDMA(3GPP))


Composite Error Vector Spec (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Vector Spec

When W-CDMA(3GPP) Demodulation is enabled, the composite Error Vector Spec trace data shows the spectrum of the composite Error Vector Time trace data. In other words, the analyzer derives the composite Error Vector Time trace data, and then windows and FFTs the data to produce the composite Error Vector Spectrum trace data.

The trace data is computed from the first slot in the measurement and the Measurement Interval and Measurement Offset parameter settings are ignored (see Measurement Interval and Offset).

Marker Frequency Correction

The analyzer's demodulator removes carrier-frequency error. Therefore, in the composite error vector spectrum display, you must add the carrier-frequency error to marker readouts to obtain exact frequency information. The carrier-frequency error (Freq Err) is shown in the Composite Error Summary (FreqErr) Table.

See also

Ch1 Comp trace data

About Trace Data (W-CDMA(3GPP))


Composite Error Vector Time (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Vector Time

When W-CDMA (3GPP) Demodulation is enabled, the Ch1 Comp Error Vector Time trace data is the error-vector, time-domain data for the composite signal.

The trace data is computed from the first slot in the measurement and the Measurement Interval and Measurement Offset parameter settings are ignored (see Measurement Interval and Offset).

Concept Information

This trace data is identical to the Chan Error Vector Time trace data except that the source data is the composite signal.  See Ch1 Chan Error Vector Time for concept information.

See also

Ch1 Comp trace data

About Trace Data (W-CDMA(3GPP))


Composite IQ Mag Error and IQ Phase Error (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path:	Trace > Data > Ch1 Comp > IQ Mag Error

or	Trace > Data > Ch1 Comp > IQ Phase Error

When W-CDMA(3GPP) Demodulation is enabled, the Ch1 Comp IQ Mag Error and Ch1 Comp IQ Phase Error traces show the error between the I/Q measured and the I/Q reference signals for the composite signal.

Ch1 Comp IQ Mag Error shows the magnitude error and Ch1 Comp IQ Phase Error shows the phase error for the composite signal.

The trace data is computed from the first slot in the measurement and the Measurement Interval and Measurement Offset parameter settings are ignored (see Measurement Interval and Offset).

Concepts

This trace data is determined just like it is for the IQ Mag Error and IQ Phase Error trace data for Digital Demodulation, see IQ Mag Error and IQ Phase Error (Digital Demod) trace data topic.

See also

Chan IQ Mag Error and IQ Phase Error trace data

Ch1 Comp trace data

About Trace Data (W-CDMA(3GPP))


Composite IQ Meas Spec and IQ Ref Spec (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > IQ Meas Spec

 or Trace > Data > Ch1 Comp > IQ Ref Spec

When W-CDMA(3GPP) Demodulation is enabled, the Ch1 Comp IQ Meas Spec and Ch1 Comp IQ Ref Spec traces show you the spectrum of the composite IQ Meas Time and composite IQ Ref Time signals respectively. The analyzer produces the spectrum by windowing and FFTing the composite I/Q measured or composite I/Q reference signal.

The trace data is computed from the first slot in the measurement and the Measurement Interval and Measurement Offset parameter settings are ignored (see Measurement Interval and Offset).

Note

The analyzer's demodulator removes carrier-frequency error. Therefore, in the error vector spectrum display, you must add the carrier-frequency error to marker readouts to obtain exact frequency information. The carrier-frequency error (Freq Err) is shown in Composite Error Summary Table (FreqErr) .

The spectrum represents the signal AFTER filtering.

Hint

By default, the analyzer shows the log(dB) magnitude when you select IQ measured spectrum. The same is true for I/Q reference.

See also

VSA Concepts (Windowing and FFTing)

Ch1 Comp trace data

About Trace Data (W-CDMA(3GPP))


Composite IQ Meas Time and IQ Ref Time (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path:	Trace > Data > Ch1 Comp > IQ Meas Time

      or	Trace > Data > Ch1 Comp > IQ Ref Time

When W-CDMA(3GPP) Demodulation is enabled, the Comp IQ Meas Time and Comp IQ Ref Time trace data are the time data results of W-CDMA(3GPP) demodulation for the composite signal.  Comp IQ Meas Time is the data results for the measured input signal.  Comp IQ Ref Time trace data is the data results that would be derived from an ideal input signal (reference signal).

The trace data is computed from the first slot in the measurement and the Measurement Interval and Measurement Offset parameter settings are ignored.

Concepts

The analyzer's demodulator produces two signals: I/Q Measured and I/Q Reference.

IQ measured signal

The IQ measured signal is the result of resampling the data to one point per chip and applying carrier locking, symbol locking, IQ origin offset compensation, filtering and system gain normalization to the incoming signal.

IQ reference signal

IQ reference signal is the ideal signal that the analyzer generates from the IQ measured signal demodulated data bits.  The analyzer detects bits from the measured IQ signal and reconstructs a sequence of ideal I and Q states. These are then treated as ideal impulses and are baseband filtered according to the reference filter and added together to form the IQ reference signal. The resultant IQ reference signal is then used compare and analyze against the IQ measured signal.

Tip

Online help for Digital Demodulation includes a block diagram that shows how I/Q measured and I/Q reference data are generated.

Time-Domain Displays

The analyzer's demodulator produces time-domain data. If you select Comp IQ Meas Time, the analyzer shows the composite IQ measured signal in the time domain. Likewise, if you select Comp IQ Ref Time, the analyzer shows the composite IQ reference signal in the time domain.

The data can be displayed in a variety of trace data formats, including I-Q, Constellation, Q-Eye, I-Eye, and Trellis-Eye formats (see Trace Formats (Digital Demodulation)) topic.

If normalization is OFF, the analyzer shows the instantaneous magnitude. If normalization is ON, the analyzer scales the composite IQ measured and composite IQ reference traces so that the RMS level is one, which produces a unitless y-axis.

Hint

For further details about normalization, See IQ Normalize.

See also

Chan IQ Meas Time and IQ Ref Time trace data

Ch1 Comp trace data Trace Data

About Trace Data (W-CDMA(3GPP))


Composite Inst Error Vector Spec (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Inst Error Vector Spec

When W-CDMA(3GPP) Demodulation is enabled, the Composite Inst Error Vector Spec trace shows the instantaneous spectrum of the Composite Error Vector Time trace. It is the non-averaged Comp Error Vector Spec trace data.

See also

Ch1 Comp trace data

About Trace Data (W-CDMA(3GPP))


Composite Inst IQ Meas Spec and IQ Ref Spec (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path:	Trace > Data > Ch1 Comp > Inst IQ Meas Spec

or	Trace > Data > Ch1 Comp > Inst IQ Ref Spec

When W-CDMA(3GPP) Demodulation is enabled, the Ch1 Comp Inst IQ Meas Spec and Ch1 Comp Inst IQ Ref Spec traces show you the instantaneous spectrum of the Comp IQ Meas Time or Comp IQ Ref Time signals. It is the non-averaged Comp IQ Meas Spec and IQ Ref Spec trace data.

See also

Ch1 Comp trace data

About Trace Data (W-CDMA(3GPP))


Correction (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 > Correction

Shows the correction trace derived by the analyzer from the calibration data. The correction trace is applied to the acquired data to compensate for phase and magnitude anomalies in the analyzer's hardware and software signal processing.

See also

About Calibration

Ch1 trace data

About Trace Data (W-CDMA(3GPP))


Inst CDE Composite (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP > Inst CDE Composite

Shows the Instantaneous Code Domain Error trace data for the composite signal. Inst CDE Composite trace data is the non-averaged CDE Composite trace data (see CDE Composite Trace Data).

Note

Inst CDE Composite is not affected by averaging.

See also

CDE composite Trace Data

Available Ch1 CDP trace data

About W-CDMA(3GPP) trace data


Inst CDE Layer (W-CDMA(3GPP))

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP > Inst CDE Layer

Shows the Instantaneous Code Domain Error trace data for all active Code Channels within the specified code layer (Spread Code Length). Inst CDE Layer trace data is the non-averaged CDE Layer trace data (see CDE Layer Trace Data).

Note

Inst CDE Layer trace data is not affected by averaging.

Selecting a CDE Layer

You select the desired code layer by selecting the Spread Code Length in the CDP-Layer Spread Code Length text box (MeasSetup > Demod Properties.. > Channel/Layer tab).

See also

CDE Layer Trace Data

Available Ch1 CDP trace data

About W-CDMA(3GPP) trace data


Inst CDP Composite (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP

Shows the Instantaneous Code Domain Power trace data for the Composite signal. It is the non-averaged CDP Composite trace data (see CDP Composite trace data).

Note

Inst CDP Composite trace data is not affected by averaging.

See also

CDP Composite Trace data

Available Ch1 CDP trace data

About W-CDMA(3GPP) trace data


Inst CDP Layer (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP

Shows the Instantaneous Code Domain Power trace data for all active Code Channels within the specified code layer (Spread Code Length or Symbol Rate). It is the non-averaged CDP Layer trace data (see CDP Layer trace data).

Note

Inst CDP Layer trace data is not affected by averaging.

Selecting a Code Layer

You select the desired code layer by selecting the Spread Code Length in the CDP-Layer Spread Code Length text box (MeasSetup > Demod Properties.. > Channel/Layer tab).

See also

CDP Layer Trace Data

Available Ch1 CDP trace data

About W-CDMA(3GPP) trace data


Inst Spectrum (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Inst Spectrum

Instantaneous Spectrum trace data is the spectral display of the pre-demodulated Time data. The Time data is Windowed and FFTed to create the Instantaneous Spectrum display.

If averaging is on, the Instantaneous Spectrum does not show the effects of averaging. To see the effects of averaging, use the Ch1 Spectrum trace data (W-CDMA).

VSA signal flow (see Digital Demodulation Block Diagram):

See also

VSA Concepts (Windowing and FFTing)

Ch1 Spectrum trace data (W-CDMA)

Ch1 trace data

About W-CDMA(3GPP) trace data


Raw Main Time
Raw Main Time (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 > Raw Main Time

Raw Main Time is the raw data read from the input hardware or playback file. For more information about this data, See Raw Main Time (Digital Demod) trace data topic.

VSA signal flow (see Digital Demodulation Block Diagram):

See also

Time trace data

Ch1 trace data

About W-CDMA(3GPP) trace data


Spectrum (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 > Spectrum

Spectrum trace data is the spectral display of the pre-demodulated Time data. The Time data is Windowed and FFTed to create the Spectrum display.

If averaging is on, Spectrum trace data is the averaged Instantaneous Spectrum trace data. When averaging is set to zero, the Spectrum trace data is equal to the Inst Spectrum trace data.

VSA signal flow (see Digital Demodulation Block Diagram):

See also

VSA Concepts (Windowing and FFTing)

About Averaging

Ch1 Inst Spectrum trace data (W-CDMA)

Ch1 trace data

About W-CDMA(3GPP) trace data


Time (W-CDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 > Time

When W-CDMA (3GPP) demodulation is enabled, the Time trace shows the time record before demodulation, as shown in the following block diagram.

The Time trace has the following characteristics:

•	It is pre-demodulated time data.

•	It is unaffected by time averaging.

•	The length and offset are determined by the Measurement Interval and Measurement Offset parameters.

VSA signal flow (see Digital Demodulation Block Diagram):

See also

Ch1 trace data

About W-CDMA(3GPP) trace data


Code Order (W-CDMA(3GPP))

(Vector Signal Analyzer application only)

Menu Path: Trace > Digital Demod tab

Lets you set the Code Domain Power display code order to Bit Reversed or Hadamard. This will determine how the code domain power trace data is displayed.

•	Bit Reversed (Default): Related Code Channels are viewed adjacent to each other on the code domain power trace data display,

•	Hadamard: Reorders related Code Channels so that they are viewed as dispersed along the X-axis as defined by the Hadamard code order on the code domain power trace data display,

Notes

Code Order effects how the Code Domain Power data is displayed and does not change the measurement results.

Using Code Order to make W-CDMA(3GPP) Code Domain Power measurements

For W-CDMA(3GPP) modulation, the Bit Reversed code order shows related channels next to each other on the code domain power display. This is a convenient way to quickly identify related Code Channels.

Another way to look at the same data is by reordering the code channels so that related Code Channels are dispersed along the X-axis as defined by the Hadamard code order.

To view related Code Channels grouped together for W-CDMA(3GPP) modulated signals select the Bit-Reversed Code Order (Trace > Digital Demod tab > Code Order text box).

You can find information for the rest of the available parameters shown in this dialog box in the Option AYA: Digital demod, Digital Demod Trace Data Property dialog box topic.

See also

Digital Demod Trace Data Property dialog box

Available Code Domain Power (CDP) trace data

Setting up a W-CDMA(3GPP) Measurement

About Opt B7N: W-CDMA(3GPP) Demodulation


About Opt B7N: cdma2000 Demodulation

Option B7N: cdma2000 adds cdma2000 (Code Domain Multiple Access 2000) demodulation capability to your 89600-Series application software. This option lets you measure cdma2000 modulated signals that are compliant to the specification TIA/EIA/ IS-2000 (Mobile Station—Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System).

With cdma2000 you can descramble, despread and demodulate cdma2000 modulated signals. This option supports configurations in the reverse link (mobile station) and forward link (base station) modes using spread rate one (SR1). The analyzer will automatically identify all active channels regardless of the Symbol Rate or Walsh Code Length.

Signal analysis capabilities including composite code domain power, composite time and channel specific analysis. Measurement results may be shown in several trace display formats as well as numeric error data formats. Flexible display scaling and marker functionality enhance these measurement capabilities.

The demodulator used in this analyzer incorporates advanced technology that does not require coherent carrier signals, or symbol-clock timing signals. The analyzer has a built-in IS-2000 filter. Signal locking requires the carrier frequency, chip rate, reverse/forward link direction and Long Code Mask to be set.

The demodulator uses the measured signal (called I/Q Meas Time) to generate an ideal signal (called IQ Ref Time). You can compare the measured signal to the reference signal to quantify and locate errors in your signal.

If you have an 89610 Vector Signal Analyzer, an optional second baseband channel allows IQ baseband measurement capability. You can also perform IQ baseband measurements on data that is from a file or the stream interface, i.e. ADS simulation.

See also

cdma2000 Available Features

Setting up a cdma2000 Measurement

About 89600 Optional Measurement Software

Tutorials for cdma2000


Available Features (cdma2000)

Features applicable to cdma2000 demodulation:

•	Standard presets for

−	cdma2000 Reverse link

−	cdma2000 Forward link

•	1.2288 MHz variable (user definable) chip rate

•	Single code domain layer or composite code-domain power and code-domain error shows (the composite display shows all code layers simultaneously). You can normalize code-domain power to display the code-domain power relative to the total signal power in the code domain.

•	Single channel time-domain displays, such as IQ measured, IQ reference, IQ magnitude/phase error, and error Vector traces.

•	Composite time-domain displays, such as IQ measured time, IQ reference time, IQ magnitude or phase error, and error vector time traces.

•	Mirrored (flipped) frequency spectrums used to remove the effects of high-side mixing or complex conjugation mismatches in simulated data.

•	Measurement offset and interval (similar to time gating) used to select specific data PCGs for analysis

•	Time gating is not available (does offer measurement offset/interval feature)

•	Averaging is available only for code domain data and is applied to numeric error data in the symbol table, as follows:

−	rms (video)—computes an average of each rms error update in the table.

−	rms exponential—is like rms (video) except that averaging continues past the average count with an exponential weighting.

−	continuous peak hold—keeps track of the peak rms error of each update in the table.

−	Time and time exponential averaging are not available.

•	The following average types are available for the pre-demodulated spectrum result:

−	rms (video)

−	rms exponential

−	continuous peak hold

•	Features that are applicable to Digital Demod but not available with W-CDMA demodulation:

−	User selectable Measurement/Reference filter

−	Pulse and Sync search

−	Equalization Filter

See also

89600-Series VSA Application Standard Features

Opt B7N: cdma2000 Available Trace Data

Opt B7N: cdma2000 Demodulation Overview

Setting up a cdma2000 Measurement


Setting up a cdma2000 Measurement

(Vector Signal Analyzer application only)

When setting up a cdma2000 demodulation measurement, there are several things you need to consider. This topic tells you how to connect your signal to an 89600-series analyzer and successfully demodulate digital signals. The information is provided in this order:

•	Connecting Your Signal to the Analyzer

•	Frequency Span

•	Input Range

•	Center Frequency

•	Long Code Mask (Reverse Link only)

•	Reverse/Forward Link Direction

•	Chip Rates, Symbol Rates and Walsh Code Length

•	Result Length

•	Mirrored Spectrum

•	Tutorials for cdma2000

Connecting Your Signal to the Analyzer

The analyzer lets you connect your carrier signal or, if your 89600-series analyzer has two input channels, the raw I (In-phase) and Q (Quadrature-phase) signals.

For all receiver configurations except I + jQ, connect your signal to Channel 1. In this case, the analyzer assumes that your signal contains both the I and Q components (the carrier signal). If your analyzer has two input channels, the analyzer ignores the second input channel.

If your analyzer has a second input channel, you can also connect the raw I (In-phase) and Q (Quadrature- phase) signals. To do this, select Input > Channels > I + jQ. With this configuration, the analyzer removes the quadrature mixer from the demodulator's signal flow, which lets you connect the I component of your signal to Channel 1; the Q component to Channel 2.

Notes

1) Selecting I+jQ turns on DC coupling.

2) When using I+jQ, use external calibration to correct for any offset or gain imbalance between the I and Q signals.

3) Ranges for Channel 1 and Channel 2 are set independently.

Frequency Span

When selecting a frequency span, select the narrowest span that includes all of your signal components (select a span that is slightly larger than the bandwidth of your signal). If you select a span that is too narrow, your measurement may have excessive errors or the analyzer may lose carrier lock. If the span is less than the (Chip Rate × 1.204), the analyzer displays "DATA?" to indicate that the results may not be accurate.

For best results, the frequency span should be set according to the following formula (filter_alpha is the filter characteristic of the Nyquist filter used to demodulate the cdma2000 signal):

Frequency Span ≥ (1.204 × Chip Rate)

If you select a span that is too wide, your measurement may be affected by excessive noise and slower speed.

Using the "Preset to Default" configuration settings will select a default span that should work well.

Input Range

The input range must be set correctly to obtain accurate measurements. Input ranges that are too low overload the analyzer's ADC. Input ranges that are too high increase noise, which increases errors reported in error data results, such as EVM.

Note

cdma2000 signals can have a relatively large Peak-to-RMS voltage ratio potentially requiring a higher range setting than for other digitally modulated signals.

Center Frequency

The analyzer's center frequency must be set within approximately ±500 Hz of the carrier frequency of the cdma2000 signal, otherwise the analyzer may not be able to lock onto your signal.

Long Code Mask (Reverse Link only)

For cdma2000 reverse link you must enter the Long Code Mask to demodulate your cdma2000 signal.

Due to very long scrambling sequence, the analyzer can generally only lock when the Long Code Mask is set to zero.

Reverse/Forward link direction

The analyzer can demodulate both reverse link and forward link cdma2000 signals using spread rate one (SR1). Therefore you must select the desired reverse or forward direction. Forward link refers to the Base Station Transceiver transmitted signal and reverse link refers to the mobile station (or User Equipment) transmitted signal.

Chip Rates, Symbol Rates and Walsh Code Length

To successfully demodulate cdma2000 signals, the analyzer chip rate must match the chip rate of your cdma2000 signal. The Walsh Code Length determines the Symbol Rate per the following equation.

Symbol Rate = Chip Rate/Walsh Code Length

Chip Rate: 1.2288 MHz

Walsh Code Length (Symbol Rate)

(Forward Link)	(Reverse Link)
—	2 (614.4 ksym/s)
4 (307.2 ksym/s)	4 (307.2 ksym/s)
8 (153.6 ksym/s)	8 (153.6 ksym/s)
16 (76.8 ksym/s)	16 (76.8 ksym/s)
32 (38.4 ksym/s)	32 (38.4 ksym/s)
64 (19.2 ksym/s)	—
128 (9.6 ksym/s)	—
Result Length

Result Length determines the amount of signal the analyzer demodulates in terms of the number of Power Control Groups (PCGs) or equivalent PCG time. Make sure that the result length is long enough to capture all the desired data.

Result Length may be entered as an integer number of PCGs, frames or time. If you choose to enter seconds, the analyzer will automatically increment your entry as necessary to obtain an integer number of PCGs.

Mirrored Spectrum

The cdma2000 demodulation provides a feature that lets you configure the analyzer's demodulator to conjugate the complex time-domain waveform. This has the effect of flipping the spectrum around the analyzer's center frequency. This feature is useful when the cdma2000 signal is inverted, or flipped due to an IF down conversion.

See also

Measurement Speed and Resolution Considerations (cdma2000)

Selecting cdma2000 Demodulation

Troubleshooting cdma2000

Tutorials for cdma2000


Measurement Speed Considerations

The following information can help maximize the measurement speed.

The primary factor in the measurement speed for cdma2000 measurements is how much input data must be processed. Reducing the result length, by decreasing the number of PCGs, is the best way to increase speed.

However, if the result length is too short, the data results may not be accurate. If the result length is less than 6 PCGs the analyzer shows the "DATA?" error message.

See also

Setting up a cdma2000 Measurement

Selecting cdma2000 Demodulation

Troubleshooting a cdma2000 Measurement


Selecting the cdma2000 Demodulator

(Vector Signal Analyzer application with option B7N only)

Menu Path: MeasSetup > Demodulator > 3G Cellular > cdma2000

Sets the analyzer's demodulator to despread and demodulate cdma2000 modulated signals. Both forward link and reverse link configurations using spread rate one (SR1) can be demodulated.

After selecting the demodulator you need to set the configuration parameters. You select one of the available Standard Presets or you can manually set them from the Demod Properties dialog box.

It's also recommended that you Setting up a cdma2000 Measurement before setting these parameters.

See also

Using cdma2000 Standard Presets

cdma2000 Demod Properties.

Setting up a cdma2000 Measurement

About Opt B7N: cdma2000 Demodulation

About VSA Optional Features

Tutorials for cdma2000


Using cdma2000 Standard Setup

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Format tab > Preset to Default button

Lets you select a cdma2000 standard preset configuration. When you select a standard preset, the analyzer automatically sets the parameters shown in the following table:

•	Reverse: cdma2000 reverse link signal

•	Forward: cdma2000 forward link signal

Note

The cdma2000 demodulator must be selected before these Standard Presets are available.

cdma2000 Standard Presets

Parameter	Forward (Link)	Reverse (Link)
Chip Rate	1.2288 MHz (SR1)	1.2288 MHz (SR1)
Long Code Mask	−	20000000000
Base Code Length	64	−
Walsh Code Length (Symbol Rate)	64 (19.2 Ksym/s)	32 (38.4 ksym/s)
Walsh Code Number	0	0
Result Length	16 PCG	16 PCG
Measurement Offset	0 PCG	0 PCG
Measurement Interval	1 PCG	1 PCG
I/Q Branch	−	I
Mirror Frequency Spectrum	OFF	OFF
IQ Normalization	ON	ON
Code Order	Hadamard	Hadamard

Note: The dash "−" means the parameter does not apply.

See also

cdma2000 Demod Properties Format tab

Selecting the cdma2000 demodulator

Setting up a cdma2000 Measurement

Troubleshooting cdma2000 Measurements

Tutorials for cdma2000


Troubleshooting (cdma2000)

(Vector Signal Analyzer application only)

This topic contains information to help you troubleshoot measurements when using cdma2000 Demodulation. You should also review Setting Up a cdma2000 Measurement for additional measurement information.

PROBLEM	POSSIBLE CAUSE	SOLUTION
Demodulation fails to lock-on to signal	Signal not present	Check test setup connections
	Carrier too far from center frequency	Adjust center frequency to ± 500 Hz of the carrier frequency
	Input signal is over-loaded or under ranged	Adjust input range
	Frequency span is too narrow	Increase frequency span
	Incorrect chip rate	Enter correct chip rate (not symbol rate or bit rate)
	No Pilot Channel—missing or level to low	Set pilot channel at Walsh Code Number Zero. Try adjusting pilot channel power level.
	Incorrect Long Code Mask	Generally only cdma2000 reverse link signals with Long Code Mask equal to zero can be demodulated.
	cdma2000 signal spectrum is inverted	Check the Mirror Frequency Spectrum setting (MeasSetup > Demodulator > Format tab).
	I/Q Offset too large	Reduce the LO feedthrough  (or DC Offset for I+jQ receiver)
	If using an Agilent ESG to generate the input signal you need to check the firmware revision level.	Use firmware revision B.03.60 or newer.
Wrong channel marked as active	Poor SNR (signal to noise ratio).	Increase signal power or remove cause of noise/distortion.
	All bits not transmitted within a physical channel.	Transmit all bits within a physical channel, or select code-domain power for the layer associated with the physical channel of interest (single-layer code-domain power displays are accurate even if the analyzer is unable to identify active channels in the composite code-domain power display).
	Data pattern induces large disparity in power between slower channels overlaid by the channel of interest.	Verify that your transmitter is transmitting properly.
ADS application has failed to work with cdma2000 demodulation	See Troubleshooting ADS measurements
See also

Setting up a cdma2000 Measurement

Measurement Speed and Resolution considerations

About Opt B7N: cdma2000 Demodulation

Troubleshooting Advanced Design System (ADS)

VSA error and status messages

VSA Troubleshooting Topics


About Dialog Box and Tabs (cdma2000)
Dialog Box and Tabs (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties

The cdma2000 Demodulation dialog box contains parameters that let you configure the analyzer to descramble > despread > demodulate and analyze cdma2000 modulated signals.

Note

The cdma2000 demodulator must be selected before this dialog box is available. To enable the demodulator > click MeasSetup > Demodulator > cdma2000

The cdma2000 Demodulation Properties dialog box contains tab headings that group similar configuration parameters as follows:

•	Format tab: Lets you access the cdma2000 demod configuration parameters. These are the parameters necessary for the analyzer to lock on to and demodulate the test signal.

•	Channel/Layer tab: Let you specify the measurement despread channel and CDP (code domain power) code layer.

•	Time tab: Lets you access the signal capture configuration parameters. You use these parameters to isolate a segment of the time record for further viewing and data analysis.

See also

Setting up a cdma2000 Measurement

Selecting cdma2000 Demodulation

Troubleshooting a cdma2000 Measurement


Channel/Layer Tab (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties

The Channel/Layer tab parameters let you specify the measurement despread channel and CDP (code domain power) code Layer.

•	Despread Channel parameters: Despread Channel parameters specify the channel used for the channel measurement data results including: Chan Error Vector, Chan IQ Meas Time, Chan IQ Ref Time, Chan Mag Error, Chan Phase Error and Chan Syms/Errs trace data (Click on the parameter name for further information):

−	Walsh Code Length (Despread Channel)

−	Walsh Code Number (Despread Channel)

−	IQ Branch

•	CDP Layer parameters: CDP Layer parameters are used to specify the active (displayed) code domain layer for the Code Domain Power (CDP) Layer and Code Domain Error (CDE) Layer trace data (Click on the parameter name for further information):

−	Walsh Code Length (CDP Layer)

See also

Format tab (cdma2000 Demodulation Properties)

Time tab (cdma2000 Demodulation Properties)

cdma2000 Demodulation Properties


Format Tab (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties

The Format tab of the cdma2000 Demodulation Properties dialog box lets you configure the analyzers cdma2000 demodulator. These are the parameters necessary for the analyzer to lock on to and demodulate the test signal.

The Format tab dialog box lets you configure these parameters (Click on the parameter name for further information):

•	Base Code Length

•	Chip Rate

•	Direction

•	IQ Normalize

•	Long Code Mask

•	Mirror Frequency Spectrum

•	Preset to Default

See also

Channel/Layer tab (cdma2000 Demodulation Properties)

Time tab (cdma2000 Demodulation Properties)

cdma2000 Demodulation Properties


Time Tab (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup. DemodProperties

The Time tab lets you access the signal analysis configuration parameters. You use these parameters to specify a segment of the time record (captured input signal) for further viewing and data analysis.

The Time tab dialog box lets you configure these parameters (Click on the parameter name for further information):

•	Measurement Interval

•	Measurement Offset

•	Result Length

Measurement Offset and Measurement Interval are used by all measurement trace data results except the following composite signal trace data: CDE Composite, CDE Layer Composite Error Summary, Composite IQ Meas Time/Spectrum, Composite IQ Ref Time/Spectrum, Composite Error Vector Time/Spectrum, Composite Mag Error and Composite Phase Error.

See also

About Measurement Interval and Offset

Format tab (cdma2000)

Channel/Layer tab (cdma2000)

cdma2000 Properties dialog box


Setting Measurement Parameters (cdma2000)

(Vector Signal Analyzer application only)

The following table shows how measurement parameters affect cdma2000 demodulation.

cdma2000 Demodulation Parameters

Time Sequence	Parameters Involved	Effect	Result	Notes
Signal setup	Range Trigger Frequency/span Input Time Corrections	Sets up basic signal parameters required for demodulation	Raw data	Any changes made in the signal setup parameters later in the time sequence require that a new measurement be performed
Demodulation	Setup parameters Chip Rate Direction-Link Long Code Mask Base Code Length	Determines the type of demodulation performed on the input time data	Demodulated, symbol-locked data in the default display format	Result length determines the amount of data that is demodulated.
Post-demodulation	Meas Offset Meas Interval Walsh-Code-Number Channel Walsh-Code-Length CDP-Layer Walsh-Code-Length	Specifies channel and determines how much data is used for the trace data results.	Demodulated data in the default display format.	Changes may be made in the display parameters without acquiring a new measurement
Display Formatting	Trace data Trace format X and Y Scale Marker IQ Normalize	Formats the data for display	Formatted, demodulated data	Changes may be made in the display parameters without acquiring a new measurement
See also

Parameter Interactions

Display Limitations

Resolution Bandwidth

Span considerations

Setting up a cdma2000 Measurement

Troubleshooting (cdma2000)


Parameter Interactions (cdma2000)

(Vector Signal Analyzer application only)

When using cdma2000 demodulation, changing one parameter may necessitate changes in other parameters to achieve the desired measurement. For example,

•	Chip rate limits frequency span.

•	Minimum frequency span may limit the chip rate (this may occur when playing back a recording or analyzing data from the stream interface).

•	Measurement Interval and Measurement Offset are limited by the Result Length

•	Base Code Length setting may restrict choices for Despread Channel Walsh Code Length and CDP Layer Walsh Code Length.

•	Changing link direction changes the valid limits for many parameters

The following topics may help you optimize your measurements and explain the reasons for changes made automatically by the analyzer.

Display Limitations

Resolution Bandwidth

Span Considerations

Measurement Speed Considerations

See also

Setting Measurement Parameters

Setting up a cdma2000 Measurement

About Measurement Interval and Offset


Display limitations (cdma2000)

All W-CDMA Channel trace data is displayed at one Point-per-Symbol and all Composite trace data is displayed at one Point-per-Chip. This causes the bandwidth displayed for the Composite IQ Meas Spectrum, the Composite IQ Ref Spectrum and the Composite Error Vector Spectrum to be less than the analyzers span setting.

The following topics may help you optimize your measurements and explain the reasons for changes made automatically by the analyzer:

Parameter Interactions

Resolution Bandwidth

Span Considerations

Measurement Speed Considerations

See also

Setting Measurement Parameters

Setting up a cdma2000 Measurements


Resolution Bandwidth (cdma2000)

Resolution bandwidth (ResBW) in cdma2000 demodulation is determined automatically by the analyzer, and cannot be set independently. Resolution bandwidth is determined by the time record length as usual, according to the following formula:

However, in cdma2000 Demodulation the time record length is determined as follows (result length is in symbols):

The following topics may help you optimize your measurements and explain the reasons for changes made automatically by the analyzer.

Parameter Interactions

Display Limitations

Span Considerations

Measurement Speed Considerations

See also

About Resolution Bandwidth

About Measurement Interval and Offset

Setting Measurement Parameters

Setting Up a cdma2000 Measurements


Span Considerations (cdma2000)

When selecting a frequency span, select the narrowest span that includes all of your signal components (select a span that is slightly larger than the bandwidth of your signal). If you select a span that is too narrow, your measurement may have excessive errors or the analyzer may lose carrier lock. If the span is less than (1+filter alpha)×chip rate, the analyzer displays "NO DATA?" to indicate that the results may not be accurate.

For best results, the frequency span should be set according to the following formula (filter_alpha is the filter characteristic of the Nyquist filter used to demodulate the cdma2000 signal):

Frequency Span ≥ (1 + Filter alpha) × Chip Rate

If you select a span that is too wide, your measurement may be affected by excessive noise and slower speed. You may want to turn the demodulator OFF (MeasSetup, Demodulator, Demod OFF) and set the span while Viewing the spectrum of your signal.

Using the "Preset to Default" configuration settings will select a default span that should work well.

The following topics may help you optimize your measurements and explain the reasons for changes made automatically by the analyzer.

Parameter Interactions

Display Limitations

Resolution Bandwidth

Measurement Speed Considerations

See also

Setting Measurement Parameters

Setting up a cdma2000 Measurements


Base Code Length (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Format tab.

Default: See cdma2000 Standard Presets Table

Lets you toggle the forward link Base Code Length to either 64 or 128.

Note

Base Code Length parameter only applies to Forward link signals.

Some cdma2000 forward link signals are based on a fundamental Walsh code length of 64 while others use 128. The Base Code Length parameter lets you decide which code length the analyzer will use as the fundamental Walsh code length.

See also

Format tab - cdma2000 Demodulation Properties

cdma2000 Demodulation Properties


Chip Rate (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Format tab

Defaults: See cdma2000 Standard Presets Table

Range: Minimum span to (10 × maximum span)

Lets you set the Chip Rate for the analyzer's demodulator. This allows you the freedom to enter nonstandard chip rates for test and analysis purposes.

Note

To demodulate a signal, the chip rate must match the chip rate of your system.

The chip rate determines the symbol rate for each Walsh Code Length per the following equation (see Chip Rate, Symbol Rate and Walsh Code Table):

Symbol Rate = Chip Rate/Walsh Code Length

The chip rate also limits the resolution bandwidth (see Resolution Bandwidth)

See also

Format tab - cdma2000 Demodulation Properties

cdma2000 Demodulation Properties


Direction (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Format tab

Defaults: See cdma2000 Standard Presets Table

Lets you select the signal direction. cdma2000 provides Forward link and Reverse link demodulation capabilities:

•	Forward link (also called the "Base Station" or the "downlink" direction)

•	Reverse link (also called the "Mobile Station" or the "uplink" direction+

See also

Format tab - cdma2000 Demodulation Properties

cdma2000 Demodulation Properties


IQ Branch (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Channel/Layer tab

Defaults: See cdma2000 Standard Presets Table

The I and Q check boxes allow you to toggle the selection of the I/Q branch signals between "I" and "Q". The cdma2000 reverse link "I" and "Q" branches of each Walsh code channel are logically separate channels. The I and Q selection determines which bits (the "I" bits or the "Q" bits) are displayed in the Channel Syms/Errs data results.

Note

This selection is available only for Reverse link.

Tip

You can use the Copy Mkr to Despread Chan marker feature to automatically enter the Walsh Code Length, Walsh Code Number and IQ Branch setting.

See also

Channel/Layer tab - cdma2000 Demodulation Properties

cdma2000 Demodulation Properties


Long Code Mask (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Format tab

Defaults: See cdma2000 Standard Presets Table

Lets you specify the cdma2000 reverse link Long Code Mask. The Long Code Mask must match the Long Code Mask of the test signal in order for the analyzer to lock to the signal. Long Code Mask is used only for cdma2000 reverse link.

Notes

cdma2000 does not support reverse link non-zero long code masks

If the Long Code Mask is non-zero, the long code sequence repeats approximately every 6 weeks, so generally the analyzer is unable to lock to a signal unless the Long Code Mask is zero. The only exception to this is if an Agilent ESG signal generator is used to generate the cdma2000 reverse link signal. In this case, the Long Code Mask should be set to 20000000000 to match the ESG, and then the analyzer should be able to lock to the signal.

See also

Format tab - cdma2000 Demodulation Properties

cdma2000 Demodulation Properties


Measurement Interval (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Time tab

Defaults: See cdma2000 Standard Presets Table

Lets you specify how much of the Result Length data is used for trace data results. Measurement Interval is entered as an integer number of PCGs (Power Control Group). One PCG is equal to 1536 chips and is 1.25 ms at the default chip rate.

Measurement Interval and Measurement Offset parameters are used to specify what segment of the Result Length data is used for data analysis, see About Measurement Interval and Offset.

See also

Result Length (cdma2000)

Measurement Offset (cdma2000)

About Measurement Interval and Offset

Time tab - cdma2000 Demodulation Properties

cdma2000 Demodulation Properties


Measurement Offset (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Time tab

Defaults: See cdma2000 Standard Presets Table

Lets you set the number of Measurement Offsets in PCGs (Power Control Group). Measurement Offset determines the start position of the Measurement Interval with respect to the first PCG within the Result Length. One PCG is equal to 1536 chips and is 1.25 ms at the default chip rate.

Measurement Interval and Measurement Offset parameters are used to specify what segment of the Result Length data is used for data analysis, see About Measurement Interval and Offset.

See also

About Measurement Interval and Offset

Result Length (cdma2000)

Measurement Interval (cdma2000)

Time tab - cdma2000 Demodulation Properties


Result Length (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Time tab

Defaults: See cdma2000 Standard Presets Table

Range: 1 t0 64 (Forward link); 1 to 48 (Reverse link)

Lets you specify the total amount of acquired and demodulated data in integer number of time PCGs (Power Control Group).  One PCG is equal to 1536 chips (1.25 ms at the default chip rate) and one frame is 16 PCGs (20 ms at the default chip rate).

Result Length must be specified for an integer number of PCGs in units of PCGs, frames or time. The analyzer will adjust the measurement time as necessary to obtain an integer number PCGs that include the specified time.

Tip

Result length is a primary factor determining measurement speed. Smaller result lengths increase measurement speed, but result lengths less than 6 PCGs may cause inaccurate measurement results.

You can learn more about this parameter at About Measurement Interval and Offset

See also

About Measurement Interval and Offset

Measurement Interval (cdma2000)

Measurement Offset (cdma2000)

Time tab - cdma2000 Demodulation Properties

cdma2000 Demodulation Properties


Despread Channel Walsh Code Length (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Channel/Layer tab.

Defaults: See cdma2000 Standard Presets Table

Range: 4 to 128 (Forward link) and 2 to 32 (Reverse link)

Lets you set the Despread Channel Walsh Code Length. The Despread Channel Walsh Code Length is used (along with the Despread Channel Walsh Code Number) to specify the channel used for the Chan Error Vector, Chan IQ Meas Time, Chan IQ Ref Time, Chan Mag Error, Chan Phase Error and Chan Syms/Errs measurement results (See About Ch1 Chan Trace Data).

Note

The text box shows the Walsh Code Length (and correlate Symbol Rate).

Selecting a Despread Channel Walsh Code Length

The text box provides a list of available cdma2000 compliant Walsh Code Length that you can select from. To set the Despread Channel Walsh Code Length, Click the text box down arrow and then click the desired Walsh Code Length.

Tip

You can use the Copy Mkr to Despread Chan marker feature to automatically enter the Despread-Channel Walsh Code Length, Walsh Code Number and IQ Branch settings.

Chip Rate, Symbol Rates, and Walsh Code Lengths

The chip rate determines the symbol rate for each Walsh Code Length, see Chip Rate, Symbol Rate and Walsh Code Table) for more information.

See also

About Ch1 Chan Trace Data

Channel/Layer tab - cdma2000 Demodulation Properties

cdma2000 Demodulation Properties


CDP Layer Walsh Code Length (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Channel/Layer tab.

Defaults: See cdma2000 Standard Presets Table

Range: 4 to 128 (Forward link) and 2 to 32 (Reverse link)

CDP Layer Walsh Code Length selects the active code domain layer (Walsh code length) for the code domain power CDP Layer and CDE Layer trace data (See About Ch1 CDP trace data). This parameter has no other effect except for the display of the CDP Layer and CDE Layer trace data.

Note

The text box shows the Walsh Code Length (and correlate Symbol Rate)

Selecting a CDP Layer Walsh Code Length

The CDP Layer text box provides a list of available cdma2000 compliant Walsh Code Length that you can select from. To set the CDP Layer Walsh Code Length, Click the text box down arrow and then click the desired Walsh Code Length.

Note

The Copy Mkr to Despread Chan marker does not automatically enter the CDP Layer Walsh Code Length.

See also

Available Ch1 CDP Trace data

CDE Layer Trace Data

CDP Layer Trace Data

Channel/Layer tab - cdma2000 Demodulation Properties

cdma2000 Demodulation Properties


Despread Channel Walsh Code Number (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Channel/Layer tab.

Defaults: See cdma2000 Standard Presets Table

Range: 0 to (Walsh Code Length −1)

Lets you set the Walsh Code Number. The Despread Channel Walsh Code Number is used (along with the Despread Channel Walsh Code Length) to specify the channel used for the Chan Error Vector, Chan IQ Meas Time, Chan IQ Ref Time, Chan Mag Error, Chan Phase Error and Chan Syms/Errs trace data results (See About Ch1 Chan Trace Data).

Tip

You can use the Copy Mkr to Despread Chan marker feature to automatically enter the Walsh Code Length, Walsh Code Number and IQ Branch setting.

See also

About Ch1 Chan trace data

Available Chip Rates, Symbol Rates and Spread Code Length

Channel/Layer tab - cdma2000 Demodulation Properties

cdma2000 Demodulation Properties


About the Channel Symbol Table (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan > Syms/Errs

When cdma2000 Demodulation is enabled, selecting Ch1 Chan Syms/Errs trace data shows the symbol table and error summary trace data for the specified Walsh code number and Walsh code length. The bottom section of the display shows the symbol table data and the upper section shows the error summary data. This topic discusses the code channel Symbol Table trace data, the Error Summary trace data is discussed under About the Channel Error Summary trace data.

The Ch1 Chan Symbol table shows the binary bits for each measured symbol in the specified Walsh code number and Walsh code length. These parameters are entered in the Despread-Channel Walsh-Code-Number and Walsh-Code-Length text boxes, located in the cdma2000 Demodulation Properties dialog box (MeasSetup > Demod Properties > Channel/Layer tab).

The first bit in the table corresponds to the first bit of the first symbol. To make the table easier to read, the analyzer shows a fixed number of bits (eight), followed by a space.

For Forward link signals, the symbol table has two bits per symbol containing both the "I" and "Q" data.

However, for Reverse link signals, "I" and "Q" data channels are logically separate signals. All trace data contains both the "I" and the "Q" branches of the signal, except the symbol table data. For Reverse signals, the symbol table has one bit per symbol. The bit is either from the "I" branch or the "Q" branch of the channel, as specified by the "IQ" Branch parameter (MeasSetup > Demod Properties > Channel/Layer tab).

In addition, the analyzer shows numbers to the left of each row. These numbers indicate the bit position of the first bit in the row. For example, if 192 is displayed by the third row, the first bit in the row is the 192nd bit in the digital data stream.

Hint

Here's an easy way to see the bits that correspond to a point in the channel constellation diagram: display the constellation diagram in one grid, the symbol table in another, and turn on the marker and marker coupling. When you place the marker on a point in the constellation diagram, the analyzer highlights the corresponding bits in the symbol table.

Hint

Use the arrow keys on the keyboard or the mouse wheel to move the marker from one symbol to the next. Or you can use the marker X Position to move to any specified symbol location.

Error Summary Data Information

You can find about the error summary data at About the Channel Error Summary Data.

See also

About the Channel Error Summary Data

About the Composite Error Summary Trace Data


About Channel Error Summary Data (cdma2000)
Channel Error Summary Data (cdma2000)

(Vector Signal Analyzer application only)

When cdma2000 Demodulation is enabled, selecting the Ch1 Chan Syms/Errs trace data shows the symbol table and error summary trace data for the specified Walsh code number and Walsh code length. The bottom section of the display shows the symbol table data and the upper section shows the error summary data. This topic discusses the code channel error summary data, the Symbol Table trace data is discussed under About the Channel Symbol Table. The following information is discussed as listed:

•	Available Channel Error Summary Data

•	Selecting Chan Error Trace Data

•	Averaging and Error Summary Data

•	Using Band Power markers to limit Error information

•	How EVM and Magnitude Error data results are calculated (%RMS)

Available Channel Error Summary Data

See Alphabetical list of Channel Error Summary Data

Selecting Chan Error Trace Data

The Ch1 Chan Error Summary Data display shows the error data for the specified Walsh code number and Walsh code length. These parameters are entered in the "cdma2000 Demodulation Properties" dialog box (MeasSetup > Demod Properties > Channel/Layer tab), Despread-Channel "Wash Code Number" and "Walsh Code Length" text boxes.

Tip

You can use the Copy Mkr to Despread Chan marker feature to automatically enter the Despread-Channel Spread Code Length, Code Channel and IQ Branch settings.

Averaging and Channel Error Summary Data

If averaging is on, averaging is applied to most numeric error data in the error Summary data with the following exceptions. The peak data values, such as peak EVM, peak Magnitude and peak Phase error are averaged only for the Continuous Peak Hold averaging type. The PCG (or slot) number is never averaged.

Error data from the current scan is not included in the average if any of these conditions occur:

•	CARRIER LOCK?

•	DATA? (if caused by a temporary condition like partial data record)

Using Band Power markers to limit Error information

If you want channel error information for all points over a selected region, you can use the band-power markers with an error trace.

For example, here's how you could compute the phase error for all points within a region. Click Trace, Data, Chan IQ Phase Error to display the IQ phase-error trace, then click Markers > Calculation and select the Band Power check box to turn on the band-power markers.

Now position the band-power markers to select the region of interest, and select RMS Sqrt (Pwr) from the Calculate text box to display the phase error for the selected region.

Hint

At this point, you could simply click Trace > Data > Chan IQ Mag Error to display the magnitude error for the same region.

How EVM and Magnitude Error data result are calculated (%RMS)

In the channel error summary data, the analyzer shows the error-vector magnitude and magnitude error as a percentage. Before computing this percentage, the analyzer normalizes the constellation diagram such that the outer-most, ideal states have a magnitude of one.

The analyzer computes the overall, percent error by first computing the error-vector magnitude and magnitude error at each symbol time.

Next, the analyzer derives the rms average for each parameter. For example, to compute the rms average for the magnitude error, the analyzer takes the square root of the sum of the squares of the individual magnitude-error values at each symbol time.

Because the magnitude of the constellation diagram's outer-most state has been normalized to one, the rms average is the overall, percent error.

See also

About the Channel Symbol Table

About the Composite Error Summary Data

About Ch1 Chan trace data


Alphabetical list of Channel Error Summary Data (cdma2000)
Available Channel Error Summary Data (cdma2000)

(Vector Signal Analyzer application only)

The following is an alphabetical list of available Channel Error Summary data (Trace, Data, Ch1 Chan Syms/Errs):

•	Chan Error Vector Magnitude (EVM)

•	Chan Magnitude Error (MagErr)

•	Chan PCG

•	Chan Phase Error (Phase Err)

For information about using error summary data with ADS, see Demod Errors and ADS.

See also

About the Channel Error Summary Data


Chan Error Vector Magnitude (cdma2000)

Chan EVM is the Error Vector Magnitude for the specified Walsh Code Number and Walsh Code Length. The display shows these EVM values; the RMS (root mean square) EVM, the Peak (largest) EVM, and the symbol number with the Peak EVM.

Chan EVM is the similar to digital demodulation EVM. See Digital Demodulation Error-vector magnitude (EVM) for further information about this trace data.

See also

Digital Demodulation Error-vector magnitude (EVM)

About the Channel Error Summary Data


Chan Magnitude Error (cdma2000)

Chan Magnitude Error (MagErr) is the difference in amplitude between the I/Q measured signal and the I/Q reference signal for the specified Code Channel and Spread Code Length.

The display shows these Magnitude error values; the RMS (root mean square) Magnitude Error, the Peak (largest) Magnitude Error, and the symbol number with the Peak Magnitude Error.

Magnitude error is an indicator of the quality of the amplitude component of the modulated signal. For example: a very high magnitude error might indicate high incidental AM modulation on the signal.

Hint

The description of Error-vector magnitude (EVM) includes a pictorial diagram that shows how Magnitude Error is derived.

See also

Digital Demodulation Error-vector magnitude (EVM)

About the Channel Error Summary Data


Chan Phase Error (cdma2000)

Chan Phase error is the difference, in phase, between the I/Q reference signal and the I/Q measured signal for the specified Code Channel and Spread Code Length.

The display shows these Phase error values; the RMS (root mean square) Phase Error, the Peak (largest) Phase Error, and the symbol number with the Peak Phase Error.

The magnitude of this parameter is an indicator of the quality of the phase component of the modulated signal. For example, a very high phase error might indicate high incidental FM modulation on the signal.

Hint

The description of Digital Demod Error-vector magnitude (EVM) includes a pictorial diagram that shows how Phase Error is derived.

See also

Digital Demodulation Error-vector magnitude (EVM)

About the Channel Error Summary Data


Chan PCG (cdma2000)

This channel parameter identifies the first PCG (Power Control Group) used in the measurement for the specified Walsh Code Number and Walsh Code Length.

The channel PCG number is available only when the measurement is triggered. For an accurate PCG number, the trigger should be a signal like an "even second" signal that is synchronized to the start of the cdma2000 frame.

The channel PCG is offset from the Composite PCG by the measurement Offset parameter.

See About Measurement Interval and Offset for more information about PCG, Result Length, Measurement Interval and Measurement Offset interaction.

See also

Comp PCG Error data

Time tab - cdma2000 Properties

About the Channel Error Summary Data


About the Composite Error Summary Data (cdma2000)
About Composite Error Summary Data (cdma2000)

(Vector Signal Analyzer application only)

When cdma2000 Demodulation is enabled, selecting the Ch1 Comp, Error Summary trace data shows the composite error summary data. The error summary display shows you error information for the composite signal.

•	Alphabetical list of Composite Error Summary Data

Composite error summary data is always computed from the first PCG in the measurement and ignores the measurement-offset parameter.

There is also channel error summary trace data (Ch1 Chan, Syms/Errs), which provides the error information for a specific code channel and code layer (see About Channel Error Summary Data)

See also

About the Channel Error Summary Data

About Ch1 Comp trace data

About Measurement Interval and Offset


Alphabetical list of Composite Error Data (cdma2000
Available Composite Error Data (cdma2000

(Vector Signal Analyzer application only)

The following is an alphabetical list of available Composite Error Summary data results (Trace, Data, Ch1 Comp, Error Summary):

•	Comp EVM (Error Vector Magnitude)

•	Comp Frequency Error (Freq Err)

•	Comp IQ Offset

•	Comp Magnitude Error (MagErr)

•	Comp PCG

•	Comp Peak Active CDE

•	Comp Peak CDE

•	Comp Phase Error (Phase Err)

•	Comp Rho

•	Comp T trigger

For information about using error summary data with ADS, see Demod Errors and ADS.

See also

About the Composite Error Summary Data


Composite Error Vector Magnitude (cdma2000)

Composite EVM is the Error Vector Magnitude for the composite signal (includes all Walsh Code Lengths (Symbol Rate) and Walsh Code Numbers). The display shows these EVM values; the RMS (root mean square) EVM, the Peak (largest) EVM, and the symbol number with the Peak EVM.

A perfect ideal signal is synthesized at the chip level and identified as the reference signal. The reference signal is subtracted from the measured signal to produce a time record of error phasors. The square root of the ratio of the mean power of the error signal to the mean power of the reference signal is computed and expressed as a percentage EVM.

This parameter is similar to digital demodulation EVM except that it is computed at the chip rate instead of the symbol rate. See Digital Demodulation Error-Vector Magnitude (EVM) for further information about this parameter.

See also

About the Composite Error Summary Data

Digital Demodulation Error-Vector Magnitude (EVM)


Composite Frequency Error (cdma2000)

Composite Frequency Error (Freq Err) shows the composite signal carrier frequency-error relative to the analyzer's center frequency. This parameter is displayed in Hertz and is the amount of frequency shift, from the analyzer's center frequency, that the analyzer must perform to achieve carrier lock.

Errors in RF frequency, LO frequency, or digitizer clock rate could all appear as carrier frequency error.

See also

About the Composite Error Summary Data

About Frequency


Composite IQ Offset (cdma2000)

Composite IQ Offset (also called I/Q origin offset) indicates the magnitude of the carrier feedthrough signal. When there is no carrier feedthrough, IQ offset is zero (−infinity dB).

This parameter is the same as the digital demod IQ Offset except that the source data is the composite signal. See Digital Demod IQ Offset for further information about this parameter.

See also

About the Composite Error Summary Data

Digital Demod IQ Offset


Composite Magnitude Error (cdma2000)

Composite Magnitude Error (MagErr) is the difference in amplitude between the I/Q measured signal and the I/Q reference signal for the composite signal.

The display shows these Magnitude error values; the RMS (root mean square) Magnitude Error, the Peak (largest) Magnitude Error, and the chip number with the Peak Magnitude Error.

This parameter is the same as the channel Magnitude Error except that the source data is the composite signal. See Channel Magnitude Error for further information about this parameter.

See also

Channel Magnitude Error

About the Composite Error Summary Data


Composite Peak Active CDE (cdma2000)

Composite Peak Active CDE is the largest active code-Channel Code Domain Error (in dB). This is the largest measured CDE for all active code channels in the composite signal.

See also

Base Code Length

CDE Composite trace data

CDE Layer trace data

About the Composite Error Summary Data


Composite Peak CDE (cdma2000)

Composite Peak CDE is the largest measured code channel—Code Domain Error. This is the largest measured CDE for all code channels (active and inactive) in the base code layer (the code layer with the smallest symbol rate) in the composite signal.

See also

Base Code Length

CDE Composite trace data

CDE Layer trace data

About the Composite Error Summary Data


Composite Phase Error (cdma2000)

Composite Phase error (Phase Err) is the difference, in phase, between the I/Q reference signal and the I/Q measured signal for composite signal (includes all Walsh Code Lengths (Symbol Rate) and Walsh Code Numbers).

The display shows these Phase error values; the RMS (root mean square) Phase Error, the Peak (largest) Phase Error, and the chip number with the Peak Phase Error.

This parameter is the same as channel Phase error except that the source data is the composite signal. See Channel Phase error for further information about this parameter.

See also

Channel Phase error

About the Composite Error Summary Data


Composite Rho (cdma2000)

Rho is the normalized correlation coefficient between the measured and ideal reference signals. Rho is computed by comparing the normalized correlated power between the measured signal and the reference signal and is designated as the waveform quality factor. The maximum value of Rho is 1.0 (which means the measured signal and reference signal are 100% identical).

A Rho value of 1.0 indicates that all of the transmitted power correlates with the ideal signal as determined by the detected sequence.

Rho is the correlated power for all active code channels ( as seen in the composite CDP trace data display).

If the signal errors are uniformly distributed, then Rho approximately equals:

See also

About the Composite Error Summary Data


Composite Slot (cdma2000)

This parameter identifies the first PCG used in the measurement for the composite signal. The composite PCG ignores the measurement offset, which is different than Channel PCG, which uses the measurement offset.

The Comp PCG number is available only when the measurement is triggered. For an accurate PCG number, the trigger should be a signal like an "even second" signal that is synchronized to the start of the cdma2000 frame.

See also

About Measurement Interval

Chan PCG trace data

About the Composite Error Summary Data


T trigger (cdma2000)

T-trigger shows the amount of time, in chips, from the trigger to the start of the sync symbol. For example, the sync symbol marks the beginning of a frame of 16 PCGs. If you select a trigger that starts measuring at the beginning of a PCG, T trigger would be 0 chips.

Note

The T trigger value is displayed only for triggered measurements.

See also

About Measurement Interval

Composite PCG

About the Composite Error Summary Data


About Trace Data (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data

This application provides trace data in the Time Domain, Frequency Domain and Code Domain. You can view code domain power trace data for the composite signal or for a specific CDP layer (symbol rate). Time domain trace data may be viewed for the composite signal or for a specific code channel. Time and spectrum trace data is also provided for the pre-demodulated and the demodulated data.

Composite Trace Data

Composite (or Comp) trace data are measurement results derived from the total signal. This includes the combined data from all code Layers (Walsh Code Lengths (Symbol Rates)) and code channels (Walsh Code Numbers).

Channel Trace Data

Channel (or Chan) trace data are measurement results for a single code channel (Walsh Code Number) within a specified code layer (Walsh Code Length (Symbol Rate)).

Trace Data Menu

To accommodate all the available measurement results and display formats; trace data has been grouped into trace data sub-menu categories. These sub-menu selections are grouped together by common measurement types as shown below:

Ch1 trace data	Time and Frequency trace data results derived from the pre-demodulated time record data.
Ch1 CDP trace data	Code Domain Power and Code Domain Error trace data results for either the composite signal or for a specified code layer.
Ch1 Chan trace data	Time domain trace data results for a single code channel.  Channel trace data results are derived from data for a single code channel (Walsh Code Number) within a specified code layer (Walsh Code Length/Symbol Rate).
Ch1 Comp trace data	Time domain and frequency domain trace data results for the Composite signal.  Composite trace data results are derived from data for the total signal, that is, the combined data from all Walsh Code Lengths (Symbol Rates) and Walsh Code Numbers.
Math	Trace data results from a math function
Register	Trace data display from a Data Register
No Data	Empty trace data display
See also

Available Features (cdma2000)

89600-Series VSA Standard Trace Data

About Channel Error Summary data (cdma2000)

About Composite Error Summary data (cdma2000)


About Ch1 Trace Data (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1

Time and frequency trace data results derived from the pre-demodulated channel 1 input data (Time Record data).

Available Ch1 Trace Data

Correction
Inst spectrum
Raw Main Time
Spectrum
Time
See also

About Trace Data (cdma2000)

Ch1 CDP trace data

Ch1 Chan trace data

Ch1 Comp trace data

89600-Series VSA Standard Trace Data


About Ch1 CDP Trace Data (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP

CDP trace data provides composite and code layer Code Domain Power and Code Domain Error trace data results.  Code Domain Power (CDP) is an analysis of the distribution of signal power across the set of code channels normalized to the total signal power.

•	CDP Composite Trace Data:    This is the CDP (Code Domain Power) and CDE (Code Domain Error) trace data results for the composite signal.  Composite trace data results are derived from data for the total signal. This includes the combined data from all Walsh Code Lengths (or Symbol Rates) and Walsh Code Numbers.

•	CDP Layer Trace Data:    This is the CDP (Code Domain Power) and CDE (Code Domain Error) trace data results for a specified code layer.  You use the CDP Layer Walsh Code Length drop-down list to specify the code layer (MeasSetup > Demod Properties… > Channel/Layer tab).

Note

You can view CDP as absolute power by clearing the IQ Normalize check box (MeasSetup, DemodProperties, Format tab).

Display Format

The data is shown in a multi-color format that assigns a unique color to each code layer and related active code channels. This makes it easy to visually identify and distinguish the active code channels (Walsh Code Number) for a given code layer (Walsh Code Length). The colors are also user definable (See Display Appearance).

Note

For CDP and CDE trace data displays with separate I/Q channel trace bars, to position the Marker to the desired Code Layer/Channel bar, you must click in close proximity to the horizontal bar that indicates the value of the code channel being measured.

Available Ch1 CDP Trace Data

CDE Composite	Inst CDE Composite
CDE Layer	Inst CDE Layer
CDP Composite	Inst CDP Composite
CDP Layer	Inst CDP Layer
See also

About Trace Data (cdma2000)

Ch1 trace data

Ch1 Chan trace data

Ch1 Comp trace data

89600-Series VSA Standard Trace Data


About Ch1 Chan Trace Data (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan

Lets you select time domain trace data for the specified code channel (Walsh Code Number) and code layer (Walsh Code Length). This includes both time domain IQ trace data and Symbol/Error table data.

For cdma2000 reverse link, the "I" and "Q" branches are logically separate signals. All channel trace data results contain both I and Q branch data, except symbol table trace data. The symbol table contains either the "I" or the "Q" bits as specified by the I/Q branch parameter.

Selecting a Code Channel (Walsh Code Number)

You specify the code channel in the Despread Channel Walsh Code Number drop-down list and the code layer in the Despread Channel Walsh Code Length drop-down list. (click MeasSetup > Demod Properties > Channel/Layer tab).

Tip

You can use the Copy Mkr to Despread Chan marker feature to automatically enter the Walsh Code Length and Walsh Code Number information for you.

Available Ch1 Chan Trace Data

Chan Error Vector Time	Chan IQ Phase Error
Chan IQ Mag Error	Chan IQ Ref Time
Chan IQ Meas Time	Chan Syms/Errs
See also

About Trace Data (cdma2000)

Ch1 trace data

Ch1 CDP trace data

Ch1 Comp trace data

89600-Series VSA Standard Trace Data


About Ch1 Comp Trace Data (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp

Lets you select time domain trace data for the composite signal. Ch1 Comp trace data give you data results computed from the total demodulated signal. All composite trace data is computed from the first PCG in the measurement. The Measurement Interval and Measurement Offset parameters are not used for composite trace data results.

Available Ch1 Comp Trace Data

Comp Error summary	Comp IQ Phase Error
Comp Error Vector Spec	Comp IQ Ref Spec
Comp Error Vector Time	Comp IQ Ref Time
Comp IQ Mag Error	Comp Inst Error Vector Spec
Comp IQ Meas Spec	Comp Inst IQ Meas Spec
Comp IQ Meas Time	Comp Inst IQ Ref Spec
See also

About Trace Data (cdma2000)

Ch1 trace data

Ch1 CDP trace data

Ch1 Chan trace data

89600-Series VSA Standard Measurement Data

Option B7N: cdma2000 Available Features


CDE Composite (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP > CDE Composite

Shows the Code Domain Error (CDE) value for each active code channel (Walsh Code Number) for all code layers (Walsh Code Lengths), along with the CDE value for each inactive code channel at the lowest code layer.  The CDE of a particular code channel is a measure of the error power in a code channel relative to the total signal power.

Note

CDE Composite trace data results are computed only from the first measured PCG (Power Control Group). This is different than CDP Composite trace data results, which can include more than the first PCG in the measurement results.

Display Format

The data is shown in a multi-color format that assigns a unique color to each code layer and related active code channels. This makes it easy to visually identify and distinguish the active code channels (Walsh Code Number) for a given code layer (Walsh Code Length). The colors are also user definable (See Display Appearance).

Note

For CDP and CDE trace data displays with separate I/Q channel trace bars, to position the Marker to the desired Code Layer/Channel bar, you must click in close proximity to the horizontal bar that indicates the value of the code channel being measured.

Tip

You can use the CDE Layer trace data display to view only one code layer (Walsh Code Length) at a time.

See also

CDE Layer trace data

CDP Composite trace data

Available Ch1 CDP trace data

About cdma2000 trace data


CDE Layer (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP > CDE Layer

Shows the Code Domain Error (CDE) value for each code channel (Walsh Code Number) within the specified code layer (Walsh Code Length).  The CDE of a particular code channel is a measure of the error power in a code channel relative to the total signal power.

Note

CDE Layer trace data results are computed only from the first measured PCG. This is different than CDP Layer trace data results, which can include more than the first PCG in the measurement results.

Display Format

The data is shown in a multi-color format that assigns a unique color to each code layer and related active code channels. This makes it easy to visually identify and distinguish the active code channels (Walsh Code Number) for a given code layer (Walsh Code Length). The colors are also user definable (See Display Appearance).

Note

For CDP and CDE trace data displays with separate I/Q channel trace bars, to position the Marker to the desired Code Layer/Channel bar, you must click in close proximity to the horizontal bar that indicates the value of the code channel being measured.

Selecting a Code Layer

You select the desired code layer by selecting the Walsh Code Length in the CDP Layer Walsh Code Length text box (MeasSetup > Demod Properties.. > Channel/Layer tab).

See also

CDE Composite trace data

CDP Layer trace data

About Measurement Interval and Offset

Available Ch1 CDP trace data

About cdma2000 trace data


CDP Composite (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP > CDP Composite

Shows the Code Domain Power trace data for the composite signal (combined code layers and channels). Code Domain Power (CDP) is an analysis of the distribution of signal power across the set of code channels normalized to the total signal power. If the Measurement Interval is greater than one, all PCGs within the Measurement Interval are averaged together to produce the CDP Composite results.

TIP

You can view CDP trace data as absolute power by clearing the IQ Normalize check box (MeasSetup, Demod Properties, Format tab).

Display Format

The data is shown in a multi-color format that assigns a unique color to each code layer and related active code channels. This makes it easy to visually identify and distinguish the active code channels (Walsh Code Number) for a given code layer (Walsh Code Length). The colors are also user definable (See Display Appearance).

Note

For CDP and CDE trace data displays with separate I/Q channel trace bars, to position the Marker to the desired Code Layer/Channel bar, you must click in close proximity to the horizontal bar that indicates the value of the code channel being measured.

The y-axis shows the power level and the x-axis shows the Walsh Code Number (code channel). The x-axis annotation and marker location are based on the lowest symbol rate (ksym/sec), or equivalently, the highest Walsh Code length. You can also reorder the channels so that all related code channels are displayed adjacent to each other (see Code Order).

This example Ch1 Composite CDP display (code order = bit reversed), Trace A Marker shows the following:

Symbol Rate:	38.4 Ksym/s
Walsh Code Length:	32
Walsh Code Number	18
Power Level:	−9.714 dB
Asterisk *:	The asterisk (*) indicates that the marker is positioned on an active channel
Tip

You can use the CDP Layer trace data display to view only one code layer (Walsh Code Length) at a time.

See also

CDP Layer trace data

Code Order trace data

About Measurement Interval and Offset

Available Ch1 CDP trace data

About cdma2000 trace data


CDP Layer (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP > CDP Layer

Shows the Code Domain Power trace data for all code channels (Walsh Code Number) within the specified code layer (Walsh Code Length). If the Measurement Interval is greater than one, all PCGs within the Measurement Interval are averaged together to produce the CDP Layer results.

Display Format

The data is shown in a multi-color format that assigns a unique color to each code layer and related active code channels. This makes it easy to visually identify and distinguish the active code channels (Walsh Code Number) for a given code layer (Walsh Code Length). The colors are also user definable (See Display Appearance).

Note

For CDP and CDE trace data displays with separate I/Q channel trace bars, to position the Marker to the desired Code Layer/Channel bar, you must click in close proximity to the horizontal bar that indicates the value of the code channel being measured.

Selecting a Code Layer

You select the desired code layer by entering the Walsh Code Length in the CDP Layer Walsh Code Length text box (MeasSetup > Demod Properties.. > Channel/Layer tab).

See also

CDP Composite trace data

About Measurement Interval and Offset

Available Ch1 CDP trace data

About cdma2000 trace data


Channel Error Vector Time
Channel Error Vector Time (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan > Error Vector Time

When 1xEV-DO Demodulation is enabled, the Error Vector Time trace data shows the time-domain error vector trace data results for the specified code channel (Walsh Code Number) and code layer (Walsh Code Length).  Error Vector Time trace data is the computed error vector between corresponding symbol points in the I/Q measured and I/Q reference signals.  You can view the data results as Error Vector Magnitude, Error Vector Phase, only the I component or only the Q component (see Trace Data Formats below).

Note

Available only for Reverse link direction channels.

Hint

You can increase the number of symbol points by increasing the Measurement Interval(see Measurement Interval).

If normalization is OFF, the analyzer shows the instantaneous magnitude for each point. If normalization is ON, the analyzer shows the error vector as a percentage (see IQ normalize for an explanation of how this percentage is derived).

Trace Data Formats

It is important to remember that the Error Vector Time trace is a time record made up of complex, time-domain data. Each point in the time record has two components: I and Q. To make sense of the data, you must select an appropriate trace data format (Trace > Format > Format: drop--down list).

•	Linear Mag :  Shows the EVM (Error Vector Magnitude).

•	Real(I) :  Shows the I component of the error vector.

•	Imag(Q) :  Shows the Q component of the error vector.

•	Wrap Phase:  Shows the Error Vector Phase error.

For example, to see the error-vector magnitude, select the Linear Mag trace format (Trace > Format > Format: Linear Mag). Selecting Linear Mag computes the square root of the sum of the squares for each complex pair of points in the time record, which is the error-vector magnitude (EVM):

See also

About Ch1 Chan trace data (cdma2000)

About cdma2000 trace data


Channel IQ Mag Error and IQ Phase Error (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan > IQ Mag Error

or Trace > Data > Ch1 Chan > IQ Phase Error

When cdma2000 Demodulation is selected, the Chan  IQ Mag Error and Chan IQ Phase Error trace data show the vector error between the I/Q measured and the I/Q reference trace data at the sampled chip times for the specified code channel (Walsh Code Number) and code layer (Walsh Code Length).

Chan  IQ Mag Error trace data shows the magnitude error and Chan IQ Phase Error trace data shows the phase error for the specified code channel (Walsh Code Number).

Selecting the Code Channel and Code Layer

Select the code channel with the Despread Channel - Walsh Code Number text box (MeasSetup > Demod Properties > Channel/Layer tab).  Select the code layer with the Despread Channel - Walsh Code Length drop-down list (MeasSetup > Demod Properties > Channel/Layer tab).

Concepts

This trace data is determined just like it is for the IQ Mag Error and IQ Phase Error trace data for Digital Demodulation, see IQ Mag Error and IQ Phase Error (Digital Demod) trace data topic.

See also

IQ Mag and IQ Phase Error (Digital Demod)

Available Ch1 Chan trace data (cdma2000)

About cdma2000 trace data


Channel IQ Meas Time and IQ Ref Time (cdma2000)

(Vector Signal Analyzer application only)

Menu Path:	Trace > Data > Ch1 Chan > IQ Meas Time

or 	Trace > Data > Ch1 Chan > IQ Ref Time

When cdma2000 Demodulation is enabled, the IQ Meas Time and IQ Ref Time traces are the demodulated time data results sampled at the chip times for the specified code channel (Walsh Code Number) and code layer (Walsh Code Length).  IQ Meas Time is the data results for the measured input signal.  IQ Ref Time trace data is the data results that would be derived from an ideal input signal (reference signal).

Concepts

The analyzer's demodulator produces two signals: I/Q Measured and I/Q Reference.

IQ measured signal

The IQ measured signal is the result of resampling the data to one point per chip and applying carrier locking, symbol locking, IQ origin offset and burst amplitude-droop compensation, filtering and system gain normalization to the incoming signal.

IQ reference signal

IQ reference signal is the ideal signal that the analyzer generates from the IQ measured signal demodulated data bits.  The analyzer detects bits from the measured IQ signal and reconstructs a sequence of ideal I and Q states. These are then treated as ideal impulses and are baseband filtered according to the reference filter and added together to form the IQ reference signal. The resultant IQ reference signal is then used compare and analyze against the IQ measured signal.

Tip

Online help for Digital Demodulation includes a block diagram that shows how I/Q measured and I/Q reference data are generated.

Compensation

Demodulation is performed with carrier lock and chip lock. In addition, the analyzer compensates for I/Q origin offset and burst amplitude-droop.

Time-Domain Displays

The analyzer's demodulator produces time-domain data. If you select IQ Meas Time, the analyzer shows the I/Q measured signal in the time domain. Likewise, if you select IQ Ref Time, the analyzer shows the I/Q reference signal in the time domain.

The data can be displayed in a variety of trace data formats, including I-Q, Constellation, Q-Eye, I-Eye, and Trellis-Eye formats (see Trace Formats (Digital Demodulation)) topic.

If normalization is OFF, the analyzer shows the instantaneous magnitude. If normalization is ON, the analyzer scales the IQ measured and IQ reference traces to map them onto the unit circle, which yields a unitless y-axis.

Hint

For further details about normalization, see online help for IQ Normalize.

Parameter Interaction

The following parameters affect how the analyzer shows the I/Q measured and I/Q reference signals:

•	Result Length determines the number of PCGs in the measurement.

•	Measurement Interval and Measurement Offset determine which PCGs will be displayed

See also

Available Ch1 Chan trace data (cdma2000)

About cdma2000 trace data


Channel Syms/Errs (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan > Syms/Errs

When cdma2000 Demodulation is enabled, selecting Ch1 Chan Syms/Errs trace data shows the channel symbol table. The symbol table provides the signal quality error summary information and the binary bits for each symbol for the specified code channel and code layer. The bottom half of the display shows the symbol bit data and the upper half shows the error summary data.

For more information see the following topics:

•	About the Channel Symbol Table

•	About the Channel Error Summary Data

•	Alphabetical list of Channel Error Summary Data

There is also composite error summary trace data (Trace > Data > Ch1 Comp > Error Summary), which provides the error information for the composite signal (see About Composite Error Summary Table).

Selecting Reverse link IQ Symbol Bit data

For Reverse link signals, the "I" and "Q" data channels are logically separate signals. All trace data results contain both the "I" and the "Q" branches of the signal, except the symbol binary bit data. The symbol data shows either the "I" or the "Q" symbol bits as specified by the I/Q channel parameter (MeasSetup > DemodProperties > Channel/Layer tab).

See also

About Ch1 Chan trace data (cdma2000)

About cdma2000 trace data


Composite Error Summary (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

When cdma2000 Demodulation is enabled, selecting the Ch1 Comp Error Summary trace data shows the composite error summary data. This is the signal quality error summary information for the composite signal.

For more information see the following topics:

•	About Composite Error Summary Data.

•	Alphabetical list of Composite Error Summary Data

There is also channel error summary trace data (Trace > Data > Ch1 Chan > Syms/Errs), which provides the error information for a specific code channel and code layer (see About Channel Error Summary Data)

See also

About Ch1 Comp trace data

About Trace Data (cdma2000)


Composite Error Vector Spec (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Vector Spec

When cdma2000 Demodulation is enabled, the composite Error Vector Spec trace data shows the spectrum of the composite Error Vector Time trace data. In other words, the analyzer derives the composite Error Vector Time trace data, and then windows and FFTs the data to produce the composite Error Vector Spectrum trace.

The trace data is computed from the first PCG in the measurement and the Measurement Interval and Measurement Offset parameter settings are ignored (see Measurement Interval and Offset).

Marker Frequency Correction

The analyzer's demodulator removes carrier-frequency error. Therefore, in the composite error vector spectrum display, you must add the carrier-frequency error to marker readouts to obtain exact frequency information. The carrier-frequency error (Freq Err) is shown in the Composite Error Summary (FreqErr) Table.

See also

Available Ch1 Comp trace data

Available Ch1 Comp trace data


Composite Error Vector Time (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Vector Time

When 1xEV-DO Demodulation is enabled, the Ch1 Comp Error Vector Time trace data is the error-vector, time-domain data for the composite signal.

The trace data is computed from the first PCG in the measurement and the Measurement Interval and Measurement Offset parameter settings are ignored (see Measurement Interval and Offset).

Concept Information

This trace data is identical to the Chan Error Vector Time  trace data except that the source data is the composite signal. See Ch1 Chan Error Vector Time for concept information.

See also

Ch1 Chan Error Vector Time

Available Ch1 Comp trace data


Composite IQ Mag Error and IQ Phase Error (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > IQ Mag Error

or Trace > Data > Ch1 Comp > IQ Phase Error

When cdma2000 Demodulation is enabled, the Ch1 Comp IQ Mag Error and Ch1 Comp IQ Phase Error traces show the error between the I/Q measured and the I/Q reference signals for the composite signal.

Ch1 Comp IQ Mag Error shows the magnitude error and Ch1 Comp IQ Phase Error shows the phase error for the composite signal.

The trace data is computed from the first PCG in the measurement and the Measurement Interval and Measurement Offset parameter settings are ignored (see Measurement Interval and Offset).

Concepts

This trace data is determined just like it is for the IQ Mag Error and IQ Phase Error trace data for Digital Demodulation, see IQ Mag Error and IQ Phase Error (Digital Demod) trace data topic.

See also

Ch1 Chan Error Vector Time

Available Ch1 Comp trace data


Composite IQ Meas Spec and IQ Ref Spec (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > IQ Meas Spec

or Trace > Data > Ch1 Comp > IQ Ref Spec

When cdma2000 Demodulation is enabled, this is the spectrum of the composite IQ Meas Time or composite IQ Ref Time trace data. The analyzer produces the spectrum by Windowing and FFTing the time trace data. The spectrum represents the signal AFTER filtering.

The trace data is computed from the first PCG in the measurement and the Measurement Interval and Measurement Offset parameter settings are ignored (see Measurement Interval and Offset).

Marker Frequency Correction

The analyzer's demodulator removes carrier-frequency error. Therefore, in the composite error vector spectrum display, you must add the carrier-frequency error to marker readouts to obtain exact frequency information. The carrier-frequency error (Freq Err) is shown in the Composite Error Summary trace data.

Hint

By default, the analyzer shows the log(dB) magnitude when you select IQ measured spectrum. The same is true for I/Q reference.

See also

VSA Concepts (Windowing and FFTing)

Chan Error Vector Time trace data

Available Ch1 Comp trace data


Composite IQ Meas Time and IQ Ref Time (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > IQ Meas Time

or Trace > Data > Ch1 Comp > IQ Ref Time

When cdma2000 Demodulation is enabled, the Comp IQ Meas Time and Comp IQ Ref Time trace data are the time data results of cdma2000 demodulation for the composite signal.   Comp IQ Meas Time is the data results for the measured input signal.  Comp IQ Ref Time trace data is the data results that would be derived from an ideal input signal (reference signal).

The trace data is computed from the first PCG in the measurement and the Measurement Interval and Measurement Offset parameter settings are ignored.

Concepts

The analyzer's demodulator produces two signals: I/Q Measured and I/Q Reference.

IQ measured signal

The IQ measured signal is the result of resampling the data to one point per chip and applying carrier locking, symbol locking, IQ origin offset compensation, filtering and system gain normalization to the incoming signal.

IQ reference signal

IQ reference signal is the ideal signal that the analyzer generates from the IQ measured signal demodulated data bits.  The analyzer detects bits from the measured IQ signal and reconstructs a sequence of ideal I and Q states. These are then treated as ideal impulses and are baseband filtered according to the reference filter and added together to form the IQ reference signal. The resultant IQ reference signal is then used compare and analyze against the IQ measured signal.

Tip

Online help for Digital Demodulation includes a block diagram that shows how I/Q measured and I/Q reference data are generated.

Time-Domain Displays

The analyzer's demodulator produces time-domain data. If you select Comp IQ Meas Time, the analyzer shows the composite IQ measured signal in the time domain. Likewise, if you select Comp IQ Ref Time, the analyzer shows the composite IQ reference signal in the time domain.

The data can be displayed in a variety of trace data formats, including I-Q, Constellation, Q-Eye, I-Eye, and Trellis-Eye formats (see Trace Formats (Digital Demodulation)) topic.

If normalization is OFF, the analyzer shows the instantaneous magnitude. If normalization is ON, the analyzer scales the composite IQ measured and composite IQ reference traces so that the RMS level is one, which produces a unitless y-axis.

Hint

For further details about normalization, See IQ Normalize.

See also

Chan Error Vector Time trace data

Available Ch1 Comp trace data


Composite Inst Error Vector Spec (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Inst Error Vector Spec

Shows the instantaneous spectrum of the composite Error Vector Time trace data. Inst Error Vector Spec trace data is the non-averaged composite Error Vector Spectrum trace data.

See also

Available Ch1 Comp trace data

Available Ch1 Comp trace data


Composite Inst IQ Meas Spec and IQ Ref Spec (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Inst IQ Meas Spec

 	or Trace > Data > Ch1 Comp > Inst IQ Ref Spec

When cdma2000 Demodulation is enabled, the Ch1 Comp Inst IQ Meas Spec and Ch1 Comp Inst IQ Ref Spec traces show you the instantaneous spectrum of the composite IQ Meas Time and composite IQ Ref Time signals respectively. It is the non-averaged IQ Meas Spec and IQ Ref Spec trace data.

See also

Chan Error Vector Time trace data

Available Ch1 Comp trace data


Correction (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 > Correction

Shows the correction trace derived by the analyzer from the calibration data. The correction trace is applied to the acquired data to compensate for phase and magnitude anomalies in the analyzer's hardware and software signal processing.

See also

About Calibration

Ch1 trace data

About Trace Data


Inst CDE Composite (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP > Inst CDE Composite

Shows the Instantaneous Code Domain Error trace data for the composite signal. Inst CDE Composite trace data is the non-averaged CDE Composite trace data (see CDE Composite Trace Data).

Note

Inst CDE Composite trace data is not affected by averaging.

See also

CDE Composite trace data

Available Ch1 CDP trace data

About cdma2000 trace data


Inst CDE Layer (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP > Inst CDE Layer

Shows the Instantaneous Code Domain Error trace data for all active code channels (Walsh Code Number) within the specified code layer (Walsh Code Length). Inst CDE Layer trace data is the non-averaged CDE Layer trace data (see CDE Layer Trace Data).

Note

Inst CDE Layer trace data is not affected by averaging.

Selecting a code Layer

You select the desired code layer by entering the Walsh Code Length in the CDP Layer Walsh Code Length text box (MeasSetup > Demod Properties.. > Channel/Layer tab).

See also

CDE Layer trace data

Available Ch1 CDP trace data

About cdma2000 trace data


Inst CDP Composite (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP > Inst CDP Composite

Shows the Instantaneous Code Domain Power trace data for the Composite signal. It is the non-averaged CDP Composite trace data (see CDP Composite trace data).

Note

Inst CDP Composite trace data is not affected by averaging.

See also

CDP Composite trace data

Available Ch1 CDP trace data

About cdma2000 trace data


Inst CDP Layer (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP > Inst CDE Layer

Shows the Instantaneous Code Domain Power trace data for all active code channels (Walsh Code Number) within the specified code layer (Walsh Code Length). It is the non-averaged CDP Layer trace data (see CDP Layer trace data).

Note

Inst CDP Layer trace data is not affected by averaging.

Selecting a Code Layer

You select the desired code layer by entering the Walsh Code Length in the CDP Layer Walsh Code Length text box (MeasSetup > Demod Properties.. > Channel/Layer tab).

See also

CDP Layer trace data

Available Ch1 CDP trace data

About cdma2000 trace data


Inst Spectrum (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Inst Spectrum

Instantaneous Spectrum trace data is the non-averaged frequency spectrum of the pre-demodulated Time trace data. It is the non-averaged Spectrum trace data.

If averaging is on, the Instantaneous Spectrum does not show the effects of averaging. To see the effects of averaging, use the Spectrum trace data.

VSA signal flow (see Digital Demodulation Block Diagram):

See also

VSA Concepts (Windowing and FFTing)

Ch1 Spectrum trace data

Available Ch1 trace data

About cdma2000 Trace Data


Raw Main Time
Raw Main Time (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 > Raw Main Time

Raw Main Time is the raw data read from the input hardware or playback file. For more information about this data, refer to the Raw Main Time (Digital Demod) trace data topic.

VSA signal flow (see Digital Demodulation Block Diagram):

See also

Time trace data (cdma2000)

Available Ch1 trace data

About cdma2000 Trace Data


Spectrum (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 > Spectrum

Spectrum trace data is the spectral display of the pre-demodulated Time data. The Time data is Windowed and FFTed to create the Spectrum display.

If averaging is on, Spectrum trace data is the averaged Instantaneous Spectrum trace data. When averaging is set to zero, the Spectrum trace data is equal to the Inst Spectrum trace data.

VSA signal flow (see Digital Demodulation Block Diagram):

See also

About Averaging

VSA Concepts (Windowing and FFTing)

Inst Spectrum trace data

Available Ch1 trace data

About cdma2000 Trace Data


Time (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 > Time

When cdma2000 demodulation is enabled, the Time trace shows the time record before demodulation, as shown in the following block diagram.

The Time trace has the following characteristics:

•	It is pre-demodulated time data.

•	It is unaffected by time averaging.

•	The length and offset are determined by the Measurement Interval and Measurement Offset parameters.

VSA signal flow (see Digital Demodulation Block Diagram):

See also

Ch1 trace data

About Trace Data


Code Order (cdma2000)

(Vector Signal Analyzer application only)

Menu Path: Trace > Digital Demod tab

Lets you set the Code Domain Power display code order to Bit Reversed or Hadamard. This will determine how the code domain power trace data is displayed.

•	Bit Reversed: Reorders related code channels (Walsh Code Number) so that they are viewed adjacent to each other on the code domain power trace data display,

•	Hadamard (Default): Related code channels (Walsh Code Number) are viewed as dispersed along the X-axis as defined by the Hadamard code order on the code domain power trace data display,

Notes

Code Order effects how the Code Domain Power data is displayed and does not change the measurement results.

Using Code Order to make cdma2000 Code Domain Power measurements

For cdma2000 modulation, the code domain power display shows related code channels (Walsh Code Number) dispersed along the X-axis as defined by the Hadamard code order. This makes visually identifying the related code channels difficult.

Another way to look at the same data is by reordering the code channels so related code channels are displayed adjacent to each other. The Bit-Reversed generation of Walsh channels provides us with the desired code number assignment.

To view related code channels (Walsh Code Number) grouped together for cdma2000 modulated signals select the Bit-Reversed Code Order.

You can find information for the rest of the available parameters shown in this dialog box at Option AYA: Digital demod, Digital Demod Trace Data Property dialog box.

See also

Digital Demod Trace Data Property dialog box

Available Code Domain Power trace data

Setting up a cdma2000 Measurement

About Opt B7N: cdma2000 Demodulation


About Option B7R: OFDM Demodulation
About Option B7R: 802.11a and HIPERLAN/2 OFDM Modulation Analysis

Option B7R: 802.11a and HIPERLAN/2 OFDM Modulation Analysis adds Orthogonal Frequency Division Multiplexing demodulation capability to your 89600-Series Vector Signal Analyzer application software. Option B7R lets you perform modulation analysis on OFDM modulated signals including these OFDM standard formats: IEEE std 802.11a-1999, HIPERLAN Type 2 and IEEE 802.11g CCK-OFDM.

While providing demodulation capabilities for standard OFDM formats, option B7R also provides the flexibility to measure nonstandard OFDM formats. The analyzer's demodulator parameters are user-definable, giving you the ability to customize the analyzer to measure non-ideal signals. User-definable parameters include subcarrier modulation format and spacing, symbol timing , burst synchronization, and error correction (see OFDM Demodulation Properties).

The digital demodulator used in this analyzer incorporates advanced technology that does not require external filtering, coherent carrier signals, or symbol-clock timing signals to lock-on to the measured signal. Signal locking requires these parameters to be set properly: center frequency, guard interval, subcarrier spacing and search length.

Along with the typical digital demodulation measurement results, several additional OFDM unique display formats and numeric error data results enhance data analysis. These include Error Vector Time, Error Vector Spectrum, Common Pilot Error, RMS Error Vector Time, and RMS Error Vector Spectrum trace data (see Available Trace Data (OFDM Demodulation). Flexible display scaling and marker functionality help you to make accurate and quick measurements.

You can display measurement data for only one OFDM subcarrier at a time (using the Carrier-to-Analyze parameter) or for selected data regions (using the Measurement interval and offset parameters). These features provide a tremendous tool for signal analysis and troubleshooting (see Result Length Parameters).

The analyzer uses the measured signal (called IQ Meas) to generate an ideal signal (called IQ Ref). Many IQ Meas and IQ Ref trace data formats and numeric error trace data are computed and available for data display and analysis. You can use this data to quantify and locate errors in your signal, see "About Symbol Table".

If you have a Vector Signal Analyzer, an optional second baseband channel allows you to make IQ baseband measurements. You can also perform IQ baseband measurements on data from a file or the stream interface.

See also

OFDM Overview

Available Features (OFDM Demodulation)

Setting up an OFDM Measurement

OFDM Demodulation Properties

About the Symbol Table

Available Trace Data (OFDM Demodulation

Tutorials for OFDM


OFDM Overview

OFDM (Orthogonal Frequency Division Multiplexing) demodulation extends the concept of single carrier modulation by using multiple subcarriers within the same single channel. The total data rate to be sent in the channel is divided between the various subcarriers. The data do not have to be divided evenly nor do they have to originate from the same information source.

IEEE 802.11a/g and HIPERLAN/2 signals are pulsed (or burst) signals. Each pulse comprises multiple symbol-times. The number of symbol-times can vary from burst to burst. Each symbol-time consists of a data region and a guard-band (also called guard interval or cyclic prefix). The guard-band is merely a repeated segment of the end of the data region that has been replicated and prepended to the beginning of the data region. The guard-band is necessary to prevent multi-path channel interference. The data region is generated by taking the inverse FFT of 52 evenly spaced subcarriers. Of these 52 subcarriers, 48 are used for data and four are used as pilots. Each subcarrier represents a single symbol. The magnitude and phase of a subcarrier indicates the symbol-value being transmitted. The magnitude and phase can vary for each subcarrier from symbol-time to symbol-time. Therefore, 52 symbols are transmitted each symbol-time. The total number of symbols transmitted during a burst depends on the number of symbol-times within that burst. All data subcarriers use the same modulation format within a burst, but the modulation format for the data carriers varies from burst to burst. The possible modulation formats for data subcarriers are BPSK, QPSK, 16QAM, and 64QAM. All pilot subcarriers are always modulated using BPSK.

The basic structure of a burst is a preamble section and a data or payload section. At the start of the burst, a preamble is transmitted at a well-known magnitude and phase. The preamble is used for channel equalization and synchronization. The data or payload symbol-times contain the data information.

For OFDM standard IEEE std 802.11a-1999, the preamble training symbols are followed by the SIGNAL data symbol and then the DATA symbols. The SIGNAL data field is transmitted using BPSK, and the data encodes the length and modulation type used for the rest of the burst.

IEEE 802.11g modulation

The IEEE 802.11g standard defines both single-carrier and OFDM modulation formats.  The single-carrier modulation formats are compatible with 802.11b and can be demodulated using the Analyzer's "WLAN-DSSS/CCK/PBCC" demodulation mode (see About Opt B7R: WLAN-DSS 802.11b/g)

IEEE 802.11g defines two different OFDM modulation formats.  One, which is mandatory in 802.11g, is an exact copy of the 802.11a format except that the carrier frequencies are in the 2.4 GHz band.  We refer to this as "IEEE 802.11g OFDM".  The other OFDM format is an optional format called CCK-OFDM that combines an 802.11b-style single-carrier preamble with an 802.11a-style OFDM data payload.  We refer to this as "IEEE 802.11g CCK-OFDM".  The Analyzer's WLAN-OFDM modulation analysis mode can demodulate and analyze either of these OFDM formats.

See also

Available Features (OFDM Demodulation)

About Option B7R: OFDM Demodulation


Available Features (OFDM)

The following features are available with OFDM Demodulation:

•	Standard OFDM demodulation presets:

−	IEEE std 802.11a-1999

−	HIPERLAN/2

−	IEEE 802.11g CCK-OFDM

•	Variable carrier spacing (default 312.5 kHz)

•	Pulse Search

•	IQ Meas constellation measurement data

•	Equalizer response measurement data

•	Common Pilot Error measurement data

•	Enhanced Error Vector trace data display

•	Mirrored (flipped) frequency spectrums used to remove the effects of high-side mixing or complex conjugation mismatches in simulated data.

•	Measurement offset and interval (similar to time gating) used to select specific data segments for analysis

•	Averaging is applicable only in the following circumstances:

−	Multi-burst averaging is available for OFDM RMS Error Vector Spectrum trace data

−	The following averaging types are available for the numeric error summary data and for the pre-demodulated spectrum trace data:

•	RMS (video)

•	RMS Exponential

•	Continuous Peak Hold

•	Time gating is not available (does offer measurement offset/interval feature)

•	By-pass 802.11g CCK WLAN-DSSS preamble to demodulate the 802.11a data payload.

•	CCDF of the OFDM burst

•	Preamble Phase err (used to show frequency settling)

These features are available with Digital Demod but not available for OFDM Demodulation:

•	Measurement\Reference filter

•	Sync search

•	IQ Mag error and IQ Phase error trace data

See also

Available Trace Data (WLAN-OFDM)

89600_Series VSA Application Standard Features

About Option B7R: 802.11a and HIPERLAN/2 OFDM Modulation Analysis

About Averaging


Setting up an OFDM Demodulation Measurement

(Vector Signal Analyzer application only.)

When setting up a OFDM demodulation measurement, there are several things you need to consider. This topic tells you how to connect your signal to an 89600-series analyzer and successfully demodulate digital signals. The information is provided in this order:

•	Connecting Your Signal to the Analyzer

•	Center Frequency

•	Frequency Span

•	Input Range

•	Search Length

•	Subcarrier Spacing

•	Symbol-time Offset

•	Guard Interval

•	Maximum Result Length

•	IEEE 802.11g modulation

Connecting Your Signal to the Analyzer

The analyzer lets you connect your carrier signal or, if your 89600-series analyzer has two input channels, the raw I (In-phase) and Q (Quadrature-phase) signals.

For all receiver configurations except I + jQ, connect your signal to Channel 1. In this case, the analyzer assumes that your signal contains both the I and Q components (the carrier signal). If your analyzer has two input channels, the analyzer ignores the second input channel.

If your analyzer has a second input channel, you can also connect the raw I (In-phase) and Q (Quadrature- phase) signals. To do this, select Input, Channels, I + jQ. With this configuration, the analyzer removes the quadrature mixer from the demodulator's signal flow, which lets you connect the I component of your signal to Channel 1; the Q component to Channel 2.

Notes

•	Selecting I+jQ turns on DC coupling.

•	When using I+jQ, use external calibration to correct for any offset or gain imbalance between the I and Q signals.

•	Ranges for Channel 1 and Channel 2 are set independently.

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Center Frequency

The analyzer's center frequency should be set to within approximately ±500 kHz of the transmitted carrier frequency or the analyzer may not be able to lock onto your signal.

The analyzer center frequency must be within 2 * Subcarrier Spacing (625 kHz for 802.11a or HIPERLAN/2) to lock properly.

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Frequency Span

When selecting a frequency span, select the narrowest span that includes all of your signal components (select a span that is slightly larger than the bandwidth of your signal). If you select a span that is too narrow, your measurement may have excessive errors or the analyzer may lose carrier lock. If the span is less than 18 MHz, the analyzer displays "DATA?" to indicate that the results may not be accurate.

If the span is too large, it may allow spurs to be aliased into the region of interest. Selecting "Show All Frequency Points" (Display, Appearance, Trace tab) can help determine if spurs are being included in the result. If so, the span should be reduced to exclude them and provide a more accurate result.

Using the "Preset to Standard" configuration settings will select the proper default span.

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Input Range

The input range must be set correctly to obtain accurate measurements. Input ranges that are too low overload the analyzer's ADC. Input ranges that are too high increase noise, which increases errors reported in error summary data, such as EVM.

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Search Length

The search length must be long enough capture a complete OFDM burst. Using long pulse lengths will increase the measurement time, but make it more likely that a pulse will be found.

If a pulse is not found a "PULSE NOT FOUND" status message will be displayed.

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Subcarrier Spacing

The subcarrier spacing must match the transmitted signal subcarrier spacing. Use the Preset to Standard default value for the specific OFDM format of interest. You can adjust the value to match a non-standard demod format.

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Symbol-time Offset

Use the Preset to Standard default value. Experienced users may adjust this parameter to fine tune the demodulator.

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Guard Interval

The guard interval must match the guard interval of the transmitted signal. Use the Preset to Standard default value for the specific OFDM demod format of interest.

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Maximum Result Length

Use the Preset to Standard default value. This will provide a good starting value for the result length.

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IEEE 802.11g modulation

The IEEE 802.11g standard defines both single-carrier and OFDM modulation formats.  The single-carrier modulation formats are compatible with 802.11b and can be demodulated using the Analyzer's "WLAN-DSSS/CCK/PBCC" demodulation mode (see About Opt B7R: WLAN-DSS 802.11b/g)

IEEE 802.11g defines two different OFDM modulation formats.  One, which is mandatory in 802.11g, is an exact copy of the 802.11a format except that the carrier frequencies are in the 2.4 GHz band.  We refer to this as "IEEE 802.11g OFDM".  The other OFDM format is an optional format called CCK-OFDM that combines an 802.11b-style single-carrier preamble with an 802.11a-style OFDM data payload.  We refer to this as "IEEE 802.11g CCK-OFDM".  The Analyzer's WLAN-OFDM modulation analysis mode can demodulate and analyze either of these OFDM formats.

See also

Selecting OFDM Demodulation

Using a Standard Setup

Troubleshooting

Tutorials for OFDM


Selecting WLAN-OFDM Demodulation

(Vector Signal Analyzer application with option B7R only.)

Menu Path: MeasSetup > Demodulator > Wireless Networking > OFDM

Sets the analyzer to demodulate WLAN-OFDM (Orthogonal Frequency Division Multiplexing) modulated signals that conform to one of these OFDM standard formats: IEEE std 802.11a-1999, HIPERLAN Type 2 and IEEE 802.11g CCK-OFDM.

Note

For IEEE 802.11g modulation see OFDM Overview topic.

After selecting the demodulator you must set the configuration parameters. You can select one of the available Standard Presets or you can manually set them from the Demod Properties dialog box.

It's also recommended that you review the Setting up an OFDM Measurement.

See also:

OFDM Overview

About VSA Options

Tutorials for OFDM


Using an OFDM Standard Setup

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Format tab > Preset to Standard button

Lets you select a OFDM (Orthogonal Frequency Division Multiplexing) standard preset configuration. When you select a standard preset, the analyzer automatically sets the parameters shown in the following table:

Note

You must specify the OFDM Demodulator before these Standard Presets are available.

	OFDM Standard Presets
Parameter	IEEE 802.11a/g OFDM	IEEE 802.11g CCK-OFDM	HYPERLAN/2
Span	31.25 MHz	31.25 MHz	31.25 MHz
Data Subcarrier Modulation	Auto Detect	Auto Detect	Auto Detect
Guard Interval	1/4 (0.8 µs)	1/4 (0.8 µs)	1/4 (0.8 µs)
Sync Type	Short Training Seq	Chan Estimation Seq	Chan Estimation Seq
Subcarrier Spacing	312.5 kHz	312.5 kHz	312.5kHz
Symbol Timing Adjust	-3.125%	-3.125%	-3.125%
Carriers to Analyze	All	All	All
Pilot Tracking	Track Phase	Track Phase	Track Phase
IQ Normalize	ON	ON	ON
Search Length	1 msec	1 msec	1 msec
Result Length	Auto Select 60 Symbol-times	Auto Select 60 Symbol-times	Auto Select 60 Symbol-times
Measurement Offset	0	0	0
Measurement Interval	60 sym-times	60 sym-times	60 sym-times
Mirror Frequency	Off	Off	Off
See also

OFDM Standards

OFDM Demodulation Properties

Selecting OFDM Demodulation

Setting up an OFDM Demodulation measurement

Troubleshooting an OFDM Measurement

Tutorials for OFDM


Troubleshooting OFDM Measurements

(Vector Signal Analyzer application only.)

This topic contains information to help you troubleshoot measurements when using OFDM Demodulation. You should also review Setting up an OFDM Demodulation Measurement for additional measurement information.

PROBLEM	POSSIBLE CAUSE	SOLUTION
Demodulation fails to lock on signal	Signal not present.	Check connections
	Carrier too far from center frequency.	Adjust center frequency. The analyzer center frequency must be within 2 * Subcarrier Spacing (625 kHz for 802.11a or HIPERLAN/2) to lock properly.
	Input is over-loaded or under ranged.	Adjust input range. Typically, the best EVM is achieved when the range is as small as possible while avoiding overloads.
	Frequency span is too narrow.	Increase frequency span. A frequency span of at least 18 MHz is typically required for 802.11a and HIPERLAN/2 signals.
	Incorrect subcarrier spacing.	Set correct subcarrier spacing. The normal subcarrier spacing for 802.11a and HIPERLAN/2 signals is 312.5 kHz.
	OFDM signal has inverted frequency spectrum	Check the Mirror Frequency Spectrum setting (MeasSetup > Demod Properties > Advanced tab).
	802.11a signal has incorrect SIGNAL symbol at start of burst	Override the auto detection of modulation type and result length (MeasSetup > Demod Properties >  Format tab and Time tab).
	HIPERLAN/2 signal is using 1/8 guard interval length instead of 1/4	If this is the case, the analyzer will get a good Sync Correlation in the Syms/Errs trace, but the IQ Meas constellation and the EVM will be bad. Set the analyzer to use 1/8 guard interval (MeasSetup >  Demod Properties >  Format tab).
	Wrong modulation format	Select correct modulation format
	Signal uses the 802.11g CCK-OFDM format	Use the Preset-to-Standard button to select "IEEE 802.11g CCK-OFDM" format.  Because a CCK-OFDM signal has a much longer preamble than other OFDM signals, it is sometimes helpful to increase the search length.
PULSE NOT FOUND error message	Search length too short.	Increase search length, or adjust triggering to ensure that the leading and trailing edges of a pulse are fully within the search length.
	Signal is not pulsed.	Both 802.11a and HIPERLAN/2 are pulsed signals. If the signal is not pulsed, try to use triggering to position the preamble just after the beginning of the search length. In this case, PULSE NOT FOUND will still be displayed, but demodulation may be successful anyway.
SYNC NOT FOUND error message	802.11a signal has incorrect Short Training Sequence (Short Sync) in burst preamble.	Try setting the analyzer to synchronize to the Channel Estimation Sequence (Long Sync) portion of the burst preamble (MeasSetup >  Demod Properties >  Advanced tab).
	VSA demodulator set incorrectly.  Attempting to demodulate an 802.11b WLAN-DSSS modulated signal.	Set the VSA demodulator to WLAN-DSSS mode. Select  (MeasSetup >  Demodulator >  WLAN-DSSS).
EVM larger than expected	I/Q misaligned using I+jQ receiver.	Under Utilities, Calibration, External Amplitude tab, select the Calibration Constants check box and adjust the delays for each input channel.
	I/Q gain imbalance using I+jQ receiver.	1) Check that impedance is identical for both input channels. 2) Adjust the gains for each input channel (Click  Utilities >  Calibration >  External Amplitude tab > Calibration Constants check box).
	Signal is transmitting incorrect pilot bits.	If the signal is transmitting incorrect pilot bits, the CPE level will be high, both in the Syms/Errs summary, and on the Common Pilot Error trace. Turning off Pilot Timing Tracking, and possibly Pilot Phase Tracking, may help (MeasSetup >  Demod Properties >  Advanced tab).
	Signal has longer than usual transition region between symbols	Change Symbol Timing Adjustment to be more negative (MeasSetup >  Demod Properties >  Advanced tab).
	Noise or interference from adjacent signals.	Reduce the span to eliminate excess noise and interfering signals.
	OFDM signal has inverted frequency spectrum	Try inverting the frequency spectrum (MeasSetup->Demod Properties->Advanced tab).  It is possible for the analyzer to appear to synchronize to a signal with inverted frequency content, because of symmetry properties of the 802.11a Short Training Sequence.  In this case, the Sync Correlation value in the error summary table will be only about 5% less than expected, but the demodulation timing and channel estimation are incorrect and the EVM will be large.
EVM increasing from beginning of burst to end (visible on Error Vector Time trace)	Signal amplitude varies during the burst.	Turn on Pilot Amplitude Tracking (MeasSetup >  Demod Properties >  Advanced tab).
EVM good at beginning of burst, then gets very large near the end of the burst	802.11a signal has incorrect length portion of SIGNAL symbol at start of burst	Override the auto detection of result length (MeasSetup >  Demod Properties >  Time tab).
EVM good, but Sync Correlation coefficient not good	Center frequency not close enough to signal carrier frequency	Adjust center frequency.
See also

Setting up a OFDM Demodulation Measurement

VSA error and status messages

VSA Troubleshooting Topics


OFDM Demodulation Properties Dialog Box

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties

The OFDM (Orthogonal Frequency Division Multiplexing) Demodulation dialog box contains parameters that let you configure the analyzer to demodulate OFDM modulated signals.

Note

The OFDM demodulator must be selected before this dialog box is available. To enable the demodulator, click MeasSetup, Demodulator, OFDM.

The dialog box contains these tabs::

•	Advanced Tab: Lets you access advanced parameters you can use to demodulate nonstandard and/or user defined OFDM signals and to manipulate trace data results.

•	Format Tab: Lets you access the OFDM demod configuration parameters. These are the parameters necessary for the analyzer to lock on to and demodulate the test signal.

•	Time Tab: Lets you access the signal capture configuration parameters. You use these parameters select the pulse search length and to isolate a segment of the time record for further viewing and data analysis.

See also

Selecting OFDM demodulation

Setting up an OFDM Measurement


Advanced Tab (OFDM Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Advanced tab

The Advanced tab of the OFDM Demodulation Properties dialog box lets you access advanced parameters you can use to demodulate user defined and/or nonstandard OFDM signals and to manipulate trace data results.

The Advanced tab dialog box allows you configure these parameters:

•	IQ Normalize

•	Mirror Frequency Spectrum

•	Pilot Tracking parameters

−	Track Amplitude

−	Track Phase

−	Track Timing

•	Sub-carrier Select parameters

−	All

−	Single Carrier

−	Pilots Only

•	Sub-carrier Spacing

•	Symbol Timing Adjust

•	Sync type parameters

−	Short Training Seq

−	Chan Estimation Seq

See also

OFDM Demodulation Properties

Format Tab - OFDM Demodulation Properties

Time Tab - OFDM Demodulation Properties


Format Tab (OFDM Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Format tab

The Format tab of the OFDM Demodulation Properties dialog box lets you configure the analyzers OFDM demodulator. These are the parameters necessary for the analyzer to lock-on to and demodulate the test signal.

The Format tab dialog box allows you configure these parameters:

•	Data Sub-carrier Modulation parameters

−	Auto Detect

−	Manual Override

•	Guard Interval parameters

•	Preset to Standard

•	Standard

See also

OFDM Demodulation Properties

Advanced Tab - OFDM Demodulation Properties

Time Tab - OFDM Demodulation Properties


Time Tab (OFDM Demodulation)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > DemodProperties > Time tab

The Time tab of the OFDM Demodulation Properties dialog box lets you access the signal capture configuration parameters. You use these parameters to select the pulse search length and to isolate a segment of the time record for further viewing and data analysis.

The Time tab dialog box allows you configure these parameters:

•	Measurement Offset

•	Measurement Interval

•	Result Length parameters

−	Auto Select

−	Max Result Length

−	Manual Override

•	Search Length

See also

OFDM Demodulation Properties

Advanced Tab - OFDM Demodulation Properties

Format Tab - OFDM Demodulation Properties

About Measurement Interval and Offset


Chan Estimation Seq  (OFDM Demod)

Sync parameters

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Advanced tab > Chan Estimation Seq

Defaults: See OFDM Standard Presets Table

When Chan Estimation Seq is selected, the analyzer synchronizes the start of the OFDM burst to the Channel Estimation Sequence symbols (also called long sync or long training symbols) synchronization type.

See Sync Type Parameters for more information about this parameter and its application.

Note

For 802.11g CCK-OFDM and HIPERLAN/2, only Channel Estimation Sequence is valid.

See also

Advanced Tab - OFDM Demodulation Properties

OFDM Demodulation Properties


IQ Normalize  (OFDM Demod)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Advanced tab > IQ Normalize

Lets you select the IQ Normalize function, see the IQ Normalize (Digital Demodulation) topic for more information..

Selected:	The IQ trace data results (including IQ Meas Time, IQ Ref Time, IQ Mag Err, IQ Phase Err, and Error Vector Time and corresponding Spectrum results) are normalized.
Cleared:	The trace data results are not normalized.
Note

Regardless of this setting, the Error Summary trace data results are always normalized.

See also

Advanced Tab - OFDM Demodulation Properties

OFDM Demodulation Properties


Short Training Seq   (OFDM Demod)

Sync: parameters

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Advanced tab > Short Training Seq

Defaults: See OFDM Standard Presets Table

When Short Training Seq is selected, the analyzer synchronizes the start of the OFDM burst to the Short Training Sequence (also called "short sync" or "short training symbols") synchronization type.

See Sync Type Parameters for more information about this parameter and its application.

Note

For 802.11g CCK-OFDM and HIPERLAN/2, only Channel Estimation Sequence is valid.

See also

Advanced Tab - OFDM Demodulation Properties

OFDM Demodulation Properties


Subcarrier Select  Parameters  (WLAN-OFDM)

(Vector Signal Analyzer application only)

Menu Path:	MeasSetup > Demod Properties > Advanced tab > ALL

Or	MeasSetup > Demod Properties > Advanced tab > Single Carrier

Or	MeasSetup > Demod Properties > Advanced tab > Pilots Only

Defaults: See OFDM Standard Presets Table

Lets you specify what Subcarrier data will be analyzed and data results displayed. The Subcarrier parameters include the following:

All:  Shows data results for all subcarriers. (-26 Through 26)

Single Carrier: Shows data results for the subcarrier number entered in the Single Carrier text box.

Pilots Only:  Shows data results for all Pilot subcarriers. Pilots subcarriers include subcarrier  -21, -7, 7 and 21.

See also

Advanced Tab - OFDM Demodulation Properties

OFDM Demodulation Properties


Sub-carrier Spacing  (OFDM Demod)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Advanced tab > Sub-carrier Spacing

Defaults: See OFDM Standard Presets Table

Lets you specify the subcarrier spacing of the OFDM signal. The subcarrier spacing must match the input signal value. However, you can adjust the value for troubleshooting purposes or to match a custom or nonstandard subcarrier spacing.

See also

Advanced Tab - OFDM Demodulation Properties

OFDM Demodulation Properties


Symbol Timing Adjust  (OFDM Demod)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Advanced tab > Symbol Timing Adjust

Defaults: See OFDM Standard Presets Table

Shifts the start of the TFFT period earlier in the symbol-time. You specify the amount of TFFT shift as a percentage of the TFFT length.

Moving the TFFT period away from the ending transition time (TTR) into the guard interval (TGI) may help avoid intersymbol interference. Make sure that the TFFT period is not shifted so much that it includes corrupt data from the transition time at the beginning of the symbol-time.

See also

Advanced Tab - OFDM Demodulation Properties

OFDM Demodulation Properties


Track Amplitude  (OFDM Demod)

Pilot Tracking: parameters

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Advanced tab > Track Amplitude

Defaults: See OFDM Standard Presets Table

When Track Amplitude is selected, the analyzer applies pilot subcarrier amplitude error correction to the pilot and data subcarriers. This is in addition to Track Phase and Track Timing error correction if selected.

See About Pilot Tracking for more information about this parameter and its application.

See also

Advanced Tab - OFDM Demodulation Properties

OFDM Demodulation Properties


Track Phase  (OFDM Demod)

Pilot Tracking: parameters

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Advanced tab > Track Phase

Defaults: See OFDM Standard Presets Table

When Track Phase is selected, the analyzer applies pilot subcarrier phase error correction to the pilot and data subcarriers. This is in addition to Track Amplitude and Track Timing error correction if selected.

See About Pilot Tracking for more information about this parameter and its application.

See also

Advanced Tab - OFDM Demodulation Properties

OFDM Demodulation Properties


Track Timing  (OFDM Demod)

Pilot Tracking: parameters

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Advanced tab > Track Timing

Defaults: See OFDM Standard Presets Table

When Track Timing is selected the analyzer applies pilot subcarrier timing error correction (frequency offset correction) to the pilot and data subcarriers. This is in addition to Track Amplitude and Track Phase error correction if selected.

See About Pilot Tracking for more information about this parameter and its application.

See also

Advanced Tab - OFDM Demodulation Properties

OFDM Demodulation Properties


Auto Detect  (OFDM Demod)

Data Sub-carrier Modulation parameters

(Vector Signal Analyzer application only)

Menu Path:  MeasSetup > Demod Properties > Format tab > Auto Detect

Defaults: See OFDM Standard Presets Table

When Auto Detect is selected, the analyzer uses information detected within the OFDM burst to automatically determine the data subcarrier modulation format. The modulation format is shown in the symbol table "ModFmt" error summary trace data.

•	For IEEE 802.11a/g OFDM and 802.11g CCK-OFDM signals the analyzer uses the SIGNAL Symbol - RATE field data to determine the subcarrier modulation format.

•	For HIPERLAN/2 OFDM signals the analyzer examines data from the second Data Symbol to determine the subcarrier modulation format. HIPERLAN/2 Demodulation does not detect the Rate information.

See Data Sub-carrier Modulation for more information about "Auto Detect" and Manual Override" Data Subcarrier Modulation modes.

See also

Format tab - OFDM Demodulation Properties


Guard Interval  (OFDM Demod)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Advanced tab>  Guard Interval

Defaults: See OFDM Standard Presets Table

Range: 0-1

The guard interval eliminates inter-symbol and inter-carrier interference. Each symbol is transmitted for a slightly longer time than the active symbol period. The extra time is the guard interval. The following selects are provided:

•	1/8: Sets the Guard Interval to 1/8 (see "Guard Interval Time Calculation" below)

•	1/4:  Sets the Guard Interval to 1/4 (see "Guard Interval Time Calculation" below)

•	Other:  Allows you to enter Guard Interval values between 0 to 1.

You set the Guard Interval time period "T(GI)" as a fraction (percentage) of the FFT time period "T(FFT)". For 802.11a you only select a Guard Interval of 1/4 (1/8 is greyed). For HIPERLAN/2 you can select a guard interval of 1/4 or 1/8. The "Other" selection allows you to input a non-standard Guard Interval value between 0 and 1.

Guard Interval (TGI)Time Calculation

The following table shows calculated Guard Interval values for a HIPERLAN/2 OFDM signal:

	Guard Interval	T(FFT)	T(GI)
	1/4	3.2 ìs	0.8 ìs
	1/8	3.2 ìs	0.4 ìs
	where: T(FFT) = FFT time period for the OFDM signal T(GI) = Guard Interval time period = Guard Interval × T(FFT)
OFDM Frame and the Guard Interval

See also

Format tab - OFDM Demodulation Properties

OFDM Demodulation Properties


Manual Override  (OFDM Demod)

Data Sub-carrier Modulation parameters

(Vector Signal Analyzer application only)

Menu Path:  MeasSetup > Demod Properties > Format tab > Manual Override

Defaults: See OFDM Standard Presets Table

When the Manual Override is selected, you can manually specify the subcarrier modulation format. The analyzer ignores the format transmitted in the OFDM burst and sets the analyzers demodulator to the modulation format specified in the Manual Override text box. The modulation format is shown in the symbol table "ModFmt" error summary trace data.

See Data Sub-carrier Modulation for more information about "Auto Detect" and "Manual Override" Data Subcarrier Modulation modes.

See also

Format tab - OFDM Demodulation Properties


Preset to Standard  (OFDM Demod)

(Vector Signal Analyzer application only)

Menu Path:  MeasSetup > Demod Properties > Format tab > Preset to Standard

Lets you select a standard OFDM Demodulation configuration. The analyzer automatically sets the required configuration parameters to demodulate the selected standard. See Using an OFDM Standard Setup for a complete list of available standards and associated parameters and default settings.

See also

Format tab - OFDM Demodulation Properties


Standard  (OFDM Demod)

(Vector Signal Analyzer application only)

Menu Path:  MeasSetup > Demod Properties > Format tab > Standard

Defaults: See OFDM Standard Presets Table

Lets you set the demodulator to one of these standard OFDM modulation formats:

Note

This does not set the configuration parameters. You can use the Preset to Standard button to automatically configure the demodulation parameters for you.

FORMAT	SPECIFICATION
IEEE std 802.11a/g OFDM	IEEE std 802.11a-1999
IEEE std 802.11g CCK-OFDM	IEEE std 802.11g/D4.0 Sept-2002
HIPERLAN/2	ETSI TS 101 475 V1.2.2 (2001-02) - Broadband Radio Access Networks (BRAN); HIPERLAN Type 2; Physical (PHY) Layer
IEEE 802.11g modulation

The IEEE 802.11g standard defines both single-carrier and OFDM modulation formats.  The single-carrier modulation formats are compatible with 802.11b and can be demodulated using the Analyzer's "WLAN-DSSS/CCK/PBCC" demodulation mode (see About Opt B7R: WLAN-DSS 802.11b/g)

IEEE 802.11g defines two different OFDM modulation formats.  One, which is mandatory in 802.11g, is an exact copy of the 802.11a format except that the carrier frequencies are in the 2.4 GHz band.  We refer to this as "IEEE 802.11g OFDM".  The other OFDM format is an optional format called CCK-OFDM that combines an 802.11b-style single-carrier preamble with an 802.11a-style OFDM data payload.  We refer to this as "IEEE 802.11g CCK-OFDM".  The Analyzer's WLAN-OFDM modulation analysis mode can demodulate and analyze either of these OFDM formats.

See also

Using a Standard Setup

Format tab - OFDM Demodulation Properties

OFDM Overview


Auto Select (OFDM Demod - Time tab)
Auto Select  (OFDM Demod)

Result Length parameters

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Time tab > Auto Select

Defaults: See OFDM Standard Presets Table

When Auto Select (Default) is selected, the analyzer automatically determines the measurement result length.  The result length is determined by comparing the input signals symbol-time length to the Max Result Length and using the smaller value

See the About Result Length (OFDM) topic for more information about how the analyzer determines the measurement result length in "Auto Select" and "Manual Override" modes.

The following figures illustrate how the analyzer determines the measurement result length in Auto Select mode when the Max Result Length is greater-than (Fig. 1) and less-than (Fig. 2) the symbol-times detected within the burst.

Figure I Max Result Length is greater-than the burst length: The measurement result length will default to the number of symbol-times detected within the burst.

Figure 2 Max Result Length is less-than or equal-to the burst length: The measurement result length will be set to the Max Result Length.

See also

Manual Override (OFDM Time tab)

About Measurement Interval and Offset

Search Length (OFDM)

Time Tab - OFDM Demodulation Properties


Manual Override (OFDM Demod - Time tab)
Manual Override  (OFDM Demod)

Result Length parameters

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Time tab > Manual Override

Defaults: See OFDM Standard Presets Table

When the Manual Override check box is selected, this specifies the measurement result length in symbol-times. The analyzer ignores the input burst symbol length and uses the Manual Override symbol length.  The analyzer will use this value even if it is longer than the measured signals burst length.  See About Result Length (OFDM) for more information about how the analyzer determines the measurement result length in "Manual Override" and "Auto Select" modes.

Note

Manual Override does not limit the result length to the number of symbols transmitted within the burst as is done in Auto Select mode. The analyzer will demodulate the total number of symbols specified by Manual Override, which if longer than the burst, could lead to unexpected and incorrect data results.

See also

About Measurement Interval and Offset

Auto Select (OFDM Time tab)

Search Length (OFDM)

Time Tab - OFDM Demodulation Properties


Max Result Length (OFDM Demod - Time tab)
Max Result Length  (OFDM Demod)

Result Length parameters

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Time tab >

Defaults: See OFDM Standard Presets Table

Range: 1367 symbol-times maximum

When Auto Select is selected, Max Result Length specifies the maximum number of symbols that can be included in the measurement result length.  Auto select mode determines the result length by comparing the Max Result Length and the burst symbol-times and using the smaller value as the measurement result length..

See Auto Select for more information about this parameter and its application.

See also

About Measurement Interval and Offset

Result Length Parameters (OFDM)

Search Length (OFDM)

Time Tab - OFDM Demodulation Properties


Measurement Interval  (OFDM Demod)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Time tab >

Defaults: See OFDM Standard Presets Table

Lets you specify an interval (segment) of the Result Length data to be demodulated and analyzed. Measurement Interval is entered as an integer number of Symbol-times. See About Measurement Interval and Offset for more information about this parameter and its application.

See also

Measurement Offset (OFDM)

Result Length Parameters (OFDM)

Search Length (OFDM)

Time Tab - OFDM Demodulation Properties


Measurement Offset  (OFDM Demod)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Time tab > Measurement Offset text box

Defaults: See OFDM Standard Presets Table

Lets you to set Measurement Offset in Symbol-times. Measurement Offset determines the start position of the Measurement Interval with respect to first Symbol-time within the Result Length. See About Measurement Interval and Offset" for more information about this parameter and its application.

See also

Measurement Interval (OFDM)

Result Length Parameters (OFDM)

Search Length (OFDM)

Time Tab - OFDM Demodulation Properties


Search Length  (OFDM Demod)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Time tab > Search Length text box

Defaults: See OFDM Standard Presets Table

Lets you specify the length of time to acquire the input signal (in seconds). This defines the length of time that the pulse search is performed.

The analyzer searches within the specified search length and demodulates the first complete pulse (or burst) found. The pulse can occur anywhere within the search length. Pulses beyond the first complete pulse are disregarded and are not demodulated. In order for the pulse search algorithm to detect a pulse edge, the pulse must be at least 15 dB above the noise floor. The resultant pulse is then demodulated.

Longer pulse lengths increase the measurement time but make it more likely that a pulse will be found. If a pulse is not found a "PULSE NOT FOUND" status message will be displayed.

See also

About Measurement Interval and Offset

Time Tab - OFDM Demodulation Properties


About OFDM Markers

OFDM modulation has four unique trace data measurements that use three-dimensional data-- that is, the data results include x-axis, y-axis, and z-axis components. Marker readouts for these displays provide data results for the x-, y- and z-axes. In general, marker movement and operation is similar to the typical two dimensional trace data displays with the added capability to position the marker on the z-axis component.

The available three-dimensional trace data are OFDM Error Vector Spectrum, OFDM Error Vector Time, OFDM IQ Meas, and OFDM IQ Ref trace data. For these displays you will notice that marker positions use both an x-axis and z-axis position and that marker readouts provide three values (see OFDM Error Vector Spectrum and OFDM Error Vector Time ).

For information about how to specify a z-axis marker position see Z Position and Offset Z Position.

For information about how to use z-axis marker search features see OFDM Marker Search and OFDM Marker Shortcut .

Marker readouts reflect the x-axis, y-axis and z-axis values for the selected marker position. For trace data that does not have z-axis data results, the Z Position parameter is greyed and the z-axis marker readout is not shown.

See Also

VSA Markers

OFDM Band Power Markers

OFDM Marker Search

OFDM Marker Keyboard


OFDM Band Power Markers

Menu Path: Markers > Calculation > Calculate list > Band Power

When OFDM Demodulation is selected, band power markers compute and display the RMS average within the region marked by the band-power markers for the following OFDM data:

•	OFDM Error Vector Spectrum trace data

•	OFDM Error Vector Time trace data

•	OFDM IQ Meas trace data

•	OFDM IQ Ref trace data

The following information will help you use band power markers with OFDM Error Vector Spectrum and OFDM Error Vector Time trace data displays:

•	Set Calculate, Band Power, Calculate to RMS Sqrt(Pwr) so the band power marker computation type matches the trace data marker readout computation type.

•	To measure a single x-axis location; select the Markers, Calculation, Band Power, Center/Width check boxes, enter the desired x-axis position in the Center text box and enter a value of 0 in the Width text box.

•	To measure a specific region it is more precise to use the Band Power marker menu than the mouse to position the band power markers:

Clear the Markers, Calculation, Band Power, Center/Width check box. Then enter the measurement region's left x-axis position in the Left text box and enter the right x-axis position in the Right text box.

See also

VSA Band Power Marker Overview

OFDM Marker Search

OFDM Marker Keyboard

About OFDM Markers


OFDM Marker Search

Menu Path: Markers > Search

The following marker search information apply to OFDM Error Vector Spectrum and OFDM Error Vector Time trace data. OFDM Markers include z-axis information--that is, each data point has a x-axis, y-axis and z-axis component (3-dimensional data). Marker readouts for these trace data results reflect x-axis, y-axis and z-axis measurement data.

Most of the OFDM Marker Search features operate identical to the analyzers typical 2-dimension trace data displays. The following information describe only the differences in operation for these unique 3-dimension OFDM trace data displays. See Marker Search Operations for standard marker search operation information.

 Peak: Select Peak to move the marker to the largest discrete value on the active trace.

 Peak Lower: Select Peak Lower to move the marker to the next lower y-value along the z-axis for the current x-axis position, this operation will not move the marker in the x-axis dimension.

(keyboard shortcut ↓)

 Peak Higher: Select Peak Higher to move the marker to the next higher y-value along the z-axis for the current x-axis position, this key will not move the marker in the x-axis dimension.

(keyboard shortcut ↑)

 Peak Right: Select Peak Right to move the marker right one x-axis point to the z-axis point that has the nearest y value to the current marker y value.

(keyboard shortcut: Ctrl + →)

 Peak Left: Select Peak Left to move the marker left one x-axis point to the z-axis point that has the nearest y value to the current marker y value.

(keyboard shortcut: Ctrl + ←)

 Minimum: Select Minimum to move the marker to the lowest discrete value on the active trace.

See also

VSA Marker Search

OFDM Band Power Markers

OFDM Marker Keyboard

About OFDM Markers


OFDM Marker Shortcuts
OFDM Marker Keyboard Shortcuts

The following shortcuts all apply for OFDM Marker Search features. The information describes only the differences in marker shortcut operation for OFDM 3-dimensional trace data displays (OFDM Error Vector Spectrum and OFDM Error Vector Time trace data). See Marker Shortcuts for information about standard marker shortcut behavior.

•	Home key - no difference.

•	End key - no difference.

•	Page Up key - no difference.

•	Page Down key - no difference.

•	← key - moves the marker to the next smaller value along the x- or z-axis as specified by the active (highlighted) marker readout. To change axis, select the non-active x- or z-axis marker readout.

•	→ key - moves the marker to the next larger value along the x- or z-axis as specified by the active (highlighted) marker readout. To change axis, select the non-active x- or z-axis marker readout.

•	↑ key - moves the marker to the next higher y-value along the z-axis for the current x-axis position, this key will not move the marker in the x-axis dimension.

•	↓ key - moves the marker to the next lower y-value along the z-axis for the current x-axis position, this operation will not move the marker in the x-axis dimension.

•	Ctrl + ← keys - moves the marker left one x-axis point to the z-axis point that has the nearest y value to the current marker y value.

•	Ctrl + → keys - moves the marker right one x-axis point to the z-axis point that has the nearest y value to the current marker y value.

See also

VSA Marker Shortcuts

OFDM Band Power Markers

OFDM Marker Search

About OFDM Markers


Data Sub-carrier Modulation (OFDM Demodulation)

(Vector Signal Analyzer application only)

Menu Path:  MeasSetup > Demod Properties > Format tab > Auto Detect

 Or:  MeasSetup > Demod Properties > Format tab > Manual Override

Data Subcarrier Modulation parameters allow you to specify the data subcarrier modulation format. The modulation format is shown in the symbol table "ModFmt" error summary trace data.

•	Auto Detect (Default): The analyzer uses information detected within the OFDM burst to automatically determine the data subcarrier modulation format

−	For IEEE 802.11a/g OFDM and IEEE 802.11g CCK-OFDM signals the analyzer uses the SIGNAL Symbol - RATE field data to determine the subcarrier modulation format.

−	For HIPERLAN/2 OFDM signals the analyzer examines data from the second Data Symbol to determine the subcarrier modulation format. HIPERLAN/2 Demodulation does not detect the Rate information.

•	Manual Override: Allows you to specify the data subcarrier modulation format. The analyzer ignores the format determined from the OFDM burst and sets the analyzers demodulator to the modulation format specified in the Manual Override text box.

The contents of this topic include the following information about the Data Subcarrier Modulation parameters:

•	OFDM Burst Structure - SIGNAL symbol (RATE data)

•	Determining the Subcarrier modulation format

OFDM IEEE 802.11a/g SIGNAL symbol - RATE Field

As shown in the following figure, the OFDM burst structure contains the Preamble symbols followed by the SIGNAL symbol and Data symbols. The SIGNAL symbol contains the RATE and LENTGH fields. The RATE field transmits the data rate, which conveys information about the type of subcarrier modulation, and the coding rate used in the rest of the packet. The encoding of the SIGNAL, single OFDM symbol, is performed with BPSK modulation of the subcarriers. These parameters do not effect the demodulation of the pilot subcarriers, which are always BPSK modulation.

Determining the Subcarrier modulation format

IEEE 802.11a/g OFDM and IEEE 802.11g CCK-OFDM Standard OFDM Signals

For IEEE 802.11a/g OFDM and IEEE 802.11g CCK-OFDM signals the subcarrier modulation format is a data rate dependent parameter. The RATE field, which is in the SIGNAL symbol, contains the data rate information, which is used to set the subcarrier modulation format according to the following table:

Data Rate (Mbits/s)	Subcarrier Modulation
6	BPSK
9	BPSK
12	QPSK
18	QPSK
24	16-QAM
36	16-QAM
48	64-QAM
54	64-QAM
HIPERLAN/2 Standard OFDM Signals

For HIPERLAN/2 standard OFDM signals the analyzer auto detects the modulation format by examining the data received in the second data symbol. HIPERLAN/2 Demodulation does not detect Rate information.

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See also

Format Tab - OFDM Demodulation Properties

OFDM Demodulation Properties


Measurement Interval and Offset (OFDM Demodulation)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Time tab > Measurement Interval text box

               or MeasSetup > Demod Properties > Time tab > Measurement Offset text box

The Measurement Interval and Measurement Offset parameters allow you to define a specific interval of the Result Length for demodulation and analysis. This feature is applicable to OFDM Demodulation.

With this feature you can quickly analyze and view specific time intervals of data. This is because the analyzer does not acquire new measurement data when the measurement interval or offset is changed. When a new measurement interval or offset is entered the analyzer re-computes the trace data results using the existing measurement data.

The following illustration shows the interrelationship between the Search Length, Result Length, Measurement Interval and Measurement Offset.

Note

The Time trace display shows only time data for the symbol-times specified by Measurement Interval parameter, except when the Measurement Interval is equal to Max Result Length. In this case, the Time trace display also shows the preamble data. See Time trace data for complete details.

•	Result Length: Total number of symbol-times included in the acquired and demodulated data.

•	Max Result Length Sets the maximum number of symbol-times that can be included in the result length. Auto Select limits the Max Result Length to the number of symbol-times within the pulse (or burst).

•	Measurement Interval: Determines what segment of the Result Length data is analyzed and displayed.

•	Measurement Offset: Sets the start position of the Measurement Interval within the Result Length.

•	Symbol-time: One OFDM symbol period which includes the IFFT/FFT period (TFFT) and guard interval period (TGI).

See also

Time Tab - OFDM Demod Properties

OFDM Demodulation Properties


Pilot Tracking (OFDM Demodulation)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Advanced tab>  Track Phase

 or MeasSetup > Demod Properties > Advanced tab>  Track Amplitude

 or MeasSetup > Demod Properties > Advanced tab>  Track Timing

When demodulating an OFDM burst, the equalizer response computed from the burst preamble is used to correct many imperfections in the OFDM signal. However, the equalizer response is not perfect, "pilot tracking" is used to correct for imperfections in the equalizer response and for imperfections that change over the length of the burst.

In each OFDM symbol, four of the subcarriers are dedicated to pilot signals in order to make the coherent detection robust against frequency offsets and phase noise. These pilot subcarriers occupy subcarriers -21, -7 , 7 and 21 and use BPSK modulation.

Pilot subcarriers transmit with a known data sequence. This information is used to determine the difference, or error, between an ideal signal and the actual received signal. Because the data is complex the analyzer calculates phase, amplitude, and timing error data. The error data can then be used to correct both pilot and data subcarrier imperfections, producing a more accurate demodulation.

The IEEE 802.11a/g and HIPERLAN/2 specifications call for tracking and correcting only the phase of the pilot subcarriers. This is the 89600 OFDM demodulation default, but if desired, you can disable phase tracking. In addition, the 89600 can optionally track and correct for amplitude and/or timing errors.

This feature is controlled by the pilot tracking check boxes (OFDM Demodulation Properties dialog box - "Advanced" tab:

•	Track Amplitude: Apply pilot subcarrier amplitude error correction to the pilot and data subcarriers.

•	Track Phase: Apply pilot subcarrier phase error correction to the pilot and data subcarriers.

•	Track Timing: Apply pilot subcarrier timing error correction to the pilot and data subcarriers.

See also

Ch Frequency Response (OFDM Demodulation)

OFDM Demodulation Properties


Result Length Parameters (OFDM Demodulation)

(Vector Signal Analyzer application only)

Menu Path:	MeasSetup > Demod Properties > Time tab > Auto Select

 	Or	MeasSetup > Demod Properties > Time tab > Manual Override

Result Length parameters allow you specify how much data is acquired and demodulated.

•	Auto Select (Default): The analyzer automatically determines the measurement result length. It compares the number of symbol-times detected within the burst to the Max Result Length parameter and uses the smaller value as the measurement result length.

•	Manual Override: The analyzer uses the value entered in the Manual Override text box as the measurement result length and ignores the number of symbol-times detected within the burst.

The contents of this topic include the following information:

•	Auto Select vs. Manual Override Result Length modes

•	Determining the Result Length in Auto Select mode

•	OFDM IEEE 802.11a/g SIGNAL Symbol

Note

The amount of data included and shown by the Time trace data display is determined from the Max Result Length and Manual Override parameters. For more information, see Time (OFDM) trace data.

Auto Select vs. Manual Override Result Length modes

The following figure illustrates the differences between how Auto Select and Manual Override modes determine the measurement result length. The table lists the measurement results lengths for Auto Select and Manual Override modes at three different result length input settings (30, 26 and 20 symbol-times) for a burst whose pulse width is fixed at 26 symbol-times.

•	30 symbol-time example - Burst pulse width is less than the result length settings:

−	Manual Override mode the analyzer uses a result length of 30 and will demodulate the full 30 symbol-times even though this is 4 symbol-times beyond the pulse width.

−	Auto Select mode the analyzer uses a result length of 26, which is the smaller value between the burst symbol-time and the Max Result Length.

•	20 and 26 symbol-time examples - Burst pulse width is greater than or equal to the result length settings:

−	Manual Override mode the analyzer uses a measurement result length equal to the Manual Override settings, which is 20 and 26 for these examples.

−	Auto Select mode uses the smaller value between the Max Result Length setting or the number of data symbol-times detected within the burst as the measurement result length which is 20 and 26 for these examples (See Determining result length in Auto Select mode).

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Determining the Result Length in Auto Select mode

When Auto Select is selected, the analyzer compares the number of symbol-times transmitted within the burst, to the Max Result Length parameter and uses the smaller value as the measurement result length. The method used to detect the number of data symbol-times within the burst is OFDM modulation format dependent.

•	IEEE 802.11a/g OFDM and IEEE 802.11g CCK-OFDM Signals: For IEEE 802.11a/g OFDM signals the analyzer uses the SIGNAL Symbol - LENGTH data field to determine the number of DATA symbol-times within the burst. The Result Length is equal to the SIGNAL Symbol-time plus the DATA Symbol-times.

•	HIPERLAN/2 OFDM signals: For HIPERLAN/2 OFDM signals the analyzer uses the detected pulse width to determine the number of data symbol-times within the burst.

OFDM IEEE 802.11a/g SIGNAL Symbol

The following figure shows the IEEE 802.11a/g OFDM burst structure, which contains the Preamble symbols followed by the SIGNAL symbol-time and Data symbol-times. The SIGNAL symbol contains the RATE and LENGTH fields. The analyzer uses the LENGTH field to determine the number of DATA symbol-times within the burst. The encoding of the SIGNAL, single OFDM symbol, is performed with BPSK modulation of the subcarriers.

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See also

Time Tab - OFDM Demodulation Properties

OFDM Demodulation Properties


Sync Type Property (OFDM Demodulation)

(Vector Signal Analyzer application only)

Menu Path:	MeasSetup > Demod Properties > Advanced tab>  Short Training Seq

 	or	MeasSetup > Demod Properties > Advanced tab>  Chan Estimation Seq

The Sync parameters control the type of synchronization used to synchronize to the start of an OFDM burst. The two available choices are "Short Training Sequence" (also called Short Sync or Short Training Symbols) and "Chan Estimation Seq" (also called Long Sync or Long Training Symbols).

•	Short Training Seq: Synchronizes the start of the OFDM burst to the OFDM Short Training Sequence.

•	Chan Estimation Seq: Synchronizes the start of the OFDM burst to the OFDM Channel Estimation Sequence.

Note

For IEEE 802.11a/g, either sync type is valid, the default is set to Short Training Sequence. For HIPERLAN/2, the only valid sync type is Channel Estimation Sequence.

The Sync type parameter also specifies the segment of the preamble used by the analyzer to compute the "Sync Corr" error data result.

OFDM IEEE 802.11a/g Training structure

The OFDM IEEE 802.11a/g preamble field (PLCP preamble SYNC) is used for synchronization. It consists of 10 short symbols (t1 through t10) and 2 long symbols (T1, T2) as shown in the following figure.

OFDM HIPERLAN/2 Training Structure

OFDM HIPERLAN/2 typical preamble training structure. The Channel Estimation Sequence is used for synchronization.

See also

Advanced Tab - OFDM Demodulation Properties

OFDM Demodulation Properties


About the Symbol Table (OFDM Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Syms/Errs

When WLAN-OFDM Demodulation is enabled, selecting Syms/Errs trace data shows the symbol table. The symbol table shows you error summary data and the symbol data (binary bits) for each symbol-time and subcarrier following the preamble. For IEEE 802.11a/g this includes symbol data for both the SIGNAL and DATA symbol-times.

Symbol Data

The bottom half of the Syms/Errs trace data display shows the raw data bits for each symbol and subcarrier following the preamble. These bits are not decoded, and include bits for all subcarrier symbols including the pilot subcarriers. The first bit in the table corresponds to the first bit of subcarrier number -26 of the first OFDM symbol following the preamble symbols in the data stream.

The default symbol table display shows the Data subcarrier symbol bits in yellow, the Pilot subcarrier symbol bits in white and all the subcarrier number 0 symbol bits are blanked (not shown).

When the symbol table marker is enabled, the marker highlights the data bits for the selected subcarrier symbol and the marker readout provides the subcarrier number, the symbol number and its value in decimal.

For IEEE 802.11a/g signals, the subcarrier modulation format used for symbol 0 (the SIGNAL symbol data, which uses BPSK modulation,1 bit/sym) may be different than the modulation format used for subsequent symbols (the DATA symbol data). The symbol table can show only one modulation format at a time, so the SIGNAL symbol (symbol 0) is displayed with the same number of bits/symbol as the DATA symbols (symbols [image] 1). The extra characters are only pad bits and do not effect measurement data results.

To make the table easier to read, the symbol data is shown in groupings of eight characters followed by a space. The characters can represent a binary digit or a hexadecimal digit as specified by the "Symbol Table Format" parameter. The number to the left of each row indicate either the bit or symbol offset position depending the symbol table format as described below:

Binary Format: The symbol data bit format is binary and each character represents a binary digit. The number to the left of each row indicates the bit offset of the first bit in the row.

Hexadecimal Format: The symbol data bit format is hexadecimal and each character represents a hexadecimal digit. The number to the left of each row indicate the subcarrier symbol offset of the first subcarrier symbol in the row.

Note

There must be at least 4 bits/symbol to use the hexadecimal format--that is, symbols that have less than 4 bits/symbol will be displayed only in binary format regardless of the Symbol Table Format setting.

Tips

•	You can chose to show the symbol data bits in either binary or hexadecimal format, see Symbol Table Format.

•	The Result Length mode and parameters determines the number of symbols shown in the table.

•	Here's an easy way to identify bits that correspond to a point in the constellation diagram; Display the constellation diagram in one grid and the symbol table in another. Then turn on the markers for both displays and enable marker coupling. When you place the marker on a point in the constellation diagram, the analyzer highlights the corresponding symbol bits in the symbol table.

•	Use the keyboard arrow keys or the mouse wheel to move the marker from one symbol to the next. You can use the Marker Position - X and Z Position parameters to move to a specific symbol location.

Error Summary Data

The top half of this display shows the Error Summary data for OFDM Demodulation. See Error Summary Data (OFDM Demodulation)) for information about OFDM Error Summary Data.

See also

Error Summary Data

Available Error Summary Data


Error Summary Data (OFDM Demodulation)
Error Summary Data (OFDM Demodulation))

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Syms/Errs

The top half of the Syms/Errs trace data display shows the Error Summary data results for OFDM Demodulation (see Available Error Summary Data).

Averaging and Error Summary Data

When averaging is on, averaging is applied to the numeric error data in the symbol/errors table with the following exception. Averaging applies only to peak EVM, peak magnitude and peak phase error data for the Continuous Peak Hold averaging type.

Error data from the current scan is not included in the average if any of these conditions exist:

•	Pulse Not Found

•	Sync Not Found

•	Carrier Unlock.

•	DATA?

•	Pulse to Short

Using Band Power markers to limit Error Information

If you want EVM error information for all points over a selected region, you can use the band-power markers with the Error Vector Spectrum and Error Vector Time trace data. The error Vector Spectrum trace data will compute the EVM for all symbols within a specified subcarrier region and Error Vector Time trace data with compute the EVM for all subcarriers within a specified symbol-time region.

For example, here's how you could compute the symbol EVM for OFDM subcarriers 11, 12 and 13. Click Trace > Data >Error Vector Spectrum to display the Error Vector Spectrum trace data, then click Markers > Calculation, select the Band Power check box to turn on the band-power markers.

Now position the band-power markers to select the region of interest; place the markers so that they are exactly on or close to the specific subcarriers of interest. Center the marker at subcarrier 12, enter 12 in the Center text box, and set the width to two carriers, enter 2 in the Width text box, this encloses the region of interest (subcarriers 11, 12 and 13). Then select RMS Sqrt (Pwr) to display the EVM in %rms, this is the EVM (%rms) for all symbols within subcarriers 11, 12 and 13.

You can use the same procedure with the Error Vector Time trace data display to find the EVM (%rms) for all subcarriers within a specific range of symbol-times.

See also

About Symbol Table Data

Available Error Summary Data


Available OFDM Error Summary Data

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Syms/Errs

The OFDM Demodulation Format determines which error summary data are displayed in the symbol table, as shown in the following table.

Yes	Indicates the error data result is shown for that demodulation format.

 --	Indicates the error data result is not available (N/A) for that demodulation format.

For information about using error summary data with ADS, see Demod Errors and ADS.

Error Summary	Demodulation Format
Data	802.11a/g OFDM	802.11g CCK-OFDM	HIPERLAN/2
Bit Rate	Yes	Yes	--
Code Rate	Yes	Yes	--
CPE	Yes	Yes	Yes
EVM (in dB)	Yes	Yes	Yes
EVM (%rms)	Yes	Yes	Yes
Freq Err	Yes	Yes	Yes
IQ Offset	Yes	Yes	Yes
ModFmt	Yes	Yes	Yes
Octets	Yes	Yes	--
PilotEVM	Yes	Yes	Yes
Symbols	Yes	Yes	--
SymClkErr	Yes	Yes	Yes
Sync Corr	Yes	Yes	Yes
See also

Error Summary Data

About Symbol Table


Bit Rate (OFDM Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Syms/Errs

Bit Rate is the OFDM data rate (Mbits/s) corresponding to the Code Rate and Modulation Format. The OFDM Demodulation Format determines whether or not the Bit Rate data is displayed in the symbol table:

IEEE 802.11a/g Signals: The Bit Rate is determined from the RATE field data in the detected SIGNAL symbol.

HIPERLAN/2 Signals: Bit Rate is not available (N/A).

See also

Available Error Summary Data

Error Summary Data


Code Rate (OFDM Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Syms/Errs

This is the OFDM data symbol convolutional coding rate. The OFDM Demodulation Format determines whether or not the Code Rate data is displayed in the symbol table:

IEEE 802.11a/g Signals: The Code Rate is determined from the RATE field data in the detected SIGNAL symbol.

HIPERLAN/2 Signals: Code Rate is not available (N/A).

See also

Available Error Summary Data

Error Summary Data


CPE (OFDM Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Syms/Errs

This is the RMS level of the Common Pilot Error trace data minus 1 expressed as a percentage of an ideal signal. Ideally the Common Pilot Error trace data has a magnitude of one and phase of zero. The CPE represents the deviation of the Common Pilot Error trace from the ideal and shows how much the OFDM burst drifts over time.

For information about the Common Pilot Error trace data, see Common Pilot Error trace data.

See also

Available Error Summary Data

Error Summary Data


EVM (dB) (OFDM Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Syms/Errs

This is the RMS value of the Error Vector Magnitudes (in dB) over the entire burst, which includes all DATA symbol and all 52 subcarriers. For IEEE 802.11a/g OFDM bursts this includes the SIGNAL symbol.

EVM (dB) is the same error data result as EVM (%rms) but is expressed in units of decibels (dB) rather than in units of percent RMS (%rms).

Note

OFDM IEEE 802.11a/g and HIPERLAN/2 specifications show EVM in units of decibels (dB).

See also

Available Error Summary Data

Error Summary Data


EVM (%rms) (OFDM Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Syms/Errs

This is the RMS value of the Error Vector Magnitudes over the entire burst, which includes all DATA symbols for all 52 subcarriers, shown as a percent of the average EVM. For IEEE 802.11a/g OFDM bursts this includes the SIGNAL symbol.

EVM (%rms) is the same error data result as EVM (dB) but is expressed in units of percent RMS (%rms) rather than in units of decibels (dB).

EVM (%rms) for OFDM is similar to EVM (%rms) for Digital Demodulation. For more information about this parameter, see Error Vector Magnitude (Digital Demod).

See also

Available Error Summary Data

Error Summary Data


Freq Err (OFDM Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Syms/Errs

This parameter shows the carrier frequency error relative to the analyzer's center frequency. This parameter is displayed in Hertz and is the amount of frequency shift, from the analyzer's center frequency, that the analyzer must perform to achieve carrier lock.

For the actual FFT demod, the carrier frequency is determined from the preamble. If you’ve set up the analyzer to sync on the channel estimation sequence only, then the short sync is ignored (see Sync Type Parameters). The frequency error reported in the summary table is the value from the final frequency estimation based on the channel estimation sequence with a fine adjustment made for any frequency error detected in the pilot tracking. The pilot tracking does not correct the signal for frequency errors, it only corrects the post-FFT symbols for phase (and amplitude, if enabled).

Errors in RF frequency, LO frequency, or digitizer clock rate could all appear as carrier frequency error.

See also

Available Error Summary Data

Error Summary Data


IQ Offset (OFDM Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Syms/Errs

IQ Offset (also called I/Q origin offset) indicates the magnitude of the carrier feedthrough signal. When there is no carrier feedthrough, IQ offset is zero (-infinity dB).

IQ Offset is the same as IQ Offset for Digital Demodulation. For more information about this parameter, see IQ Offset (Digital Demod).

See also

Available Error Summary Data

Error Summary Data


ModFmt (OFDM Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Syms/Errs

This is the modulation format used by the analyzer to demodulate the data subcarriers.

For more information about how the analyzer determines the modulation format, see Data Sub-carrier Modulation.

See also

Available Error Summary Data

Error Summary Data


Octets (OFDM Demdulation)
Octets (OFDM Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Syms/Errs

This is the number of decoded Octets transmitted in the OFDM burst. The OFDM Demodulation Format determines whether or not the Octet data is displayed in the symbol table:

IEEE 802.11a/g Signals: The Octets data is determined from the LENGTH and RATE fields in the detected SIGNAL symbol.

HIPERLAN/2 Signals: Octets is not available (N/A) because the coding rate is not known.

See also

Available Error Summary Data

Error Summary Data


PilotEVM (OFDM Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Syms/Errs

This is the RMS value of the Error Vector Magnitudes (in dB) of the four pilot subcarriers for all symbols over the entire burst. For 802.11a this includes the SIGNAL symbol.

Note

IEEE 802.11a/g OFDM and HIPERLAN/2 specifications show EVM in units of decibels (dB).

See also

Available Error Summary Data

Error Summary Data


Symbols (OFDM Demdulation)
Symbols (OFDM Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Syms/Errs

This is the number of DATA symbols transmitted in the OFDM burst.

•	IEEE 802.11a/g Signals: The Symbols data is the number of DATA symbol-times within the burst after the SIGNAL symbol-time. The number of DATA symbol-times is obtained from the SIGNAL symbol - LENGTH data.

•	HIPERLAN/2 Signals: Symbol data is not available (N/A).

OFDM IEEE 802.11a/g SIGNAL Symbol

The following figure shows the IEEE 802.11a/g OFDM burst structure, which contains the Preamble symbols followed by the SIGNAL symbol-time and Data symbol-times. The SIGNAL symbol contains the RATE and LENTGH fields. The LENGTH field provides the number of DATA symbol-times within the burst (This is the Symbols Error Summary data result). The encoding of the SIGNAL, single OFDM symbol, is performed with BPSK modulation of the subcarriers.

Note

For IEEE 802.11a/g signals, the Error Vector Spectrum and Error Vector Time trace data displays shows the number of symbol-times specified by the Result Length parameter and not the Symbols data result.

See also

About Result Length parameters

About Measurement Interval and Offset parameters

Available Error Summary Data

Error Summary Data


SymClkErr

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Syms/Errs

This is the symbol clock frequency error, which is the difference between the ideal and actual symbol clock frequency in ppm. A symbol clock frequency that is less than ideal will make the OFDM symbol time to take longer than required and cause the OFDM subcarrier spacing to decrease. A symbol clock frequency that is greater than ideal will make the symbol times take less time than required and cause the OFDM subcarrier spacing to increase. In either case this creates subcarrier interference and increases the signal's EVM. The resultant error value is a unitless fraction, which is multiplied by 1,000,000 to obtain SymClkErr in ppm.

Note

The 802.11a and HIPERLAN/2 standards require the symbol clock frequency error tolerance to be ± 20-ppm maximum. The transmit center frequency and the symbol clock frequency shall be derived from the same reference oscillator.

Note

The 802.11g and HIPERLAN/2 standards require the symbol clock frequency error tolerance to be ± 25 ppm maximum. The transmit center frequency and the symbol clock frequency shall be derived from the same reference oscillator.

See also

Available Error Summary Data

Error Summary Data


Sync Corr (OFDM Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Syms/Errs

Sync Corr is a cross correlation of the preamble synchronization of the measured signal to an ideal signal. It is a figure of merit indicating the quality of the segment of the preamble used for synchronization. The preamble segment used to compute the Sync Corr is either the short training sequence or the channel estimation sequence as specified by the OFDM Demodulation Properties Sync type parameter. A value of 1 indicates perfect correlation and a value of 0 indicates no correlation.

Large Frequency Errors and Incorrect Sync Corr Values

Large frequency errors (approximately 100 kHz or more) may cause the analyzer to show incorrect low Sync Corr values. These values are a result of frequency error and do not necessarily indicate poor signal quality. Therefore, for low Sync Corr values you always need to validate the cause of the low Sync Corr data result.

If the Sync Corr is low and the frequency error is large, check the EVM. If the EVM is low, the measured signal data is good and the low Sync Corr value can generally be ignored. To correct for frequency errors, adjust the center frequency so that the Freq Err decreases to approximately 0 Hz. If the Sync Corr increases in value then the contributing factor to the initial low Sync Corr value was the frequency error and not the measured signal.

See also

Available Error Summary Data

Error Summary Data


Available Trace Data (OFDM Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: Trace, Data

Measurement trace data available with WLAN-DSSS Demodulation.

                            OFDM Demodulation
                   Available Measurement Trace Data

CCDF	Inst Spectrum
CDF	PDF
Ch Frequency Response	Preamble Error
Common Pilot error	Raw Main Time
Correction	RMS Error Vector Spectrum
Eq Impulse Response	RMS Error Vector Time
Error Vector Spectrum	Search Time
Error Vector Time	Spectrum
IQ Meas	Syms/Errs
IQ Ref	Time
See also

Available Features (WLAN-OFDM)

89600-Series VSA Application Standard Trace Data

About Opt B7R: OFDM Demodulation


CCDF  (WLAN-OFDM)

Menu Path: Trace > Data >Ch1 CCDF

CCDF trace data displays the complementary cumulative density function (CCDF) for the selected input channel.

The CCDF is computed from the segment of the OFDM burst specified by the Measurement Interval and Measurement Offset.  In addition, if the Offset is zero and the Interval is equal to the result length, the burst preamble is included in the CCDF.

The analyzer plots CCDF using units of percent (%) for the y-axis and power (dB) for the x-axis. Power on the x-axis is relative to the signal average power, so 0 dB is the average power of the signal. Therefore, a marker readout of

Trace A Marker 2 dB 12 %

means there is a 12% probability that the signal power will be 2 dB or more above the average power.

For more information, go to the VSA application CCDF trace data topic.

See Also

CDF (WLAN-OFDM)

Available Trace Data (OFDM)


CDF   (WLAN-OFDM)

Menu Path: Trace > Data >Ch1 CCDF

CDF trace data displays the cumulative density function (CDF) for the selected input channel. CDF is computed by integrating the PDF (Probability Density Function). CDF is explained in online help for the CCDF trace data—for further details, see that topic.

The CDF is computed from the segment of the OFDM burst specified by the Measurement Interval and Measurement Offset.  In addition, if the Offset is zero and the Interval is equal to the result length, the burst preamble is included in the CCDF.

See Also

Available Trace Data (OFDM)


Ch Frequency Response (OFDM)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data >Ch Frequency Response

When OFDM Demodulation is enabled, this is the measured equalizer frequency response for the burst, based on analyzing the preamble of the burst. It contains one complex value for each subcarrier, plus an interpolated value at the middle unused subcarrier (a total of 53 values).

This is similar to, but not the same as, the Digital Demod channel equalizer frequency response. The differences are:

•	Digital Demod computes this by comparing the IQ Meas Time and IQ Ref Time data, while OFDM digital demod computes it from the preamble of the burst.

•	Digital Demod typically uses a running average to average multiple scans when computing the equalizer frequency response. OFDM demodulation does not average, but computes a new equalizer response for each burst.

•	The equalization filter is inherent to OFDM Demodulation, it cannot be enabled/disabled like in Digital Demod.

See also

Equalizer Impulse Response (OFDM)

Available Trace Data (OFDM)


Common Pilot Error (OFDM)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data >Common Pilot Error

When OFDM Demodulation is enabled, the Common Pilot Error trace data shows the difference between the measured and ideal pilot subcarrier symbols. The CPE error summary data provides the RMS level of the Common Pilot Error trace data as a percentage of the ideal signal (see CPE error summary data)

Residual phase and frequency settling that occurs following the preamble is measured via the Common Pilot Error display.  With Phase Tracking turned ON, this display shows the average phase error of the four OFDM pilots as a function of time (i.e. versus data symbol number).  To convert to frequency units, select Trace Format equal Group Delay.

At each symbol-time in the burst, the measured symbol values of the four pilot subcarriers are compared with the ideal values. The differences are averaged together, producing a single complex value for each symbol-time. Normally the phase of this trace is displayed, showing how the pilot phase changes over the burst. You can also look at the magnitude of this trace to see signal magnitude changes over the burst.

Example Common Pilot Error trace data: Demodulated IEEE 802.11a/g burst with a result length of 25 symbol-times (0 through 24 sym). The left trace shows the magnitude error and the right trace shows the phase error.

Trace Data Parameter: OFDM Common Pilot Error

Trace A Marker:	Symbol-time 4	Magnitude = -0.023 dB

Trace C Marker:	Symbol-time 4	Phase = -275.3113 mdeg

See also

Available Trace Data (OFDM)


Correction (OFDM)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data >Correction

Shows the correction curve used to correct for the frequency response of the input hardware and input digital filtering. The correction trace is applied to the acquired data to compensate for phase and magnitude anomalies in the analyzer's hardware and software signal processing.

See also

About Calibration

Available Trace Data (OFDM)


Eq Impulse Response (OFDM)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data >Eq Impulse Response

When OFDM Demodulation is enabled, Eq Impulse Response trace data shows the impulse response of the equalization filter.

This is similar to, but not the same as, the Digital Demod Eq Impulse response. The differences are:

•	Digital Demod computes this by comparing the IQ Meas Time and IQ Ref Time data, while OFDM digital demod computes it from the preamble of the burst.

•	Digital Demod typically uses a running average to average multiple scans when computing the equalizer impulse response. OFDM demodulation does not average, but computes a new equalizer response for each burst.

•	The equalization filter is inherent to OFDM Demodulation, it cannot be enabled/disabled like Digital Demod.

See also

Ch Frequency Response (OFDM)

Available Trace Data (OFDM)


Error Vector Spectrum (OFDM)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data >Error Vector Spectrum

OFDM Error Vector Spectrum shows the signal EVM vs. time and frequency. It provides both the RMS average Error Vector Magnitude and the individual Error Vector Magnitudes (EVM) for each subcarrier for all symbols within the burst. The individual symbol EVMs are displayed by common subcarrier number--that is, for a particular subcarrier all the symbol EVMs for that subcarrier are shown. This provides a convenient way to view all the subcarrier EVMs at a particular subcarrier for all symbol-times in the burst. The trace data includes data results for both the pilot and data subcarriers, subcarrier 0 is not used.

Symbol EVM is the error vector magnitude between the measured (IQ Meas) symbol vector and an ideal (IQ Ref) symbol vector. RMS Error Vector Spectrum trace data is the average error vector magnitude of all the symbol EVMs at a particular subcarrier for all symbol-times within the burst (see RMS Error Vector Spectrum trace data).

Tip

You can decrease (or limit) the number of symbol-times included and displayed in the data results with the Max Result Length format parameter. The TimeLen value on the display shows the number of symbol-times included in the data results.

Interpreting the Display

The y-axis annotates the EVM magnitude and the x-axis annotates the OFDM Subcarrier number, which range from -26 through +26 (52 subcarriers in all, subcarrier 0 is not used). The z-axis annotates the symbol position. The display format shows all the symbols at a particular subcarrier, for all the symbol-times within the burst. Placing a marker on a subcarrier provides the subcarrier number, the symbol number, the subcarrier EVM (for that particular symbol) and the RMS average EVM (for that particular subcarrier).

The Error Vector Spectrum trace data uses a multi-color display that assigns a unique color to the pilot subcarriers, the data subcarriers and the RMS Error Vector Spectrum trace data, The colors are also user definable (see Display Appearance).

Example Error Vector Spectrum trace data: Demodulated OFDM IEEE 802.11a/g signal with a result length of 4 symbol-times

Trace data display symbols:

−	Red squares: Identifies Data subcarrier symbol EVMs.

−	White squares: Identifies Pilot subcarrier symbol EVMs.

−	Green vertical lines: Identifies common subcarrier positions.

−	White line: Plot of the RMS average symbol EVM for each subcarrier. This is the same as the OFDM RMS Error Vector Spectrum trace data display.

−	White diamond: Identifies the marker position.

Trace A Marker trace data:

−	Subcarrier number:	-11 (subcarrier 0 is not used)

−	Symbol number:	3

−	Symbol EVM:	2.7396 % (for symbol 3 at subcarrier -11)

−	RMS Average EVM:	1.6752 % Avg (all symbols at subcarrier -11)

Note

The TimeLen trace parameter is the total number of symbol-times included in the measurement. For IEEE 802.11a/g signals, this includes both the SIGNAL and DATA Symbol-times. The first symbol-time in the measurement is data for the SIGNAL symbol-time.


Error Vector Time (OFDM)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data >Error Vector Time

OFDM Error Vector Time trace data shows the signal EVM vs. Time and frequency. It provides the individual symbol EVMs for each subcarrier, at each symbol, for all symbol-times within the burst Each symbol-time shows the symbol EVMs for all 52 subcarriers (subcarrier 0 is not used). The trace data includes data results for the pilot and data subcarriers. This display allows you to easily attain information about the signal modulation quality as a function of the symbol-times.

There is also a plot (white line) of the RMS average EVM at each symbol-time (includes all 52 subcarriers at that symbol-time). This is same data and plot used in the OFDM RMS Error Vector Time trace data display.

Symbol EVM is the magnitude of the error vector between the measured symbol vectors (IQ Meas) and ideal symbol vectors (IQ Ref). RMS Error Vector Time trace data is the average of the symbol EVMs of all the subcarriers at each symbol-time (see RMS Error Vector Time trace data).

Tip

You can decrease (or limit) the number of symbol-times included and displayed in the data results with the Max Result Length format parameter.

Interpreting the Display

The y-axis annotates the EVM magnitude and the x-axis annotates the OFDM symbol number (which range from 0 through last symbol-time within the burst). The z-axis annotates the OFDM subcarrier number (which includes all 52 subcarriers, subcarrier 0 is not used). Each x-axis symbol-time on the display shows the individual symbol EVMs for all subcarriers at that particular symbol-time. Placing a marker on a symbol provides the symbol number, the subcarrier number, the symbol EVM and the RMS average of symbol EVMs at that particular symbol-time.

The Error Vector Time trace data uses a multi-color display that assigns a unique color to the pilot subcarriers, the data subcarriers and the RMS Error Vector Spectrum trace data, The colors are also user definable (see Display Appearance).

Example Error Vector Time trace data: Demodulated OFDM IEEE 802.11a/g signal with a result length of 15 symbol-times (0 through 14).

Trace data display symbols:

−	Red squares: Identifies the data subcarrier EVMs.

−	White squares: pilot subcarrier symbol EVMs.

−	Green vertical lines: Identifies common OFDM Symbol-times.

−	White line: Plot of the RMS average symbol EVM at each symbol-time. This is the same trace data as the OFDM RMS Error Vector Time trace data.

−	White diamond: Identifies the marker position.

Trace A Marker trace data:

−	Symbol-time number:	3

−	Subcarrier number:	-11 (subcarrier 0 is not used)

−	Symbol EVM:	2.7396 % (for subcarrier -11, symbol 3)

−	RMS average symbol EVM:	2.575 % Avg (for all subcarriers at symbol 3)

Note

The TimeLen trace parameter is the total number of symbol-times included in the measurement. For IEEE 802.11a/g signals, this includes both the SIGNAL and DATA Symbol-times. The first symbol-time in the measurement is data for the SIGNAL symbol-time.


Inst Spectrum (OFDM)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data >Inst Spectrum

Same as Digital Demod Inst Spectrum, this is the instantaneous (pre-demodulated) spectrum of the input signal. If averaging is not on, this is identical to the Spectrum data (refer to the Digital Demodulation Block Diagram).

See also

Available Trace Data (OFDM)


IQ Meas (OFDM)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data >IQ Meas

When OFDM Demodulation is enabled, IQ Meas is the measured IQ symbol values of the subcarriers. There is one complex value for each subcarrier for each symbol-time in the burst.

Normally this trace data is displayed as a constellation. The constellation display shows both data and pilot subcarriers, the pilots and data values are shown with different colors.

This is similar to Digital Demod IQ Meas Time. The difference is that there are 52 values at each symbol-time, rather than just a single value.

See also

Available Trace Data (OFDM)


IQ Ref (OFDM)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data >IQ Ref

When OFDM Demodulation is enabled, IQ Ref is the reference IQ values of the subcarriers. There is one complex value for each subcarrier for each symbol-time in the burst.

Normally this trace data is displayed as a constellation. The constellation shows both data and pilot subcarrier symbols, the pilots and data values are shown with different colors.

This is similar to Digital Demod IQ Ref Time. The difference is that there are 52 values at each symbol-time, rather than just a single value.

See also

Available Trace Data (OFDM)


PDF  (WLAN-OFDM)

Menu Path: Trace > Data >Ch1, PDF

PDF trace data displays the Probability Density Function of the selected channel. PDF indicates the probability that a given level has occurred.

The PDF is computed from the segment of the OFDM burst specified by the Measurement Interval and Measurement Offset.  In addition, if the Offset is zero and the Interval is equal to the result length, the burst preamble is included in the CCDF.

See PDF (Digital Demodulation) topic for more detailed information about this trace data.

See also

CDF (WLAN-OFDM)

CCDF (WLAN-OFDM)

Available Trace Data (OFDM)


Preamble Error (WLAN-OFDM)

Menu Path: Trace > Data >Ch1, PDF

Preamble Error shows the correlation between segments of the measured preamble signal with the ideal preamble signal. You can specify the Preamble Error measurement for either the Short Training Sequence or the Channel Estimation Sequence (Long Training sequence) segments of the preamble.

A perfectly stable signal would show a constant phase and magnitude for each point in the Preamble Error trace.

Selecting the Preamble

You can select the desired preamble training sequence with the Short Training Seq and Chan Estimation Seq Sync parameters (MeasSetup > Demod Properties > Advanced tab).

Measurement Concepts

Preamble Error calculates the correlation between the measured preamble symbol (Short Sync or Channel Estimation training sequence) and a computed ideal waveform.  The result is a complex number that describes the preamble error (i.e. deviation from ideal) in both magnitude and phase.

 To represent this error as a function of time, the preamble symbol is divided into ten equal segments, each 0.8 microseconds in length.  The average error is calculated individually for each segment, and the ten data points plotted as the displayed measurement trace.

Interpreting the Preamble Trace Data Display

The y-axis of the measurement display defaults to either magnitude or phase.  The x-axis is calibrated in absolute time, relative to the beginning of the first data symbol.  The x-axis value for each of the plotted data points denotes the ending time for the 0.8 microsecond segment over which the error was computed.

Notice that the Preamble Error trace measurement start and stop times for the Short Training sequence is between -16 uSec and -8 uSec and for the Channel Estimation Sequence its between -8 uSec to 0 uSec.

Trace A shows the Preamble Error in terms of phase vs time but you can also show the data results in terms of frequency vs time (see Trace C). To show the information in terms of frequency, change the trace format to Group Delay (Trace > Format > Format drop-down list "Group Delay")

Trace A Marker Data:	Preamble Error trace data for the Short Training Sequence
in terms of Phase vs Time

Preamble Location: - 11.2 uSec before the start of the Payload Data Fields

Preamble Error:       - 580.1268 mdeg's

Trace C Marker Data:	Preamble Error trace data for the Short Training Sequence
in terms of Frequency vs Time

Preamble Location:  - 11.2 uSec before the start of the Payload Data Fields

Preamble Error:          108.00568 Hz

Converting Phase Error to Frequency Deviation

When measuring the settling of a WLAN signal, it may be useful to view the phase transient in units of frequency.  This involves calculating the slope of the phase error with respect to the x-axis units (time).  To perform this conversion automatically, simply change the Trace Data setting from Phase to Delay, which will cause the results to be shown in Hertz.  The analyzer’s calculation, shown below, yields the average frequency during the two 0.8 microsecond segments centered on the displayed measurement point:

Freq(n) = [Phase(n+1) – Phase(n-1)] / 0.16 uSec,

 	 where n = displayed measurement points, from 2 to 9.

Converting Frequency Deviation to Frequency Error

Before the VSA calculates preamble phase/frequency error, it calculates and removes any static frequency error (i.e. Transmit Center Frequency error).  This error component is displayed as a single value on the Symbols/Errors table, and represents the average frequency offset, relative to the VSA’s center frequency, calculated across a specific period of time.  As shown in the following table, this measurement period always includes the entire preamble, but may or may not include the data payload symbols that follow, depending on the Phase Tracking ON/OFF setting in the OFDM demodulator.

Freq Err Includes:	Short Sync. Sequence	Channel Est. Sequence	Data Symbols
Phase Tracking = ON	•	•	•
Phase Tracking = OFF	•	•
Thus, to convert the relative frequency deviation shown on the Preamble Error plot to an absolute frequency error, it is only necessary to add the Frequency Error value shown on the Symbols/Errors table.

Short Sync versus Channel Estimation

In the current implementation of this measurement, there is a residual uncertainty of approximately 5-10 degrees for preamble phase errors measured during the Channel Estimation sequence.   This is due to the longer periodicity of this sequence, which makes the measurement quite sensitive to even small timing misalignments.  For this reason, this measurement mode is recommended only in cases where relatively large amounts of preamble error are expected.

Measuring Data Symbol Frequency Errors

Residual phase and frequency settling that occurs after the preamble is measured via the “Common Pilot Error ” display.  With Phase Tracking turned ON, this display shows the average phase error of the four OFDM pilots as a function of time (i.e. versus data symbol number).  To convert to frequency units, select Trace Format  = Group Delay.

See also

Common Pilot Error

Available Trace Data (OFDM)


Raw Main Time (OFDM)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data >Ch1, Raw Main Time

Raw Main Time is the raw data read from the input hardware or playback file. For more information about this data, refer to the Raw Main Time (Digital Demod) trace data topic.

VSA signal flow (see Digital Demodulation Block Diagram):

See Also

Time trace data (WLAN-OFDM)


RMS Error Vector Spectrum (OFDM)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data >RMS Error Vector Spectrum

The Error Vector Magnitude is the computed difference between IQ Measured vector magnitude and IQ Reference vector magnitudes, it is a complex value at each subcarrier for each OFDM symbol. The RMS Error Vector Spectrum is the RMS average EVM for each subcarrier for all symbols within the burst.

The "xRMS:__" trace data display parameter shows the number of symbols included in the RMS average EVM.

Averaging

Multiple-burst averaging is available for the RMS Error Vector Spectrum trace data. When averaging is turned on, the RMS Error Vector Spectrum trace contains data averaged over the number of bursts specified in the "Count" text box of the MeasSetup Properties dialog box, Average tab (see Average Tab)

The "__x" value in the RMS:__xRMS__ trace data display parameter shows the number of bursts included in the average.

See also

Available Trace Data (OFDM)


RMS Error Vector Time (OFDM)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data >RMS Error Vector Time

The difference between IQ Meas and IQ Ref is the error vector, which would have a complex value at each subcarrier at each symbol-time. The RMS Error Vector Time looks at the error vector values for each symbol-time, and does an RMS average of these values over all of the 52 used subcarriers. The result is a time trace, which shows the average error vector magnitude at each symbol-time.

See also

Available Trace Data (OFDM)


Search Time (OFDM)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Search Time

When WLAN-OFDM Demodulation is enabled, the Search Time trace shows time-data before pulse search and demodulation. This is the acquired time data used to search for the pulse (or burst). The value of Search Length determines the length of the Search Time trace (refer to the Digital Demodulation Block Diagram).

See also

Available Trace Data (OFDM)


Spectrum (OFDM)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Spectrum

When OFDM Demodulation is enabled, the Spectrum trace is the averaged, Instantaneous Spectrum display, as shown in the following block diagram. If averaging is off, the Spectrum and Instantaneous Spectrum displays are identical.

The Spectrum trace has the following characteristics:

•	It is derived from pre-demodulated time data, which is 20% larger than the result length.

•	It is averaged if averaging is ON and the average type is rms, rms exponential, or peak averaging.

Note

If averaging is ON, a scan is not included in the average if any of these conditions exist: Pulse Not Found, Sync Not Found, Carrier Unlock, or certain DATA? conditions.

VSA signal flow (see Digital Demodulation Block Diagram):

See also

Available Trace Data (OFDM)


Syms/Errs (OFDM)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data > Syms/Errs

When OFDM Demodulation is enabled, the Syms/Errs trace data shows the symbol table trace data for OFDM demodulation. The symbol table shows you error summary data and the symbol data (raw binary bits) for each OFDM symbol and subcarrier following the preamble. See following topics for information about the symbol table and error summary data:

About the Symbol Table (OFDM Demodulation)

About the Error Summary Data (OFDM Demodulation)

Available Error Summary Data

See also

Available Trace Data (OFDM)


Time (OFDM)

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data >Time

When OFDM Demodulation is enabled, the Time trace shows the time record before digital demodulation and after pulse search, as shown in the following block diagram (refer to the Digital Demodulation Block Diagram).

The amount of data included in the Time trace display is a function of the Result Length, Measurement Interval and Measurement Offset parameters. The following topics describe how these parameters affect the Time trace data:

Time Trace Data and the Result Length parameters

•	Auto Select mode: The Time Trace data shows the data specified by the Max Result Length parameter:

−	If Max Result Length is greater than the burst length, the Time trace data shows the entire burst +/- 10% of the burst length (also includes preamble data).

−	If Max Result Length is less than the burst length, the Time trace data shows the number of symbol-times specified by the Max Result Length parameter plus 10% of the Max Result Length just before the start of the burst. This also includes preamble data.

For more information about how the Max Result Length parameter determines the measurement result length, see About Result Length Parameters.

•	Manual Override mode: The Time Trace data shows data for the number of symbol-times specified by the Manual Override parameter plus 10% of the Manual Override Length just before the start of the burst. This also includes preamble data.

For more information about how the Manual Override parameter determines the measurement result length data, see About Result Length Parameters .

Time Trace Data and the Measurement Interval/Offset parameters

•	Measurement Interval not equal to Max Result Length

When you use the Measurement Interval and Offset parameters to specify the acquired measurement data, the Time Trace Data includes only the data specified by the Measurement Interval parameter. The display shows only data for the symbol-times specified within the Measurement Interval, all other data before and after the Measurement Interval will be excluded. This also means that preamble data will not be shown when using Measurement Interval and Offset parameters.

•	Measurement Interval equal to Max Result Length

When the Measurement Interval is equal to Max Result Length, the Time trace data is controlled and specified by the Max Result Length parameter, see Auto Select mode, Max Result Length described previously for more information.

For more information about how Measurement Interval and Measurement Offset determine the measurement result length data, refer to Measurement Interval/Offset.

Time Trace data and Averaging

Time Trace data is unaffected by time averaging.

See also

Available Trace Data (OFDM)


About Option B7R: WLAN-DSSS 802.11b/g Modulation Analysis
About Option B7R: WLAN-DSSS/CCK/PBCC/CCK/PBCC 802.11b/g Modulation Analysis

Option B7R:" WLAN-DSSS/CCK/PBCC/CCK/PBCC 802.11b/g Modulation Analysis" adds Wireless Local Area Network (WLAN) - Direct Sequence Spread Spectrum (DSSS) signal analysis to your 89600-series Vector Signal Analyzer application software for IEEE Std 802.11b and IEEE Std 802.11g modulated signals.

IEEE Std 802.11b	Wireless LAN Medium Access Control and Physical Layer specification.  Higher-Speed Physical Layer Extension in the 2.4 GHz Band
IEEE Std 802.11g	Wireless LAN Medium Access Control and Physical Layer specification.  Further Higher-Speed Physical Layer Extension in the 2.4 GHz Band
The original IEEE 802.11 standard defined direct sequence spread spectrum (DSSS) signals with data rates at 1Mb/sec and 2Mb/sec in the 2.4 GHz Industrial Scientific and Medical (ISM) frequency band. The IEEE 802.11b standard extends this with complementary code keying (CCK) modulation at 5.5 Mb/sec and 11 Mb/sec. In addition, 802.11b defines an optional packet binary convolutional code (PBCC) mode at 5.5 Mb/sec and 11 Mb/sec, and defines an optional shorter preamble.

The draft IEEE 802.11g standard adds the ability to use 802.11a OFDM formatted signals in the 2.4 GHz ISM band, defines additional optional 802.11b-compatible PBCC modes at 22 Mb/sec and 33 Mb/sec, and defines an optional 802.11b-compatible "CCK-OFDM" mode that is a combination of the 802.11a OFDM format with an 802.11b-compatible preamble.

In "WLAN – DSSS/CCK/PBCC" mode, the analyzer will support automatic detection, demodulation, and de-spreading of the four mandatory 802.11b signal formats (1, 2, 5.5, and 11 Mb/sec), as well as detection and decoding of the optional 802.11b and 802.11g PBCC formats.  The analyzer will detect but not demodulate the optional CCK-OFDM format (the 802.11b-compatible preamble will be demodulated, but the 802.11a-compatible data will not be demodulated). You can use the WLAN-OFDM mode to demodulate the OFDM segment of the burst.  The analyzer will automatically detect, demodulate, de-spread, and de-scramble both the standard 802.11b preamble and the optional short 802.11b preamble, in order to detect the expected burst length and modulation type.

The following table shows a comparison of the data rates with mandatory and optional modulation formats for the WLAN IEEE std 802.11 versions a, b and g:

WLAN IEEE Std 802.11 Data Rate Comparison Chart

	802.11b @ 2.4 GHz	802.11g @ 2.4 GHz	802.11a @ 5.2 GHz
Data Rate	Mandatory	Optional	Mandatory	Optional	Mandatory	Optional
1 Mbps	Barker	----	Barker	----	----	----
2 Mbps	Barker	----	Barker	----	----	----
5.5 Mbps	CCK	PBCC	CCK	PBCC	----	----
6 Mbps	----	----	OFDM	CCK-OFDM	OFDM	----
9 Mbps	----	----	----	OFDM, CCK-OFDM	----	OFDM
11 Mbps	CCK	PBCC	CCK	PBCC	----	----
12 Mbps	----	----	OFDM	CCK-OFDM	OFDM	----
18 Mbps	----	----	---	OFDM, CCK-OFDM	----	OFDM
22 Mbps	----	----	----	PBCC	-	----
24 Mbps	----	----	OFDM	CCK-OFDM	OFDM	----
33 Mbps	----	----	----	PBCC	----	----
36 Mbps	----	----	OFDM	OFDM, CCK-OFDM	----	OFDM
48 Mbps	----	----	OFDM	OFDM, CCK-OFDM	----	OFDM
54 Mbps	----	----	OFDM	OFDM, CCK-OFDM	----	OFDM
The following figure shows the IEEE STD 802.11b PPDU frame with Long preamble:

The following figure shows the IEEE STD 802.11b PPDU frame with Short preamble:

See also

Available Features (WLAN-DSSS/CCK/PBCC/CCK/PBCC Demodulation)

About 89600 Optional Measurement Software


Available Features  (WLAN-DSSS/CCK/PBCC Demodulation)

The following topics describe WLAN-DSS demodulation features:

WLAN-DSSS/CCK/PBCC/CCK/PBCC Available Features:

WLAN-DSSS/CCK/PBCC/CCK/PBCC Demodulation Limitations:

Digital Demod features not available for WLAN-DSSS/CCK/PBCC/CCK/PBCC demodulation

WLAN-DSSS/CCK/PBCC/CCK/PBCC Demodulation Available Features:

•	One configuration standard preset for IEEE Std 802.11b and IEEE Std 802.11g WLAN-DSSS/CCK/PBCC (Wireless LAN - Direct Sequence Spread Spectrum ) standard signals.

•	Support for decoding the optional IEEE Std  802.11b or IEEE Std 802.11g PBCC modes.

•	Support for demodulating the preamble of 802.11g CCK-OFDM bursts (the OFDM payload can be demodulated using the analyzer's WLAN-OFDM mode)

•	Features specific to IEEE 802.11b:

−	Analyze variable-length pulses.

−	Demodulate long and short preamble formats.

−	Auto-select and manual-override pulse length modes.

−	Auto-detect and manual-override payload data modulation format modes.

−	Generation of 802.11b reference from either raw chips or de-spread symbols.

−	Adjustable chip rate.

−	Adjustable chip timing.

−	Equalization Filter determined from detected 802.11b preamble information.

−	De-spread data results.

−	PPDU frame Header information (similar to WLAN-OFDM demodulation).

−	Ability to disable the descrambler

•	Pulse Search

•	IQ Normalization.

•	Mirrored (flipped) frequency spectrums used to remove the effects of high-side mixing or complex conjugation mismatches in simulated data.

•	Measurement offset and interval (similar to time gating) used to select specific data segments for analysis

•	Averaging is applicable only in the following circumstances:

−	IQ Meas Spec and IQ Ref trace data

−	Error Vector Spectrum trace data

−	The following averaging types are available for the numeric error summary data and for the pre-demodulated spectrum trace data:

•	RMS (video)

•	RMS Exponential

•	Continuous Peak Hold

WLAN-DSSS/CCK/PBCC Demodulation limitations:

•	No support for IEEE Std 802.11 FHSS (Frequency Hopped Spread Spectrum).

•	No support for IEEE Std 802.11b Channel Agility.

Digital Demod features not available for WLAN-DSSS/CCK/PBCC demodulation:

•	Measurement\Reference filter

•	Sync search

•	Multiple points per Chip/Symbol

•	Arbitrary constellation rotation

See also

WLAN-DSSS/CCK/PBCC Available Trace Data

89600-Series VSA Application Standard Features

WLAN-DSSS/CCK/PBCC Demodulation Overview

About Averaging


Setting Up a Measurement  (WLAN-DSSS/CCK/PBCC Demodulation)

(Vector Signal Analyzer application only.)

When setting up a WLAN-DSSS/CCK/PBCC demodulation measurement, there are several things you need to consider. This topic tells you how to connect your signal to an 89600-series analyzer and successfully demodulate digital signals. The information is provided in this order:

•	Connecting Your Signal to the Analyzer

•	Center Frequency

•	Frequency Span

•	Input Range

•	Chip Rate

•	Search Length

•	Maximum Result Length

Connecting Your Signal to the Analyzer

The analyzer lets you connect your carrier signal or, if your 89600-series analyzer has two input channels, the raw I (In-phase) and Q (Quadrature-phase) signals.

For all receiver configurations except I + jQ, connect your signal to Channel 1. In this case, the analyzer assumes that your signal contains both the I and Q components (the carrier signal). If your analyzer has two input channels, the analyzer ignores the second input channel.

If your analyzer has a second input channel, you can also connect the raw I (In-phase) and Q (Quadrature- phase) signals. To do this, select Input, Channels, I + jQ. With this configuration, the analyzer removes the quadrature mixer from the demodulator's signal flow, which lets you connect the I component of your signal to Channel 1; the Q component to Channel 2.

Notes

•	Selecting I+jQ turns on DC coupling.

•	When using I+jQ, use external calibration to correct for any offset or gain imbalance between the I and Q signals.

•	Ranges for Channel 1 and Channel 2 are set independently.

Return to Top of Page.

Center Frequency

The analyzer's center frequency should be set to within approximately ±500 kHz of the transmitted carrier frequency.  The analyzer can lock to the signal when the center frequency is off by up to +/- 2.5 MHz, but EVM values may be higher if not within +/- 500 kHz.

Return to Top of Page.

Frequency Span

When selecting a frequency span, select the narrowest span that includes all of your signal components (select a span that is slightly larger than the bandwidth of your signal). If you select a span that is too narrow, your measurement may have excessive errors or the analyzer may lose carrier lock. If the span is less than 19.8 MHz, the analyzer displays "DATA?" to indicate that the results may not be accurate.

If the span is too large, it may allow spurs to be aliased into the region of interest. Selecting "Show All Frequency Points" (Display, Appearance, Trace tab) can help determine if spurs are being included in the result. If so, the span should be reduced to exclude them and provide a more accurate result.

Using the "Preset to Standard "configuration setting will select a suitable default span.

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Input Range

The input range must be set correctly to obtain accurate measurements. Input ranges that are too low overload the analyzer's ADC. Input ranges that are too high increase noise, which increases errors reported in error summary data, such as EVM.

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Chip Rate

Use the Preset to Standard default value. Experienced users may adjust this parameter to fine-tune the demodulator.

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Search Length

The search length must be long enough capture a complete burst. Using long search lengths will increase the measurement time, but make it more likely that a pulse will be found.

If a pulse is not found a "PULSE NOT FOUND" status message will be displayed.

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Maximum Result Length

Use the Preset to Standard default value. This will provide a good starting value for the result length.

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See also

Selecting WLAN-DSSS/CCK/PBCC Demodulation

Using a Standard Setup

Troubleshooting


Selecting WLAN-DSSS/CCK/PBCC Demodulation

(Vector Signal Analyzer application with option B7R only.)

Menu Path: MeasSetup > Demodulator > WLAN-DSSS/CCK/PBCC

Sets the analyzer to demodulate WLAN-DSSS/CCK/PBCC modulated signals.

After selecting the demodulator you must set up the configuration parameters. You can select the Standard Preset or you can configure the analyzer manually from the Demod Properties dialog box.

It's also recommended that you review the Setting up an WLAN-DSSS/CCK/PBCC Measurement.

See also:

WLAN-DSSS/CCK/PBCC Overview


Using a Standard Setup  (WLAN-DSSS/CCK/PBCC Demodulation)

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Format tab > Preset to Standard button

Lets you select a WLAN-DSSS/CCK/PBCC (Wireless LAN - Direct Sequence Spread Spectrum) modulation standard preset configuration. When you select "Preset to Standard", the analyzer automatically sets the parameters shown in the following table:

Note

You must select the WLAN-DSSS/CCK/PBCC Demodulator before these Standard Presets are available.

WLAN-DSSS/CCK/PBCC Preset to Standard

Property	IEEE 802.11b
Span	34.375 MHz
Data Modulation Format	Auto Detect
Search Length	1 msec
Result Length	Auto Select (2816 chips Max)
Measurement Offset	22 chips
Measurement Interval	2794 chips
IQ Normalize	ON
Mirror Frequency Spectrum	OFF
Chip Rate	11 MHz
Clock Adjust	0 chips
Equalization Filter	OFF
Eq Filter Length	21 chips
See also

Setting Up a Measurement

Selecting WLAN-DSSS/CCK/PBCC Demodulation

Troubleshooting WLAN-DSSS/CCK/PBCC


Troubleshooting  (WLAN-DSSS/CCK/PBCC Demodulation)

(Vector Signal Analyzer application only.)

This topic contains information to help you troubleshoot measurements when using WLAN-DSSS/CCK/PBCC Demodulation. You should also review Setting up an WLAN-DSSS/CCK/PBCC Demodulation Measurement for additional measurement information.

PROBLEM	POSSIBLE CAUSE	SOLUTION
Demodulation fails to lock on signal or	Signal not present.	Check connections
SYNC NOT FOUND" error message.	Carrier too far from center frequency.	Adjust center frequency. The analyzer center frequency must be within 2.5 MHz to lock-on.  For good EVM measurements, set the center frequency to within 550 kHz.
	Input is over-loaded or under ranged.	Adjust input range. Typically, the best EVM is achieved when the range is as small as possible while avoiding overloads.
	Frequency span is too narrow.	Increase frequency span. A frequency span of at least 19.8 MHz is typically required for 802.11b/g DSSS signals.
	Signal has inverted frequency spectrum	Check the Mirror Frequency Spectrum setting (MeasSetup > Demod Properties > Advanced tab).
	Signal has incorrect PLCP Header at start of burst	Override the auto detection of modulation type and result length (MeasSetup >  Demod Properties >  Format tab and Time tab).
	Wrong modulation format	Select correct modulation format
	Input signal scrambler disabled	Disable the analyzer's descrambler (MeasSetup->Demod Properties->Advanced tab).
	Maximum result length shorter than preamble length	Increase maximum result length (MeasSetup->Demod Properties->Time tab).
	Signal is a WLAN-OFDM modulated signal	Switch the analyzer to WLAN-OFDM mode.
Analyzer locks, but data bits incorrect	Signal has inverted frequency spectrum	Check the Mirror Frequency Spectrum setting (MeasSetup > Demod Properties > Advanced tab). Note that the burst Preamble and Header are usually BPSK modulated, so would be unaffected by an inverted frequency spectrum.  But the data portion of the burst is generally QPSK modulated and the detected data bits will be incorrect if the frequency spectrum is inverted.
PULSE NOT FOUND error message	Search length too short.	Increase search length, or adjust triggering to ensure that the leading and trailing edges of a pulse are fully within the search length.
	Signal is not pulsed.	WLAN-DSSS/CCK/PBCC is pulsed signals. If the signal is not pulsed, try to use triggering to position the preamble just after the beginning of the search length. In this case, PULSE NOT FOUND will still be displayed, but demodulation may be successful anyway.
EVM larger than expected	I/Q misaligned using I+jQ receiver.	Click Utilities > Calibration >  Amplitude tab > Calibration Constants check box, and adjust the delays for each input channel.
	I/Q gain imbalance using I+jQ receiver.	1) Check that impedance is identical for both input channels. 2) Click Utilities > Calibration >  Amplitude tab > Calibration Constants check box,  and adjust the gains for each input channel.
	Noise or interference from adjacent signals.	Reduce the span to eliminate excess noise and interfering signals.
EVM good at beginning of burst, then gets very large near the end of the burst	Signal has incorrect Length segment of PLCP Header at start of burst	Override the auto detection of result length (MeasSetup > Demod Properties > Time tab).
See also

Setting Up a WLAN-DSSS/CCK/PBCC Measurement

VSA error and status messages

VSA Troubleshooting Topics


WLAN-DSSS Demod Properties
WLAN-DSSS/CCK/PBCC Demod Properties Dialog Box

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup, Demod Properties

The WLAN-DSSS/CCK/PBCC (Wireless LAN - Direct Sequence Spread Spectrum) Demodulation dialog box contains parameters that let you configure the analyzer to demodulate WLAN-DSSS/CCK/PBCC modulated signals.

Note

The  WLAN-DSSS/CCK/PBCC Demodulator must be selected before this dialog box id available.

The dialog box contains these tabs::

•	Advanced Tab: Lets you access advanced parameters including Chip Rate, Clock Adjust, Equalization Filter, Descramble mode select, IQ Normalize and Mirror Frequency select.

•	Format Tab: Lets you access the WLAN-DSSS/CCK/PBCC demod configuration parameters including: Preset to Standard and Data Modulation Format properties,

•	Time Tab: Lets you access the signal capture configuration parameters. You use these parameters select the pulse search length and to isolate a segment of the time record for further viewing and data analysis. The parameters include: Search Length, Result Length, Measurement Offset and Measurement Interval parameters.

See also

Selecting WLAN-DSSS/CCK/PBCC Demodulator

Setting up an WLAN-DSSS/CCK/PBCC Measurement


Advanced Tab  (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Advanced Tab

The Advanced Tab of the WLAN-DSSS/CCK/PBCC Demodulation Properties dialog box lets you access advanced parameters you can use to demodulate nonstandard WLAN-DSSS/CCK/PBCC signals

The Advanced Tab dialog box allows you configure these parameters:

•	Chip Rate

•	Clock Adjust

•	Equalization Filter

−	Filter Length

•	Descramble Mode

•	IQ Normalize

•	Mirror Frequency Spectrum

•	Track Phase

See Also

WLAN-DSSS/CCK/PBCC Demod Properties - Format tab

WLAN-DSSS/CCK/PBCC Demod Properties - Time tab

WLAN-DSSS/CCK/PBCC Demod Properties - Dialog Box


Format Tab  (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only.)

Menu Path: MeasSetup > Demod Properties > Format tab

The Format tab of the WLAN-DSSS/CCK/PBCC Demodulation Properties dialog box lets you configure the analyzers WLAN-DSSS/CCK/PBCC demodulator. These are the parameters necessary for the analyzer to lock-on to and demodulate the test signal.

The Format tab dialog box allows you configure these parameters:

•	Data Modulation Format properties:

−	Auto Detect

−	Manual Override

•	Preset To Standard

See Also

WLAN-DSSS/CCK/PBCC Demod Properties - Advanced Tab

WLAN-DSSS/CCK/PBCC Demod Properties - Time tab

WLAN-DSSS/CCK/PBCC Demod Properties - Dialog Box


Time Tab  (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup. DemodProperties, Time tab

The Time tab of the WLAN-DSSS/CCK/PBCC Demodulation Properties dialog box lets you access the signal capture configuration parameters. You use these parameters to select the pulse search length and to isolate a segment of the time record for further viewing and data analysis.

The Time tab dialog box allows you configure these parameters:

•	Search Length

•	Result Length parameters:

−	Auto Select

•	Max Result Length

−	Manual Override

•	Measurement Offset

•	Measurement Interval

See Also

WLAN-DSSS/CCK/PBCC Demod Properties - Advanced Tab

WLAN-DSSS/CCK/PBCC Demod Properties - Format tab

WLAN-DSSS/CCK/PBCC Demod Properties - Dialog Box


Chip Rate  (WLAN-DSSS/CCK/PBCC)

Menu Path: MeasSetup > Demod Properties > Advanced Tab > Chip Rate

Defaults: Refer to WLAN-DSSS/CCK/PBCC Standard Presets Table

Lets you set the Chip Rate for the analyzer's demodulator. This allows you the freedom to enter nonstandard chip rates for test and analysis purposes.

Note

To demodulate a signal, the chip rate must match the chip rate of your system.

For more information about standard WLAN-DSSS/CCK/PBCC chip rate and corresponding data rates Refer to "About Data Modulation Formats" topic.

See Also

About WLAN-DSSS/CCK/PBCC Modulation

Advanced Tab - WLAN-DSSS/CCK/PBCC Demod Properties


Clock Adjust (WLAN-DSSS/CCK/PBCC)

Menu Path: MeasSetup > Demod Properties > Advanced Tab > Clock Adjust

Defaults: Refer to WLAN-DSSS/CCK/PBCC Standard Presets Table

Range: -0.5 to + 0.5 chips

Clock Adjust determines when the analyzer's digital demodulator samples the I/Q trajectory.

The WLAN-DSSS/CCK/PBCC demodulator used in this analyzer does not require symbol-clock timing signals to determine the location of chip detection-decision points. Instead, the demodulator uses an algorithm to determine chip locations.

Some digital communications systems contain non-linearity's that can bias the digital demodulator's estimation of the chip clock position. You can use clock adjust to compensate for this "offset" and obtain a lower EVM (Error Vector Magnitude).

The Clock Adjust  (or Offset) is entered in chips. By default, the offset is zero (0) chips. You can specify an offset from −0.5 to +0.5 chips.

You can see the effects of changing clock adjust by displaying a constellation diagram or eye diagram. Increasing (or decreasing) clock adjust:

•	Shifts the detection-decision points in the constellation diagram.

•	Slides the eye diagram right or left (remember that in the eye diagram, the chip locations remain in a fixed location on the display; therefore, changing the location of chips has the effect of horizontally shifting the eye diagram).

Additional Tips

Here are some additional Tips that may help you use clock adjust:

•	Specifying a clock adjust only affects the I/Q measured trace. It does not affect the I/Q reference trace.

•	Use the eye diagram with an eye length of one (1) to observe the accuracy of the symbol clock timing. You may also want to monitor the EVM (Error Vector Magnitude) in the symbol table summary while adjusting clock adjust to obtain the optimum symbol timing.

Clock adjust is reset to 0.0 when you select Preset.

See also

Advanced Tab - WLAN-DSSS/CCK/PBCC Demodulation Properties

WLAN-DSSS/CCK/PBCC Demodulation Properties


Descramble Mode

Menu Path: MeasSetup > Demod Properties > Advanced Tab > Clock Adjust

Defaults: Refer to WLAN-DSSS/CCK/PBCC Standard Presets Table

Descramble Mode lets you enable/disable the WLAN 802.11b/g descrambler. With this feature you can separately view the descrambled or raw data bits for the preamble, header or payload data fields. The Preamble data bits are shown in the DSSS Preamble Syms trace data display, The Header data bits are shown in the DSSS Header Syms trace data display and the Payload data bits are shown in the DSSS Syms/Errs trace data display:

•	On:  The WLAN Descrambler is ON, the Preamble, Header and Payload data bits are descrambled.

•	OFF:  The WLAN Descrambler is OFF, the Preamble, Header and Payload data bits are not descrambled.

•	Preamble Only:  Only the Preamble data bits are descrambled. The Header data bits and Payload data bits are not descrambled.

•	Preamble & Header Only:  Only the Preamble and Header data bits are descrambled. The Payload data bits are not descrambled.

Using Descramble Mode

The Descramble Mode demodulation property in conjunction with the DSSS Preamble Syms trace data, DSSS Header Syms trace data and Syms/Errs trace data displays provide an easy way to separately validate and/or troubleshoot the signals Preamble, Header and/or Payload data bits.

If the analyzer shows the "Could not detect burst type" message, you can use these features to verify the signals synchronization bits in the PLCP Preamble SYNC field and modulation type bits in the PLCP Header SIGNAL data field.

Note

The Descrambler mode should generally be set to match the scrambling of the incoming signal.  If the input signal has the preamble scrambled, the analyzer must descramble the preamble in order to properly sync to the preamble.  Similarly, if the input signal has the header scrambled, the analyzer must descrambler the header in order to properly detect the data modulation type and burst length.  If you disable descrambling of the header, you may need to manually specify the Data Modulation Type (MeasSetup -> Demod Properties -> Format tab) and Result Length (MeasSetup -> Demod Properties -> Time tab).

See also

Advanced Tab - WLAN-DSSS/CCK/PBCC Demodulation Properties

WLAN-DSSS/CCK/PBCC Demodulation Properties


Equalization Filter  (WLAN-DSSS/CCK/PBCC)

Menu Path: MeasSetup > Demod Properties > Advanced Tab > Equalization Filter

Defaults: Refer to WLAN-DSSS/CCK/PBCC Standard Presets Table

Select the Equalization Filter check box to apply the analyzer's equalization filter to your measurement. Specify the filter length in the Filter Length text box.

Equalization and WLAN-DSSS/CCK/PBCC modulation

A general overview of equalization is included in the "About Equalization (WLAN-DSSS/CCK/PBCC)"and Using Equalization (WLAN-DSSS/CCK/PBCC) topics.

Equalization and EVM measurements

The 802.11b specification does not allow for equalization prior to computing EVM. This means that any linear distortion, such as group delay distortion in the IF, will increase EVM. When EVM is high the equalizer can be used as a diagnostic tool. If use of the equalizer significantly improves the EVM result, then the channel frequency response should be examined for flatness problems (i.e. group delay distortion). If it does not, then the problem is more likely related to noise, non-linear distortion, or spurious error.

See also

Filter Length (WLAN-DSSS/CCK/PBCC)

Advanced Tab - WLAN-DSSS/CCK/PBCC Demodulation Properties

WLAN-DSSS/CCK/PBCC Demodulation Properties dialog box


Filter Length  (WLAN-DSSS/CCK/PBCC)

Equalization Filter parameters

Menu Path: MeasSetup > Demod Properties > Advanced Tab > Filter Length text box

Default:	With first use, 21 chips, otherwise, previous value.

Range:	3 to 99 chips, odd values only.

The Filter Length parameter sets the filter length for the analyzer's equalization filter.

Note

This parameter is available only when the Equalization Filter check box is selected.

Selecting a Filter Length

In general, the best filter length is the smallest that meets your measurement requirements. For measurements at the transmitter, the filter length may only need to be a few chips in length. Longer filter lengths may be needed to measure multi-path environments.

The number of chips determines the maximum filter length that you can enter, as follows:

Filter Length ≤ [result length] − 2

For example, if the result length is 50 chips, the maximum filter length is 47.

See also

About Equalization (WLAN-DSSS/CCK/PBCC)

Using the Equalization Filter (WLAN-DSSS/CCK/PBCC)

Advanced Tab - WLAN-DSSS/CCK/PBCC Demodulation Properties

WLAN-DSSS/CCK/PBCC Demodulation Properties


IQ Normalize  (WLAN-DSSS/CCK/PBCC)

Menu Path: MeasSetup > Demod Properties > Advanced Tab > IQ Normalize

Defaults: Refer to WLAN-DSSS/CCK/PBCC Standard Presets Table

Lets you select the IQ Normalize function, see the IQ Normalize (Digital Demodulation) topic for more information..

Selected:	The IQ trace data results (including IQ Meas Time, IQ Ref Time, IQ Mag Err, IQ Phase Err, and Error Vector Time and corresponding Spectrum results) are normalized.
Cleared:	The trace data results are not normalized.
Note

Regardless of this setting, the Error Summary trace data results are always normalized.

See also

Advanced Tab - WLAN-DSSS/CCK/PBCC Demodulation Properties

WLAN-DSSS/CCK/PBCC Demodulation Properties


Mirror Frequency Spectrum  (WLAN-DSSS/CCK/PBCC)

Menu Path: MeasSetup > Demod Properties > Advanced Tab > Mirror Frequency Spectrum

Defaults: Refer to WLAN-DSSS/CCK/PBCC Standard Presets Table

Lets you correctly demodulate frequency spectrums that are mirrored (flipped) about the center frequency. The default frequency spectrum is assumed not mirrored. This parameter does not change the displayed spectrum trace data.

Cleared:  Does not mirror the frequency spectrum.

Selected:  Mirrors the frequency spectrum about the analyzer center frequency.

Note

The display of the spectrum data will not change with this parameter. To mirror the display, clear the Mirror Frequency Spectrum check box, and select the MeasSetup Properties dialog box, Frequency tab > Mirror Frequency check box.

See also

Advanced Tab - WLAN-DSSS/CCK/PBCC Demodulation Properties

WLAN-DSSS/CCK/PBCC Demodulation Properties


Track Phase   (WLAN-DSSS/CCK/PBCC)

Menu Path: MeasSetup > Demod Properties > Advanced Tab > Phase Tracking

Defaults: Refer to WLAN-DSSS/CCK/PBCC Standard Presets Table

Track Phase removes phase drift error from the demodulated trace data results.

Clear (Default):  Track Phase is NOT enabled.

Selected:  Track Phase is enabled.

The Track Phase parameter enables tracking of phase drift within the WLAN burst.  This may be useful if the carrier frequency drifts significantly during a burst.  Circular arcs in the constellation of the IQ Meas Time trace display is an indicator of phase drift.  The Track Phase parameter can be used to remove the phase drift, which will improve the IQ constellation trace and reduce the EVM data results.  Frequency drift can also cause poor equalizer performance, so selecting Track Phase may improve equalizer results.

See also

Advanced Tab - WLAN-DSSS/CCK/PBCC Demodulation Properties

WLAN-DSSS/CCK/PBCC Demodulation Properties


Preset To Standard  (WLAN-DSSS/CCK/PBCC)

Menu Path: MeasSetup > Demod Properties > Format tab > Preset to Standard command button

Defaults: Refer to WLAN-DSSS/CCK/PBCC Standard Presets Table

Lets you select the standard WLAN-DSSS Demodulation configurations. The analyzer automatically sets the required configuration parameters to demodulate 802.11b and 802.11g DSSS/CCK/PBCC modulated signals.

Refer to Using WLAN-DSSS/CCK/PBCC Standard Setups for a complete list of available standards, associated parameters and default settings.

See Also

Format Tab - WLAN-DSSS/CCK/PBCC Demodulation Properties


Measurement Interval  (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Time tab > Measurement Interval text box

Defaults: Refer to WLAN-DSSS/CCK/PBCC Standard Presets Table

Refer to About Measurement Interval and Offset(WLAN-DSSS/CCK/PBCC) for more information about this parameter and its application.

See also

About Measurement Interval and Offset(WLAN-DSSS/CCK/PBCC)

Search Length (WLAN-DSSS/CCK/PBCC)

Time Tab - WLAN-DSSS/CCK/PBCC Demodulation Properties


Measurement Offset  (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Time tab > Measurement Offset text box

Defaults: Refer to WLAN-DSSS/CCK/PBCC Standard Presets Table

Refer to About Measurement Interval and Offset(WLAN-DSSS/CCK/PBCC) for more information about this parameter and its application.

See also

About Measurement Interval and Offset(WLAN-DSSS/CCK/PBCC)

Search Length (WLAN-DSSS/CCK/PBCC)

Time Tab - WLAN-DSSS/CCK/PBCC Demodulation Properties


Search Length (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Time tab > Search Length text box

Defaults: Refer to WLAN-DSSS/CCK/PBCC Standard Presets Table

Lets you specify the length of time to acquire the input signal (in seconds). This defines the length of time that the pulse search is performed.

The analyzer searches within the specified search length and demodulates the first complete pulse (or burst). The pulse can occur anywhere within the search length. Pulses beyond the first complete pulse are disregarded and are not demodulated. In order for the pulse search algorithm to detect a pulse edge, the pulse must be at least 15 dB above the noise floor. The resultant pulse is then demodulated.

Longer pulse lengths increase the measurement time but make it more likely that a pulse will be acquired. If a pulse is not found a "PULSE NOT FOUND" status message will be displayed.

Even if no pulse is found, the analyzer will attempt to demodulate starting at the beginning of the Search Length,  If a PLCP Preamble Sync pattern is found near the start of the search length, the demodulation will be correct.

See also

About Measurement Interval and Offset

Time Tab - WLAN-DSSS/CCK/PBCC Demodulation Properties


About Equalization  (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only.)

Menu Path:  MeasSetup > Demod Properties > Advanced Tab

Equalization removes linear errors from modulated signals by dynamically creating and applying a FIR compensating filter. Linear errors can come from filters in a transmitter or receiver's IF, or from the presence of multiple paths in the transmission path, such as reflections in a cable system. These types of problems appear as group-delay distortion, frequency-response errors (tilt, ripple), and reflections or multipath distortion.

Equalization allows measurement of some impaired channels and can be used to isolate linear from non- linear error mechanisms.

Important Concepts

The following paragraphs highlight important concepts About Equalization:

•	The primary application of the equalizer's impulse-response display is for evaluating multi-path environments. Multi-path environments usually require longer filter lengths.

•	The primary application of the equalizer's frequency-response display is for evaluating the transmitter or receiver signal-path for errors such as passband ripple and group-delay distortion. Short filter lengths usually work well for these types of measurements.

•	The analyzer estimates new filter coefficients with each measurement.

See also

Using Equalization (WLAN-DSSS/CCK/PBCC)

Equalization Filter demodulation property - (WLAN-DSSS/CCK/PBCC)


Using Equalization  (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only.)

Menu Path:  MeasSetup > Demod Properties > Advanced tab

You select the Equalization Filter check box to apply the analyzer's equalization filter to your measurement.

Note

Equalization uses the measured signals preamble to determine the coefficients of the equalization filter.

Selecting a Frequency Span

For best results, make sure you select a frequency span that contains all energy of your signal. If significant energy from your signal falls outside of the displayed frequency span, equalization will not work on your signal.

Equalization Parameters

You can define the length of the equalization filter (in chips) with the Filter Length. The Equalization Filter check box controls whether the filter is applied to the measurement data or not.

Phase Drift effects

 Frequency drift can cause poor equalizer performance.  The Track Phase demodulation parameter can be used to remove the phase drift, which may improve equalizer results (MeasSetup > Demod Properties > Advanced tab > Track Phase check box).

Viewing Impulse Response or Frequency Response

You can view the impulse response or the frequency response of the equalized channel by clicking Trace >  Data > and selecting EQ Impulse Response or Ch Frequency Response.

See also

About Equalization

Equalization Filter demodulation property - (WLAN-DSSS/CCK/PBCC)


About Data Modulation Format  (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Format tab > Auto Detect

Or   MeasSetup > Demod Properties > Format tab > Manual Override

Data Modulation parameters allow you to specify how the VSA determines the input signal's PSDU data modulation format. The available modes are Auto-detect and Manual Override:

•	Auto Detect (default):    The analyzer automatically determines the data modulation format. For IEEE 802.11b and 802.11g DSSS modulated signals, the analyzer uses the SIGNAL and SERVICE field data within the PLCP Header to determine the data modulation format.

•	Manual Override:    Allows you to manually specify the PSDU data modulation format. The analyzer ignores the format transmitted in the WLAN-DSSS/CCK/PBCC burst and sets the analyzers demodulator to the modulation format specified in the Manual Override text box.

The following table lists the available WLAN-DSSS/CCK/PBCC data modulation formats and the corresponding payload characteristics:

Data Modulation Formats and Payload Characteristics

Data Modulation Formats	Spread  Sequence Code scheme	Data Rate (Mbps)	Symbol Rate (Msps)	Chip Rate (Mcps)	Bits per Symbol	Modulation
Barker1	11 Chip Barker	1	1	11	1	DBPSK
Barker2	11 Chip Barker	2	1	11	2	DQPSK
CCK 5.5	8 chip CCK	5.5	1.375	11	4	DQPSK
CCK 11	8 chip CCK	11	1.375	11	8	DQPSK
PBCC5.5	PBCC	5.5	11	na	0.5	QPSK
PBCC11	PBCC	11	11	na	1	QPSK
PBCC22	PBCC	22	11	na	2	8PSK
PBCC33	PBCC	33	16.5	na	2	8PSK
The next figure shows the SIGNAL and SERVICE field data structures within the IEEE STD 802.11b/g PPDU frame:

See Also

Format Tab - WLAN-DSSS/CCK/PBCC Demodulation Properties

About WLAN-DSSS/CCK/PBCC Demodulation


About Measurement Interval and Offset   (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only)

Menu Path:	MeasSetup > Demod Properties > Time tab > Measurement Interval text box

Or	MeasSetup > Demod Properties > Time tab > Measurement Offset text box

Defaults: Refer to WLAN-DSSS/CCK/PBCC Standard Presets Table

The Measurement Interval and Measurement Offset parameters allow you to define a specific interval of the Result Length for demodulation and analysis. This feature is applicable to WLAN-DSSS/CCK/PBCC Demodulation.

Measurement Interval    Lets you specify an interval (segment) of the Result Length data to be demodulated and analyzed. Measurement Interval is entered in chips, which is rounded to the nearest whole number of data symbols, as determined from the input signals data rate and modulation format.

Measurement Offset:    Lets you to set the Measurement Offset in Chips. Measurement Offset determines the start position of the Measurement Interval with respect to the first Chip of the PLCP Preamble.  Measurement Interval is entered in chips, which is rounded to the nearest whole number of data symbols, as determined from the input signals data rate and modulation format.

Note

The default measurement offset is set to 22 chips, which is 2 microseconds at the default chip rate.  This is because the 802.11b and 802.11g specifications allow for up to 2 microseconds of ramp-up at the start of the burst.  It is generally not desirable to include that ramp-up in the EVM calculations.

With this feature you can quickly analyze and view specific time intervals of data. This is because the analyzer does not acquire new measurement data when the measurement interval or offset is changed. When a new measurement interval or offset is entered the analyzer re-computes the trace data results using the existing measurement data.

Trace Data Results

The Measurement Interval and Measurement Offset affect nearly all measurement results, including the Preamble Syms and Header Syms trace data, and the region over which EVM is calculated.  The only trace data not affected by Measurement Interval and Measurement Offset are the Error Summary values for Sync Correlation, Frequency Error, Burst Type, Bit Rate, Octets, and Data Length.  The "802.11b 1000 chip Peak EVM" is computed from the first 1000 chips starting at the Measurement Offset.

The following illustration shows the interrelationship between the Search Length, Result Length, Measurement Interval and Measurement Offset.

Note

The Time trace display shows only time data for the chips specified by the Measurement Interval parameter, except when the Measurement Offset and Measurement Interval is equal to Max Result Length. In this case, the Time trace display includes the burst data +/- 10 % on either side of the burst. Refer to Time trace data for complete details.

•	Result Length: Total number of chips included in the acquired and demodulated data.

•	Max Result Length Sets the maximum number of chips that can be included in the result length. Auto Select limits the Max Result Length to the number of chips within the pulse (or burst).

See also

Time Tab - WLAN-DSSS/CCK/PBCC Demod Properties

WLAN-DSSS/CCK/PBCC Demodulation Properties


About Result Length  (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Time tab > Max Result Length text box

Defaults: Refer to WLAN-DSSS/CCK/PBCC Standard Presets Table

Range: 250,000 chips maximum

Result Length specifies the total number of chips included in the acquired and demodulated data.  There are two modes of selecting the Result Length analysis data, Auto Select and Manual Override:

Auto Select:	When Auto Select (Default) is selected, the analyzer automatically determines the measurement result length. The result length is determined by comparing the input signals chip length to the Max Result Length value and using the smaller number.

•	Max Result Length:  When Auto Select is selected, Max Result Length specifies the maximum number of chips that can be included in the measurement result length. The number of chips is rounded to the nearest whole number of data symbols, as determined from the input signals data rate and modulation format.

Manual Override:  When the Manual Override check box is selected, this specifies the measurement result length in chips. The number of chips is rounded to the nearest whole number of data symbols, as determined from the input signals data rate and modulation format.  The analyzer ignores the input burst chip length and uses the Manual Override chip length. The analyzer will use this value even if it is longer than the measured signals burst length

Note

Manual Override does not limit the result length to the number of chips transmitted within the burst as is done in Auto Select mode. The analyzer will demodulate the total number of chips specified by Manual Override, which if longer than the burst, could lead to unexpected and incorrect data results.

The result length includes the PLCP Preamble and Header.  For bursts that use the long format preamble, the first 1584 chips are preamble, and the next 528 chips are header, so the data segment of the burst starts at chip number 2112.  For bursts that use the short format preamble, the first 792 chips are preamble, and the next 264 chips are header, so the data segment of the burst starts at chip number 1056.  The PLCP header specifies the length of the data segment of the burst in microseconds. This value must be multiplied by 11 to get the length of the Data segment of the burst in chips.

The formula for determining the burst length when the Long PLCP preamble format:

Burst Length In Chips = 2112 + DataLenInMicroSec * 11

When the Short PLCP Preamble  format:

Burst Length In Chips = 1056 + DataLenInMicroSec * 11

To make sure that the entire burst is demodulated, the Result Length or Max Result Length parameter should be set to a value at least this large.

Trace Data Results

The Measurement Interval and Measurement Offset affect nearly all measurement results, including the Preamble Syms and Header Syms trace data, and the region over which EVM is calculated.  The only trace data not affected by Measurement Interval and Measurement Offset are the Error Summary values for Sync Correlation, Frequency Error, Burst Type, Bit Rate, Octets, and Data Length.  The "802.11b 1000 chip Peak EVM" is computed from the first 1000 chips starting at the Measurement Offset.

Note

The default measurement offset is set to 22 chips, which are 2 microseconds at the default chip rate.  This is because the 802.11b and 802.11g specifications allow for up to 2 microseconds of ramp-up at the start of the burst.  It is generally not desirable to include that ramp-up in the EVM calculations.

Auto Select Example

When Auto-Select is selected, the result length is determined by comparing the input signals chip length to the Max Result Length value and using the smaller number. The chip length is determined from the input signal PLCP Header data.

•	Figure 1  -  Max Result Length is less-than or equal to the burst length: The measurement result length will be set to the Max Result Length value.

•	Figure 2  -  Max Result Length is greater the burst length: The measurement result length will default to the number of chips detected within the burst.

Manual Override Example

Manual Override does not limit the result length to the number of chips transmitted within the burst as is done in Auto Select mode. The analyzer will demodulate the total number of chips specified by Manual Override, which if longer than the burst, could lead to unexpected and incorrect data results.

See also

About Measurement Interval and Offset(WLAN-DSSS/CCK/PBCC)

Search Length (WLAN-DSSS/CCK/PBCC)

Time Tab - WLAN-DSSS/CCK/PBCC Demodulation Properties


About Symbol Table  (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only.)

Menu Path: Trace >  Data > Syms/Errs

When WLAN-DSSS/CCK/PBCC demodulation is enabled, selecting the Syms/Errs trace data displays the symbol table. The symbol table shows the error summary data and the symbol data (binary bits) for each PSDU payload data symbol.

Symbol Data

The bottom half of the symbol table shows the symbol data bits for the demodulated signal as described in the following table for the specified demodulation format:

Modulation Format	Symbol Table Data
Barker, CCK	Shows the PSDU Payload symbol data bits.
PBCC	Shows the coded, covered symbol data bits (PSDU Payload data after descrambling)
For the demodulated PSDU payload data symbols, only the data bits for the specified measurement interval and offset will be displayed.

The first bit in the symbol table corresponds to the first bit of the first payload data symbol following the PLCP Preamble/Header data. For PPDU frames with long preamble it's symbol number 192 and for short preamble its symbol number 96

When the symbol table marker is enabled, the trace marker highlights the data symbol bits for the highlighted symbol and the marker readout provides the symbol number and its decimal value.

To make the table easier to read, the data bits are shown in groupings of eight characters followed by a space. The characters can represent a binary digit or a hexadecimal digit as specified by the Symbol Table parameter. The number to the left of each row indicate either the bit or symbol offset position depending the symbol table format as described below:

Binary Format: The symbol data bit format is binary and each character represents a binary digit. The number to the left of each row indicates the bit offset of the first bit in the row.

Hexadecimal Format: The symbol data bit format is hexadecimal and each character represents a hexadecimal digit. The number to the left of each row indicate the symbol offset of the first symbol in the row.

Note

There must be at least 4 bits/symbol to use the hexadecimal format, that is, symbols that have less than 4 bits/symbol will only be displayed in binary format regardless of the Symbol Table Format setting.

The following Tips will help you to use the Symbol Table:

•	You can chose to show the symbol data bits in either binary or hexadecimal format, see the Symbol Table topic.

•	The measurement interval and offset determines the number of symbols (in chips) shown in the table. However, the table only shows PSDU payload data symbols, never preamble or header symbols.

•	Here's an easy way to identify symbol bits and their corresponding symbol points in the constellation diagram: Display the constellation diagram in one grid and the symbol table in another. Then turn on the markers for both displays and enable marker coupling. When you place the marker on a point in the constellation diagram, the analyzer highlights the corresponding symbol bits in the symbol table.

•	Marker Movement: You can use the keyboard arrow keys or the mouse wheel to move the marker from one symbol to the next. You can use the Marker Position - X Position parameter to move the marker to a specific symbol location.

Error Summary Data

The top half of this display shows the modulation quality error data results and PLCP Header information for WLAN-DSSS/CCK/PBCC demodulation See Symbol Table Error Summary Data (WLAN-DSSS/CCK/PBCC) for information about WLAN-DSSS/CCK/PBCC Demodulation Error Summary data.

See also

Symbol Table Error Summary Data

Available Error Summary Data


About Error Summary Data  (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only.)

Menu Path: Trace >  Data > Syms/Errs

The top half of the symbol table shows the modulation quality error data results and PLCP Header information for WLAN-DSSS/CCK/PBCC modulation (refer to Available Symbol Table Error Summary Data).

Averaging and Error Summary Data

The following averaging types are available for the numeric error summary data:

•	RMS (video)

•	RMS Exponential

•	Continuous Peak Hold

Error data from the current scan is not included in the average if any of these conditions exist:

•	Sync Not Found

•	Carrier Unlock.

•	DATA?

Using Band Power markers to limit Error Information

If you want error information for all points over a selected region, you can use the band-power markers with an error trace.

For example, here's how you could compute the phase error for all points within a region. Click Trace >  Data > IQ Phase Error to display the IQ phase-error trace, then click Markers, Calculation and select the Band Power check box to turn on the band-power markers.

Now position the band-power markers to select the region of interest, and select RMS Sqrt (Pwr) to display the phase error for the selected region.

Hint

At this point, you could simply click Trace >  Data > IQ Mag Error to display the magnitude error for the same region.

How EVM and Magnitude Error Data is calculated (%RMS)

In the symbol table, the analyzer displays the error-vector magnitude, magnitude error, and phase error, as a percentage. Before computing this percentage, the analyzer normalizes the constellation diagram such that the outer-most, ideal states have a magnitude of one.

The analyzer computes the overall, percent error by first computing the error-vector magnitude, magnitude error, and phase error at each chip time.

Next, the analyzer derives the rms average for each parameter. For example, to compute the rms average for the magnitude error, the analyzer takes the square root of the sum of the squares of the individual magnitude-error values at each symbol time.

Because the magnitude of the constellation diagram's outer-most state has been normalized to one, the rms average is the overall, percent error.

See Also

Available Error Summary Data

Symbol Table Overview


Available Error Summary Data  (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only.)

The following table lists the available WLAN-DSSS/CCK/PBCC modulation error data results and PLCP Header information.

Tip

Refer to the About the Symbol Table topic for an overview of the symbol table. Refer to the Symbol Table Error Summary Data for an overview of the symbol-table error summary data.

            Available Error Data

Bit Rate	Mag Err (%rms)
Burst Type	Octets
Data Len	Phase Err
EVM (%rms)	Quad Err
Freq Err	Status
Gain Imb	Sync Corr
IQ Offset

For information about using error summary data with ADS, see Demod Errors and ADS.

See Also

Error Summary Data  (WLAN-DSSS/CCK/PBCC)


Bit Rate (WLAN-DSSS/CCK/PBCC)

Bit Rate is the modulation data rate as detected in the PLCP Header.

For more information about standard WLAN-DSSS/CCK/PBCC bit data rates refer to the "About Data Modulation Formats" topic.

See Also

Available Error Summary Data


Burst Type  (WLAN-DSSS/CCK/PBCC)

Burst Type is the detected spread sequence code scheme/PLCP PPDU format type.

Example

A WLAN-DSSS/CCK/PBCC Burst Type of "CCK11/short" uses the 8 chip, CCK spread sequence code scheme at 11 Mcps chip rate with a Short PLCP PPDU format.

For a list of 802.11b Burst types refer to the "About Data Modulation Formats" topic.

Note

A burst type with "/short" appended to the coding scheme indicates a Short PLCP PPDU format, otherwise the burst has a Long PLCP PPDU format.

See Also

List of available Burst Types

Available Error Summary Data


Data Len  (WLAN-DSSS/CCK/PBCC)

This is the time length of the PSDU (payload data) in seconds as detected in the PLCP Header.

See Also

Available Error Summary Data


802.11b 1000 chip Peak EVM  (WLAN-DSSS/CCK/PBCC)

This is the normalized Error Vector Magnitude as defined in section 18.4.7.8 "Transmit modulation accuracy", of the IEEE Std 802.11b - 1999 Wireless LAN specification.

The "802.11b 1000-chip Peak EVM" is computed per section 18.4.7.8 with the following comments or exceptions:

•	The resultant 802.11b 1000 chip Peak EVM is the normalized Peak EVM value.

•	For 802.11g PBCC formats using 8PSK modulation, the specified formulas are adjusted so the 802.11b 1000 chip Peak EVM results are meaningful.

•	The 1000 chip sample requirement are taken from the first 1000 chips in the measurement interval, if the measurement interval (or the burst length) is less than 1000 chips the "802.11b 1000-chip Peak EVM" is not computed and a value of zero is returned.

•	The computed 802.11b 1000 chip Peak EVM includes the extra factor of 1/sqrt(2), which is not part of the EVM (%rms) calculation.

Note

The IEEE Std 802.11b - 1999 specification requires that the worst-case normalized Error Vector Magnitude is less than or equal to 35 %

Note

We also provide the percent rms EVM for the specified measurement interval (refer to the EVM (WLAN-DSSS/CCK/PBCC) topic).

See Also

EVM (%rms)

Available Error Summary Data


EVM  (WLAN-DSSS/CCK/PBCC)

EVM (error vector magnitude) is the magnitude of the error vector at the measured chip location. The error vector is the vector difference between the I/Q measured-signal phasor and the I/Q reference-signal phasor:

•	EVM (%rms) is the Root Mean Square of the error vectors, within the measurement interval, computed and expressed as a percentage of the square root of the mean power of an ideal signal.

•	EVM Pk at chip is the EVM and number of the chip with the worst-case peak EVM expressed as a percentage of the square root of the mean power of the ideal signal.

Note

We also provide the normalized Error Vector Magnitude as defined in section 18.4.7.8 "Transmit modulation accuracy", of the IEEE Std 802.11b - 1999 Wireless LAN specification (refer to the 802.11b Peak EVM topic).

See Also

802.11b Peak EVM

Available Error Summary Data


Freq Err  (WLAN-DSSS/CCK/PBCC)

This error data shows the carrier frequency-error relative to the analyzer's center frequency. This error data is displayed in Hertz and is the amount of frequency shift, from the analyzer's center frequency, that the analyzer must perform to achieve carrier lock.

Errors in RF frequency, LO frequency, or digitizer clock rate could all appear as carrier frequency error.

See Also

Available Error Summary Data


Gain Imb  (WLAN-DSSS/CCK/PBCC)

Gain Imbalance compares the gain of the I signal with the gain of the Q signal, as follows:

The effects of IQ gain imbalance are best viewed in constellation diagrams, where the width of the constellation diagram is different than its height.

Because gain imbalance is expressed as a logarithmic value, it may be a positive or negative value.

See also

IQ Gain Imbalance and Quadrature Skew Parameter Interaction

Quadrature Skew

See Also

Available Error Summary Data


IQ Offset  (WLAN-DSSS/CCK/PBCC)

IQ Offset (also called I/Q origin offset) indicates the magnitude of the carrier feedthrough signal. When there is no carrier feedthrough, IQ offset is zero (-infinity dB).

IQ origin offset is easily seen in the constellation diagram, as shown below:

In the above illustration, "x" is the center of the constellation diagram. When "x" occurs at the origin, the IQ offset is zero. When "x" is not at the origin, the IQ offset is the magnitude of the vector (in dB) between "x" and the origin.

The carrier feedthrough shown in the symbol table is computed only at the chip times (the instant in time when chips are detected).

See Also

Available Error Summary Data


Mag Err  (WLAN-DSSS/CCK/PBCC)

Mag Err (magnitude error) is the vector magnitude difference between the I/Q measured signal and the I/Q reference signal at the measured chip time expressed as a percentage of the square root of the mean power of the ideal signal.

The Mag Err data result also provide the chip time with the worst-case peak magnitude error value expressed as a percentage of the square root of the mean power of the ideal signal.

See Also

Available Error Summary Data


Octets  (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only.)

Menu Path: Trace >  Data > Syms/Errs

This is the number of decoded Octets in the PSDU computed from the PLCP header data.

See Also

Available Error Summary Data


Phase Err  (WLAN-DSSS/CCK/PBCC)

Phase Err (phase error) is the phase difference between the I/Q reference signal and the I/Q measured signal measured at the chip time.

Mag Err data result also provide the chip time with the worst-case peak phase error value.

See Also

Available Error Summary Data


Quad Err  (WLAN-DSSS/CCK/PBCC)

Quad Err (Quadrature Skew Error) indicates the orthogonal error between the I and Q signals. Ideally, I and Q should be orthogonal (90 degrees apart). A quadrature skew error of 3 degrees means I and Q are 87 degrees (or 93 degrees) apart.

See also

IQ Gain Imbalance and Quadrature Skew Parameter Interaction

Gain Imbalance (WLAN-DSSS/CCK/PBCC)

Available Error Summary Data


Status (WLAN-DSSS/CCK/PBCC)

The status line provides summary messages indicating the status of demodulation of the PPDU including the PLCP Preamble status, the PLCP Header status and the PSDU MAC status.  The Status message string format is as follows:

Status  = [the PLCP Preamble status, the PLCP Header status, the PSDU data status]

PLCP Preamble status messages

The PLCP Preamble status indicates whether the SFD (Preamble Start Frame Delimiter) was found.

No SFD found  -  The SFD (Preamble Start Frame Delimiter) was NOT found

SFD OK  -  The SFD (Preamble Start Frame Delimiter) was found

PLCP Header status messages

The PLCP Header status string indicates the status of the PLCP Header:

Invalid header bits  -  Some of the data bits in the PLCP Header were incorrect, but the analyzer was still able to determine the data length and data modulation format.

Header CRC failed -  The header looked correct except for the CRC, which did not match the rest of the header data.

Invalid header phase shift - An extra (incorrect) 90 degree phase shift was detected at the start of the header.

Header OK - means that the header appears correct and the header CRC passed.

<empty string> - means that the result length was not long enough to capture the entire header, so we don't know the status.

PSDU MAC status messages

The PSDU MAC status indicates the status of the PSDU MAC frame.  .

blank  -  If the result length and measurement interval do not contain the entire burst, then this part of the string is left blank

MACFCS failed  -  The PSDU MAC frame check sum fails.

MACFCS OK  -  The PSDU MAC frame check sum passes.

See Also

Available Error Summary Data


Sync Corr  (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only.)

Menu Path: Trace >  Data > Syms/Errs

Sync Corr is a cross correlation of the preamble  of the measured signal to an ideal Barker sequence. It is a figure of merit indicating the quality of the PLCP preamble synchronization (SYNC) data fields. A value of 1 indicates perfect correlation and a value of 0 no correlation.

The CCDF is computed from the segment of the OFDM burst specified by the Measurement Interval and Measurement Offset.

See Also

Available Error Summary Data


Available Trace data  (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only.)

Menu Path: Trace, Data

Measurement trace data available with WLAN-DSSS/CCK/PBCC Demodulation.

                                    WLAN-DSSS/CCK/PBCC
                          Measurement Trace Data

CCDF	IQ Meas Spec
CDF	IQ Meas Time
PDF	IQ Ref Spec
Ch Frequency Response	IQ Ref Time
Correction	IQ Mag Error
Eq Impulse Response	IQ Phase Error
Error Vector Spectrum	Raw Main Time
Error Vector Time	Search Time
Inst Error Vector Spec	Spectrum
Inst IQ Meas Spec	Syms/Errs
Inst IQ Ref Spec	Header Syms
Inst Spec	Preamble Syms
Time
See also

WLAN-DSSS/CCK/PBCC Available Features

89600-Series VSA Standard Measurement Data

About Opt B7R: WLAN-DSSS/CCK/PBCC Demodulation


CCDF  (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only)

Menu Path: Trace >  Data > Ch1 CCDF

CCDF trace data displays the complementary, cumulative density function (CCDF) for the selected input channel.

The analyzer plots CCDF using units of percent (%) for the y-axis and power (dB) for the x-axis. Power on the x-axis is relative to the signal average power, so 0 dB is the average power of the signal. Therefore, a marker readout of

Trace A Marker 2 dB 12 %

means there is a 12% probability that the signal power will be 2 dB or more above the average power.

For more information, go to the VSA application CCDF trace data topic.

See Also

Available Trace Data


CDF  (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only)

Menu Path: Trace >  Data > Ch1 CDF

CDF trace data displays the cumulative density function (CDF) for the selected input channel. CDF is computed by integrating the PDF (Probability Density Function).

The CDF is computed from the segment of the OFDM burst specified by the Measurement Interval and Measurement Offset.

For more information see the CCDF (WLAN-DSSS/CCK/PBCC) and CDF trace data topics.

See Also

Available Trace Data


PDF  (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only)

Menu Path: Trace >  Data > Ch1 CDF

PDF trace data displays the Probability Density Function for the selected input channel.  PDF indicates the probability that a given level has occurred.

The PDF is computed from the segment of the OFDM burst specified by the Measurement Interval and Measurement Offset.

Overview

PDF is equivalent to a normalized histogram. A histogram shows how the amplitude of a signal is distributed between its maximum and minimum values. Amplitude is displayed on the X-axis, and number of counts on the Y-axis.

The number of averages for a histogram determines the number of counts in the histogram; in other words, how many records are measured—the records are not "averaged". If averaging is off or if exponential averaging is selected, the measurement continues indefinitely. Keep in mind that the accuracy of the histogram is dependent on the frequency span, time-record length, and number of averages (if averaging is on).

Histograms are used for such things as determining the statistical properties of noise and monitoring the performance of electromechanical positioning systems.

PDF trace data is normalized by multiplying the number of averages by the number of points in the time record, then dividing this value by the ΔV spacing on the X-axis. The probability of a signal falling between two points is equal to the integral of the curve between those points.

PDF trace data displays the number of points used in its computation above the trace (Pts:). It also displays the average level (Avg:) above the trace.

See Also

Available Trace Data


Ch Frequency Response (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only.)

Menu Path: Trace >  Data > Ch Frequency Response

When WLAN-DSSS/CCK/PBCC Demodulation is enabled and the equalizer is ON, the Ch Frequency Response trace shows the frequency response of the channel for which the equalizer is correcting. Ch Frequency Response is computed as the inverse of the equalization filter's frequency response. The data is complex and is normally displayed in units of magnitude, phase, or group delay.

Frequency Span

The Ch Frequency Response is shown with a bandwidth equal to the Chip Rate, because it is computed from one-point-per-chip data.  Because of aliasing, it may not accurately reflect the true channel frequency response.

For further details, refer to Using the Equalization Filter topic.

See Also

Eq Impulse Response trace data (WLAN-DSSS/CCK/PBCC)

About Equalization (WLAN-DSSS/CCK/PBCC)

Available Trace Data


Correction  (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only.)

Menu Path: Trace >  Data > Correction

Shows the correction curve used to correct for the frequency response of the analyzer's input hardware and input digital filtering. The correction trace is applied to the acquired data to compensate for phase and magnitude anomalies in the analyzer's hardware and software signal processing.

See also

About Calibration

Available Trace Data


Eq Impulse Response (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only.)

Menu Path: Trace >  Data > Eq Impulse Response

When WLAN-DSSS/CCK/PBCC Demodulation is enabled and the equalizer is ON, the Eq Impulse Response trace shows the impulse response computed from the 802.11b or 802.11g preamble.

For further details, refer to Using the Equalization Filter topic.

See Also

Ch Frequency Response trace data (WLAN-DSSS/CCK/PBCC)

About Equalization (WLAN-DSSS/CCK/PBCC)

Available Trace Data (WLAN-DSSS/CCK/PBCC)


Error Vector Time  (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only.)

Menu Path: Trace >  Data > Error Vector Time

When WLAN-DSSS/CCK/PBCC Demodulation is enabled, the Error Vector Time trace data is the error-vector, time-domain trace data over the specified measurement interval. It is the computed error vector for each corresponding chip time in the IQ measured and IQ reference signals: You can view the data results as Error Vector Magnitude, Error Vector Phase, only the I component or only the Q component (see Trace Data Formats below).

If normalization is OFF, the analyzer displays the instantaneous magnitude for each point. If normalization is ON, the analyzer displays the error vector as a percentage ( IQ normalize explains how this percentage is derived).

Trace Data Formats

It is important to remember that the Error Vector time trace is a time record made up of complex, time-domain data. Each point in the time record has two components: I and Q. The following data can be viewed by selecting appropriate trace format (Trace > Format > Format: drop--down list):

Linear Mag :  Displays the EVM (Error Vector Magnitude).

Real(I) :  Displays the I component of the error vector.

Imag(Q) :  Displays the Q component of the error vector.

Wrap Phase:  Displays the Error Vector Phase error.

Hint

If the Error Vector Time is different than expected, see the troubleshooting Tips in Troubleshooting, Digital Demodulation.

See also

Available Trace Data (WLAN-DSSS/CCK/PBCC)


Error Vector Spectrum (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only.)

Menu Path: Trace >  Data > Error Vector Spec

When WLAN-DSSS/CCK/PBCC Demodulation is enabled, the Error Vector Spec trace shows the spectrum of the Error Vector Time trace. In other words, the analyzer derives the Error Vector Time trace, and then windows and FFTs this trace to produce the Error Vector Spectrum trace.

The analyzer's demodulator removes carrier-frequency error. Therefore, in the error vector spectrum display, you must add the carrier-frequency error to marker readouts to obtain exact frequency information. The carrier-frequency error (Freq Err) is shown in the symbol table.

Note

The center frequency and span for error vector spectrum is identical to IQ measured spectrum. For details, see IQ Measured Time.

See also

Available Trace Data (WLAN-DSSS/CCK/PBCC)


Header Syms  (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only.)

Menu Path: Trace >  Data > Header Syms

When WLAN-DSSS/CCK/PBCC Demodulation is enabled, the DSSS Header Syms trace data shows the 802.11b PLCP Header data bits.

Note

You can use the Descramble Mode demodulation property to view either the descrambled or the raw Header data bits.

See also

Preamble Syms trace data (WLAN-DSSS/CCK/PBCC/CCK/PBCC)

Available Trace Data (WLAN-DSSS/CCK/PBCC)


Inst Error Vector Spectrum  (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only.)

Menu Path: Trace >  Data > Inst Err Vect Spec

When Digital Demodulation is enabled, the Inst Err Vector Spec trace shows the instantaneous spectrum of the Error Vector Time trace. This is the non-averaged Error Vector Spec trace data.

The analyzer's digital demodulator removes carrier-frequency error. Therefore, in the error vector spectrum display, you must add the carrier-frequency error to marker readouts to obtain exact frequency information. The carrier-frequency error (Freq Err) is shown in the symbol table.

Note

The center frequency and span for error vector spectrum is identical to IQ measured spectrum. For details, see IQ Measured Time.

See also

Available Trace Data (WLAN-DSSS/CCK/PBCC)


Inst IQ Meas Spec and IQ Ref Spec  (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only.)

Menu Path:	Trace >  Data > Inst IQ Meas Spec

or Trace >  Data > Inst IQ Ref Spec

When WLAN-DSSS/CCK/PBCC Demodulation is enabled, the Inst IQ Meas Spec and Inst IQ Ref Spec traces are the instantaneous spectrum of the IQ Meas Time or IQ Ref Time signals. It is the non-averaged IQ Meas Spec and IQ Ref Spec trace data.

Note

The analyzer's digital demodulator removes carrier-frequency error. Therefore, in the error vector spectrum display, you must add the carrier-frequency error to marker readouts to obtain input signals frequency information. The carrier-frequency error (Freq Err) is shown in the symbol table.

See also

Available Trace Data (WLAN-DSSS/CCK/PBCC)


Inst Spectrum  (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only.)

Menu Path: Trace >  Data > Inst Spectrum

When WLAN-DSSS/CCK/PBCC Demodulation is enabled, the Instantaneous Spectrum trace is the frequency spectrum display of the pre-demodulated time data. The time data is WINDOWed and FFTed to create the Instantaneous Spectrum display.

If averaging is on, the Instantaneous Spectrum does not show the effects of averaging. To see the effects of averaging, use the Spectrum trace data.

The following block diagram is part of the Digital Demodulation Block Diagram and shows the Instantaneous Spectrum signal flow.

Note

The Inst Spectrum trace is derived from pre-demodulated time data, which is 20% longer than the result length.

See also

Spectrum Trace Data (WLAN-DSSS/CCK/PBCC)

Available Trace Data (WLAN-DSSS/CCK/PBCC)


IQ Mag Error and IQ Phase Error (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only.)

Menu Path: Trace >  Data > IQ Mag Error or IQ Phase Error

When WLAN-DSSS/CCK/PBCC Demodulation is enabled, the IQ Mag Error and IQ Phase Error traces show the error between the I/Q measured and the I/Q reference signals at each demodulated chip time. IQ Mag Error is the magnitude error and IQ Phase Error is the phase error.

IQ Mag Error:

The analyzer compares the magnitude, for each chip time, of the I/Q measured signal with the magnitude of the I/Q reference signal. The analyzer then displays the difference, in magnitude, between the two signals.

If normalization is OFF, the analyzer displays the instantaneous magnitude error. If normalization is ON, the analyzer displays the magnitude error as a percentage ( IQ Normalize on/off explains how this percentage is derived).

IQ Phase Error:

The analyzer compares the unwrapped phase, for each chip time, of the I/Q measured signal with the unwrapped phase of the I/Q reference signal. The analyzer then displays the phase difference between the two signals.

Phase Drift Compensation

Circular arcs in the constellation of the IQ Meas Time trace display is an indicator of phase drift.  The Track Phase demodulation parameter can be used to remove the phase drift, which will improve the IQ constellation trace and reduce the EVM data results  (MeasSetup > Demod Properties > Advanced tab > Track Phase check box).

See also

Available Trace Data (WLAN-DSSS/CCK/PBCC)


IQ Meas Spec and IQ Ref Spec  (WLAN-DSSS/CCK/PBCC)

Vector Signal Analyzer application only.)

Menu Path: Trace >  Data > IQ Meas Spec or IQ Ref Spec

When WLAN-DSSS/CCK/PBCC Demodulation is enabled, IQ Meas Spec and IQ Ref Spec is the frequency spectrum of the IQ Meas Time and IQ Ref Time trace data respectively. The analyzer produces the spectrum by windowing and FFTing the I/Q measured or I/Q reference data.

Note

The analyzer's demodulator removes carrier-frequency error. Therefore, in IQ Meas Spec and IQ Ref Spec displays, you must add the carrier-frequency error to marker readouts to obtain the input signals frequency information. The carrier-frequency error (Freq Err) is shown in the symbol table.

Tip

By default, the analyzer displays the data in log(dB) magnitude format. You can change the format in the Trace Properties dialog box [click Trace, Format, Format select box]

The span for the displayed spectrum is a function of the chip rate:

where: Span-Demod is the span displayed when you select IQ measured spectrum or IQ reference spectrum.

It is possible to set the chip rate such that Span-Demod exceeds the information bandwidth of the analyzer. The information bandwidth of the analyzer is set with the span frequency property

The following illustration shows the case where Span-Demod exceeds span.

The illustration shows an "x" in the region where Span-Demod exceeds span. Because the analyzer essentially filters out all information outside of span, the analyzer will not show information that may exist in this region.

Aliasing

It is important to know that the analyzer uses one sample rate to acquire data, and another sample rate (Sample-Rate-Demod) to display the demodulated data:

      Sample Rate = 1.28 x [span]
Sample_rate_demod = chip rate

As shown, the frequency span property determines the sample rate used to acquire data, whereas the chip rate determines the sample rate used to display demodulated data.

See also

Available Trace Data (WLAN-DSSS/CCK/PBCC)


IQ Meas and IQ Ref Time  (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only.)

Menu Path: Trace >  Data > IQ Meas Time or IQ Ref Time

When WLAN-DSSS/CCK/PBCC Demodulation is enabled, the IQ Meas Time and IQ Ref Time traces are the demodulated time data results sampled at the chip times. The analyzer's demodulator produces two signals: I/Q Measured and I/Q Reference. This topic provides the following information:

•	I-Q Meas Time trace data description

•	I-Q Ref Time trace data description

•	Compensation information

•	Time-Domain Trace Data Display information

I-Q Meas Time

The measured time data sampled at exactly the chip times with IQ origin offset, system gain normalization and carrier locking applied to the input signal.

I-Q Ref Time

This is reference time data generated by the analyzer from data acquired from the measured signal. This is an ideal representation of the measured input signal (IQ Meas Time). The resultant IQ reference signal is used for computing data analysis results and can be viewed simultaneously with the IQ measured signal for data comparisons.

Tip

Online help for Digital Demodulation includes a block diagram that shows how I/Q measured and I/Q reference data are generated.

Compensation

I/Q origin offset and burst amplitude-droop

Demodulation is performed with carrier lock and chip lock. In addition, the analyzer compensates for I/Q origin offset and burst amplitude-droop.

Phase Drift

Circular arcs in the constellation of the IQ Meas Time trace display is an indicator of phase drift.  The Track Phase demodulation parameter can be used to remove the phase drift, which will improve the IQ constellation trace and reduce the EVM data results  (MeasSetup > Demod Properties > Advanced tab > Track Phase check box).

  which may improve equalizer results.

Time-Domain Displays

The analyzer's digital demodulator produces time-domain data. If you select IQ measured Time, the analyzer displays the I/Q measured signal in the time domain. Likewise, if you select IQ reference Time, the analyzer displays the I/Q reference signal in the time domain. The data can be displayed in many formats including IQ Polar diagrams, Constellation diagrams, Eye diagrams and more (refer to the Selecting a Trace Format topic)

If normalization is OFF, the analyzer displays the instantaneous magnitude. If normalization is ON, the analyzer scales the IQ measured and IQ reference traces to map them onto the unit circle, which yields a unitless y-axis.

Hint

For further details about normalization, see IQ Normalize.

Parameter Interaction

The following parameters affect how the analyzer displays the I/Q measured and I/Q reference signals:

•	The Result Length parameters (Auto Select, Max Result Length and Manual Override) determine the measurement acquisition time, which in turn, determines the length of the displayed trace data.

•	The Measurement Offset/Interval parameters limit the displayed trace data.

See also

Available Trace Data (WLAN-DSSS/CCK/PBCC)


Preamble Syms (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only.)

Menu Path: Trace >  Data > Preamble Syms

When WLAN-DSSS/CCK/PBCC Demodulation is enabled, the DSSS Preamble Syms trace data shows the 802.11b PLCP Preamble data bits.

Note

You can use the Descramble Mode property to view either the descrambled or the raw Preamble data bits.

See also

Header Syms trace data (WLAN-DSSS/CCK/PBCC/CCK/PBCC)

Available Trace Data (WLAN-DSSS/CCK/PBCC)


Raw Main Time  (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only.)

Menu Path: Trace >  Data > Ch1, Raw Main Time

Raw Main Time is the raw data read from the input hardware or playback file. For more information about this data, refer to the Raw Main Time (Digital Demod) trace data topic.

VSA signal flow (see Digital Demodulation Block Diagram):

See Also

Time trace data (WLAN-DSSS/CCK/PBCC)

Available Trace Data (WLAN-DSSS/CCK/PBCC)


Search Time  (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only.)

Menu Path: Trace >  Data > Search Time

When WLAN-DSSS/CCK/PBCC Demodulation is enabled, the Search Time trace shows time-data before pulse search and demodulation. This is the acquired time data used to search for the pulse (or burst). The value of Search Length determines the length of the Search Time trace.

VSA signal flow (see Digital Demodulation Block Diagram):

See also

Available Trace Data (WLAN-DSSS/CCK/PBCC)


Spectrum  (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only.)

Menu Path: Trace >  Data > Inst Spectrum

When WLAN-DSSS/CCK/PBCC Demodulation is enabled, the Spectrum trace is the averaged, Inst Spectrum trace data, as shown in the following block diagram (the block diagram is part of the Digital Demodulation Block Diagram). If averaging is OFF, the Spectrum and Instantaneous Spectrum displays are identical.

The Spectrum trace has the following characteristics:

•	It is derived from pre-demodulated time data, which is 20% larger than the result length.

•	It is averaged if averaging is ON and the average type is RMS(Video), RMS(Video) Exponential or Continuous Peak Hold averaging.

Note

If averaging is ON, a scan is not included in the average if any of these conditions exist: Pulse Not Found, Sync Not Found, Carrier Unlock, or certain DATA? conditions.

See also

Inst Spectrum

Available Trace Data (WLAN-DSSS/CCK/PBCC)


Syms/Errs   (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only.)

Menu Path: Trace >  Data > Syms/Errs

When 	WLAN-DSSS/CCK/PBCC Demodulation is enabled, selecting the Syms/Errs trace data displays the symbol table. The symbol table shows you error information and the binary bits for each symbol.

Go to the About the Symbol Table for more information.

See also

Symbol Table Error Summary Data

Alphabetical Listing: Symbol Table Error Summary Data

Available Trace Data (WLAN-DSSS/CCK/PBCC)


Time  (WLAN-DSSS/CCK/PBCC)

(Vector Signal Analyzer application only.)

Menu Path: Trace >  Data > Time

When WLAN-DSSS/CCK/PBCC Demodulation is enabled, the Time trace shows the time record before digital demodulation and after pulse search, as shown in the following block diagram (refer to the Digital Demodulation Block Diagram).

The amount of data included in the Time trace display is a function of the Result Length, Measurement Interval and Measurement Offset parameters. The following topics describe how these parameters affect the Time trace data:

Time Reference

The time reference for the time data is the idealized start of the PLCP preamble.  If the preamble uses the long format, this means that the PLCP Header will start at time = 144us, and the PSDU data will start at time = 192us.  If the preamble uses the short format, this means that the PLCP Header will start at time=72us, and the PSDU data will start at time = 96us.

Note

It may be useful to zoom in on the ramp-up at the start of the burst, by setting the X-axis to display from time = -10us to time = +10us.  This results in grid lines spaced 2us apart.  The ramp-up should take less than 2us and should be near the middle of this display.

Time Trace Data and the Result Length parameters

•	Auto Select mode: The Time Trace data shows the data specified by the Max Result Length parameter:

−	If Max Result Length is greater than the burst length, the Time trace data shows the entire burst +/- 10% of the burst length.

−	If Max Result Length is less than the burst length, the Time trace data shows the number of Chips specified by the Max Result Length parameter plus 10% of the Max Result Length just before the start of the burst. This also includes preamble data.

•	Manual Override mode: The Time Trace data shows data for the number of symbol-times specified by the Manual Override parameter plus 10% of the Manual Override Length just before the start of the burst.

For more information about how the Manual Override parameter determines the measurement result length data, see About Result Length Parameters .

Time Trace Data and the Measurement Interval/Offset parameters

•	Measurement Interval not equal to Max Result Length

When you use the Measurement Interval and Offset parameters to specify the acquired measurement data, the Time Trace Data includes only the data specified by the Measurement Interval parameter. The display shows only data for the symbol-times specified within the Measurement Interval, all other data before and after the Measurement Interval will be excluded.

•	Measurement Interval equal to Max Result Length

When the Measurement Interval is equal to Max Result Length, the Time trace data is controlled and specified by the Max Result Length parameter, see Auto Select mode, Max Result Length described previously for more information.

For more information about how Measurement Interval and Measurement Offset determine the measurement result length data, refer to Measurement Interval/Offset.

See also

Available Trace Data (WLAN-DSSS/CCK/PBCC)


About Option B7N: 1xEVDO Demodulation
About Option B7N: 1xEV-DO Demodulation

Option B7N: 1xEV-DO adds 1xEV-DO (1x-Evolution Data Only) demodulation capability to your 89600-Series application software. This option lets you measure and analyze 1xEV-DO modulated signals that are defined in these Telecommunications Industry Association (TIA) and Electronics Industry Alliance (EIA) standard specifications:

3GPP2 C.S0024 v 2.01	1xEV-DO High Rate Packet Data Air Interface Specification
3GPP2 C.S0032 v1.0	1xEV-DO Inter-Operability Specification (IOS) for CDMA 2000 Access Network
3GPP2 C.S0033 v1.0	1xEV-DO Inter-Operability Specification (IOS) for CDMA 2000 Access Network
3GPP2 C.P9012	Recommended Minimum Performance Standards for 1xEV-DO High Rate Packet Data Access Terminal
TIA/EIA/IS-856	1xEV-DO High Rate Packet Data Air Interface Specification
With option B7N: 1xEV-DO you can descramble, despread and demodulate 1xEV-DO modulated signals. This option supports configurations in the reverse link (Mobile Station or Access Terminal) and forward link (Base Station or Access Network) channels. The analyzer will automatically identify all active channels regardless of the Symbol Rate or Walsh Code Length.

Signal analysis capabilities including composite code domain power, composite time and channel specific analysis. Measurement results may be shown in several trace display formats as well as numeric error data formats. Flexible display scaling and marker functionality enhance these measurement capabilities.

The demodulator used in this analyzer incorporates advanced technology that does not require coherent carrier signals, or symbol-clock timing signals. The analyzer has a built-in IS-2000 filter. Signal locking requires the carrier frequency, chip rate, reverse/forward link direction and Long Code Mask to be set.

The demodulator uses the measured signal (called I/Q Meas Time) to generate an ideal signal (called IQ Ref Time). The analyzer uses these signals to provide signal comparison trace data, modulation quality data results and error summary data (see About Trace Data).

Measurement result data include: Time and Frequency domain trace data, Code Domain Power (composite or layer specific) trace data, Channel trace data results and Overall Error Summary data results.

If you have a Vector Signal Analyzer, an optional second baseband channel allows IQ baseband measurement capability. You can also perform IQ baseband measurements on data that is from a file or the stream interface, i.e. ADS simulation.

See also

1xEV-DO Modulation Overview

1xEV-DO Available Features

Setting up a 1xEV-DO Measurement

About 89600 Optional Measurement Software


1xEV-DO Modulation Overview

(Vector Signal Analyzer application only)

1xEV-DO is the name applied to the first evolution (1xEV) of a 3GPP communications system optimized for Data Only (DO) information. 1xEV-DO is a 3G Cellular industry standard based upon the original cdma2000 3G standard.  1xEV-DO incorporates Data Only services into the 3G system, by sacrificing voice-service parameters, to increase packet data throughput.  1xEV-DO is defined in the following standards documents:

•	3GPP2 C.S0024 v2.01 1xEV-DO High Rate Packet Data Air Interface

•	3GPP2 C.S0032 1xEV-DO Inter-Operability Specification (IOS) for CDMA 2000 Access Network

•	3GPP2 C.P9012 Recommended Minimum Performance Standards for 1xEV-DO High Rate Packet Data Access Terminal

•	TIA/EIA/IS-856 1xEV-DO High Rate Packet Data Air Interface Specification

Although similar to the cdma2000 specification, 1xEV-DO incorporates the following differences. In the reverse link (mobile unit) transmission, 1xEV-DO is very similar to cdma2000, with power control bits replaced by Reverse Rate Indication (RRI) information.  1xEV-DO reverse link also adds a rate request channel (DRC) and an acknowledge channel (ACK).  In the forward link, 1xEV-DO provides a TDM structure including Preamble, Pilot, MAC, and Traffic channels.  The 1xEV-DO forward link Traffic channel consists of 16 code channels, which may be mapped to different complex constellations including QPSK, 8PSK, and 16QAM.  The 1xEV-DO forward link is always sent by the BTS at full power.  1xEV-DO also differs from cdma2000 in that a full frame is equal to 16 slots (26.667ms), with each slot occupying 1.667ms.

RF Characteristics

1xEV-DO uses what is known as High Rate Packet Data, using the same final spread rate of 1.2288 Mcps as does cdma2000 SR1. It also uses the same digital filter to reduce the final modulation bandwidth, with the result that 1xEV-DO is spectrally compatible with cdma2000 SR1. Both 1xEV-DO and cdma2000 SR1 can use the same amplifiers, combiners, and antennas to reduce the installation cost of 1xEV-DO.

Although 1xEV-DO is compatible with much of the existing cdma2000 infrastructure, the two systems may not simultaneously occupy the same channel. Each 1xEV-DO channel requires a paired 1.25 MHz clear channel, therefore it cannot be overlaid with cdma2000 channels.

Forward Link

A 1xEV-DO base station (BTS) is referred to as the "access network". 1xEV-DO relies on the Global Positioning System (GPS) for intercell synchronization, in the same manner as cdma2000. The 1xEV-DO system is well suited for data transmission in the forward link, as it is optimized for high-speed packet data communications from base stations to mobile stations. Average delivery rates of about 600 kbs on a continuous basis have been demonstrated. When compared to the recent IS-95-B design in cdma2000, 1xEV-DO shows about a 6X improvement in the overall network data rate

The largest contribution to overall increased data throughput is the ability of 1xEV-DO to negotiate for increased data rates for individual users or mobiles, as only one user is served at a time. This and other contributing factors are described in detail in the Design Elements section below.

Frame Structure

The frame structure is different from that used for cdma2000 and IS-95 systems, as they are based on 20 ms frames set by the codec used for speech. The frame period for 1xEV-DO is 26.667 ms, which is also the period of one pilot channel. Each frame is divided up into 16 slots of 1.667 ms.

Design Elements

When compared to a voice communication system of cdma2000, the following design elements of the forward link contribute to raise the data rate:

•	Full power - The cell is always at full power, resulting in no overhead needed for statistical variations of multiple users.

•	Best serving cell - When in soft handoff, the mobile selects the best serving cell and can only request and receive data from that cell.

•	Efficient data delivery - The base station can send data to a mobile at times when its rate request is higher than the running average of the base station, and will avoid sending data when the requested rate is lower than the running average.

The forward link is always transmitted at its full power, using a rate control scheme instead of a power control scheme, as in cdma2000. The data is TDM (time division multiplexed) to the various users or mobiles, with only one being served at any time. Each mobile measures signal-to-noise ratio (SNR) on the forward link pilot every slot, 1.667 ms, and sends a data rate request to the base station every 1.667 ms. The base station decides which mobile should be served next. The maximum data transfer from the network will be achieved if only the most favorable links get served, however, this is accomplished at the expense of the distant users.

Forward Channel TDM Structure

The following four different channels are used and are Time Division Multiplexed (TDM):

•	Traffic Channel - The data following the turbo coder is scrambled by mixing with a PN sequence, the initial state of which is based on known parameters, and is unique for each user. At the same initial value of the PN sequence, every packet starts. QPSK modulation is used for data rate up to 1.2288 Mbps. Higher order modulation, with either 8PSK with 3 bits per symbol or 16QAM with 4 bits per symbol, is used for higher data rates. The levels of the I and Q symbols are mathematically chosen so that the average power becomes 1. The I and Q channels are mapped into 16 parallel Walsh cover, each of length 16. The I and Q outputs with the Walsh covers signals are added together.

•	Preamble - At the beginning of the transmission to one user, there is a preamble that is embedded in the data. This preamble contains the user ID for the data, and its repeat rate is determined by the data rate; lower data rates require higher repeat values. At its largest, the preamble will fill more than a half the first slot.

•	Medium Access Control (MAC) - This layer consists of the reverse power control (RPC) and the reverse activity (RA) channels. The power control bits are sent in parallel to all mobiles with an open connection. Each one is assigned a different 64-bit Walsh code which gets transmitted on either the I or Q channel. The codes 0 through 3 are reserved. The Walsh code 4 is the RA cover. The Walsh codes 5 through 63 are allocated to RPC. One Walsh code is allocated for power control to each active reverse link. Power control bits for all of the reverse links are sent in parallel as part of the MAC channel. These are made of 4 repetitions of an assigned Walsh code of length 64. The RA channel is used to indicate that the sector is busy decoding multiple reverse link signals.

•	Pilot - The pilot signal is gated on for only 192 chips per slot. The differentiator between cells and sectors is still the PN offset of the pilot channel.

The data structure per slot can be illustrated as follows:

Reverse Link Coding

The reverse link for 1xEV-DO has a structure similar to that for cdma2000, except that in addition to a data channel, the following channels are also included:

•	Reverse Rate Indication (RRI) - This replaces with the power control bits to indicate of which data rate is requested by the mobile.

•	Data Request Channel (DRC) - This contains a 4-bit word in each slot to allow the choice of up to 16 different transmission rates. Different Walsh covers are used to indicate which PN offset in the active set is preferred for transmission.

•	Ack Channel - This acknowledgement channel is only transmitted after the mobile detects a frame with its preamble, meaning the packet is directed to that mobile. The 1 bit on this channel, which is transmitted for a half slot, is used to indicate a successful reception or an erasure.

The Pilot in 1xEV-DO is still punctured but the information carried is different:

In cdma2000, the Pilot is punctured in a 3:1 ratio (3 Pilot, 1 Data) to carry power control bits. The puncture period is 1 Power Control Group, or 1.25 ms. The data rate for PCB is 16 bits per 20 ms frame.

In 1xEV-DO, the puncture pattern is 7:1 on each slot (7 Pilot, 1 Data). The underlying data is coded, and the transmission rate is 3 bits per 26.667 ms frame.

In 1xEV all signaling is performed on the data channel so there is no Dedicated Control Channel. The data channel can support 5 data rates, which are separated in powers of 2 (256 through 4096 bits, or 9.6 through 153.6 kbps). These rates are achieved by varying the repeat factor. The highest rate uses a Turbo coder with lower gain.

Reverse Link Scrambling

The Pilot, ACK, DRC, and Data channels are added with each other in a manner that maps some into I (in phase sequence) and some into Q (quadrature phase sequence) for eventual spreading. The final spreading is made similarly to cdma2000 with HPSK. In 1xEV-DO, the long code used for spreading is Seeded with a fixed pattern at the start of every Pilot sequence, every 26.667 ms. There are separate masks, 42 bits long, for the I and Q long spreading codes. In 1xEV-DO, the long code generator is based on system time, or in other words a continuous clock.

Compatibility with IS-2000

When interpreting TIA/EIA/IS-2000 in the context of TIA/EIA/IS-856, the terms for TIA/EIA/IS-2000 should be mapped as follows:

TIA/EIA/IS-2000	TIA/EIA/IS-856
BS	AN
Base Station	Access Network
BSC	AN
Base Station Control	Access Network
Call	Connection
MS	AT
Mobile Station	Access Terminal
See also

About Option B7N: 1xEVDO Demodulation

1xEV-DO Demod Features

Setting up a 1xEV-DO Measurement

Selecting 1xEV-DO Demodulation


Available Features (1xEV-DO)

Features applicable to 1xEV-DO demodulation:

•	Standard presets for

−	1xEV-DO Reverse link

−	1xEV-DO Forward link

•	1.2288 MHz variable (user definable) chip rate

•	Single code domain layer or composite code-domain power and code-domain error shows (the composite display shows all code layers simultaneously). You can normalize code-domain power to display the code-domain power relative to the total signal power in the code domain.

•	Single channel time-domain displays, such as IQ measured, IQ reference, IQ magnitude/phase error, and error Vector traces (reverse link direction only).

•	Composite time-domain displays, such as IQ measured time, IQ reference time, IQ magnitude or phase error, and error vector time traces.

•	Mirrored (flipped) frequency spectrums used to remove the effects of high-side mixing or complex conjugation mismatches in simulated data.

•	Measurement offset and interval (similar to time gating) used to select specific data slots for analysis

•	Averaging is available only for code domain data and is applied to numeric error data in the Error Summary table, as follows:

−	rms (video) — computes an average of each rms error update in the table.

−	rms exponential — like rms (video) except that averaging continues past the average count with an exponential weighting.

−	continuous peak hold — keeps track of the peak rms error of each update in the table.

−	Time and time exponential averaging are not available.

•	These average types are available for the pre-demodulated spectrum result.

−	rms (video)

−	rms exponential

−	continuous peak hold

See also

89600-Series VSA Application Standard Features

Opt B7N: 1xEV-DO Available Trace Data

Opt B7N: 1xEV-DO Demodulation Overview

Setting up a 1xEV-DO Measurement


Setting up a 1xEV-DO Measurement

(Vector Signal Analyzer application only)

When setting up a 1xEV-DO demodulation measurement, there are several things you need to consider. This topic tells you how to connect your signal to an 89600-series analyzer and successfully demodulate digital signals. The information is provided in this order:

•	Connecting Your Signal to the Analyzer

•	Frequency Span

•	Input Range

•	Center Frequency

•	Reverse/Forward Link Direction

•	Chip Rates, Symbol Rates and Walsh Code Length

•	Result Length

•	Mirrored Spectrum

Connecting Your Signal to the Analyzer

The analyzer lets you connect your carrier signal or, if your 89600-series analyzer has two input channels, the raw I (In-phase) and Q (Quadrature-phase) signals.

For all receiver configurations except I + jQ, connect your signal to Channel 1. In this case, the analyzer assumes that your signal contains both the I and Q components (the carrier signal). If your analyzer has two input channels, the analyzer ignores the second input channel.

If your analyzer has a second input channel, you can also connect the raw I (In-phase) and Q (Quadrature- phase) signals. To do this, select Input, Channels, I + jQ. With this configuration, the analyzer removes the quadrature mixer from the demodulator's signal flow, which lets you connect the I component of your signal to Channel 1; the Q component to Channel 2.

Notes

1) Selecting I+jQ turns on DC coupling.

2) When using I+jQ, use external calibration to correct for any offset or gain imbalance between the I and Q signals.

3) Ranges for Channel 1 and Channel 2 are set independently.

Frequency Span

When selecting a frequency span, select the narrowest span that includes all of your signal components (select a span that is slightly larger than the bandwidth of your signal). If you select a span that is too narrow, your measurement may have excessive errors or the analyzer may lose carrier lock. If the span is less than the (Chip Rate × 1.204), the analyzer shows "DATA?" to indicate that the results may not be accurate.

For best results, the frequency span should be set according to the following formula (filter_alpha is the filter characteristic of the Nyquist filter used to demodulate the 1xEV-DO signal):

Frequency Span ≥ (1.204 × Chip Rate)

If you select a span that is too wide, your measurement may be affected by excessive noise and slower speed.

Using the "Preset to Default" configuration settings will select a default span that should work well.

Input Range

The input range must be set correctly to obtain accurate measurements. Input ranges that are too low overload the analyzer's ADC. Input ranges that are too high increase noise, which increases errors reported in error data results, such as EVM.

Note

1xEV-DO signals can have a relatively large Peak-to-RMS voltage ratio potentially requiring a higher range setting than for other digitally modulated signals.

Center Frequency

The analyzer's center frequency must be set within approximately ±500 Hz of the carrier frequency of the 1xEV-DO signal, otherwise the analyzer may not be able to lock onto your signal.

The pilot PN Offset index must mach the system PN Offset index (forward link direction only).

Reverse/Forward link direction

The analyzer can demodulate both reverse link and forward link 1xEV-DO signals . Therefore you must select the input signals reverse or forward direction. Forward link is refers to the Base Station Transceiver (or Access Network) transmitted signal and Reverse link refers to the mobile station (or Access Terminal) transmitted signal.

Tip

You can use the Preset to Default command button to auto-configure the analyzer to measure standard 1xEV-DO Forward or Reverse link signals.

Chip Rates, Symbol Rates and Walsh Code Length

To successfully demodulate 1xEV-DO signals, the analyzer chip rate must match the chip rate of your 1xEV-DO signal. The Walsh Code Length determines the Symbol Rate per the following equation.

Symbol Rate = Chip Rate/Walsh Code Length

Chip Rate: 1.2288 MHz

Walsh Code Length (Symbol Rate)

(Forward Link)	(Reverse Link)
	4 (307.2 ksym/s)
	8 (153.6 ksym/s)
16 (76.8 ksym/s)	16 (76.8 ksym/s)
32 (38.4 ksym/s)
64 (19.2 ksym/s)	—
Result Length

Result Length determines the amount of signal the analyzer demodulates in terms of the number of Power Control Groups (slots) or equivalent slots time. Make sure that the result length is long enough to capture all the desired data.

Result Length may be entered as an integral number of half slots, frames or time. If you choose to enter seconds, the analyzer will automatically increment your entry as necessary to obtain an integer number of slots.

Mirrored Spectrum

The 1xEV-DO demodulation provides a feature that lets you configure the analyzer's demodulator to conjugate the complex time-domain waveform. This has the effect of flipping the spectrum around the analyzer's center frequency. This feature is useful when the 1xEV-DO signal is inverted, or flipped due to an IF down conversion.

See also

1xEV-DO Modulation Overview

1xEV-DO Available Features

Setting up a 1xEV-DO Measurement


Selecting 1xEV-DO Demodulator

(Vector Signal Analyzer application with option B7N only)

Menu Path: MeasSetup > Demodulator > 3G Cellular > 1xEV-DO

Sets the analyzer's demodulator to despread and demodulate 1xEV-DO modulated signals. Both forward link and reverse link signals can be demodulated.

After selecting the demodulator you need to set the configuration parameters. You can select one of the available Standard Presets or you can manually set them from the Demod Properties dialog box.

It's also recommended that you review the Setting up a 1xEV-DO Measurement topic before setting these parameters.

See Also

Using Standard 1xEV-DO Presets

Setting up a 1xEV-DO Measurement

1xEV-DO Available Features

1xEV-DO Modulation Overview

About 89600 Optional Measurement Software


Using Standard Setups/Presets

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Format tab > Preset to Default button

Lets you select a 1xEV-DO standard preset configuration. When you select a standard preset, the analyzer automatically sets the parameters shown in the following table:

•	Reverse: 1xEV-DO reverse link signal

•	Forward: 1xEV-DO forward link signal

Note

The 1xEV-DO Demodulator must be selected before these Standard Presets are available.

1xEV-DO Standard Presets

Parameter	Forward (Link)	Reverse (Link)
Span:	1.5 MHz	1.5 MHz
Chip Rate:	1.2288 MHz	1.2288 MHz
Direction:	Forward	Reverse
Analyze Channel:	Pilot	--
PN Offset:	0x64 chips	--
Data modulation Type:	QPSK	--
Long Code Mask:	--	0x3FFFFFFFFFF
Long Code Mask Q:	--	0x3FFFFFFFFFF
Mirror Frequency Spectrum:	Clear	Clear
IQ Normalization:	Selected	Selected
Despread Channel: Walsh Code Length: Walsh Code Number: IQ Channel:	32 (38.3 ksym/s)† 0 †     --	16 (76.8 ksym/s) 0 I
CDP Layer: Walsh Code Length	32 (38.3 ksym/s)	6 (76.8 ksym/s)
Active Channel detection: Predefined Active Channel: Detection Mode:	Clear   --	Clear Auto
Result Length:	5 slots (8.3 ms)	5 slots (8.3 ms)
Measurement Offset:	0 slot (0 ms)	0 slot (0 ms)
Measurement Interval:	1 slot (1.67 ms)	1 slot (1.67 ms)
Preamble: Auto Detect: Include Overall Results: Length:	Selected Selected 64 chips	--    --    --
I/Q Combined:	Selected	--
Include IQ Offset in EVM:	Selected	Selected
Combine TDM channels for composite results:	Clear	--

Notes:	The dash "--" means the parameter does not apply.
† unavailable, not selectable

See Also

Selecting the 1xEV-DO Demodulator

Setting up a 1xEV-DO Measurement

1xEV-DO Available Features

1xEV-DO Modulation Overview


Troubleshooting
Troubleshooting (1xEV-DO)

(Vector Signal Analyzer application only)

This topic contains information to help you troubleshoot measurements when using 1xEV-DO Demodulation. You should also review Setting up a 1xEV-DO Measurement for additional measurement information.

PROBLEM	POSSIBLE CAUSE	SOLUTION
Demodulation fails to lock-on to signal	Signal not present	Check test setup connections
	Carrier too far from center frequency	Adjust center frequency to ± 500 Hz of the carrier frequency
	Input signal is over-loaded or under ranged	Adjust input range
	Frequency span is too narrow	Increase frequency span
	Incorrect chip rate	Enter correct chip rate (not symbol rate or bit rate)
	No Pilot Channel — missing or level to low	Set pilot channel at Walsh Code Number Zero. Try adjusting pilot channel power level.
	Incorrect Long Code Mask	Reverse link analysis requires correct setting for both I and Q Long Code Masks.
	1xEV-DO signal spectrum is inverted	Check the Mirror Frequency Spectrum setting (MeasSetup > Demodulator > Format tab).
	I/Q Offset too large	Reduce the LO feedthrough  (or DC Offset for I+jQ receiver)
Wrong channel marked as active	Poor SNR (signal to noise ratio).	Increase signal power or remove cause of noise/distortion.  Will try to force known 1xEV-DO channels to be recognized as active.  See "Active Channel Detection" parameter topic.
	All bits not transmitted within a physical channel.	Transmit all bits within a physical channel, or select code-domain power for the layer associated with the physical channel of interest (single-layer code-domain power displays are accurate even if the analyzer is unable to identify active channels in the composite code-domain power display).
	Data pattern induces large disparity in power between slower channels overlaid by the channel of interest.	Verify that your transmitter is transmitting properly.
ADS application has failed to work with 1xEV-DO demodulation	See Troubleshooting ADS measurements
See also

Setting up a 1xEV-DO Measurement

About Opt B7N: 1xEV-DO Demodulation

VSA error and status messages

VSA Troubleshooting Topics


1xEV-DO Demodulation Properties Dialog Box

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties

The 1xEV-DO Demodulation dialog box contains parameters that let you configure the analyzer to descramble, despread, demodulate and analyze 1xEV-DO modulated signals.

Note

The 1xEV-DO Demodulator must be selected before this dialog box is available. To enable the demodulator, click MeasSetup > Demodulator > 3G Cellular > 1xEV-DO.

The 1xEV-DO Demodulation Properties dialog box contains tab headings that group similar configuration parameters as follows:

•	Format tab: Contains the 1xEV-DO demod configuration parameters. These parameters must be set to match the transmitter modulation format for the analyzer to lock on to and demodulate the signal.

•	Channel/Layer tab: Contains the parameters to select specific code layers and code channels for the Despread Channel and CDP Layer trace data results.

•	Time tab: Contains the time capture configuration parameters. You use these parameters to specify what segment of the time record (captured input signal) will be used for data analysis and trace data results.

•	Advanced tab:  Contains the Preamble Detection parameters; "Auto Detect", "Preamble Length" and "Include in Overall results".  Also provides the "IQ Combined", "Include IQ Offset in EVM" and "Combine TDM channels for composite results" parameters. These parameters are used to modify how the measurement is computed.

See also

Setting up a 1xEV-DO Measurement

Troubleshooting a 1xEV-DO Measurement


Advanced Tab  (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties

The Advanced tab provides the Preamble Detection parameters; "Auto Detect", "Preamble Length" and "Include in Overall results".  Also provides the "IQ Combined", "Include IQ Offset in EVM" and "Combine TDM channels for composite results" parameters. These parameters are used to modify how the measurement is computed.

The Advanced tab provides the following parameters:

•	Preamble

−	Auto Detect  (Forward Direction only)

•	Preamble Length (Forward Direction only)

−	Include in overall results  (Forward Direction only)

•	I/Q Combined check box  (Forward Direction only)

•	Include IQ Offset in EVM

•	Combine TDM channels for composite results (Forward Direction only)

See also

Format tab (1xEV-DO Demodulation Properties)

Time tab (1xEV-DO Demodulation Properties)

Channel/Layer Tab

1xEV-DO Demodulation Properties dialog box


Channel/Layer Tab (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties

The Channel/Layer tab provides the parameters to select specific code layers and code channels for the Despread Channel and CDP Layer trace data results.

Despread Channel parameters: Despread Channel parameters specify the code channel and layer used for the reverse direction channel trace data results including: Chan Error Vector, Chan IQ Meas Time, Chan IQ Ref Time, Chan Mag Error, Chan Phase Error and Chan Syms/Errs trace data:

−	Walsh Code Length (Reverse Direction only)

−	Walsh Code Number  (Reverse Direction only)

−	IQ branch option buttons (Reverse Direction only)

CDP Layer parameters: CDP Layer parameters are used to specify the active (displayed) code domain layer for the Code Domain Power (CDP) Layer and Code Domain Error (CDE) Layer trace data.  The selected Analysis Channel and Direction limits the available CDP Layers (see About CDP trace data).

−	Walsh Code Length

Active Channel Detection parameters: These parameters specify how the active code channels are determined for a measurement (see Active Channel Detection):

−	Predefined Active Channel

Data W16 (0:15) (Forward Direction only)

Data W4 (2): Q (Reverse Direction only)

ACK W8 (4): I (Reverse Direction only)

DRC W16 (8): Q (Reverse Direction only)

Pilot W16 (0): I (Reverse Direction only)

−	Detection Mode:

Auto (Reverse Direction only)

Semi-Auto (Reverse Direction only)

Predefined (Reverse Direction only)

See also

Advanced tab (1xEV-DO Demodulation Properties)

Format tab (1xEV-DO Demodulation Properties)

Time tab (1xEV-DO Demodulation Properties)

1xEV-DO Demodulation Properties dialog box


Format Tab (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties

The Format tab of the 1xEV-DO Demodulation Properties dialog box lets you configure the analyzers 1xEV-DO Demodulator.  These parameters must be set to match the transmitter modulation format for the analyzer to lock on to and demodulate the signal.

The Format tab lets you configure these parameters (Click on the parameter name for further information):

•	Preset to Default

•	Chip Rate

•	Direction

•	Analysis Channel (forward direction only)

•	PN Offset (forward direction only)

•	Data Modulation Type (forward direction only)

•	Long Code Mask (reverse direction only)

•	Long Code Mask Q (reverse direction only)

•	IQ Normalize

•	Mirror Frequency Spectrum

See also

Advanced tab (1xEV-DO Demodulation Properties)

Channel/Layer tab (1xEV-DO Demodulation Properties)

Time tab (1xEV-DO Demodulation Properties)

1xEV-DO Demodulation Properties dialog box


Time Tab (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup. DemodProperties

Contains the time capture configuration parameters. You use these parameters to specify what segment of the time record (captured input signal) will be used for data analysis and trace data results.

The Time tab lets you configure these parameters:

•	Result Length

•	Measurement Offset

•	Measurement Interval

Measurement Offset and Measurement Interval are used by all measurement trace data results except the following composite signal trace data: Composite IQ Meas Time/Spectrum, Composite IQ Ref Time/Spectrum, Composite Error Vector Time/Spectrum, Composite Mag Error, Composite Phase Error, Composite Error Summary data.  Also reverse direction CDE Composite, CDE Layer and certain Error Summary data results are affected by the selection of Measurement Offset and Interval.

See also

About Measurement Interval and Offset

Advanced tab (1xEV-DO Demodulation Properties)

Format tab (1xEV-DO Demodulation Properties)

Channel/Layer tab (1xEV-DO Demodulation Properties)

1xEV-DO Demodulation Properties dialog box


Setting Measurement Parameters (1xEV-DO)

(Vector Signal Analyzer application only)

The following table shows how measurement parameters affect 1xEV-DO demodulation.

1xEV-DO Demodulation Parameters

Time Sequence	Parameters Involved	Effect	Result	Notes
Signal setup	Range Trigger Frequency/span Input Time Corrections	Sets up basic signal parameters required for demodulation	Raw data	Any changes made in the signal setup parameters later in the time sequence require that a new measurement be performed
Demodulation	Setup parameters Chip Rate Direction-Link Long Code Mask	Determines the type of demodulation performed on the input time data	Demodulated, symbol-locked data in the default display format	Result length determines the amount of data that is demodulated.
Post-demodulation	Meas Offset Meas Interval Walsh-Code-Number CDP-Layer: Walsh-Code-Length, Walsh Code Number, Data Modulation Type, most parameters in the Demodulation Properties dialog box.	Specifies channel and determines how much data is used for the trace data results.	Demodulated data in the default display format.	Changes may be made in the display parameters without acquiring a new measurement
Display Formatting	Trace data Trace format X and Y Scale Marker IQ Normalize	Formats the data for display	Formatted, demodulated data	Changes may be made in the display parameters without acquiring a new measurement
See also

Parameter Interactions

Display Limitations

Resolution Bandwidth

Span considerations

Setting up a 1xEV-DO Measurement

Troubleshooting (1xEV-DO)


Parameter Interactions (1xEV-DO)

(Vector Signal Analyzer application only)

When using 1xEV-DO demodulation, changing one parameter may necessitate changes in other parameters to achieve the desired measurement. For example,

•	Chip rate limits frequency span.

•	Minimum frequency span may limit the chip rate (this may occur when playing back a recording or analyzing data from the stream interface).

•	Measurement Interval and Measurement Offset are limited by the Result Length

•	Changing link direction changes the valid limits for many parameters

The following topics may help you optimize your measurements and explain the reasons for changes made automatically by the analyzer:

•	Display Limitations

•	Resolution Bandwidth

•	Span considerations

See also

Setting up a 1xEV-DO Measurement

Troubleshooting (1xEV-DO)


Display limitations (1xEV-DO)

All 1xEV-DO Channel trace data is displayed at one Point-per-Symbol and all Composite trace data is displayed at one Point per Chip. This causes the bandwidth displayed for the Composite IQ Meas Spectrum, the Composite IQ Ref Spectrum and the Composite Error Vector Spectrum to be less than the analyzers span setting.

The following topics may help you optimize your measurements and explain the reasons for changes made automatically by the analyzer:

•	Parameter Interactions

•	Resolution Bandwidth

•	Span considerations

See also

Setting up a 1xEV-DO Measurement

Troubleshooting (1xEV-DO)


Resolution Bandwidth (1xEV-DO)

Resolution bandwidth (ResBW) in 1xEV-DO demodulation is determined automatically by the analyzer, and cannot be set independently. Resolution bandwidth is determined by the time record length according to the following formula:

However, in 1xEV-DO Demodulation the time record length is determined as follows (result length is in symbols):

The following topics may help you optimize your measurements and explain the reasons for changes made automatically by the analyzer;

•	Parameter Interactions

•	Display Limitations

•	Span considerations

See also

Setting up a 1xEV-DO Measurement

Troubleshooting (1xEV-DO)


Span Considerations (1xEV-DO)

When selecting a frequency span, select the narrowest span that includes all of your signal components (select a span that is slightly larger than the bandwidth of your signal). If you select a span that is too narrow, your measurement may have excessive errors or the analyzer may lose carrier lock. If the span is less than 1.024 × chip rate, the analyzer shows "NO DATA?" to indicate that the results may not be accurate.

For best results, the frequency span should be set according to the following formula (filter_alpha is the filter characteristic of the Nyquist filter used to demodulate the 1xEV-DO signal):

Frequency Span ≥ 1.024 × Chip Rate

If you select a span that is too wide, your measurement may be affected by excessive noise and slower speed. You may want to turn the demodulator OFF (MeasSetup, Demodulator, Demod OFF) and set the span while Viewing the spectrum of your signal.

Using the "Preset to Default" configuration settings will select a default span that should work well.

The following topics may help you optimize your measurements and explain the reasons for changes made automatically by the analyzer.

•	Parameter Interactions

•	Display Limitations

•	Resolution Bandwidth

See also

Setting up a 1xEV-DO Measurement

Troubleshooting (1xEV-DO)


Analysis Channel  (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Format tab

Default: Pilot, see 1xEV-DO Standard Defaults Table

Lets you specify the forward channel that will be used for analysis and trace data results.  Use the drop-down list to select one of these forward link channels:

Pilot - Pilot channel

MAC - Medium Access Control channel.

Data  - Data channel (Forward Traffic channel or Control channel data).

Preamble - Preamble channel

•	Pilot - The Pilot Channel shall consist of all-'0' symbols transmitted on the I channel with Walsh cover 0. Each slot shall be divided into two half slots, each of which contains a pilot burst.

•	MAC - Forward Medium Access Channel. The Mac channel consists of two sub-channels: the Reverse Power Control  (RPC) channel and the Reverse Activity (RA) channel. The RA channel transmits a reverse link activity bit (RAB) stream.  The MAC channel symbol is BPSK modulated on one of 64 64-ary Walsh codeword (covers). MAC symbol Walsh covers are transmitted 4 times per slot in two bursts of 64 chips each. The two burst are transmitted immediately preceding and following the pilot burst in a slot.

•	Data  - The Data channel comprises either the Forward Traffic Channel or Control Channel data. The Traffic Channel carries user data packets transmitted at variable data rates from 38 kbps to 2.4576 Mbps utilizing QPSK, 8PSK  or 16QAM symbol modulation. The Control Channel carries control messages, and it may also carry user traffic. Each channel is further decomposed into code-division-multiplexed quadrature Walsh channels.

•	Preamble  - The Preamble section is not present in every slot, and may change length depending upon the data rate.  The Preamble may be 64, 128, 256, 512, or 1024 chips in length and replaces an equivalent number of chips in the Data channel of a slot.

For more information, see 1xEV-DO Modulation Overview - "Forward Channel TDM Structure"

See Also

Format Tab - 1xEV-DO Demodulation Properties

1xEV-DO Demodulation Properties


Chip Rate (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Format tab

Default: 1.2288 MHz, see 1xEV-DO Standard Defaults Table

Range: Minimum span to (10 × maximum span)

Lets you set the Chip Rate for the analyzer's demodulator. This parameter provides the capability to enter nonstandard chip rates for test and analysis purposes.

Note

To demodulate a signal, the chip rate must match the chip rate of your system.

The chip rate also limits the resolution bandwidth.

See Also

Format Tab - 1xEV-DO Demodulation Properties

1xEV-DO Demodulation Properties


Data Modulation Type  (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Format tab

Default: QPSK (See 1xEV-DO Standard Defaults Table)

Lets you to specify the forward link Data (Traffic/Control) channel modulation format.  Use the drop-down list to select one of these modulation formats:

QPSK modulation

8PSK modulation

16QAM modulation

For more information, see 1xEV-DO Modulation Overview - "Forward Channel TDM Structure"

See Also

Format Tab - 1xEV-DO Demodulation Properties

1xEV-DO Demodulation Properties


Direction  (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Format tab

Default: Forward, see 1xEV-DO Standard Defaults Table

The Direction property lets you specify the air interface link direction for 1xEV-DO demodulation.  Use the drop-down list to select one of these directions:

Forward link:  Signal transmission from the Access Network (or "Base Station") to the Access Terminal (or "Mobile Station")

Reverse link:  Signal transmission from the Access Terminal (or "Mobile Station") to the Access Network (or "Base Station")

See Also

Format Tab - 1xEV-DO Demodulation Properties

1xEV-DO Demodulation Properties


About Active Channel Detection (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Channel/Layer tab

Default: Cleared, see 1xEV-DO Standard Defaults Table

These parameters allow you to control what 1XEV-DO channel data is included in the composite trace data results.  The available channel data and detection modes are dependent upon the signal link Direction as described in the following sections.

Forward Direction signals

Allows you to specify the detection mode for the following forward link Predefined Active Channel data channel:

Predefined Active Channel

Data W16(0:15)  -  Forward Traffic Data channel, code layer 16, code channels 0 through 16

Selected:  Forces the analyzer to include all Data channel data in the composite trace data results.

Cleared:  The analyzer uses auto-detect mode to determine the active "Data" code channels.  Only data from the active code channels are included in the composite trace data results.

Reverse Direction signals

For reverse link direction signals, depending upon the selected Detection Mode, the following "Predefined Active Channel" forward direction TDM channels may or may not be included in the composite trace data results:

Predefined Active Channels

 W4(2): Q	-  Data channel for code layer 4, code channel 2.

ACK W8(4): I  	-  Acknowledgement channel, code layer 8, code channel 4, the I branch.

DRC W16(8): Q	-  Data Request Channel, code layer 16, code channel 8, the Q branch.

Pilot W16(0): I  	-  Pilot channel, code layer 16, code channel 0, the I branch

Detection Mode

 option

The analyzer uses auto-detect mode to determine which of the available "Predefined Active Channel" channels are included in the composite trace data results.  The "Predefined Active Channel" selections are not available in Auto mode.

•	Semi-Auto option

Cleared Predefined Active Channel check boxes

The analyzer uses auto-detect mode to determine which cleared Data, ACK, DRC or Pilot channel data is included in the composite trace data results.

Selected Predefined Active Channel check boxes

Forces the analyzer to include the selected Data, ACK, DRC or Pilot channel data in the composite trace data results.

•	Predefined option

Cleared Predefined Active Channel check boxes

The analyzer does not include the cleared Data, ACK, DRC or Pilot channel data in the composite trace data results.

Selected Predefined Active Channel check boxes

Forces the analyzer to include the selected Data, ACK, DRC or Pilot channel data in the composite trace data results.

Measurement TIP

You can use this feature to troubleshoot a problem forward link Data channel.  For example, if a Data channel is supposed to be active but cannot be detected by the analyzer, the Composite EVM result will appear better than it actually is. To include the missing data channel, select Data W16 (0:15) and all Data channels will be included in the Composite EVM measurement result.

See also

Channel/Layer tab - 1xEV-DO Demodulation Properties

1xEV-DO Demodulation Properties


Combine TDM channels for composite results

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Advanced tab

Default: Cleared, see 1xEV-DO Standard Defaults Table

When the Combine TDM channels for composite results parameter is selected, the composite trace data results will include the combined data from all forward direction TDM channels.  This parameter overrides the Analysis Channel parameter setting.

Selected:  The composite trace data results include data from the combined TDM channels (Data channel, MAC, Pilot and Preamble channels).

Cleared:  The composite trace data results only include data for the TDM channel specified by the Analysis Channel parameter (Meas Setup > Demod Properties > Format tab).

Note

The Combine TDM channels for composite results parameter only applies to the Composite trace data results.  This parameter does not affect CDP trace data results.

See also

Advanced tab - 1xEV-DO Demodulation Properties

1xEV-DO Demodulation Properties


Include IQ Offset in EVM

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Advanced tab

Default: Selected, see 1xEV-DO Standard Defaults Table

Controls weather the IQ Offset Error is included in the Composite Error Summary trace data results (see Composite IQ Offset).  For forward link measurements, this also affects the Overall Error Summary trace data results.

Selected:  IQ Offset error data is included in the Error Summary trace data results

Cleared:   IQ Offset error data is NOT included in the Error Summary trace data results

See also

Advanced Tab - 1xEV-DO Demodulation Properties

1xEV-DO Demodulation Properties


IQ Branch   (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Channel/Layer tab

Default: see 1xEV-DO Standard Defaults Table

The "I" and "Q" options control which IQ branch data bits are shown in the Channel Symbol/Errors trace data results.  The Reverse "I" and "Q" branches of each code channel are logically separate channels.

"I" option:   Selects I branch Chan Symbol/Errors trace data results.

"Q" option:  Selects Q branch Chan Symbol/Errors trace data results.

Note

IQ branch option is available only for the Reverse direction.

Tip

You can use the Copy Mkr To Despread Channel marker feature to automatically enter the Spread Code Length, Code Channel and IQ Branch setting.

See also

Channel/Layer tab - 1xEV-DO Demodulation Properties

1xEV-DO Demodulation Properties


I/Q Combined  (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Advanced tab

Default: Selected, see 1xEV-DO Standard Defaults Table

The I/Q Combined parameter controls how the CDP trace data results are displayed.  This parameter only applies to the forward link Data channel analysis.

Selected:  Show the combined IQ branch CDP trace data.

Cleared:  Show the separate I and Q branch CDP trace data.

Note

The I/Q Combined selection is only available when the Forward direction (click MeasSetup > Demod Properties > Format tab > Direction > Forward) and Data Analysis Channel is selected (click MeasSetup > Demod Properties > Format tab >Analysis Channel > Data).

See also

Advanced tab - 1xEV-DO Demodulation Properties

1xEV-DO Demodulation Properties


IQ Normalize  (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Format tab

Default: Selected (see 1xEV-DO Standard Defaults Table )

Lets you select the IQ Normalize function, see the IQ Normalize (Digital Demodulation) topic for more information..

Selected:	Normalization ON.
Cleared:	Normalization OFF
Note

Regardless of this setting, the Error Summary trace data results are always normalized.

See Also

Format Tab - 1xEV-DO Demodulation Properties

1xEV-DO Demodulation Properties


Long Code Mask

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Format tab

Default: 3FFFFFFFFFF (see 1xEV-DO Standard Defaults Table )

Ranged: 0 to 3FFFFFFFFFF

Specifies the I channel Long Code Mask (Reverse direction Only).

See Also

Format Tab - 1xEV-DO Demodulation Properties

1xEV-DO Demodulation Properties


Long Code Mask Q

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Format tab

Default: 3FFFFFFFFFF (see 1xEV-DO Standard Defaults Table )

Ranged: 0 to 3FFFFFFFFFF

Specifies the Q channel Long Code Mask (Reverse direction Only).

See Also

Format Tab - 1xEV-DO Demodulation Properties

1xEV-DO Demodulation Properties


Measurement Interval  (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Time tab

Default: see 1xEV-DO Standard Defaults Table

Lets you specify how much of the Result Length data is used for trace data results. Measurement Interval can be specified in increments of half (0.5) slots.  One slot is equal to 2048 chips or 1.667 ms long at the default chip rate.

Note

Measurement Interval does not affect composite trace data results or CDE trace data results

Measurement Interval and Measurement Offset parameters are used to specify what segment of the Result Length data is used for data analysis, see About Measurement Interval and Offset.

See also

Measurement Offset(1xEV-DO)

Result Length (1xEV-DO)

About Measurement Interval and Offset

Time tab - 1xEV-DO Demodulation Properties

1xEV-DO Demodulation Properties


Measurement Offset  (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Time tab

Default: see 1xEV-DO Standard Defaults Table

Lets you set the number of Measurement Offsets in increments of half (0.5) slots. Measurement Offset determines the start position of the Measurement Interval with respect to the first slot within the Result Length.   One slot is equal to 2048 chips or 1.667 ms long at the default chip rate.

Measurement Interval and Measurement Offset parameters are used to specify what segment of the Result Length data is used for data analysis, see About Measurement Interval and Offset.

See also

Measurement Interval (1xEV-DO)

Result Length (1xEV-DO)

About Measurement Interval and Offset

Time tab - 1xEV-DO Demodulation Properties

1xEV-DO Demodulation Properties


Mirror Frequency Spectrum  (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Format tab

Default: Cleared, see 1xEV-DO Standard Defaults Table

Lets you correctly demodulate frequency spectrums that are mirrored (flipped) about the center frequency. The default frequency spectrum is assumed not mirrored. This parameter does not change the displayed spectrum trace data.

Cleared:  Does not mirror the frequency spectrum.

Selected:  Mirrors the frequency spectrum about the analyzer center frequency.

Note

The display of the spectrum data will not change with this parameter. To mirror the display, clear the Mirror Frequency Spectrum check box, and select the MeasSetup Properties dialog box, Frequency tab, Mirror Frequency check box.

See Also

Format Tab - 1xEV-DO Demodulation Properties

1xEV-DO Demodulation Properties


PN Offset  (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Format tab

Default: 0 x64 chips, see 1xEV-DO Standard Defaults Table

Range: 0 to 511 x64 chips

Lets you specify the forward link pilot PN sequence - Offset Index.

Pilot channels are identified by an offset index in the range from 0 through 511 inclusive. This offset shall specify the offset value (in units of 64 chips) of the pilot PN sequence from the zero-offset pilot PN sequence,

For more information, see 1xEV-DO Modulation Overview - "Forward Channel TDM Structure"

See Also

Format Tab - 1xEV-DO Demodulation Properties

1xEV-DO Demodulation Properties


 Preamble Auto Detect  (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Advanced tab

Default: Selected, see 1xEV-DO Standard Defaults Table

Controls how the analyzer determines the Preamble Length.

Selected:   The analyzer uses the input signal data to determine the forward channel Preamble Length.

Cleared:   The analyzer ignores the input data and uses the Preamble Length in the Preamble Length text box.

Note

This only applies to forward link direction measurements.

See also

Advanced Tab - 1xEV-DO Demodulation Properties

1xEV-DO Demodulation Properties


Preamble Length  (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Advanced tab

Default:  64 chips, see 1xEV-DO Standard Defaults Table

Ranged:  0 to 1,024 chips

Allows you to manually specify the forward channel Preamble Length (in chips).  This parameter is controlled by the Preamble Auto Detect property as described in the following table.

Auto Detect Setting	Preamble Length
Clear:	The analyzer uses the Preamble Length.
Selected:	Unavailable - The analyzer  does not use the Preamble Length.
Note

This only applies to forward link direction measurements.

See also

Advanced Tab - 1xEV-DO Demodulation Properties

1xEV-DO Demodulation Properties


Preamble Include in overall results

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Advanced tab

Default: Selected, see 1xEV-DO Standard Defaults Table

Controls weather the Preamble data is included in the Overall trace data results.

Selected:  Preamble data is included in the Overall trace data result

Cleared:   Preamble data is NOT included in the Overall trace data result

Note

This only applies to forward link direction measurements.

See also

Advanced Tab - 1xEV-DO Demodulation Properties

1xEV-DO Demodulation Properties


Preset to Default  (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Format tab

Default: Forward, see 1xEV-DO Standard Defaults Table

 Range: Forward, Reverse

Lets you select standard 1xEV-DO Demodulation configurations. The analyzer automatically sets the required configuration parameters to demodulate either Forward or Reverse link signals.

See Using 1xEV-DO Standard Setups/Presets for a complete list of available presets, associated parameters and default settings.

See Also

Format Tab - 1xEV-DO Demodulation Properties

1xEV-DO Demodulation Properties


Result Length  (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Time tab

Default: see 1xEV-DO Standard Defaults Table

Range: 1 to 64

Lets you specify the total amount of acquired and demodulated data in integer number of time slots.  One slot is 1.6667 ms (2048 chips) and one frame equals 16 slots (26.666 ms at the default chip rate). See the About Measurement Interval and Offset topic or more information.

Tip

Result length is a primary factor determining measurement speed. Smaller result lengths increase measurement speed, but larger result lengths allow more useful analysis when changing Interval and Offset, since new data will not need to be acquired.

See Also

Measurement Interval (1xEV-DO)

Measurement Offset (1xEV-DO)

About Measurement Interval and Offset

Time tab - 1xEV-DO Demodulation Properties

1xEV-DO Demodulation Properties


Walsh Code Length - Despread Channel   (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Channel/Layer tab

Default: 32 (38.4 ksym/s), see 1xEV-DO Standard Defaults Table

Range:  2 to 32 (Reverse link only)

This text box shows the current Walsh Code Length used for Code Domain Power analysis.  You cannot specify or change the Despread Channel - Walsh Code Length.

Note

Reverse direction only. Unavailable for Forward direction.

See also

Channel/Layer tab - 1xEV-DO Demodulation Properties

1xEV-DO Demodulation Properties


Walsh Code Length - CDP Layer   (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Channel/Layer tab

Default: see 1xEV-DO Standard Defaults Table

Range:  4 to 128 (Forward link) and 2 to 32 (Reverse link)

CDP Layer Walsh Code Length selects the active code domain layer (Walsh code length) for the code domain power CDP Layer and CDE Layer trace data results. Available choices depend upon the link Direction, Analysis Channel and CDP Channel type.

Note

This parameter has no other effect except for the display of the CDP Layer and CDE Layer trace data.

Selecting a CDP Layer Walsh Code Length

The CDP Layer provides a drop-down list of available 1xEV-DO compliant Walsh Code Lengths.

Chip Rate: 1.2288 MHz

Walsh Code        Length	Forward Link (Data/Pilot/MAC)	Reverse Link (Pilot/RRI/DRC/ACK)
2 (614.4 ksym/s)	--/--/--	Y/Y/Y/Y
4 (307.2 ksym/s)	Y/Y/Y	Y/Y/Y/Y
8 (153.6 ksym/s)	Y/Y/Y	Y/Y/Y/Y
16 (76.8 ksym/s)	Y/Y/Y	Y/Y/Y/--
32 (38.4 ksym/s)	--/Y/Y	--/--/--/--
64 (19.2 ksym/s)	--/--/Y	--/--/--/--
Note

The Copy Mkr to Despread Chan marker does not automatically enter the CDP Layer Walsh Code Length.

See also

Channel/Layer tab - 1xEV-DO Demodulation Properties

1xEV-DO Demodulation Properties


Walsh Code Number - Despread Channel    (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Channel/Layer tab

Default: see 1xEV-DO Standard Defaults Table

Range:  0 to (Walsh Code Length -1)

Lets you specify the Walsh Code Number.

The Despread Channel Walsh Code Number is used to specify the code channel for the channel trace data measurement results (Chan Error Vector, Chan IQ Meas Time, Chan IQ Ref Time, Chan Mag Error, Chan Phase Error and Chan Syms/Errs trace data).

Note

Reverse direction only. Unavailable for Forward direction.

See also

Channel/Layer tab - 1xEV-DO Demodulation Properties

1xEV-DO Demodulation Properties


About the Channel Symbol Table  (1xEV-DO)
(Reverse Direction Only)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan > Syms/Errs

When 1xEV-DO Demodulation is enabled, selecting Ch1 Chan Syms/Errs trace data shows the symbol table and error summary trace data for the specified Walsh code number and Walsh code length. The bottom section of the display shows the symbol table data and the upper section shows the error summary data. This topic discusses the code channel Symbol Table trace data, the Error Summary trace data is discussed in the About the Channel Error Summary trace data topic.

Note

These data results only apply to reverse link direction signals.

The Ch1 Chan Symbol table shows the binary bits for each measured symbol in the specified Walsh code number and Walsh code length. These parameters are specified in the Despread Channel Walsh-Code Number and Walsh Code Length drop-down lists, located in the 1xEV-DO Demodulation Properties dialog box (MeasSetup > Demod Properties > Channel/Layer tab).

The first bit in the table corresponds to the first bit of the first symbol. To make the table easier to read, the analyzer shows a fixed number of bits (eight), followed by a space.

For Reverse link signals, the "I" and "Q" data channels are logically separate signals. All trace data contains both the "I" and the "Q" channels of the signal, except the symbol table data.  The symbol table shows either the "I" channel symbol bits or the "Q" channel symbol bits. The "I" and "Q" channel data is specified by the "IQ" branch parameters in the Demod Properties Channel/Layer tab (MeasSetup > Demod Properties > Channel/Layer tab).

In addition, the analyzer shows numbers to the left of each row. These numbers indicate the bit position of the first bit in the row. For example, if 192 is displayed by the third row, the first bit in the row is the 192nd bit in the digital data stream.

Hints

•	Here's an easy way to show the bits that correspond to a point in the channel constellation diagram: Display the constellation diagram in one grid, the symbol table in another and then turn on the Show Markers and the Couple Marker feature. When you place the marker on a point in the constellation diagram, the analyzer highlights the corresponding bits in the symbol table.

•	Use the arrow keys on the keyboard or the mouse wheel to move the marker from one symbol to the next. Or you can use the marker X Position to move to any specified symbol location.

Error Summary Data Information

See About the Channel Error Summary Data.

See also

About the Composite Error Summary Trace Data


About Channel Error Summary Data (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan > Syms/Errs

When 1xEV-DO Demodulation is enabled, selecting the Ch1 Chan Syms/Errs trace data shows the symbol table and error summary trace data for the specified Walsh code number and Walsh code length. The bottom section of the display shows the symbol table data and the upper section shows the error summary data. This topic discusses the code channel error summary data, the Symbol Table trace data is discussed in About the Channel Symbol Table topic. The following information is discussed as listed:

Note

These data results only apply to reverse link direction signals.

The following subjects are discussed in this topic:

•	Available Channel Error Summary Data

•	Selecting Chan Error Trace Data

•	Averaging and Error Summary Data

•	Using Band Power markers to limit Error information

•	EVM, Magnitude and Phase Error data results (%rms)

Available Channel Error Summary Data

Available Channel Error Summary Data

Selecting Chan Error Trace Data

The Ch1 Chan Error Summary Data display shows the error data for the specified Walsh code number and Walsh code length. These parameters are entered in the "1xEV-DO Demodulation Properties" dialog box (MeasSetup, Demod Properties, Channel/Layer tab), Despread-Channel "Walsh Code Number" and "Walsh Code Length" text boxes.

Tip

You can use the Copy Mkr to Despread Chan marker feature to automatically enter the Despread-Channel Spread Code Length, Code Channel and IQ Channel settings.

Averaging and Channel Error Summary Data

If averaging is on, averaging is applied to most numeric error data in the error Summary data with the following exceptions. The peak data values, such as peak EVM, peak Magnitude and peak Phase error are averaged only for the Continuous Peak Hold averaging type. The slots (or slot) number is never averaged.

Error data from the current scan is not included in the average if either of these conditions occur:

•	CARRIER LOCK?

•	DATA? (if caused by a temporary condition like partial data record)

Using Band Power markers to limit Error information

If you want channel error information for all points over a selected region, you can use the band-power markers with an error trace.

For example, here's how you could compute the phase error for all points within a region. Click Trace, Data, Chan IQ Phase Error to display the IQ phase-error trace, then click Markers, Calculation and select the Band Power check box to turn on the band-power markers.

Now position the band-power markers to select the region of interest, and select RMS Sqrt (Pwr) from the Calculate text box to display the phase error for the selected region.

Hint

At this point, you could simply click Trace, Data, Chan IQ Mag Error to display the magnitude error for the same region.

EVM, Magnitude and Phase Error data results (%RMS)

In the channel error summary data, the analyzer shows the error-vector magnitude and magnitude error as a percentage. Before computing this percentage, the analyzer normalizes the constellation diagram such that the outer-most, ideal states have a magnitude of one.

The analyzer computes the overall percent error by first computing the error-vector magnitude and magnitude error at each symbol time.

Next, the analyzer derives the rms average for each parameter. For example, to compute the rms average for the magnitude error, the analyzer takes the square root of the sum of the squares of the individual magnitude-error values at each symbol time.

Because the magnitude of the constellation diagram's outer-most state has been normalized to one, the rms average is the overall, percent error.

Additional Error Summary Data

1xEV-DO Demodulation also provides these additional Error Summary Tables:

•	About Overall Error summary Data

•	About the Composite Error Summary Data

See also

About the Channel Symbol Table

About Ch1 Chan trace data


Available Channel Error Summary Data (1xEVDO)
Available Channel Error Summary Data (1xEV-DO)
(Reverse Direction Only)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan > Syms/Errs

The following Channel Error Summary data is available for 1xEV-DO reverse link direction signals:

•	Chan Error Vector Magnitude  (reverse direction only)

•	Chan Magnitude Error (MagErr)  (reverse direction  only)

•	Chan Phase Error (Phase Err)  (reverse direction only)

•	Slots  (reverse direction only)

Using ADS software

For information about using error summary data with ADS, see Demod Errors and ADS.

See also

About the Channel Error Summary Data


Chan Error Vector Magnitude (1xEVDO)
Chan Error Vector Magnitude (1xEV-DO)
(Reverse Direction Only)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan > Syms/Errs

Chan EVM (%rms) is the Root Mean Square (RMS) of the error vectors computed and expressed as a percentage of the square root of the mean power of the ideal signal (see EVM, Magnitude and Phase Error data results (%rms) topic). To the right of the EVM value is the symbol with the largest (or Peak) EVM (% Pk) and its value.

The error vector is the magnitude of the vector, at the detected symbol location for the specified code channel, which connects the I/Q reference-signal phasor to the I/Q measured-signal phasor as shown in the following figure:

Note

This data result only applies to reverse link direction signals.

See also

About the Channel Error Summary Data


Chan Magnitude Error (1xEVDO)
Chan Magnitude Error (1xEV-DO)
(Reverse Direction Only)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan > Syms/Errs

Chan Magnitude Error (MagErr) is the difference in amplitude between the I/Q measured signal and the I/Q reference signal, for the specified Code Channel and Spread Code Length, expressed as a percentage of the square root of the mean power of the ideal signal (see EVM, Magnitude and Phase Error data results (%rms) topic). To the right of the MagErr value is the symbol with the largest (or Peak) MagErr (% Pk) and its value.

Note

This data result only applies to reverse link direction signals.

Magnitude error is an indicator of the quality of the amplitude component of the modulated signal. For example: a very high magnitude error might indicate high incidental AM modulation on the signal.

Hint

The description of Error-vector magnitude (EVM) includes a pictorial diagram that shows how Magnitude Error is derived.

See also

About the Channel Error Summary Data


Chan Phase Error (1xEVDO)
Chan Phase Error (1xEV-DO)
(Reverse Direction Only)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan > Syms/Errs

Chan Phase error is the difference in phase between the I/Q reference signal and the I/Q measured signal at the measured symbol times for the specified Code Channel and Spread Code Length  (see EVM, Magnitude and Phase Error data results (%rms) topic). To the right of the Phase Error is the symbol with the largest (or Peak) Phase Error (% Pk) and its value.

Note

This data result only applies to reverse link direction signals.

The magnitude of this parameter is an indicator of the quality of the phase component of the modulated signal. For example, a very high phase error might indicate high incidental FM modulation on the signal.

See also

About the Channel Error Summary Data


Chan Slots  (1xEV-DO)
(Reverse Direction Only)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan > Syms/Errs

The Chan Slot data result provides the start and stop slot numbers of the Measurement Interval used as input data for the Chan (Channel) trace data results (see About Measurement Interval and Offset).

Starting Slot:  The starting slot is equal to the first measurement slot in the Result Length plus the Measurement Offset.

Stopping Slot:  The "to" slot is equal to the starting slot number plus the Measurement Interval.

See also

Measurement Interval

Measurement Offset

Result Length

About the Channel Error Summary Data


About Composite Error Summary Data (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

When 1xEV-DO Demodulation is enabled, selecting the Ch1 Comp Error Summary trace data shows the composite error summary data. This is the error summary data results for the composite signal.

Composite error summary data is always computed from the first slots in the measurement and ignores the measurement-offset parameter.

Available Composite Error Summary Data Results

•	Available Composite Error Summary Data

Composite EVM, Magnitude and Phase Error data results (%RMS)

In the composite error summary data, the analyzer shows the error-vector magnitude and magnitude error as a percentage. Before computing this percentage, the analyzer normalizes the constellation diagram such that the outer-most, ideal states have a magnitude of one.

The analyzer computes the overall percent error by first computing the error-vector magnitude and magnitude error at each symbol time.

Next, the analyzer derives the rms average for each parameter. For example, to compute the rms average for the magnitude error, the analyzer takes the square root of the sum of the squares of the individual magnitude-error values at each symbol time.

Because the magnitude of the constellation diagram's outer-most state has been normalized to one, the rms average is the overall, percent error.

Additional Error Summary Data

1xEV-DO Demodulation also provides these additional Error Summary data tables:

•	About Overall Error summary Data

•	About Channel Error Summary Data

See also

Available Composite Error Summary Data

About Measurement Interval and Offset


Available Composite Error Data (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

The following is a list of available Composite Error Summary data results:

•	Meas Chan   (forward direction only)

•	Rho

•	EVM (Error Vector Magnitude)

•	Pk CDE  (reverse direction only)

•	Magnitude Error

•	Phase Error (Phase Err)

•	Frequency Error

•	IQ Offset

•	Slot

•	Time Offset

•	Preamble  (forward direction only)

•	Pilot  (reverse direction only)

•	RRI  (reverse direction only)

•	ACK  (reverse direction only)

•	DRC  (reverse direction only)

•	Data  (reverse direction only)

Using ADS software

For information about using error summary data with ADS, see Demod Errors and ADS.

See also

About the Composite Error Summary Data


Composite Meas Chan  (1xEV-DO)
(Forward Direction Only)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

This is the 1xEV-DO forward link channel being used for the composite trace data analysis. The forward link channel is specified in the Analysis Channel demodulation property (MeasSetup > Demod Properties > Format tab > Analysis Channel drop-down list).

See also

Available Composite Error Summary Data

About the Composite Error Summary Data


Composite Rho (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

Rho is the normalized correlation coefficient between the actual transmitted signal and the reference signal.  The maximum value of Rho is 1.0, which means the measured signal and reference signal are 100% identical.

A Rho value of 1.0 indicates that all of the transmitted power correlates with the ideal signal as determined by the detected sequence.

Rho is the correlated power for all active code channels (as shown in the composite CDP trace data display).

See also

Available Composite Error Summary Data

About the Composite Error Summary Data


Composite Error Vector Magnitude (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

Composite EVM is the Error Vector Magnitude for the composite signal. Chan EVM (%rms) is the Root Mean Square (RMS) of the error vectors computed and expressed as a percentage of the square root of the mean power of the ideal signal (see About Composite Error Summary Data). To the right of the EVM value is the chip with the largest (or Peak) EVM (% Pk) and its value.

A perfect ideal signal is synthesized at the chip level and identified as the reference signal. The reference signal is subtracted from the measured signal to produce a time record of error phasors. The square root of the ratio of the mean power of the error signal to the mean power of the reference signal is computed and expressed as a percentage EVM.

Note

You can select to Not include the Composite IQ Offset error in the EVM error results with the "Include IQ Offset in EVM" demodulation property (MeasSetup > Demod Properties > Advanced tab)

This parameter is similar to Chan EVM except that it is computed at the chip rate instead of the symbol rate (see Chan EVM (Error-Vector Magnitude)).

See also

Available Composite Error Summary Data

About the Composite Error Summary Data


Composite Pk CDE  (1xEV-DO)
(Reverse Direction Only)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

Composite Peak CDE is the largest measured code-channel Code Domain Error. This is the largest measured CDE for all code channels (active and inactive) in the base code layer (the code layer with the smallest symbol rate) in the composite signal.

See also

Available Composite Error Summary Data

About the Composite Error Summary Data


Composite Magnitude Error (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

Composite Magnitude Error (MagErr) is the difference in amplitude between the I/Q measured signal and the I/Q reference signal, for the composite signal, expressed as a percentage of the square root of the mean power of the ideal signal (see About Composite Error Summary Data). To the right of the MagErr value is the chip with the largest (or Peak) Magnitude Error (% Pk) and its value.

This parameter is similar to Chan MagErr except that it is computed from the composite signal at the chip rate instead of the symbol rate (see Channel Magnitude Error).

See also

Available Composite Error Summary Data

About the Composite Error Summary Data


Composite Phase Error (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

Composite Phase error is the difference in phase between the I/Q reference signal and the I/Q measured signal, for the composite signal, at the measured chip times (see About Composite Error Summary Data). To the right of the Phase Error is the chip with the largest (or Peak) Phase Error (% Pk) and its value.

This parameter is the same as channel Phase error except that the source data is the composite signal. See Channel Phase error for further information about this parameter.

See also

Available Composite Error Summary Data

About the Composite Error Summary Data


Composite Frequency Error (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

Composite Frequency Error (Freq Err) shows the composite signal carrier frequency-error relative to the analyzer's center frequency. This parameter is displayed in Hertz and is the amount of frequency shift, from the analyzer's center frequency, that the analyzer must perform to achieve carrier lock.

Errors in RF frequency, LO frequency, or digitizer clock rate could all appear as carrier frequency error.

See also

Available Composite Error Summary Data

About the Composite Error Summary Data


Composite IQ Offset (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

Composite IQ Offset (also called I/Q origin offset) indicates the magnitude of the carrier feedthrough signal. When there is no carrier feedthrough, IQ offset is zero (-infinity dB).

Note

You can select to Not include the Composite IQ Offset error in the EVM error results with the "Include IQ Offset in EVM" demodulation property (MeasSetup > Demod Properties > Advanced tab)

IQ origin offset is easily seen in the constellation diagram, as shown below:

In the above illustration, "x" is the center of the constellation diagram. When "x" occurs at the origin, the IQ offset is zero. When "x" is not at the origin, the IQ offset is the magnitude of the vector (in dB) between "x" and the origin.

The carrier feedthrough shown in the symbol table is computed only at the symbol times (the instant in time when symbols are detected).

See also

Available Composite Error Summary Data

About the Composite Error Summary Data


Composite Slot  (1xEV-DO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

This is the number of the slot being analyzed. This is the input data used to compute the Composite CDP trace data and Composite trace data results.

Composite Error Summary data

The slot specifies the data used to compute Composite Error Summary data results except for the reverse link Pilot, DDI, ACK, DRC and Data channel power data results. The input data used to compute the these data results is specified by the Result Length, Measurement Interval and Measurement Offset parameters

See also

Available Composite Error Summary Data

About the Composite Error Summary Data


Composite Preamble  (1xEV-DO)
(Forward Direction Only)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

This is the detected Preamble channel length (in chips) (see Preamble Length property). This value is only computed when the Analysis Channel is set to Preamble or Data and Auto Preamble Detection is enabled (MeasSetup > Demod Properties > Channel/Layer tab)

See also

Available Composite Error Summary Data

About the Composite Error Summary Data


Composite Time Offset   (1xEV-DO)
(Reverse Direction Only)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

Time Offset is the time interval from the start of a trigger event to the start of the 1xEV-DO Frame used for data analysis.

See also

Available Composite Error Summary Data

About the Composite Error Summary Data


Composite Pilot   (1xEV-DO)
(Reverse Direction Only)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

This is the measured Pilot channel power (dBc) relative to the total composite signal power. This is computed over the specified Measurement Interval and Offset relative to the first analyzed slot (Composite slot).

See also

About Measurement Interval and Offset

Available Composite Error Summary Data

About the Composite Error Summary Data


Composite RRI   (1xEV-DO)
(Reverse Direction Only)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

This is the measured RRI channel power (dBc) relative to the total composite signal power and the measured RRI channel power (dB) relative to the Pilot Channel power. This is computed over the specified Measurement Interval and Offset relative to the first analyzed slot (Composite slot).

See also

About Measurement Interval and Offset

Available Composite Error Summary Data

About the Composite Error Summary Data


Composite ACK   (1xEV-DO)
(Reverse Direction Only)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

This is the measured ACK channel power (dBc) relative to the total composite signal power and the measured ACK channel power (dB) relative to the Pilot Channel power. This is computed over the specified Measurement Interval and Offset relative to the first analyzed slot (Composite slot).

See also

About Measurement Interval and Offset

Available Composite Error Summary Data

About the Composite Error Summary Data


Composite DRC    (1xEV-DO)
(Reverse Direction Only)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

This is the measured DRC channel power (dBc) relative to the total composite signal power and the measured DRC channel power (dB) relative to the Pilot Channel power. This is computed over the specified Measurement Interval and Offset relative to the first analyzed slot (Composite slot).

See also

About Measurement Interval and Offset

Available Composite Error Summary Data

About the Composite Error Summary Data


Composite Data   (1xEV-DO)
(Reverse Direction Only)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

This is the measured Data channel power (dBc) relative to the total composite signal power and the measured Data channel power (dB) relative to the Pilot Channel power. This is computed over the specified Measurement Interval and Offset relative to the first analyzed slot (Composite slot).

See also

About Measurement Interval and Offset

Available Composite Error Summary Data

About the Composite Error Summary Data


Available Overall Error Summary Data (1xEV-DO)

(Forward Direction Only)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Overall >Error Summary

Available Overall 1 and Overall 2 Error Summary Data

The following data results apply for both the Overall 1 and Overall 2 measurement data:

Overall 1/2 Rho

Overall 1/2 EVM  (Error Vector Magnitude)

Overall 1/2 Mag Err  (Magnitude Error)

Overall 1/2 Phase Err  (Phase Error)

Overall 1/2 Freq Err  (Frequency Error)

Overall 1/2 IQ Offset

Using ADS software

For information about using error summary data with ADS (EEsof Advanced Design System), see Demod Errors and ADS.

Additional Error Summary Data

1xEV-DO Demodulation also provides these additional Error Summary data tables:

See also

About Overall trace data

About Trace Data (1xEV-DO)


Overall Rho  (1xEV-DO)
(Forward Direction Only)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Overall >Error Summary

Rho is the normalized correlation coefficient between the actual transmitted signal and the reference signal.

Preamble Channel Data

You can select to NOT include the Preamble data in the Overall trace data results with the "Preamble - Include in overall results" demodulation property (MeasSetup > Demod Properties > Advanced tab).

Overall 1 data results apply to the Overall 1 measurement data and Overall 2 data results apply to the Overall 2 measurement data.

See Also

About Ch1 Overall Trace Data


Overall EVM  (Error Vector Magnitude)  (1xEV-DO)
(Forward Direction Only)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Overall >Error Summary

Overall EVM (Error Vector Magnitude) is the vector magnitude difference between the I/Q measured signal and the I/Q reference signal for the specified Overall 1 or Overall 2 measurement data.

Overall EVM is the similar to digital demodulation EVM. See Digital Demodulation Error-vector magnitude (EVM) for further information about this trace data.

Preamble Channel Data

You can select to NOT include the Preamble data in the Overall trace data results with the "Preamble - Include in overall results" demodulation property (MeasSetup > Demod Properties > Advanced tab).

Overall 1 data results apply to the Overall 1 measurement data and Overall 2 data results apply to the Overall 2 measurement data.

See Also

About Ch1 Overall Trace Data


Overall Mag Err  (Magnitude Error)  (1xEV-DO)
(Forward Direction Only)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Overall >Error Summary

Overall Magnitude Error (MagErr) is the difference in amplitude between the I/Q measured signal and the I/Q reference signal for the Overall 1 and Overall 2 measurement data.

For more information see Magnitude Err (Digital Demod).

Preamble Channel Data

You can select to NOT include the Preamble data in the Overall trace data results with the "Preamble - Include in overall results" demodulation property (MeasSetup > Demod Properties > Advanced tab).

Overall 1 data results apply to the Overall 1 measurement data and Overall 2 data results apply to the Overall 2 measurement data.

See Also

About Ch1 Overall Trace Data


Overall Phase Err  (Phase Error)  (1xEV-DO)
(Forward Direction Only)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Overall >Error Summary

Overall Phase Error (MagErr) is the difference in Phase between the I/Q measured signal and the I/Q reference signal for the Overall 1 and Overall 2 measurement data.

For more information see Phase Err (Digital Demod).

Preamble Channel Data

You can select to NOT include the Preamble data in the Overall trace data results with the "Preamble - Include in overall results" demodulation property (MeasSetup > Demod Properties > Advanced tab).

Overall 1 data results apply to the Overall 1 measurement data and Overall 2 data results apply to the Overall 2 measurement data.

See Also

About Ch1 Overall Trace Data


Overall Freq Err  (Frequency Error)  (1xEV-DO)
(Forward Direction Only)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Overall >Error Summary

Overall Frequency Error (Freq Err) shows the signal carrier frequency-error relative to the analyzer's center frequency. This parameter is displayed in Hertz and is the amount of frequency shift, from the analyzer's center frequency, that the analyzer must perform to achieve carrier lock.

Errors in RF frequency, LO frequency, or digitizer clock rate could all appear as carrier frequency error.

Preamble Channel Data

You can select to NOT include the Preamble data in the Overall trace data results with the "Preamble - Include in overall results" demodulation property (MeasSetup > Demod Properties > Advanced tab).

Overall 1 data results apply to the Overall 1 measurement data and Overall 2 data results apply to the Overall 2 measurement data.

See Also

About Ch1 Overall Trace Data


Overall IQ Offset  (1xEV-DO)
(Forward Direction Only)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Overall >Error Summary

Overall IQ Offset (also called I/Q origin offset) indicates the magnitude of the carrier feedthrough signal. When there is no carrier feedthrough, IQ offset is zero (−infinity dB).

This parameter is the same as the digital demod IQ Offset except that the source data is the Overall 1 and Overall 2 data regions. See Digital Demod IQ Offset for further information about this parameter.

Preamble Channel Data

You can select to NOT include the Preamble data in the Overall trace data results with the "Preamble - Include in overall results" demodulation property (MeasSetup > Demod Properties > Advanced tab).

Overall 1 data results apply to the Overall 1 measurement data and Overall 2 data results apply to the Overall 2 measurement data.

See Also

About Ch1 Overall Trace Data


About Trace Data (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data

This application provides trace data results in the Time Domain, Frequency Domain and Code Domain. You can view code domain power trace data for the composite signal or for a specific CDP layer (symbol rate). Time domain trace data may be viewed for the composite signal or for a specific code channel.  Pre-demodulated and demodulated Time and Spectrum trace data is also provided.

Composite Trace Data

Composite (or Comp) trace data are measurement results derived from the total signal. This includes the combined data from all code Layers (Walsh Code Lengths (Symbol Rates)) and code channels (Walsh Code Numbers).

Channel Trace Data

Channel (or Chan) trace data are measurement results derived from a single code channel (Walsh Code Number) within the measured code layer (Walsh Code Length (Symbol Rate)).

Trace Data Menu

To accommodate all the available measurement results and display formats; trace data results are grouped into trace data sub-menu categories. These sub-menu categories are grouped together by common measurement types as described below:

Ch1 trace data:	Time and Frequency trace data results derived from the pre-demodulated time record data.
Ch1 CDP trace data:	Code Domain Power and Code Domain Error trace data results for either the composite signal or for a specified code layer.
Ch1 Chan trace data:	Time domain trace data results for a single code channel.  Channel trace data results are derived from data for a single code channel (Walsh Code Number) within a specified code layer (Walsh Code Length/Symbol Rate).
Ch1 Comp trace data:	Time domain and frequency domain trace data results for the Composite signal.  Composite trace data results are derived from data for the total signal, that is, the combined data from all Walsh Code Lengths (Symbol Rates) and Walsh Code Numbers.
Ch1 Overall trace data	Error Summary data for the Overall data results.
Math:	Trace data results derived from a math function
Register:	Trace data results derived from Data Register data
No Data:	Active trace as empty.
See also

89600-Series VSA Standard Measurement Data

89600-Series VSA Standard Trace Data

About Channel Error Summary data (1xEV-DO)

About Composite Error Summary data (1xEV-DO)


About Ch1 Trace Data (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1

Time and Frequency trace data results derived from the pre-demodulated channel 1 input data (Time Record data):

Available Ch1 Trace Data

Correction

Inst spectrum

Raw Main Time

Spectrum

Time

See also

About Trace Data (1xEV-DO)

Ch1 CDP Trace Data (1xEV-DO)

Ch1 Chan Trace Data (1xEV-DO)

Ch1 Comp Trace Data (1xEV-DO)


About Ch1 CDP Trace Data (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP

CDP trace data provides composite and code layer Code Domain Power and Code Domain Error trace data results.  Code Domain Power (CDP) is an analysis of the distribution of signal power across the set of code channels normalized to the total signal power.

Note:

CDP Composite trace data results are computed from data specified by the Measurement Interval and Offset parameters.  The forward link CDP composite results are for the specified Analysis Channel (see Analysis Channel parameter).  When Preamble is selected by Analysis Channel, CDP measurements only exist for cases where the preamble length is detected to be 1024 chips.

Note

CDE Composite, reverse link, trace data results are computed from the first measured half (0.5) slot. There are no CDE forward link trace results.

•	CDP Composite Trace Data:    This is the CDP (Code Domain Power) and CDE (Code Domain Error) trace data result for the composite signal.  Composite trace data results are derived from data for the total signal. This includes the combined data from all Walsh Code Lengths (or Symbol Rates) and Walsh Code Numbers.

•	CDP Layer Trace Data:    This is the CDP (Code Domain Power) and CDE (Code Domain Error) trace data results for a specified code layer.  You use the CDP Layer Walsh Code Length drop-down list to specify the code layer (MeasSetup > Demod Properties… >  Channel/Layer tab).

TIP

You can view CDP as absolute power by clearing the IQ Normalize check box (MeasSetup, DemodProperties, Format tab).

Display Format

The data is shown in a multi-color format that assigns a unique color to each code layer and related active code channels. This makes it easy to visually identify and distinguish the active code channels (Walsh Code Number) for a given code layer (Walsh Code Length). The colors are also user definable (See Display Appearance).

Note

For CDP and CDE trace data displays with separate I/Q channel trace bars, to position the Marker to the desired Code Layer/Channel bar, you must click in close proximity to the horizontal bar that indicates the value of the code channel being measured.

Available Ch1 CDP Trace Data

CDE Composite †	Inst CDE Composite †
CDE Layer †	Inst CDE Layer †
CDP Composite	Inst CDP Composite
CDP Layer	Inst CDP Layer
†  Reverse direction Only

See also

About Trace Data (1xEV-DO)

Ch1 trace data

Ch1 Chan Trace Data (1xEV-DO)

Ch1 Comp Trace Data (1xEV-DO)


About Ch1 Chan Trace Data (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan

Time domain trace data results for a single code channel (Walsh Code Number) within a specified code layer (Walsh Code Length/Symbol Rate) for reverse direction channels only.  This includes both time domain IQ trace data and Symbol/Error table data.

Note

For 1xEV-DO demodulation, the Chan Trace Data is only available for Reverse link direction channels.

For 1xEV-DO reverse link, the "I" and "Q" branches are logically separate signals. All channel trace data results contain both I and Q branch data, except symbol table trace data. The symbol table shows either the "I" symbol bits or the "Q" symbol bits as determined by the I/Q branch setting.

Selecting a Code Channel

You specify the code channel in the Despread Channel Walsh Code Number drop-down list and the code layer in the Despread Channel Walsh Code Length drop-down list. (click MeasSetup > Demod Properties > Channel/Layer tab).

Tip

You can use the Copy Mkr To Despread Chan marker feature to automatically enter the Spread Code Length and Code Channel information for you.

Available Ch1 Chan Trace Data  (Reverse Direction Only)

Chan Error Vector Time	Chan IQ Phase Error
Chan IQ Mag Error	Chan IQ Ref Time
Chan IQ Meas Time	Chan Syms/Errs
See also

About Trace Data (1xEV-DO)

Ch1 trace data

Ch1 CDP Trace Data (1xEV-DO)

Ch1 Comp Trace Data (1xEV-DO)


About Ch1 Comp Trace Data (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp

Time domain and frequency domain trace data results for the composite signal.  The Composite signal includes data for the total signal, that is, the combined data from all code channels and layers. All composite trace data results are computed from the first time slot. The Measurement Interval and Measurement offset parameters are not used for composite trace data results.

Note

Composite, forward link, trace data results are computed from the first measured slot.  Composite, reverse link, trace data results are computed from the first measured half (0.5) slot.

Available Ch1 Comp Trace Data

Comp Error summary	Comp IQ Phase Error
Comp Error Vector Spec	Comp IQ Ref Spec
Comp Error Vector Time	Comp IQ Ref Time
Comp IQ Mag Error	Comp Inst Error Vector Spec
Comp IQ Meas Spec	Comp Inst IQ Meas Spec
Comp IQ Meas Time	Comp Inst IQ Ref Spec
See also

About Trace Data (1xEV-DO)

Ch1 trace data

Ch1 CDP Trace Data (1xEV-DO)

Ch1 Chan Trace Data (1xEV-DO)


About Overall Trace data  (1xEV-D0)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Overall

These are the Error Summary data results for the Overall 1 and Overall 2 measurement data.

Preamble Channel Data

You can select to include (or not to include) the Preamble data in the Overall trace data results with the "Preamble - Include in overall results" demodulation property (MeasSetup > Demod Properties > Advanced tab).

Available Overall 1 and Overall 2 Error Summary Data

The following data results apply for both the Overall 1 and Overall 2 measurement data:

Overall 1/2 Rho

Overall 1/2 EVM  (Error Vector Magnitude)

Overall 1/2 Mag Err  (Magnitude Error)

Overall 1/2 Phase Err  (Phase Error)

Overall 1/2 Freq Err  (Frequency Error)

Overall 1/2 IQ Offset

Additional Error Summary Data

•	About Channel Error summary Data

•	About Composite Error Summary Data

See also

About Trace Data (1xEV-DO)

Ch1 trace data

Ch1 CDP Trace Data (1xEV-DO)

Ch1 Chan Trace Data (1xEV-DO)


CDE Composite Trace Data  (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP > CDE Composite

Shows the Code Domain Error (CDE) value for each active code channel (Walsh Code Number) for all code layers (Walsh Code Lengths), along with the CDE value for each inactive code channel at the lowest code layer.  The CDE of a particular code channel is a measure of the error power in a code channel relative to the total signal power.

Note

Available only for Reverse link direction channels.

Note

CDE Composite trace data results are computed from the first measured half (0.5) slot. This is different than CDP Composite trace data results, which use Measurement Interval and Offset to determine the measurement data.

Display Format

The data is shown in a multi-color format that assigns a unique color to each code layer and related active code channels. This makes it easy to visually identify and distinguish the active code channels (Walsh Code Number) for a given code layer (Walsh Code Length). The colors are also user definable (See Display Appearance).

Note

For CDP and CDE trace data displays with separate I/Q channel trace bars, to position the Marker to the desired Code Layer/Channel bar, you must click in close proximity to the horizontal bar that indicates the value of the code channel being measured.

TIP

You can use the CDE Layer trace data to view only one code layer (Walsh Code Length) at a time.

See also

CDE Layer trace data

CDP Composite trace data

Available Ch1 CDP trace data

About 1xEV-DO trace data


CDE Layer Trace Data  (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP > CDE Layer

Shows the Code Domain Error (CDE) value for each code channel (Walsh Code Number) within the specified code layer (Walsh Code Length).  The CDE of a particular code channel is a measure of the error power in a code channel relative to the total signal power.

Note

Available only for Reverse link direction channels.

Note

CDE Composite trace data results are computed from the first measured half (0.5) slot. This is different than CDP Composite trace data results, which use Measurement Interval and Offset to determine the measurement data.

Display Format

The data is shown in a multi-color format that assigns a unique color to each code layer and related active code channels. This makes it easy to visually identify and distinguish the active code channels (Walsh Code Number) for a given code layer (Walsh Code Length). The colors are also user definable (See Display Appearance).

Note

For CDP and CDE trace data displays with separate I/Q channel trace bars, to position the Marker to the desired Code Layer/Channel bar, you must click in close proximity to the horizontal bar that indicates the value of the code channel being measured.

Selecting a Code Layer

You select the desired code layer by selecting a Walsh Code Length from the CDP Layer Walsh Code Length drop-down list (MeasSetup > Demod Properties.. > Channel/Layer tab).

See also

CDE Composite trace data

CDP Layer trace data

About Measurement Interval and Offset

Available Ch1 CDP trace data

About 1xEV-DO trace data


CDP Composite Trace Data  (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP > CDP Composite

Shows the Code Domain Power trace data for the composite signal (combined code layers and channels). Code Domain Power (CDP) is an analysis of the distribution of signal power across the set of code channels normalized to the total signal power. If the Measurement Interval is greater than one, all slots within the Measurement Interval are averaged together to produce the CDP Composite results.

Note:

CDP Composite trace data results are computed from data specified by the Measurement Interval and Offset parameters.  The forward link CDP composite results are for the specified Analysis Channel (see Analysis Channel parameter).  When Preamble is selected by Analysis Channel, CDP measurements only exist for cases where the preamble length is detected to be 1024 chips.

TIP

You can view CDP trace data as absolute power by clearing the IQ Normalize check box (MeasSetup, Demod Properties, Format tab).

Display Format

The data is shown in a multi-color format that assigns a unique color to each code layer and related active code channels. This makes it easy to visually identify and distinguish the active code channels (Walsh Code Number) for a given code layer (Walsh Code Length). The colors are also user definable (See Display Appearance).

Note

For CDP and CDE trace data displays with separate I/Q channel trace bars, to position the Marker to the desired Code Layer/Channel bar, you must click in close proximity to the horizontal bar that indicates the value of the code channel being measured.

The y-axis shows the power level and the x-axis shows the Walsh Code Number (code channel). The x-axis annotation and marker location are based on the lowest symbol rate (ksym/sec), or equivalently, the highest Walsh Code length. You can also reorder the channels so that all related code channels are displayed adjacent to each other (see Code Order).

This example shows the Ch1 Composite CDP display (code order = bit reversed) for a reverse link signal, Trace A Marker shows the following:

Symbol Rate:	307.2 Ksym/s
Walsh Code Length:	4
Walsh Code Number	2
IQ branch	Q branch
Power Level:	−0.417 dB
Asterisk *:	The asterisk (*) indicates that the marker is positioned on an active channel
Tip

You can use the CDP Layer trace data display to view only one code layer (Walsh Code Length) at a time.

See also

CDE Composite trace data

CDP Layer trace data

About Measurement Interval and Offset

Available Ch1 CDP trace data

About 1xEV-DO trace data


CDP Layer Trace Data  (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP > CDP Layer

Shows the Code Domain Power trace data for all code channels (Walsh Code Number) within the specified code layer (Walsh Code Length). If the Measurement Interval is greater than one, all slots within the Measurement Interval are averaged together to produce the CDP Layer results.

Note:

CDP Composite trace data results are computed from data specified by the Measurement Interval and Offset parameters.  The forward link CDP composite results are for the specified Analysis Channel (see Analysis Channel parameter).  When Preamble is selected by Analysis Channel, CDP measurements only exist for cases where the preamble length is detected to be 1024 chips.

TIP

You can view CDP trace data as absolute power by clearing the IQ Normalize check box (MeasSetup, Demod Properties, Format tab).

Display Format

The data is shown in a multi-color format that assigns a unique color to each code layer and related active code channels. This makes it easy to visually identify and distinguish the active code channels (Walsh Code Number) for a given code layer (Walsh Code Length). The colors are also user definable (See Display Appearance).

Note

For CDP and CDE trace data displays with separate I/Q channel trace bars, to position the Marker to the desired Code Layer/Channel bar, you must click in close proximity to the horizontal bar that indicates the value of the code channel being measured.

Selecting a Code Layer

You select the desired code layer by entering the Walsh Code Length in the CDP Layer Walsh Code Length text box (MeasSetup > Demod Properties > Channel/Layer tab).

See also

CDP Composite trace data

About Measurement Interval and Offset

Available Ch1 CDP trace data

About 1xEV-DO trace data


Channel Error Vector Time Trace Data  (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan > Error Vector Time

When 1xEV-DO Demodulation is enabled, the Error Vector Time trace data shows the time-domain error vector trace data results for the specified code channel and code layer (Spread Code Length).  Error Vector Time trace data is the computed error vector between corresponding symbol points in the I/Q measured and I/Q reference signals.  You can view the data results as Error Vector Magnitude, Error Vector Phase, only the I component or only the Q component (see Trace Data Formats below).

Note

Available only for Reverse link direction channels.

Hint

You can increase the number of symbol points by increasing the Measurement Interval(see Measurement Interval).

If normalization is OFF, the analyzer shows the instantaneous magnitude for each point. If normalization is ON, the analyzer shows the error vector as a percentage (see IQ normalize for an explanation of how this percentage is derived).

Trace Data Formats

It is important to remember that the Error Vector Time trace is a time record made up of complex, time-domain data. Each point in the time record has two components: I and Q. To make sense of the data, you must select an appropriate trace data format (Trace > Format > Format: drop--down list).

•	Linear Mag :  Shows the EVM (Error Vector Magnitude).

•	Real(I) :  Shows the I component of the error vector.

•	Imag(Q) :  Shows the Q component of the error vector.

•	Wrap Phase:  Shows the Error Vector Phase error.

For example, to see the error-vector magnitude, select the Linear Mag trace format (Trace > Format > Format: Linear Mag). Selecting Linear Mag computes the square root of the sum of the squares for each complex pair of points in the time record, which is the error-vector magnitude (EVM):

See also

About Ch1 Chan trace data (1xEV-DO)

About 1xEV-DO trace data


Channel IQ Mag Error and IQ Phase Error Trace Data  (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan > IQ Mag Error

or Trace > Data > Ch1 Chan > IQ Phase Error

When 1xEV-DO Demodulation is selected, the Chan  IQ Mag Error and Chan IQ Phase Error trace data show the vector error between the I/Q measured and the I/Q reference trace data at the sampled chip times for the specified code channel (Walsh Code Number) and code layer (Walsh Code Length).

Note

Available only for Reverse link direction channels.

Chan  IQ Mag Error trace data shows the magnitude error and Chan IQ Phase Error trace data shows the phase error for the specified code channel (Walsh Code Number).

Selecting the Code Channel and Code Layer

Select the code channel with the Despread Channel - Walsh Code Number text box (MeasSetup > Demod Properties > Channel/Layer tab).  Select the code layer with the Despread Channel - Walsh Code Length drop-down list (MeasSetup > Demod Properties > Channel/Layer tab).

Concepts

This trace data is determined just like it is for the IQ Mag Error and IQ Phase Error trace data for Digital Demodulation, see IQ Mag Error and IQ Phase Error (Digital Demod) trace data topic.

See also

About Ch1 Chan trace data (1xEV-DO)

About 1xEV-DO trace data


Channel IQ Meas Time and IQ Ref Time Trace Data  (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path:	Trace > Data > Ch1 Chan > IQ Meas Time

        or	Trace > Data > Ch1 Chan > IQ Ref Time

When 1xEV-DO Demodulation is enabled, the IQ Meas Time and IQ Ref Time traces are the demodulated time data results, sampled at the chip times, for the specified code channel (Walsh Code Number) and code layer (Walsh Code Length).  IQ Meas Time is the data results for the measured input signal.  IQ Ref Time trace data is the data results that would be derived from an ideal input signal (reference signal).

Note

Available only for Reverse link direction channels.

Concepts

The analyzer's demodulator produces two signals: I/Q Measured and I/Q Reference.

IQ measured signal

The IQ measured signal is the result of resampling the data to one point per chip and applying carrier locking, symbol locking, IQ origin offset and burst amplitude-droop compensation, filtering and system gain normalization to the incoming signal.

IQ reference signal

IQ reference signal is the ideal signal that the analyzer generates from the IQ measured signal demodulated data bits.  The analyzer detects bits from the measured IQ signal and reconstructs a sequence of ideal I and Q states. These are then treated as ideal impulses and are baseband filtered according to the reference filter and added together to form the IQ reference signal. The resultant IQ reference signal is then used compare and analyze against the IQ measured signal.

Tip

Online help for Digital Demodulation includes a block diagram that shows how I/Q measured and I/Q reference data are generated.

Time-Domain Displays

The analyzer's demodulator produces time-domain data. If you select IQ Meas time, the analyzer shows the I/Q measured signal in the time domain. Likewise, if you select IQ Ref Time, the analyzer shows the I/Q reference signal in the time domain.

The data can be displayed in a variety of trace data formats, including I-Q, Constellation, Q-Eye, I-Eye, and Trellis-Eye formats (see Trace Formats (Digital Demodulation)) topic.

If normalization is OFF, the analyzer shows the instantaneous magnitude. If normalization is ON, the analyzer scales the IQ measured and IQ reference traces to map them onto the unit circle, which yields a unitless y-axis.

Hint

For further details about normalization, see online help for IQ Normalize.

The following parameters affect how the analyzer shows the I/Q measured and I/Q reference signals:

•	Result Length determines the number of slots in the measurement.

•	Measurement Interval and Measurement Offset determine which slots will be displayed

See also

About Ch1 Chan trace data (1xEV-DO)

About 1xEV-DO trace data


Channel Syms/Errs Trace Data  (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan > Syms/Errs

When 1xEV-DO Demodulation is enabled, selecting Ch1 Chan Syms/Errs trace data shows the channel symbol table. The symbol table shows you error information and the binary bits for each symbol for the specified code channel and code layer. The bottom section of the display shows the symbol data and the upper section shows the error summary data

Note

Available only for Reverse link direction channels.

For more information see the following topics:

•	About Channel Symbol Table

•	About Channel Error Summary Data

•	Available Channel Error Summary Data

There is also composite error summary trace data (Trace > Data > Ch1 Comp > Error Summary), which provides the error information for the composite signal (see About Composite Error Summary Table).

Selecting Reverse link IQ Symbol data

For Reverse link signals, the "I" and "Q" data channels are logically separate signals. All trace data contains both the "I" and the "Q" branches of the signal, except the symbol binary bit data. The symbol data shows either the "I" or the "Q" symbol bits as specified by the I/Q channel parameter (MeasSetup > DemodProperties > Channel/Layer tab).

See also

About Ch1 Chan trace data (1xEV-DO)

About 1xEV-DO trace data


Composite Error Summary Trace Data  (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

When 1xEV-DO Demodulation is enabled, selecting the Ch1 Comp Error Summary trace data shows the composite error summary data. This is the signal quality error summary information for the composite signal.

Note

Composite, forward link, trace data results are computed from the first measured slot.  Composite, reverse link, trace data results are computed from the first measured half (0.5) slot.

For more information see the following topics:

•	About Composite Error Summary Data

•	Available Composite Error Summary Data

For the reverse link direction, there is also channel error summary trace data (Trace > Data > Ch1 Chan > Syms/Errs), which provides the error information for a specific code channel and code layer (See About Channel Error Summary Data)

See also

About Ch1 Comp trace data (1xEV-DO)

About 1xEV-DO trace data


Composite Error Vector Spec Trace Data  (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Vector Spec

When 1xEV-DO Demodulation is enabled, the composite Error Vector Spec trace data shows the spectrum of the composite Error Vector Time trace data. In other words, the analyzer derives the composite Error Vector Time trace data, and then windows and FFTs the data to produce the composite Error Vector Spectrum trace data.

Composite, forward link, trace data results are computed from the first measured slot.  Composite, reverse link, trace data results are computed from the first measured half (0.5) slot.  The Measurement Interval and Measurement Offset parameters have no effect on this measurement.

Marker Frequency Correction

The analyzer's demodulator removes carrier-frequency error. Therefore, in the composite error vector spectrum display, you must add the carrier-frequency error to marker readouts to obtain exact frequency information. The carrier-frequency error (Freq Err) is shown in the Composite Error Summary trace data.

Note

For forward link measurements, the Time-Division nature of the signal produces non-contiguous composite time data when specifying an Analysis Channel.  To include the entire slot, and therefore have useful FFT information, select the Combine TDM channels for composite results parameter.

See also

About Ch1 Comp trace data (1xEV-DO)

About 1xEV-DO trace data


Composite Error Vector Time Trace Data  (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Vector Time

When 1xEV-DO Demodulation is enabled, the Ch1 Comp Error Vector Time trace data is the error-vector, time-domain data for the composite signal.

Composite, forward link, trace data results are computed from the first measured slot.  Composite, reverse link, trace data results are computed from the first measured half (0.5) slot.  The Measurement Interval and Measurement Offset parameters have no effect on this measurement.

Concept Information

This trace data is identical to the Chan Error Vector Time trace data except that the source data is the composite signal. See the Chan Error Vector Time trace data topic for concept information.

Note

For forward link measurements, the segment of the signal included in the trace data depends on the Analysis Channel and Combine TDM channels for composite results parameter settings.

Tip

For forward link measurements, the trace background annotation indicates what segment of the 1xEV-DO frame is being analyzed. The trace display colors can be changed with the Display Appearance.properties.

See also

About Ch1 Comp trace data (1xEV-DO)

About 1xEV-DO trace data


Composite IQ Mag Error and IQ Phase Error Trace Data  (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path:	Trace > Data > Ch1 Comp > IQ Mag Error

     	or	Trace > Data > Ch1 Comp > IQ Phase Error

When 1xEV-DO Demodulation is enabled, the Ch1 Comp IQ Mag Error and Ch1 Comp IQ Phase Error trace data show the error between the I/Q measured and the I/Q reference signals for the composite signal.

Ch1 Comp IQ Mag Error shows the magnitude error and Ch1 Comp IQ Phase Error shows the phase error for the composite signal.

Composite, forward link, trace data results are computed from the first measured slot.  Composite, reverse link, trace data results are computed from the first measured half (0.5) slot.  The Measurement Interval and Measurement Offset parameters have no effect on this measurement.

Concepts

This trace data is determined just like it is for the IQ Mag Error and IQ Phase Error trace data for Digital Demodulation, see IQ Mag Error and IQ Phase Error (Digital Demod) trace data topic.

Note

For forward link measurements, the segment of the signal included in the trace data depends on the Analysis Channel and Combine TDM channels for composite results parameter settings.

Tip

For forward link measurements, the trace background annotation indicates what segment of the 1xEV-DO frame is being analyzed. The trace display colors can be changed with the Display Appearance.properties.

See also

About Ch1 Comp trace data (1xEV-DO)

About 1xEV-DO trace data


Composite IQ Meas Spec and IQ Ref Spec Trace Data  (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > IQ Meas Spec

or Trace > Data > Ch1 Comp > IQ Ref Spec

When 1xEV-DO Demodulation is enabled, Comp  IQ Meas Spec and Comp IQ Ref Spec is the spectrum of the Composite IQ Meas Time or Composite IQ Ref Time trace data respectively. The analyzer produces the spectrum by Windowing and FFTing the composite I/Q measured or composite I/Q reference signal. The spectrum represents the signal AFTER filtering.

Composite, forward link, trace data results are computed from the first measured slot.  Composite, reverse link, trace data results are computed from the first measured half (0.5) slot.  The Measurement Interval and Measurement Offset parameters have no effect on this measurement.

Note

For forward link measurements, the Time-Division nature of the signal produces non-contiguous composite time data when specifying an Analysis Channel.  To include the entire slot, and therefore have useful FFT information, select the Combine TDM channels for composite results parameter.

Marker Frequency Correction

The analyzer's demodulator removes carrier-frequency error. Therefore, in the composite error vector spectrum display, you must add the carrier-frequency error to marker readouts to obtain exact frequency information. The carrier-frequency error (Freq Err) is shown in the Composite Error Summary trace data.

Hint

By default, the analyzer shows the log(dB) magnitude when you select IQ measured spectrum. The same is true for I/Q reference.

See also

VSA Concepts (Windowing and FFTing)

About Ch1 Comp trace data (1xEV-DO)

About 1xEV-DO trace data


Composite IQ Meas Time and IQ Ref Time Trace Data  (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path:	Trace > Data > Ch1 Comp > IQ Meas Time

      or	Trace > Data > Ch1 Comp > IQ Ref Time

When 1XEV-DO Demodulation is enabled, the Comp IQ Meas Time and Comp IQ Ref Time trace data are the time data results of 1XEV-DO demodulation for the composite signal.   Comp IQ Meas Time is the data results for the measured input signal.  Comp IQ Ref Time trace data is the data results that would be derived from an ideal input signal (reference signal).

Composite, forward link, trace data results are computed from the first measured slot.  Composite, reverse link, trace data results are computed from the first measured half (0.5) slot.  The Measurement Interval and Measurement Offset parameters have no effect on this measurement.

Concepts

The analyzer's demodulator produces two signals: I/Q Measured and I/Q Reference.

IQ measured signal

The IQ measured signal is the result of resampling the data to one point per chip and applying carrier locking, symbol locking, IQ origin offset compensation, filtering and system gain normalization to the incoming signal.

IQ reference signal

I-Q reference signal is the ideal input that the analyzer generates from IQ measured signal.  The analyzer detects bits from the measured IQ signal and reconstructs a sequence of ideal I and Q states. These are then treated as ideal impulses and are baseband filtered according to the reference filter and added together to form the IQ reference signal. The resultant IQ reference signal is then used compare and analyze against the IQ measured signal.

Time-Domain Displays

The analyzer's demodulator produces time-domain data. If you select Comp IQ Meas Time, the analyzer shows the composite IQ measured signal in the time domain. Likewise, if you select Comp IQ Ref Time, the analyzer shows the composite IQ reference signal in the time domain.

The data can be displayed in a variety of trace data formats, including I-Q, Constellation, Q-Eye, I-Eye, and Trellis-Eye formats (see Trace Formats (Digital Demodulation)) topic.

Note

For forward link measurements, the segment of the signal included in the trace data depends on the Analysis Channel and Combine TDM channels for composite results parameter settings.

Tip

For forward link measurements, the trace background annotation indicates what segment of the 1xEV-DO frame is being analyzed. The trace display colors can be changed with the Display Appearance.properties.

Normalization

If normalization is OFF, the analyzer shows the instantaneous magnitude. If normalization is ON, the analyzer scales the composite IQ measured and composite IQ reference traces so that the RMS level is one, which produces a unitless y-axis.

Hint

For further details about normalization, See IQ Normalize.

See also

About Ch1 Comp trace data (1xEV-DO)

About 1xEV-DO trace data


Composite Inst Error Vector Spec Trace Data  (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Inst Error Vector Spec

Shows the instantaneous spectrum of the composite Error Vector Time trace data. Inst Error Vector Spec trace data is the non-averaged composite Error Vector Spectrum trace data.

Composite, forward link, trace data results are computed from the first measured slot.  Composite, reverse link, trace data results are computed from the first measured half (0.5) slot.  The Measurement Interval and Measurement Offset parameters have no effect on this measurement.

See also

About Ch1 Comp trace data (1xEV-DO)

About 1xEV-DO trace data


Comp Inst IQ Meas Spec and IQ Ref Spec Trace Data  (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Inst IQ Meas Spec

or Trace > Data > Ch1 Comp > Inst IQ Ref Spec

When 1xEV-DO Demodulation is enabled, the Comp Inst IQ Meas Spec and Comp Inst IQ Ref Spec trace data show you the instantaneous spectrum of the composite IQ Meas Time and composite IQ Ref Time signals respectively.  It is the non-averaged the Comp Inst IQ Meas Spec and Comp Inst IQ Ref Spec trace data (see IQ Meas Spec and IQ Ref Spec trace data).

Composite, forward link, trace data results are computed from the first measured slot.  Composite, reverse link, trace data results are computed from the first measured half (0.5) slot.  The Measurement Interval and Measurement Offset parameters have no effect on this measurement.

See also

About Ch1 Comp trace data (1xEV-DO)

About 1xEV-DO trace data


Correction Trace Data  (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 > Correction

Shows the correction trace derived by the analyzer from the calibration data. The correction trace is applied to the acquired data to compensate for phase and magnitude anomalies in the analyzer's hardware and software signal processing.

See also

About Calibration

Ch1 trace data

About 1xEV-DO trace data


Inst CDE Composite Trace Data  (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP > Inst CDE Composite

Shows the Instantaneous Code Domain Error trace data for the composite signal. Inst CDE Composite trace data is the non-averaged CDE Composite trace data (see CDE Composite trace data).

Note

CDE Composite trace data results are computed from the first measured half (0.5) slot. This is different than CDP Composite trace data results, which use Measurement Interval and Offset to determine the measurement data.

Note

Inst CDE Composite trace data is not affected by averaging.

See also

About Averaging

Available Ch1 CDP trace data

About 1xEV-DO trace data


Inst CDE Layer Trace Data  (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP > Inst CDE Layer

Shows the Instantaneous Code Domain Error trace data for all active code channels (Walsh Code Number) within the specified code layer (Walsh Code Length). Inst CDE Layer trace data is the non-averaged CDE Layer trace data (see CDE Layer trace data).

Note

CDE Composite trace data results are computed from the first measured half (0.5) slot. This is different than CDP Composite trace data results, which use Measurement Interval and Offset to determine the measurement data.

Note

Inst CDE Layer trace data is not affected by averaging.

Selecting a Code Layer

You select the desired code layer by selecting a Walsh Code Length from the CDP Layer Walsh Code Length drop-down list (MeasSetup > Demod Properties.. > Channel/Layer tab).

See also

About Averaging

Available Ch1 CDP trace data

About 1xEV-DO trace data


Inst CDP Composite Trace Data  (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP > Inst CDP Composite

Shows the Instantaneous Code Domain Power trace data for the Composite signal. It is the non-averaged CDP Composite trace data (see CDP Composite trace data).

Note:

CDP Composite trace data results are computed from data specified by the Measurement Interval and Offset parameters.  The forward link CDP composite results are for the specified Analysis Channel (see Analysis Channel parameter).  When Preamble is selected by Analysis Channel, CDP measurements only exist for cases where the preamble length is detected to be 1024 chips.

Note

Inst CDP Composite trace data is not affected by averaging.

See also

About Averaging

Available Ch1 CDP trace data

About 1xEV-DO trace data


Inst CDP Layer Trace Data  (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP > Inst CDE Layer

Shows the Instantaneous Code Domain Power trace data for all active code channels (Walsh Code Number) within the specified code layer (Walsh Code Length). It is the non-averaged CDP Layer trace data (see CDP Layer trace data).

Note:

CDP Composite trace data results are computed from data specified by the Measurement Interval and Offset parameters.  The forward link CDP composite results are for the specified Analysis Channel (see Analysis Channel parameter).  When Preamble is selected by Analysis Channel, CDP measurements only exist for cases where the preamble length is detected to be 1024 chips.

Note

Inst CDP Layer trace data is not affected by averaging.

Selecting a Code Layer

You select the desired code layer by entering the Walsh Code Length in the CDP Layer Walsh Code Length text box (MeasSetup > Demod Properties > Channel/Layer tab).

See also

About Averaging

Available Ch1 CDP trace data

About 1xEV-DO trace data


Inst Spectrum Trace Data  (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Inst Spectrum

Shows the instantaneous spectral display of the pre-demodulated Time trace data.  It is the non-averaged Spectrum trace data.

If averaging is on, the Instantaneous Spectrum does not show the effects of averaging. To see the effects of averaging, use the Spectrum trace data.

VSA signal flow (see Digital Demodulation Block Diagram):

See also

VSA Concepts (Windowing and FFTing)

About Averaging

Ch1 trace data

About 1xEV-DO trace data


Raw Main Time Trace Data  (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 > Raw Main Time

Raw Main Time is the raw data read from the input hardware or playback file. For more information about this data (see Raw Main Time (Digital Demod) trace data.

VSA signal flow (see Digital Demodulation Block Diagram):

See also

Ch1 trace data

About 1xEV-DO trace data


Spectrum Trace Data  (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 > Spectrum

Shows the spectral display of the pre-demodulated Time data. The Time data is Windowed and FFTed to create the Spectrum display (see VSA Concepts).

If averaging is on, Spectrum trace data is the averaged Instantaneous Spectrum trace data. When averaging is set to zero, the Spectrum trace data is equal to the Inst Spectrum trace data.

VSA signal flow (see Digital Demodulation Block Diagram):

See also

About Averaging

Ch1 trace data

About 1xEV-DO trace data


Time Trace Data  (1xEVDO)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 > Time

When 1xEV-DO demodulation is enabled, the Time trace shows the time record before demodulation, as shown in the following block diagram.

VSA signal flow (see Digital Demodulation Block Diagram):

The Time trace has the following characteristics:

•	It is pre-demodulated time data.

•	It is unaffected by time averaging.

•	The length and offset are determined by the Measurement Interval and Measurement Offset parameters.

See also

Ch1 trace data

About 1xEV-DO trace data


About Opt B7N: TD-SCDMA  Demodulation

Option B7N: "3G Modulation Analysis" adds TD-SCDMA (Time Division - Synchronous Code Domain Multiple Access) demodulation capability to your 89600-Series application software. The TD-SCDMA option provides modulation analysis for China Wireless Telecommunication Standard: 3G digital cellular telecommunications system; TD-SCDMA System for Mobile (TSM) (see TD-SCDMA Overview) compliant signals:

Demodulation      Format	Specification
TSM	CWTS TSM v 3.0.0 CWTS TSM v 2.0.0†
	†with symbol conversion
With TD-SCDMA you can descramble, despread and demodulate TD-SCDMA modulated signals, both uplink and downlink directions.  The analyzer's demodulator parameters are user-definable, giving you the ability to customize the analyzer to measure and analyze non-ideal signals. User-definable parameters include the chip rate, filter alpha, Active Slot Threshold, downlink/uplink pilot codes, scramble codes, midamble base codes and more (see TD-SCDMA Demodulation Properties).

The digital demodulator used in this analyzer incorporates advanced technology that does not require coherent carrier signals or symbol-clock timing signals. The analyzer has a built-in root raised-cosine filter, with user definable alpha (defines roll-off factor for chip shaping).

Along with typical digital demodulation trace data results, TD-SCDMA provides many unique Time Domain, Frequency Domain and Code Domain trace data results including the following:

•	Time data analysis: CCDF, CDF and PDF trace data for an individual timeslot and sub-frame.

•	Analysis Time and Analysis Spec trace data allow you to show the time and frequency data for individual timeslots.

•	The Overall trace data allows you to show time data for the entire sub-frame.

For an overview of all the available trace data results see the "About Trace Data" topic.

There are also three numeric error summary tables, each provide various summary and error information for different segments of the TD-SCDMA signal:

•	The Overall Error Summary table provides chip timing error data, Total power, Data power and Midamble power for each timeslot within the specified sub-frame.

•	The Composite Error Summary table provides error data for the composite signal for a specific timeslot and sub-frame.

•	The Channel Error Summary table provides error data for an individual code channel and layer for a specified timeslot and sub-frame.

If you have an 89610 Vector Signal Analyzer, an optional second baseband channel allows IQ baseband measurement capability. You can also perform IQ baseband measurements on data that is from a file or the stream interface.

See also

TD-SCDMA Modulation Overview

TD-SCDMA Available features

Setting up a TD-SCDMA measurement

Selecting TD-SCDMA Demodulation

About 89600 Optional Measurement Software


TD-SCDMA Modulation Overview

Principles of TD-SCDMA (Time Division Synchronous Code Domain Multiple Access)

TD-SCDMA (Time Division Synchronous Code Domain Multiple Access) is a multiple access technology, which is a combination of code division multiple access (CDMA) and time division multiple access (TDMA).  TDD (Time Division Duplexing) is used in TD-SCDMA to separate the uplink and downlink.  The frame length (or the TDD interval) of TD-SCDMA is 5 ms and the whole frame is divided into downlink and uplink by the two switching points.  Both the uplink and downlink periods are divided into time-slot and the total number of time-slots is 7.  The ratio for uplink/downlink can be re-configured to provide symmetric or asymmetric data services.  Within each time slot, the CDMA is implemented with the maximum spreading factor of 16.  In other words, up to 16 code channels can be within the same time-slot.

In TD-SCDMA the CDMA chip rate is 1.28 Mcps and each carrier occupies 1.6 MHz bandwidth.

Resource Unit (RU)

Compared with GSM, the smallest unit in the frame of TD-SCDMA is the basic Resource Unit (RU), which is defined by frequency, time-slot (TS), and code channel with spreading factor. The basic RU uses a spreading factor of 16. Notice that halving the Spreading Factor doubles the number of RU's.

TD-SCDMA Frame Structure at 1.28Mcps

All physical channels utilize a three-layer structure comprising Super frame, radio frame and Sub-frame.

•	Time Slot (TS): 7 total Time Slots (0 through 6),  864 chips in duration.

•	Uplink (UL) and Downlink (DL) time slots are separated by switching points. There are two switching points per sub-frame. One switch point is fixed at the end of TS0, the other may be moved to the end of any other time slot.

•	TS0 is always allocated as downlink.

•	TS1 is always allocated as uplink.

•	Three special Time Slots (TS):

−	DwPTS: Downlink Pilot Time Slot, 96 chips

−	UpPTS: Uplink Pilot Time Slot, 160 chips.

−	GP: main Guard Period for TDD operation, 96 chips

•	The system supports symmetric and asymmetric mode by properly configuring the number of DL and UL time slots.

A physical channel is defined by frequency, timeslot, channelization code, burst type and Radio Frame allocation. The scrambling code and the basic midamble code are broadcast and may be constant within a cell.  When a physical channel is established, a start frame is given.  The physical channels can either be of infinite duration or finite duration, defined for the given allocation.

TD-SCDMA Burst Structure

A physical channel in TDD is a burst, which is transmitted in a particular timeslot within allocated Radio Frames. The allocation can be continuous or discontinuous.  A burst is the combination of two data symbol fields, a midamble and a guard period. The duration of a burst is one timeslot. Several bursts can be transmitted at the same time from one transmitter. In this case, the data part must use different OVSF (orthogonal variable spreading factor) channelization codes, but the same scrambling code.  The midamble part has to use the same basic midamble code, but can use different midamble shifts.

The data part of the burst is spread with a combination of channelization code and scrambling code.  The channelization code is an OVSF code, which can have a spreading factor of 1, 2, 4, 8 or 16. The data rate of the physical channel depends upon the used OVSF code and spreading factor.

The following figure shows a typical TD-SCDMA Frame Structure for a traffic time slot including the symbol numbering convention. It assumes a Spreading Factor of 1 and Data fields containing 352 symbols each.

•	Time Slot (Burst):

−	Each time slot is 675 us, 864 chips.

•	Data Symbols:

−	Two Data fields at 352 chips each. The number of symbols depend on the Spreading Factor.  May include optional TPC power control bits, TFCI bits and uplink SS  (synchronization shift) synchronization bits.

•	GP (Guard Period):

−	16 chips, used to avoid time slot multi-path interference

•	Midamble field:

−	144 chips formed from one of 128 basic midamble sequences with 128 chips each.

−	The 128 sequences are divided into 32 groups corresponding to 32 SYNC-DL codes.

−	Each group consists of 4 different basic midamble sequences.

−	Basic midamble sequences are used as training sequences for:

•	Channel estimation for uplink and downlink.

•	Power measurements.

•	Maintaining uplink synchronization.

DwPTS:  Downlink Pilot Time Slot

−	Used for DL synchronization and cell initial search.

−	96 chip length: 32 chips for GP, 64 synchronization.

−	The GP used to avoid Interference between the last DL traffic TS and the DL sync pilot burst.

−	32 different SYNC-DL group codes, used to distinguish base stations.

−	Transmitted radially in all direction with no beam forming capability.

UpPTS:  Uplink Pilot Time Slot

−	Used for UL initial synchronization, random access and measurement for adjacent cell handoff.

−	160 chip length: 128 for SYNC, 32 for GP

−	The GP fields are used to separate the UL pilot from the traffic UL time slot.

−	There are 256 different SYNC codes, which can be divided into 32 groups and each group includes 8 different SYNC codes, i.e., each base station has 8 different SYNC codes.

−	BTSC gets initial beam forming parameters from the UL terminal signal.

Code/ID Allocation (see Code/ID Tab - TD-SCDMA Demodulation Properties)

There are 32 possible code groups and 32 SYNC-DL sequences. Each SYNC-DL code corresponds to a group of 4 different basic midamble codes for a total of 128 non-overlapping midamble codes. The basic midamble code divided by 4 determines the SYNC-DL code number. The same basic midamble code is used throughout the frame and is associated with a corresponding scramble code (128 total).

Each code group associates 8 different SYNC-UL codes per code group for a total of 256 different SYNC-UL code sequences (32 * 8).

This table shows the relationship between the SYNC-DL and SYNC-UL sequences, the scrambling codes and the midamble codes for each code group.

•	Downlink Pilot Code ID:  Downlink Pilot Synchronization is used for DL synchronization and cell initial search. There are 32 different SYNC-DL group codes, which are used to distinguish base stations.

•	Uplink Pilot Code ID: Uplink Pilot Synchronization (UpPTS) is used for UL initial synchronization, random access and measurement for adjacent cell handoff.  There are 256 different SYNC codes, which can be divided into 32 groups and each group includes 8 different SYNC codes, i.e., each base station has 8 different SYNC codes.

•	Scramble Code ID: Scrambling codes are cell specific and are used to identify separate cells.  There are 128 different scrambling codes, which are associated with a corresponding basic midamble code.

•	Basic Midamble code ID: Basic Midamble code ID's are training sequences for uplink and downlink channel estimation, power measurements and maintaining uplink synchronization. There are 128 different sequences divided into 32 groups corresponding to 32 SYNC-DL codes.  Each group consists of 4 different basic midamble sequences, i.e. each BS has 4 different midambles.

Modulation of the SYNC-DL

The SYNC-DL sequence are modulated with respect to the midamble in time slot 0.

Four consecutive phases (phase quadruple) of the SYNC-DL are used to indicate the presence of the P-CCPCH (Primary Common Control Channel) in the following 4 sub-frames. In case the presence of a P-CCPCH is indicated, the next following sub-frame is the first sub-frame of the interleaving period. As QPSK is used for the modulation of the SYNC-DL, the phases 135, 45, 225, 135 and 315, 225, 315, 45 are used.

The total number of phase quadruples is 2 (S1 and S2). A quadruple always starts with an even system frame number ((SFN mod 2) = 0).

Table:    Sequence for the phase modulation for the SYNC-DL

Name	Phase   Quadruple	Meaning
S1	135, 45, 225, 135	There is a P-CCPCH in the next four frames.
S2	315, 225, 315, 45	There is no P-CCPCH in the next four frames.


Available Features (TD-SCDMA)

Features applicable to TD-SCDMA demodulation:

•	Standard Demodulation preset:

−	TSM:  China Wireless Telecommunication Standard: 3G digital cellular telecommunications system: TD-SCDMA System for Mobile

•	1.28 MHz variable (user definable) chip rate.

•	Single code domain layer or composite code-domain power and code-domain error displays (the composite display shows all code layers simultaneously). You can normalize code-domain power to display the code-domain power relative to the total signal power in the code domain.

•	Single channel time-domain displays, such as IQ measured, IQ reference, IQ magnitude/phase error, and error vector traces.

•	Composite time-domain displays, such as IQ measured time, IQ magnitude or phase error, and error Vector time traces.

•	Adjustable filter Alpha (default 0.22)

•	Mirrored (flipped) frequency spectrums can be used to remove the effects of high-side mixing.

•	Measurement offset and interval (similar to time gating) used to select specific data slots for analysis

•	Time gating is not available (does offer measurement offset/interval feature)

•	Averaging is available only for code domain trace data and is only applied to the numeric error summary data in the symbol table, as follows:

−	rms (video) - computes an average of each rms error update in the table.

−	rms exponential - is like rms (video) except that averaging continues past the average count with an exponential weighting.

−	continuous peak hold - keeps track of the peak rms error of each update in the table.

−	Time and time exponential averaging are not available.

•	Average types available for the pre-demodulated spectrum, code domain power and code domain error trace data results.

−	rms (video)

−	rms exponential

−	continuous peak hold)

•	Features that are applicable to Digital Demod but not available with TD-SCDMA demodulation:

−	Measurement/Reference filter

−	Pulse and Sync search

−	Equalization Filter

See also

89600-Series VSA Standard Features

Setting up a TD-SCDMA measurement

About VSA Optional Features

About Opt B7N: TD-SCDMA Demodulation


Setting Up a Measurement (TD-SCDMA)

(Vector Signal Analyzer application only)

When setting up a TD-SCDMA demodulation measurement, there are several things you need to consider. This topic tells you how to connect your signal to an 89600-series analyzer and successfully demodulate TD-SCDMA signals. The information is provided in this order:

Connecting Your Signal to the Analyzer

The analyzer lets you connect your carrier signal or, if your 89600-series analyzer has two baseband input channels, the raw I (In-phase) and Q (Quadrature-phase) signals.

For all receiver configurations except I + jQ, connect your signal to Channel 1. In this case, the analyzer assumes that the carrier signal contains both the I and Q components. If your analyzer has two input channels, the analyzer ignores the second input channel.

If your analyzer has a second input channel, you can also connect the raw I (In-phase) and Q (Quadrature- phase) signals. To do this, select Input, Channels, I + jQ. With this configuration, the analyzer removes the quadrature mixer from the demodulator's signal flow, which lets you connect the I component of your signal to Channel 1; the Q component to Channel 2.

Notes

1) Selecting I+jQ turns on DC coupling.

2) When using I+jQ, use external calibration to correct for any offset or gain imbalance between the I and Q signals.

3) Ranges for Channel 1 and Channel 2 are set independently.

Connecting to an Agilent ESA analyzer

Due to ESA memory limitations, and demodulation algorithm latency requirements, the 89600 VSA software is not able to perform TD-SCDMA demodulation at all when the ESA is in the alias-protected mode.  When the ESA is in the non-alias protected mode, this also limits the result length to 5 sub-frames with a Start Boundary of "Sub-frame" and 2 sub-frames with a Start Boundary of "2 Frames".  This 2 sub-frame limitation on results synchronized to 2 frame boundaries can be removed by supplying an external 2-frame trigger and setting the Start Boundary to "Sub-frame".  The trigger delay can then be used to adjust where the boundary is located within the Result Length (see ESA Setup).

Center Frequency

The analyzer's center frequency must be set within approximately ±500 Hz of the carrier frequency of the TD-SCDMA ( signal, otherwise the analyzer may not be able to lock onto your signal.

Frequency Span

When selecting a frequency span, select the narrowest span that includes all of your signal components (select a span that is slightly larger than the bandwidth of your signal). If you select a span that is too narrow, your measurement may have excessive errors or the analyzer may lose carrier lock. If the span is less than the chip rate * (1+filter alpha), the analyzer displays "DATA?" to indicate that the results may not be accurate.

For best results, the frequency span should be set according to the following formula (filter alpha is the filter characteristic of the Nyquist filter used to demodulate the TD-SCDMA signal):

Frequency Span ≥ (1 + Filter alpha) × Chip Rate

If you select a span that is too wide, your measurement may be affected by excessive noise and slower speed.

Using the "Preset to Default" configuration settings will select a default span that should work well.

Input Range

The input range must be set correctly to obtain accurate measurements. Input ranges that are too low overload the analyzer's ADC. Input ranges that are too high increase noise, which increases errors reported in error summary data, such as EVM.

Code/ID Parameters

You must set the Code/ID parameters to the system values to demodulate the test signal (see Code Allocation Overview):

•	Downlink Pilot code ( SYNC-DL ID) (if active)

•	Uplink Pilot code (SYNC-UL ID) (if active)

•	Scramble code

•	Basic Midamble code

Traffic Timeslots

The Max Users (K) parameter must be set for each active timeslot to demodulate the test signal.

Chip Rates, Symbol Rates and Spread Code Length

To successfully demodulate TD-SCDMA signals, the analyzer chip rate must match the chip rate of your TD-SCDMA signal. The "Preset to Default" demodulation property will set the chip rate as required for the selected TD-SCDMA modulation format.

Result Length

Result Length determines the time capture length of the input signal that the analyzer demodulates in terms of the number of sub-frames. Make sure that the result length is long enough to capture all the desired data.

Filtering

For TD-SCDMA demod, the measurement filter is a root-raised cosine filter with user definable alpha capability (default alpha value = 0.22). This differs from the filtering capabilities available with either digital demod or Video demodulation. With those two demod types you had the option of selecting a measurement and reference filter, not available for TD_SCDMA demodulation (see Digital Demod "About Filters topic).

Mirrored Spectrum

TD-SCDMA demodulation provides a feature that lets you configure the analyzer's demodulator to conjugate the complex time-domain waveform. This has the effect of flipping the spectrum around the analyzer's center frequency. This feature is useful when the TD-SCDMA signal is inverted, or flipped due to an IF down conversion.

Triggered Measurements

When making triggered measurements, the demodulation algorithm requires some amount of data prior to the beginning of the desired sub-frame, in order for demodulation to begin on that sub-frame.  This is handled internally but if there are delay differences between the sub-frame boundary in the incoming signal and the trigger then the Trigger Delay may need to be adjusted in order to supply enough data before the beginning of the sub-frame.  For instance, if an external trigger occurs 20 us after the beginning of the desired sub-frame then Trigger Delay would need to be set to -20 us.

Averaging

Averaging is available only for code domain data and is applied to numeric error data in the symbol table, as follows:

−	rms (video)—computes an average of each rms error update in the table.

−	rms exponential—is like rms (video) except that averaging continues past the average count with an exponential weighting.

−	continuous peak hold—keeps track of the peak rms error of each update in the table.

−	Time and time exponential averaging are not available.

The following average types are available for the pre-demodulated spectrum result:

−	rms (video)

−	rms exponential

−	continuous peak hold

See also

Selecting TD-SCDMA Demod

About Opt B7N: TD-SCDMA Demodulation

Troubleshooting TD-SCDMA


Measurement Speed Considerations (TD-SCDMA)

The primary factor in the measurement speed for TD-SCDMA measurements is the amount of input data that must be processed. Reducing the result length is the best way to increase speed.

See also

Setting Up a TD-SCDMA Measurement

Selecting TD-SCDMA Demod

About Opt B7N: TD-SCDMA Demodulation

Troubleshooting TD-SCDMA


Selecting TD-SCDMA Demodulation

(Vector Signal Analyzer application with option B7N only)

Menu Path: MeasSetup > Demodulator > 3G Cellular > TD-SCDMA

Sets the analyzer to demodulate TD-SCDMA modulated signals.

After selecting the demodulator you need to set the configuration parameters. You can use the Preset to Default Format property to automatically set the configuration parameters or you can manually set them from the Demod Properties dialog box.

It's also recommended that you review the Setting up a TD-SCDMA Measurement topic before setting these parameters.

Connecting to an Agilent ESA analyzer

Due to ESA memory limitations, and demodulation algorithm latency requirements, the 89600 VSA software is not able to perform TD-SCDMA demodulation at all when the ESA is in the alias-protected mode.  When the ESA is in the non-alias protected mode, this also limits the result length to 5 sub-frames with a Start Boundary of "Sub-frame" and 2 sub-frames with a Start Boundary of "2 Frames".  This 2 sub-frame limitation on results synchronized to 2 frame boundaries can be removed by supplying an external 2-frame trigger and setting the Start Boundary to "Sub-frame".  The trigger delay can then be used to adjust where the boundary is located within the Result Length (see ESA Setup).

Note

There are special limitations when connected to an Agilent ESA analyzer, for specific information see  ESA Setup

See also

Using Standard Presets

Setting Up a TD-SCDMA Measurement

Measurement speed and resolution considerations

TD-SCDMA modulation overview

About Opt B7N: TD-SCDMA Demodulation

Troubleshooting TD-SCDMA

Tutorial for TDSCDMA


Using a TD-SCDMA Standard Setup

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Format tab > Preset to Default button

Click Preset to Default to set the analyzer to demodulate and analyze a TSM compliant, TD-SCDMA, modulated signal. The following table provides a list of the parameters and settings that are set when using the Preset to Default property:

Note

The TD-SCDMA demodulator must be selected before these Standard Presets are available.

Preset to Default

Parameter	TSM †
Span	1.6 MHz
Chip Rate	1.28 MHz
Alpha	0.22
Normalize	Selected
Mirror Frequency Spectrum	OFF
Downlink Pilot SYNC code	0
Uplink Pilot SYNC code Code Group	0 selected
Scramble Code Code Group	0 selected
Basic Midamble Code Group	0 selected
Traffic Timeslot (TS): Max Users (K) Timeslot	16 (All 7 TS's) TS0
Despread Channel: Spread Code Length Code Channel	16 (80 kHz) 0
CDP Layer: Spread Code Length	16 (80 kHz)
Result Length	1 sub-frame
Start Boundary	Sub-frame
Time Reference	DwPTS (Downlink PTS)
Analysis Time Slots	TS0
	†  China Wireless Telecommunication Standard: 3G digital cellular telecommunications system; TD-SCDMA System for Mobile,  CWTS TSM 05.04 v 3.0.0
See also

TD-SCDMA Demodulation Properties dialog box

Setting Up a TD-SCDMA Measurement

Measurement speed and resolution considerations

TD-SCDMA modulation overview

About Opt B7N: TD-SCDMA Demodulation

Troubleshooting TD-SCDMA


Troubleshooting (TD-SCDMA)

(Vector Signal Analyzer application only)

This topic contains information to help you troubleshoot measurements when using TD-SCDMA Demodulation. You should also review the "Setting up a TD-SCDMA Measurement" topic for additional measurement information.

PROBLEM	POSSIBLE CAUSE	SOLUTION
Demodulation fails to lock-on to signal	Signal not present	Check test setup connections
	Carrier too far from center frequency	Adjust center frequency to ± 500 Hz of the carrier frequency
	Input signal is over-loaded or under ranged	Adjust input range
	Frequency span is too narrow	Increase frequency span
	Incorrect Chip Rate	Enter the correct chip fate (not symbol or  bit rate)
	No Pilot Channel: missing or level to low	Set pilot channel at Walsh Code Number Zero. Try adjusting pilot channel power level.
	TD-SCDMA signal spectrum is inverted	Check the Mirror Frequency Spectrum setting (MeasSetup > Demodulator > Format tab).
	I/Q Offset too large	Reduce the LO feedthrough  (or DC Offset for I+jQ receiver)
Wrong channel marked as active	Poor SNR (signal to noise ratio).	Increase signal power or remove cause of noise/distortion.
	All bits not transmitted within a physical channel.	Transmit all bits within a physical channel, or select code-domain power for the layer associated with the physical channel of interest (single-layer code-domain power displays are accurate even if the analyzer is unable to identify active channels in the composite code-domain power display).
	Data pattern induces large disparity in power between slower channels overlaid by the channel of interest.	Verify that your transmitter is transmitting properly.
ADS application has failed to work with TD-SCDMA demodulation	See Troubleshooting ADS measurements
See also

Setting Up a TD-SCDMA Measurement

Measurement speed and resolution considerations

About Opt B7N: TD-SCDMA Demodulation

VSA error and status messages

VSA Troubleshooting Topics


TD-SCDMA Demodulation Properties Dialog Box

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties

The TD-SCDMA Demodulation dialog box contains parameters that let you configure the analyzer to descramble, despread and demodulate TD-SCDMA modulated signals.

Note

The TD-SCDMA demodulator must be selected before this dialog box is accessible. To enable the demodulator, click MeasSetup > Demodulator > 3G Cellular > TD-SCDMA.

The TD-SCDMA Demodulation Properties dialog box contains tab headings that group similar configuration parameters as follows:

•	Format tab: These properties are used to configure the analyzers TD-SCDMA demodulator. The parameters include: Chip Rate, filter Alpha, Active Slot Threshold and Mirror Frequency Spectrum parameters.  The Normalize parameter is also accessed on this tab.

•	Code/ID tab: These properties specify the TD-SCDMA code allocation parameters including: Downlink Pilot, Uplink Pilot, Scramble and Basic Midamble codes.  Also, the Traffic Timeslots configuration, Max Users (K) parameter, is located here.

•	Channel/Layer tab: These properties specify the Despread Channel (code channel and code layer) parameters and CDP Layer (code layer) parameters used to configure the Channel Trace Data and CDP Trace Data displays respectively.  You can reconfigure these parameters and get new trace data results without the need to acquire new data.  The new data results are re-computed from the current data record.

•	Time tab: These properties configure the data analysis parameters including: Result Length, Start Boundary, Time Reference, Analysis Timeslot and Analysis Sub-frame parameters. You use these parameters to specify what segment of the time record that will be used for data analysis and trace data results. You can reconfigure these parameters and get new trace data results without acquiring new data.  The new data results are re-computed from the current data record, except on the first occurrence. On the first occurrence, the trace data results are computed from the Analysis Timeslot and Analysis Subframe settings.

See also

Selecting TD-SCDMA demodulator

Setting up a TD-SCDMA Measurement

Troubleshooting TD-SCDMA

TD-SCDMA Modulation Overview


Channel/Layer Tab (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties

These properties allow you to specify the Despread Channel (code channel and code layer) parameters and CDP Layer (code layer) parameters used to configure the Channel Trace Data and CDP Trace Data displays respectively.

You can reconfigure these parameters and get new trace data results without the need to acquire new data.  The new data results are re-computed from the current data record.

•	Despread Channel parameters: Lets you specify the timeslot and code channel with spreading factor that is used for the channel measurement data results which include: Chan Error Vector, Chan IQ Meas Time, Chan IQ Ref Time, Chan Mag Error, Chan Phase Error and Chan Syms/Errs trace data (Click on the parameter name for further information):

−	Spread Code Length (Despread Channel)

−	Code Channel (Despread Channel)

•	CDP Layer parameters: Lets you specify the active (displayed) code domain layer for the Code Domain Power (CDP) Layer and Code Domain Error (CDE) Layer trace data:

−	Spread Code Length (Despread Channel)

See Also

Code/ID Tab (TD-SCDMA Demodulation Properties)

Time Tab (TD-SCDMA Demodulation Properties)

Format Tab (TD-SCDMA Demodulation Properties)

TD-SCDMA Demodulation Properties Dialog Box


Code/ID tab (TSCDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties

These properties specify the TD-SCDMA code allocation parameters including: Downlink Pilot, Uplink Pilot, Scramble and Basic Midamble codes.  Also, the Traffic Timeslots configuration, Max Users (K) parameter, is located here.

The Format tab dialog box lets you configure these parameters (Click on the parameter name for further information):

•	Downlink Pilot

•	Uplink Pilot

−	Code Group

•	Scramble

−	Code Group

•	Basic Midamble

−	Code Group

•	Traffic Timeslots

−	Max Users (K)

−	for Timeslot

See Also

TD-SCDMA - Code/ID Allocation Overview

TD-SCDMA Modulation Overview

Channel/Layer Tab (TD-SCDMA Demodulation Properties)

Time Tab (TD-SCDMA Demodulation Properties)

Format Tab (TD-SCDMA Demodulation Properties)

TD-SCDMA Demodulation Properties Dialog Box


Format Tab (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties

These properties are used to configure the analyzers TD-SCDMA demodulator. The parameters include: Chip Rate, filter Alpha, Active Slot Threshold and Mirror Frequency Spectrum parameters.  The Normalize parameter is also accessed on this tab

The Format tab dialog box lets you configure these parameters (Click on the parameter name for further information):

•	Active Slot Threshold

•	Alpha

•	Chip Rate

•	Normalize

•	Mirror Frequency Spectrum

•	Preset to Default

See also

Channel/Layer Tab (TD-SCDMA Demodulation Properties)

Code/ID Tab (TD-SCDMA Demodulation Properties)

Time Tab (TD-SCDMA Demodulation Properties)

TD-SCDMA Demodulation Properties Dialog Box

TD-SCDMA Modulation Overview


Time Tab (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup. DemodProperties

These properties configure the data analysis parameters. You use these parameters to specify what segment of the time record  (captured input signal) that will be used for data analysis and trace data results.

You can reconfigure these parameters and get new trace data results without acquiring new data.  The new data results are re-computed from the current data record, except on the first occurrence. On the first occurrence, the trace data results are computed from the Analysis Timeslot and Analysis Subframe settings.

The Time tab dialog box lets you configure these parameters (Click on the parameter name for further information):

•	Analysis Sub-frame

•	Analysis Timeslot

•	Start Boundary

•	Result Length

•	Time Reference

See also

Channel/Layer Tab (TD-SCDMA Demodulation Properties)

Code/ID Tab (TD-SCDMA Demodulation Properties)

Format Tab (TD-SCDMA Demodulation Properties)

TD-SCDMA Demodulation Properties Dialog Box

TD-SCDMA Modulation Overview


Active Slot Threshold  (TD-SCDMA)

Menu Path: MeasSetup > Demod Properties > Format tab

Default: -30dBc (See TD-SCDMA Standard Presets Table )

Range:   -120 to 0dBc

Lets you set the Active Slot detection threshold, dB below the slot with the largest measured power.

See Also

Format Tab (TD-SCDMA)

Demod Properties Dialog Box (TD-SCDMA)


Alpha  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Format tab

Default: 0.22 (See TD-SCDMA Standard Presets Table )

Range: .05 to 1.0

Lets you set the measurement filter (Root-raised Cosine) alpha.

For more information, see "About Filters and "Alpha/BT.

See Also

Format Tab (TD-SCDMA)

Demod Properties Dialog Box (TD-SCDMA)


Basic Midamble

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Code/ID tab

Default: 0 (See TD-SCDMA Standard Presets Table)

Range: 0 to 127

Lets you specify the Basic Midamble code ID. Basic Midamble code ID are training sequences for uplink and downlink channel estimation, power measurements and maintaining uplink synchronization (see TD-SCDMA - Code/ID Allocation Overview ).

Code Group:  Controls the allowable Basic Midamble ID sequence coding criteria as follows:

Selected:	Only allows Basic Midamble ID sequences that comply with standard coding allocation criteria.

Cleared:	Allows non-standard Basic Midamble ID sequence allocation.

See Also

Uplink Pilot Code ID parameter

Scrambling Code ID parameter

Downlink Pilot Code ID parameter

TD-SCDMA Modulation Overview

Code/ID Tab (TD-SCDMA)

TD-SCDMA Demod Properties dialog box


Chip Rate   (TD-SCDMA)

Menu Path: MeasSetup > Demod Properties > Format tab

Default: 1.28 MHz (See TD-SCDMA Standard Presets Table )

Range:   minimum span to (10 * maximum span)

Lets you set the Chip Rate for the analyzer's demodulator. This allows you the freedom to enter nonstandard chip rates for test and analysis purposes.

Note

To demodulate a signal, the chip rate must match the chip rate of your system.

See Also

Format Tab (TD-SCDMA)

Demod Properties Dialog Box (TD-SCDMA)


Code Channel   (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Channel/Layer tab

Default: 0, see TD-SCDMA Standard Presets Table

Lets you set the Despread Channel - Code Channel. The Despread Channel - Code Channel is used, along with the Despread Channel - Spread Code Length, to specify the active code channel and layer used for the channel trace data measurement results (Including: Chan Error Vector, Chan IQ Meas Time, Chan IQ Ref Time, Chan Mag Error, Chan Phase Error and Chan Syms/Errs trace data results).

Tip

You can use the Copy Mkr To Despread Channel marker feature to automatically enter the Spread Code Length, Code Channel and IQ Branch setting.

See Also

Channel/Layer Tab (TD-SCDMA Demodulation Properties)

TD-SCDMA Demodulation Properties Dialog Box


Downlink Pilot  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Code/ID tab

Default: 0 (See TD-SCDMA Standard Presets Table )

Range: .0 to 31

Lets you specify the Downlink Pilot Synchronization ID sequence.  These codes are used for DL synchronization and cell initial search (see TD-SCDMA - Code/ID Allocation Overview).

See Also

Uplink Pilot Code ID parameter

Scrambling Code ID parameter

Basic Midamble Code ID parameter

TD-SCDMA Overview - Code Allocation

Code/ID Tab (TD-SCDMA)

TD-SCDMA Demod Properties dialog box


for Timeslot  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Code/ID tab

Default:TS0 (See TD-SCDMA Standard Presets Table )

Lets you specify the timeslot that is associated with the specified Max Users (K) parameter.

TIP

You can use the "All" selection to associate all timeslots with the specified Max User (K) value.

See Also

Code/ID Tab (TD-SCDMA)

TD-SCDMA Demod Properties dialog box


Max Users (K)  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Code/ID tab

Default:16 (See TD-SCDMA Standard Presets Table )

Range:2, 4, 6, 8, 10, 12, 14, 16

Lets you specify the number of Maximum Users (K) that will be associated with the timeslots specified by the for timeslot parameter.

TIP

You can use the "All" for timeslot parameter selection to associate all timeslots with the specified Max User (K) value.

See Also

Code/ID Tab (TD-SCDMA)

TD-SCDMA Demod Properties dialog box


Mirror Frequency Spectrum   (TD-SCDMA)

Lets you correctly demodulate frequency spectrums that are mirrored (flipped) about the center frequency. The default frequency spectrum is assumed not mirrored. This parameter does not change the displayed spectrum trace data.

Cleared:  Does not mirror the frequency spectrum.

Selected:  Mirrors the frequency spectrum about the analyzer center frequency.

Mirror Frequency lets you configure the analyzer's demodulator to conjugate the complex time-domain waveform. This has the effect of flipping the spectrum around the analyzer's center frequency. This feature is useful when the TD-SCDMA signal is inverted, or flipped due to an IF down conversion.

Note

The display of the spectrum data will not change with this parameter. To mirror the display, clear the Mirror Frequency Spectrum check box, and select the MeasSetup Properties dialog box, Frequency tab, Mirror Frequency check box.

See Also

Mirror Frequency Spectrum(Digital Demodulation)

Format Tab (TD-SCDMA)

Demod Properties Dialog Box (TD-SCDMA)


Normalize  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Format tab

Default:checked (See TD-SCDMA Standard Presets Table )

When the Normalize check box is selected, the analyzer applies trace data normalization to the trace data results, see IQ Normalize (Digital Demod) for detailed information.

See Also

Format Tab (TD-SCDMA)

Demod Properties Dialog Box (TD-SCDMA)


Scramble  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Code/ID tab

Default: 0 (See TD-SCDMA Standard Presets Table)

Range: .0 to 127

Lets you specify the scramble code ID. There are 128 different scrambling codes, which are associated with a corresponding basic midamble code.  Scrambling codes are cell specific and are used to identify separate cells (see TD-SCDMA - Code/ID Allocation Overview).

Code Group:  Controls the allowable scramble code ID coding criteria as follows:

Selected:	Only allows Scramble Code ID sequences that comply with standard coding allocation criteria.

Cleared:	Allows non-standard Scramble Code ID sequence allocation.

See Also

Uplink Pilot Code ID parameter

DownLink Pilot Code ID parameter

Basic Midamble Code ID parameter

TD-SCDMA Modulation Overview

Code/ID Tab (TD-SCDMA)

TD-SCDMA Demod Properties dialog box


Spread Code Length  (TD-SCDMA)
(Despread Channel)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Channel/Layer tab

Default: 16 (80 ksyms/s), see TD-SCDMA Standard Presets Table

Lets you set the Despread Channel - Spread Code Length. The Despread Channel - Spread Code Length is used, along with the Despread Channel - Code Channel, to specify the active code layer and channel used for the channel trace data measurement results ( including: Chan Error Vector, Chan IQ Meas Time, Chan IQ Ref Time, Chan Mag Error, Chan Phase Error and Chan Syms/Errs trace data results).

Note

The text box shows both the Spread Code Length (Symbol Rate).

Selecting Despread Channel Spread Code Length

Click one of the available TD-SCDMA compliant Spread Code Lengths from the drop-down list.

Tip

You can use the Copy Mkr To Despread Channel marker feature to automatically enter the Despread-Channel Spread Code Length, Code Channel and IQ Branch settings.

See Also

Channel/Layer Tab (TD-SCDMA Demodulation Properties)

TD-SCDMA Demodulation Properties Dialog Box


Spread Code Length    (TD-SCDMA)
(CDP Layer)

Menu Path: MeasSetup > Demod Properties > Channel/Layer tab

Default: 16 (80 ksyms/s), see TD-SCDMA Standard Presets Table

CDP Layer - Spread Code Length selects the active code domain layer (Spread Code Length) for the CDP Layer trace data. This parameter has no other effect except for the display of the CDP Layer and CDE Layer trace data.

Selecting a CDP Layer - Spread Code Length

Click one of the available TD-SCDMA compliant Spread Code Lengths from the drop-down list.

Note

The Copy Mkr To Despread Channel marker does not automatically enter the CDP Layer Spread Code Length.

See Also

Channel/Layer Tab (TD-SCDMA Demodulation Properties)

TD-SCDMA Demodulation Properties Dialog Box


Time Reference  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Time tab

Default: DwPTS (See TD-SCDMA Standard Presets Table)

Lets you specify the time reference used to compute the Overall Error Summary - Timing Error data results (see Overall Timing Error):

DwPTS (Downlink Pilot:	Overall Timing Error uses the Downlink Pilot Time Slot as the time reference
UpPTS  (Uplink Pilot):	Overall Timing Error uses the Uplink Pilot Time Slot as the time reference
Trigger Point:	Overall Timing Error uses a trigger event as the time reference.  The Trigger Point is taken to be the start of a sub-frame.
Note: Triggered Measurements

When making triggered measurements, the demodulation algorithm requires some amount of data prior to the beginning of the desired sub-frame, in order for demodulation to begin on that sub-frame.  This is handled internally but if there are delay differences between the sub-frame boundary in the incoming signal and the trigger then the Trigger Delay may need to be adjusted in order to supply enough data before the beginning of the sub-frame.  For instance, if an external trigger occurs 20 us after the beginning of the desired sub-frame then Trigger Delay would need to be set to -20 us.

See Also

Result Length, Start Boundary and Analysis Parameters

Time Tab (TD-SCDMA)

TD-SCDMA Demod Properties dialog box


Uplink Pilot  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Code/ID tab

Default: 0 (See TD-SCDMA Standard Presets Table)

Range: .0 to 255

Lets you specify the Uplink Pilot synchronization ID sequence (SYNC-UL) (see TD-SCDMA - Code/ID Allocation Overview).

Code Group controls the allowable Uplink Pilot ID sequence coding criteria as follows:

•	Selected:  Only allows Uplink Pilot ID sequences that comply with standard coding allocation criteria.

•	Cleared:  Allows non-standard Uplink Pilot ID sequence allocation.

See Also

TD-SCDMA Modulation Overview

Code/ID Tab (TD-SCDMA)

TD-SCDMA Demod Properties dialog box


Result Length, Start Boundary and Analysis Parameters  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: MeasSetup > Demod Properties > Time tab > Result Length

or	MeasSetup > Demod Properties > Time tab > Start Boundary

or	MeasSetup > Demod Properties > Time tab > Analysis Timeslot

or	MeasSetup > Demod Properties > Time tab > Analysis Sub-frame

Defaults: (See TD-SCDMA Standard Presets Table)

You need to specify the Result Length, Start Boundary, Analysis Sub-frame and Analysis Timeslot parameters to completely define the segment of the TD-SCDMA frame that is demodulated and analyzed.

Result Length:   specifies the total amount of acquired and demodulated data that is used for data analysis and display. The Result Length is specified as an integer number of sub-frames.

Start Boundary:  specifies when to start the Result Length data capture. The Start Boundary can be specified as Sub-frame or 2 frames (see Selecting a Start Boundary below):

Sub-frames	Starts the result length data capture at the first demodulated sub-frame.

2 Frames:	Starts the results length data capture at even numbered frames.

Note

The analyzer acquires enough data to ensure that the Start Boundary and the specified Result Length data will be captured.

Analysis Sub-frame lets you specify which sub-frame, within the acquired Result Length, is used for analysis and trace data measurement results. The available selections include the acquired subframes.

Analysis Timeslot lets you specify which sub-frames timeslot, within the selected Analysis Sub-frame, is used for analysis and trace data measurement results. The available selections include timeslots 0 through 6, the DwPTS and UpPTS timeslots.

Selecting a Start Boundary

Tip

To automatically enter the Timeslot and Sub-frame information you can use the Copy Mkr To Analysis TS/SF marker feature, from the Overall Time trace data display, simply right click on the trace display and select "Copy Mkr To Analysis TS/SF".

Data Analysis Example

The following example shows how to set the Result Length, Start Boundary, Analysis Sub-frame and Analysis Times Slot parameters to specify time slot 3 in Subframe number 1 as the Analysis timeslot:

Start Boundary = Sub-frame

Result Length = 2 Sub-frames

Analysis Sub-frame = 1

Analysis Timeslot = TS3.

Note: Using Triggered Measurements

When making triggered measurements, the demodulation algorithm requires some amount of data prior to the beginning of the desired sub-frame, in order for demodulation to begin on that sub-frame.  This is handled internally but if there are delay differences between the sub-frame boundary in the incoming signal and the trigger then the Trigger Delay may need to be adjusted in order to supply enough data before the beginning of the sub-frame.  For instance, if an external trigger occurs 20 us after the beginning of the desired sub-frame then Trigger Delay would need to be set to -20 us.

See Also

Time Reference Parameter - Time tab

TD-SCDMA Overview

Time Tab (TD-SCDMA)

TD-SCDMA Demod Properties dialog box


About the Channel Symbol Table (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan > Error Summary

When TD-SCDMA Demodulation is enabled, selecting Ch1 Chan Error Summary trace data shows the symbol table and error summary trace data for the specified Sub-frame, Time Slot, Code Channel and Spread Code Length. The bottom section of the display shows the symbol table data and the upper section shows the error summary data. This topic discusses the code channel Symbol Table trace data, the Error Summary trace data is discussed under About the Channel Error Summary trace data.

Symbol Data

The bottom half of the symbol table shows the raw data symbol bits for each measured symbol in the specified Sub-frame, Time Slot, Spread Code Length and Code Channel.

Note

If you are demodulating a CWTS TSM 05.04 v2.0.0 specified signal, the raw symbol bits will need to be converted to obtain the correct bit order.  Go to the "Demodulated Raw Bit Conversion for TSM v2.0.0 Signals" topic below for more information.

Note

Detection of the DwPTS Phase Coding, and hence accuracy the Demodulated Symbols, depends on low phase noise input data.  Because of this, it may be necessary to lock frequency references, between the 89600 hardware and the device under test, in order to achieve good results for these measurements.

Selecting Data

The Sub-frame and Time Slot parameters are specified in the TD-SCDMA Demodulation Properties box - Time tab (MeasSetup > Demod Properties > Time tab). The Code Channel and Code Layer are specified in the Despread-Channel parameters of the TD-SCDMA Demodulation Properties box - Channel/Layer tab (MeasSetup > Demod Properties > Channel/Layer tab).

Interpreting the Symbol Table

When the symbol table marker is enabled, the trace marker highlights the data symbol bits for the selected symbol and the marker readout provides the symbol number and its value in decimal.

Note

When the DwPTS phase encoding is "unknown", the downlink traffic timeslot symbols may be rotated due to a phase uncertainty in the signal.  Because the uplink traffic timeslots are not phase related to DwPTS timeslot, this applies at all times for the Uplink timeslot symbols.

To make the table easier to read, the data bits are shown in groupings of eight characters followed by a space. The characters represent a binary digit and the number to the left of each row indicate either the bit offset position as described below:

For example, if 192 is displayed to the left of third row, the first bit in the third row is the 192nd bit in the digital data stream.

Measurement Tips:

•	Here's an easy way to see the bits that correspond to a point in the channel IQ constellation diagram: display the IQ constellation diagram in one grid, the symbol table in another, and turn on the Marker and Marker Coupling. When you place the marker on a point in the constellation diagram, the analyzer highlights the corresponding bits in the symbol table.

•	Use the arrow keys on the keyboard or the mouse wheel to move the marker from one symbol to the next. Or you can use the marker X Position to move to any specified symbol location.

Error Summary Data

You can find about the error summary data at About the Channel Error Summary Data.

See also

About the Channel Error Summary Data

Available Chan Error Summary Data

About Chan Trace Data


Demodulated Raw Bit Conversion for TSM v2.0.0 Signals (TD-SCDMA)

This topic discusses the need to correct the symbol bit data when demodulating CWTS TSM 05.04 v 2.0.0 specified signals.

Option B7N:TD-SCDMA provides modulation analysis for CWTS TSM 05.04 v 3.0.0 specified signals.  You can also demodulate CWTS TSM 05.04 v 2.0.0 specified signals, but if you do, you will need to apply these conversions to obtain the correct raw data bits.

Concepts

The channel specific multiplier in TSM v3.0.0 causes the detected symbol rotated by +/- Pi/2 or +- Pi.  The multiplication is channel specific, thus the conversion needs to be done by the code channel.

Currently the analyzer supports TSM v3.0.0 for the physical layer measurement. With the additional conversion listed below, we also support TSM v2.0.0.

Here is the conversion scheme for TSM v2.0.0 signal measured by analyzer TD-SCDMA personality (QPSK modulation case).

1.	Spread Factor = 16

Channel Code 0, 5, 6, 16

Setup Bits	Glacier Measured Bits
"00"	"11"
"01"	"10"
"10"	"01"
"11"	"00"
Channel Code 1, 8, 12, 13

Setup Bits	Glacier Measured Bits
"00"	"10"
"01"	"00"
"10"	"11"
"11"	"01"
Channel Code 4, 9, 11, 14

Setup Bits	Glacier Measured Bits
"00"	"01"
"01"	"11"
"10"	"00"
"11"	"10"

Channel Code 2, 3, 7, 10                          No Difference

2.	Spread Factor = 8.

Channel Code 1, 2

Setup Bits	Glacier Measured Bits
"00"	"01"
"01"	"11"
"10"	"00"
"11"	"10"

Channel Code 3, 5

Setup Bits	Glacier Measured Bits
"00"	"11"
"01"	"10"
"10"	"01"
"11"	"00"
Channel Code 4, 6

Setup Bits	Glacier Measured Bits
"00"	"10"
"01"	"00"
"10"	"11"
"11"	"01"
Channel Code 0, 7      -    No Difference

3.	Spread Factor = 4.

Channel Code 2

Setup Bits	Glacier Measured Bits
"00"	"01"
"01"	"11"
"10"	"00"
"11"	"10"

Channel Code 3

Setup Bits	Glacier Measured Bits
"00"	"11"
"01"	"10"
"10"	"01"
"11"	"00"

Channel Code 0

Setup Bits	Glacier Measured Bits
"00"	"10"
"01"	"00"
"10"	"11"
"11"	"01"

Channel Code 1      -    No Difference

4.	Spread Factor = 2.

Channel Code 0      -    No Difference

Channel Code 1

Setup Bits	Glacier Measured Bits
"00"	"01"
"01"	"11"
"10"	"00"
"11"	"10"
Spread Factor = 1.      -    No Difference


Channel Error Summary Data  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan > Error Summary

The upper half of the symbol table shows Error Summary trace data for the specified Sub-frame, Time Slot, Code Channel and Spread Code Length.  This topic discusses the Channel Error Summary data results, the Symbol data is discussed in the About the Channel Symbol Table topic. The following Error Data topics are discussed and presented as listed:

•	Available Channel Error Summary Data

•	Selecting the Code Channel and Layer

•	Averaging and Error Data Results

•	Using Band Power markers to limit Error Information

•	How EVM and Magnitude Error data results are calculated (%RMS)

Available Channel Error Summary Data

See Available Channel Error Summary Data

Selecting Chan Error Trace Data

The Sub-frame and Time Slot parameters are specified in the TD-SCDMA Demodulation Properties box - Time tab (MeasSetup > Demod Properties > Time tab). The Code Channel and Code Layer are specified in the Despread-Channel parameters of the TD-SCDMA Demodulation Properties box - Channel/Layer tab (MeasSetup > Demod Properties > Channel/Layer tab).

Tip

From the Overall Time trace data display you can use the Copy Mkr To Analysis TS/SF marker feature to automatically enter the Timeslot and Sub-frame information (Right click on the trace > Select Copy Mkr To Analysis TS/SF).

From the Comp CDP trace data display you can use the Copy Mkr To Despread Channel marker feature to automatically enter the Despread-Channel Spread Code Length and  Code Channel settings  (Right click on the trace > Select Copy Mkr To Despread Channel).

Averaging and Error data results

If averaging is on, averaging is applied to most numeric error data in the error summary table with the following exceptions. The peak data values, such as peak EVM, peak Magnitude and peak Phase error are averaged only for the Continuous Peak Hold averaging type. The Slot number is never averaged.

Error data from the current scan is not included in the average if any of these conditions occur:

•	CARRIER LOCK?.

•	DATA? (if caused by a temporary condition like partial data record)

Using Band Power markers to limit Error Information

If you want error information for all points over a selected region, you can use the band-power markers with an error trace.

For example, here's how you could compute the phase error for all points within a region. Click Trace > Data > Chan IQ Phase Error to display the IQ phase-error trace, then click Markers > Calculation and select the Band Power check box to turn on the band-power markers.

Now position the band-power markers to select the region of interest, and select RMS Sqrt (Pwr) to display the phase error for the selected region.

Hint

At this point, you could simply click Trace > Data > Chan IQ Mag Error to display the magnitude error for the same region.

How EVM (%rms) and Magnitude Error (%rms) data results are calculated (%RMS)

In the channel error summary table, the analyzer shows the error-vector magnitude and magnitude error as a percentage. Before computing this percentage, the analyzer normalizes the constellation diagram such that the outer-most, ideal states have a magnitude of one.

The analyzer computes the overall, percent error by first computing the error-vector magnitude and magnitude error at each symbol time.

Next, the analyzer derives the rms average for each parameter. For example, to compute the rms average for the magnitude error, the analyzer takes the square root of the sum of the squares of the individual magnitude-error values at each symbol time.

Because the magnitude of the constellation diagram's outer-most state has been normalized to one, the rms average is the overall, percent error.

Additional Error Summary Data

TD-SCDMA demodulation also provides these additional Error Summary data tables:

•	Composite Error Summary table provides error data for the composite signal for a specific timeslot and sub-frame.

•	Overall Error Summary table provides chip timing error data and Total power, Data power and Midamble power for each timeslot within the burst.

See also

About Trace Data (TD-SCDMA)


Available Chan Error Summary Data  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan > Error Summary

Available Chan Error Summary Data Results

Chan EVM (Error Vector Magnitude

Chan Magnitude Error (MagErr)

Chan Phase Error (Phase Err)

Chan Code Phase

For information about using error summary data with ADS, see Demod Errors and ADS.

See also

About Error Summary Data (TD-SCDMA)


Chan EVM (Error Vector Magnitude)  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan > Error Summary

Chan EVM is the Error Vector Magnitude for the specified Sub-frame, Time Slot, Code Channel and Spread Code Length. The display shows these EVM values; the RMS (root mean square in percent) EVM, the Peak (largest) EVM, and the symbol number with the Peak EVM.

Chan EVM is similar to digital demod EVM. See Digital Demod Error Vector Magnitude (EVM) for further information about this trace data.

See also

Available Error Summary Data (TD-SCDMA)

About Error Summary Data (TD-SCDMA)


Chan Magnitude Error (MagErr)  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan > Error Summary

Chan Magnitude Error (MagErr) is the difference in amplitude between the I/Q measured signal and the I/Q reference signal for the specified Sub-frame, Time Slot, Code Channel and Spread Code Length.

Magnitude error is an indicator of the quality of the amplitude component of the modulated signal. For example: a very high magnitude error might indicate high incidental AM modulation on the signal.

The display shows these Magnitude error values; the RMS (root mean square) Magnitude Error, the Peak (largest) Magnitude Error, and the symbol number with the Peak Magnitude Error.

Hint

The description of Error-vector magnitude (EVM) includes a pictorial diagram that shows how Magnitude Error is derived.

See also

Available Error Summary Data (TD-SCDMA)

About Error Summary Data (TD-SCDMA)


Chan Phase Error (Phase Err)  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan > Error Summary

Chan Phase error is the difference, in phase, between the I/Q reference signal and the I/Q measured signal for the specified Sub-frame, Time Slot, Code Channel and Spread Code Length.

The magnitude of this parameter is an indicator of the quality of the phase component of the modulated signal. For example, a very high phase error might indicate high incidental FM modulation on the signal.

The display shows these Phase error values; the RMS (root mean square) Phase Error, the Peak (largest) Phase Error, and the symbol number with the Peak Phase Error.

Hint

The description of Digital Demod Error-vector magnitude (EVM) includes a pictorial diagram that shows how Phase Error is derived.

See also

Available Error Summary Data (TD-SCDMA)

About Error Summary Data (TD-SCDMA)


Chan Code Phase Error  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan > Error Summary

Chan Code Phase is the phase of the code channel relative to the DwPTS pilot time slot.

See also

Available Error Summary Data (TD-SCDMA)

About Error Summary Data (TD-SCDMA)


About Composite Error Summary Data  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

When TD-SCDMA  Demodulation is enabled, selecting the Ch1 Comp, Error Summary trace data shows the composite error summary data. The error summary display provides the summary error information for the composite signal.

Note

Composite denotes trace data results for the composite signal (includes all Spread Code Lengths (Symbol Rate) and Code Channels).

•	Available Composite Error Summary Data

Additional Error Summary Data

TD-SCDMA demodulation also provides these additional Error Summary data tables:

•	Channel Error Summary table provides error data for an individual code channel and layer for a specified timeslot and sub-frame.

•	Overall Error Summary table provides chip timing error data and Total power, Data power and Midamble power for each timeslot within the burst.

See also

About Comp Trace Data

About Trace Data (TD-SCDMA)


Available Composite Error Summary Data  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

Available Composite Error Summary Data

Rho

EVM (Error Vector Magnitude)

Magnitude Error (Mag Err)

Phase Error

Frequency Error (Freq Err)

IQ Offset Error

IQ Quad Error

IQ Gain Imbalance (IQ Gain Imb)

Peak Active CDE   (Pk Active CDE)

Peak CDE  (Pk CDE)

For information about using error summary data with ADS, see Demod Errors and ADS.

See Also

About Composite Error Summary Data


Comp Rho  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

Rho is the normalized correlation coefficient between the measured and ideal reference signals. Rho is computed by comparing the normalized correlated power between the measured signal and the reference signal and is designated as the waveform quality factor. The maximum value of Rho is 1.0 (which means the measured signal and reference signal are 100% identical).

A Rho value of 1.0 indicates that all of the transmitted power correlates with the ideal signal as determined by the detected sequence.

Rho is the correlated power for all active code channels (as seen in the composite CDP trace data display).

See Also

Available Composite Error Summary Data

About Composite Error Summary Data


Comp EVM (Error Vector Magnitude)  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

Composite EVM is the Error Vector Magnitude for the composite signal. The display shows these EVM values; the RMS (root mean square) EVM, the Peak (largest) EVM, and the symbol number with the Peak EVM.

A perfect ideal signal is synthesized at the chip level and identified as the reference signal. The reference signal is subtracted from the measured signal to produce a time record of error phasors. The square root of the ratio of the mean power of the error signal to the mean power of the reference signal is computed and expressed as a percentage EVM.

This parameter is similar to digital demodulation EVM except that it is computed at the chip rate instead of the symbol rate. See Digital Demodulation Error-Vector Magnitude (EVM) for further information about this parameter.

See Also

Available Composite Error Summary Data

About Composite Error Summary Data


Comp Magnitude Error (Mag Err)  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

Composite Magnitude Error (MagErr) is the difference in amplitude between the I/Q measured signal and the I/Q reference signal for the composite signal.

The display shows these Magnitude error values; the RMS (root mean square) Magnitude Error, the Peak (largest) Magnitude Error, and the chip number with the Peak Magnitude Error.

This error data is the same as the channel Magnitude Error except that the source data is the composite signal. See Channel Magnitude Error for further information about this parameter.

See Also

Available Composite Error Summary Data

About Composite Error Summary Data


Comp Phase Error  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

Composite Phase error is the difference, in phase, between the I/Q reference signal and the I/Q measured signal for composite signal.

The display shows these Phase error values; the RMS (root mean square) Phase Error, the Peak (largest) Phase Error, and the chip number with the Peak Phase Error.

This parameter is the same as channel Phase error except that the source data is the composite signal. See Channel Phase error for further information about this parameter.

See Also

Available Composite Error Summary Data

About Composite Error Summary Data


Comp Frequency Error (Freq Err)  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

Composite Frequency Error (Freq Err) shows the composite signal carrier frequency-error relative to the analyzer's center frequency. This parameter is displayed in Hertz and is the amount of frequency shift, from the analyzer's center frequency, that the analyzer must perform to achieve carrier lock.

Errors in RF frequency, LO frequency, or digitizer clock rate could all appear as carrier frequency error.

See Also

About Frequency

Available Composite Error Summary Data

About Composite Error Summary Data


Comp IQ Offset Error  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

Composite IQ Offset (also called I/Q origin offset) indicates the magnitude of the carrier feedthrough signal. When there is no carrier feedthrough, IQ offset is zero (-infinity dB).

IQ origin offset is easily seen in the constellation diagram, as shown below:

In the above illustration, "x" is the center of the constellation diagram. When "x" occurs at the origin, the IQ offset is zero. When "x" is not at the origin, the IQ offset is the magnitude of the vector (in dB) between "x" and the origin.

The carrier feedthrough shown in the symbol table is computed only at the chip times (the instant in time when symbols are detected).

See Also

Available Composite Error Summary Data

About Composite Error Summary Data


Comp  Quad Error  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

Quad Err (Quadrature Skew Error) indicates the orthogonal error between the I and Q signals. Ideally, I and Q should be orthogonal (90 degrees apart). A quadrature skew error of 3 degrees means I and Q are 87 degrees (or 93 degrees) apart.

For more information see IQ Gain Imbalance and Quadrature Skew Parameter Interaction.

See Also

IQ Gain Imbalance and Quadrature Skew Parameter Interaction

Comp IQ Gain Imb

Available Composite Error Summary Data

About Composite Error Summary Data


Comp IQ Gain Imbalance (IQ Gain Imb)  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

IQ Gain Imbalance compares the gain of the I signal with the gain of the Q signal, as follows:

The effects of IQ gain imbalance are best viewed in constellation diagrams, where the width of the constellation diagram is different than its height.

Because Gain Imbalance detection requires absolute phase information, this result is questionable when the DwPTS phase coding is not known, i.e. displayed as "unknown" in the Overall Error Summary table.  Because uplink traffic timeslots are not phase related to DwPTS, this applies at all times in the uplink case.

Note

Detection of the DwPTS Phase Coding, and hence accuracy of Gain Imbalance, depends on low phase noise input data.  Because of this, it may be necessary to lock frequency references, between the 89600 hardware and the device under test, in order to achieve good results for these measurements.

See Also

IQ Gain Imbalance and Quadrature Skew Parameter Interaction

Quad Err

Available Composite Error Summary Data

About Composite Error Summary Data


Comp Peak Active CDE   (Pk Active CDE)  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

Composite Peak Active CDE is the largest active code-Channel Code Domain Error (in dB). This is the largest measured CDE for all active code channels in the composite signal.

See Also

Available Composite Error Summary Data

About Composite Error Summary Data


Comp Peak CDE  (Pk CDE)   (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

Composite Peak CDE is the largest measured code-channel Code Domain Error. This is the largest measured CDE for all code channels (active and inactive) in the base code layer (the code layer with the smallest symbol rate) in the composite signal.

See Also

Available Composite Error Summary Data

About Composite Error Summary Data


About Overall Error Summary Data  (TD-SCDMA)
Overall Error Summary Table

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Overall > Error Summary

When TD-SCDMA Demodulation is enabled, Overall Error Summary table provides error and summary data for individual timeslots within the measured burst.

 The available Overall Error summary data includes: DwPTS Phase Coding information and individual timeslot error data which includes Chip Timing, Total Power, Midamble Power and Data field Power error information.

•	Available Overall Error Summary data

Additional Error Summary Data

TD-SCDMA demodulation also provides these additional Error Summary data tables:

•	Channel Error Summary table provides error data for an individual code channel and layer for a specified timeslot and sub-frame.

•	Composite Error Summary table provides error data for the composite signal for a specific timeslot and sub-frame.

See also

About Overall Trace Data

About Trace Data (TD-SCDMA)


Available Overall Error Summary Data
Overall Error Summary Table

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Overall > Error Summary

Available Overall Error Summary Data

•	DwPTS Phase coding

•	Timing Error (Timing Err)

•	Total Power (TotPwr)

•	Midamble Power (MidambPwr)

•	Data Power (DataPwr)

For information about using error summary data with ADS, see Demod Errors and ADS.

Additional Error Summary Data

TD-SCDMA demodulation also provides these additional Error Summary data tables:

Channel Error Summary table provides error data for an individual code channel and layer for a specified timeslot and sub-frame.

Composite Error Summary table provides error data for the composite signal for a specific timeslot and sub-frame.

See Also

About Overall Error Summary Data


Overall DwPTS Phase coding  (TD-SCDMA)
Overall Error Summary Table

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Overall > Error Summary

DwPTS phase coding indicates which phase quadruple was detected. The phase quadruple is used to identify the presence of the P-CCPCH (Primary Common Control Channel), For more information see Modulation of the SYNC-DL Overview topic.

Note

Detection of the DwPTS Phase Coding, and hence accuracy of Gain Imbalance and the Demodulated Symbols, depends on low phase noise input data.  Because of this, it may be necessary to lock frequency references, between the 89600 hardware and the device under test, in order to achieve good results for these measurements. Increasing the Result Length may also improve data results

DwPTS  phase coding	Phase   Quadruple	Meaning
none	-----	Phase not coded
unavailable	-----	Not enough data or unrecognizable phase coding
S1	135, 45, 225, 135	Detected S1 phase quadruple
S2	315, 225, 315, 45	Detected S2 phase quadruple
Result Length and Start Boundary Requirements

To successfully determine the DwPTS phase coding, the Result Length should be set to a value >= 4 sub-frames and/or the Start Boundary = 2 Frames.

The Result Length and Start Boundary parameters are in the TD-SCDMA Demod Properties - Time tab dialog box (MeasSetup > Demod Properties > Time tab).

See Also

Available  Overall Error Summary Data

About Overall Error Summary Data


Overall Timing Error (Timing Err)  (TD-SCDMA)
Overall Error Summary Table

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Overall > Error Summary

Timing error shows the difference in time (in chips) between the measured and ideal start times for the indicated timeslot relative to the specified Time Reference.

You can specify either the DwPTS (DownIink Pilot), UpPTS (Uplink Pilot) or Trigger Point as the time reference using the TD-SCDMA demodulation properties - Time Reference parameter (MeasSetup > Demod Properties > Time tab > Time Reference parameter drop-down list):

Time Reference	Description
DwPTS (DownIink Pilot):	Timing Error is relative to the start of the DwPTS time slot
UpPTS (Uplink Pilot):	Timing Error is relative to the start of the UpPTS time slot
Trigger Point:	Timing Error is relative to the Trigger Event, including trigger delay, taken to be the start of a sub-frame.
Note

The Timing Error is 0 for the specified Time Reference i.e. if DwPTS is selected as the time reference, then its timing error is 0 chips.

See Also

Time Reference parameter - TD-SCDMA Demod Properties

Available  Overall Error Summary Data

About Overall Error Summary Data


Overall Power (TD-SCDMA)
Overall Error Summary Table

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Overall > Error Summary

The Overall Error Summary table provides the absolute power measurement (in dbm) for the TotPwr (Total power), the MidambPwr (Midamble power) and the DataPwr (Data field power) for each timeslot within the analyzed sub-frame.  This includes power data results for sub-frame timeslots 0 through 6, the DwPTS pilot and UpPTS pilot timeslots.

The data results are for the analyzed sub-frame, which is specified in the Analysis Sub-frame parameter list box (MeasSetup > DemodProperties > Time tab > Analysis Sub-frame).

See Also

Available  Overall Error Summary Data

About Overall Error Summary Data


About Trace Data  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data

This application provides trace data results in the Time Domain, Frequency Domain and Code Domain.

Trace Data Menu

To accommodate all the available measurement results and display formats; trace data results are grouped into trace data sub-menu categories. These sub-menu categories are grouped together by common measurement types as described below:

Ch1 trace data	Time and frequency trace data results derived from the pre-demodulated data.
Ch1: CDP trace data:	CDP (Code Domain Power) and CDE (Code Domain Error) trace data results for either the composite signal or for a specified code layer.  CDP Layer trace data results include data from all code channels within one specified code layer (Spread Code Length).  CDP Composite trace data results are for the total signal, includes data from all code channels and code layers.
Ch1: Chan trace data:	Time domain trace data results for a single code channel.  "Chan" (Channel) trace data results are derived from data for a single code channel within a specified code layer (Spread Code Length (Symbol Rate)).
Ch1 Comp trace data	Time domain and frequency domain trace data results for the Composite signal.  Composite trace data results are derived from data for the total signal. This includes the combined data from all code channels and code layers (Spread Code Lengths)
Ch1 Overall trace data	Time domain trace data results derived from the channel 1 pre-demodulated TD-SCDMA burst data.  This is the TD-SCDMA burst time data that will be used for frequency domain and code domain data analysis.
Math	Trace data results derived from a math function
Register	Trace data results derived from Data Register data
No Data	Active trace as empty.
See also

About Chan Symbol Table

About Chan Error Summary data

About Composite Error Summary data

About Overall Error Summary data

89600-Series VSA Standard Measurement Data


Ch1 Trace Data (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1

Time and frequency trace data results derived from the pre-demodulated channel 1 input data (Time Record data).

Available Ch1 Trace Data

Analysis CCDF	Correction
Analysis CDF	Inst Analysis Spectrum
Analysis PDF	Inst Raw Spectrum
Analysis Spec	Raw Main Time
Analysis Timeslot	Raw Spectrum
See also

About Trace Data (TD-SCDMA)


Ch1 CDP Trace Data (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP

CDP (Code Domain Power) and CDE (Code Domain Error) trace data results for either the composite signal or for a specified code layer.  Code Domain Power (CDP) is an analysis of the distribution of signal power across the set of code channels normalized to the total signal power.

•	CDP Composite Trace Data:    This is the CDP (Code Domain Power) and CDE (Code Domain Error) trace data results for the composite signal.  Composite trace data results are derived from data for the total signal. This includes the combined data from all Spread Code Lengths (or Symbol Rates) and Code Numbers.

•	CDP Layer Trace Data:    This is the CDP (Code Domain Power) and CDE (Code Domain Error) trace data results for a specified code layer.  You use the CDP Layer Spread Code Length drop-down list to specify the code layer (MeasSetup > Demod Properties… >  Channel/Layer tab).

Note

You can view CDP as absolute power by clearing the IQ Normalize check box (MeasSetup > Demod Properties > Format tab).

The data is shown in a multi-color format that assigns a unique color to each code layer and related active code channels. This makes it easy to visually identify and distinguish the active Code Channels for a given code layer (Spread Code Length). The colors are also user definable (See Display Appearance).

Available Ch1 CDP Trace Data

CDE Composite	Inst CDE Composite
CDE Layer	Inst CDP Composite
CDP Composite	Inst CDE Layer
CDP Layer	Inst CDP Layer
See also

About Trace Data (TD-SCDMA)


Ch1 Chan Trace Data (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan

Time domain trace data results for a single code channel (Code Length) within a specified code layer (Spread Code Length/Symbol Rate). This includes both time domain IQ trace data and Symbol/Error table data.

Selecting a Code Channel

You specify the code channel in the Despread Channel Code Length drop-down list and the code layer in the Despread Channel Spread Code Length drop-down list. (click MeasSetup > Demod Properties > Channel/Layer tab).

Tip

You can use the Copy Mkr To Despread Chan marker feature to automatically enter the Spread Code Length and Code Channel information for you.

Available Ch1 Chan Trace Data

Chan Error Summary	Chan IQ Meas Time
Chan Error Vector Time	Chan IQ Ref Time
Chan IQ Mag Error
Chan IQ Phase Error
See also

About Trace Data (TD-SCDMA)


Ch1 Comp Trace Data (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp

Time domain and frequency domain trace data results for the Composite signal.  The Composite signal includes data for the total signal, that is, the combined data from all code channels and layers.

Available Ch1 Comp Trace Data

Comp Error summary	Comp IQ Phase Error
Comp Error Vector Spec	Comp IQ Ref Spec
Comp Error Vector Time	Comp IQ Ref Time
Comp IQ Mag Error	Comp Inst Error Vector Spec
Comp IQ Meas Spec	Comp Inst IQ Meas Spec
Comp IQ Meas Time	Comp Inst IQ Ref Time
See also

About Trace Data (TD-SCDMA)


Ch1 Overall Trace Data

(Vector Signal Analyzer application only.)

Menu Path: Trace > Data

When TD-SCDMA demodulation is enabled, Overall trace data shows data results for the pre-demodulated input data.

Available Ch1 Overall Trace Data

Overall Error Summary

Overall Filtered Time

Overall Time

See also

About Trace Data (TD-SCDMA)


Ch1 Analysis  CCDF Trace Data (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Overall > Analysis CCDF

CCDF trace data displays the complementary, cumulative density function (CCDF) for the selected Sub-frame (SF) and Timeslot (TS).

Tip

Analysis Timeslot and Analysis Sub-frame parameter entry shortcut:  Right click on the desired Timeslot in the Overall Time trace data display, then select Copy Marker to Analysis TS/SF.

Overview

The complementary, cumulative density function (CCDF) is a statistical-power calculation and can be performed only on time-domain data. As its name suggests, CCDF is the complement of CDF, and is defined as follows:

 CDF(K) = Probability(x ≤ K)
 CCDF(K) = Probability(x ≥ K)

CCDF provides better resolution than CDF for low probability signals, especially when log format is used for the y-axis.

The analyzer plots CCDF using units of percent (%) for the y-axis and power (dB) for the x-axis. Power on the x-axis is relative to the signal average power, so 0 dB is the average power of the signal. Therefore, a marker readout of

Trace A Marker 2 dB 12 %

means there is a 12% probability that the signal power will be 2 dB or more above the average power.

CCDF Calculation:

1.	Calculate the RMS value for all measured samples; this becomes the 0 dB point at the left end of the x-axis.

2.	Normalize all samples to the RMS value in units of dB.

3.	Determine which x-axis bin each sample belongs in between 0 and 20 dB.

4.	Calculate the total number of samples that are greater than or equal to each x-axis bin and plot as a percent of the number of samples measured.

Restarting the Power Measurement

Selecting CCDF, restarting the measurement, or changing most measurement parameters restarts the CCDF measurement. For example, changing the range or center frequency resets the number of samples used in the CCDF measurement to zero and restarts the CCDF measurement.

Tips

Note the following when making CCDF measurements:

•	For best results, set the analyzer's displayed frequency span to include all the energy of your signal. In other words, make sure the displayed frequency span includes the entire bandwidth of the measured signal.

•	The CCDF measurement does not restart:

−	After a calibration

−	After you continue a paused measurement

•	Many channel specific changes restart the CCDF measurement on both channels, such as changing the range, or input coupling.

•	The analyzer displays DATA? if the average power drifts 8 to 10 dB from the average power measured in the first time record. For example, the analyzer would display DATA? if you measured a transmitter signal that was off when the CCDF measurement started but then turned on later in the measurement.

See also

Ch1 Trace Data

About Trace Data TD-SCDMA


Ch1 Analysis CDF Trace Data (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Overall > Analysis CDF

CDF trace data displays the cumulative density function (CDF) for the selected Analysis Timeslot and Analysis Sub-frame.  CDF is computed by integrating the PDF (Probability Density Function).

For more information see the CCDF (TD-SCDMA) and CDF trace data topics.

Tip

Analysis Timeslot and Analysis Sub-frame parameter entry shortcut:  Right click on the desired Timeslot in the Overall Time trace data display, then select Copy Marker to Analysis TS/SF.

See also

Ch1 Trace Data

About Trace Data TD-SCDMA


Ch1 Analysis PDF Trace Data   (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Overall > Analysis PDF

PDF trace data displays the Probability Density Function for the selected Sub-frame (SF) and Timeslot (TS).  PDF indicates the probability that a given level has occurred.

Tip

Analysis Timeslot and Analysis Sub-frame parameter entry shortcut:  Right click on the desired Timeslot in the Overall Time trace data display, then select Copy Marker to Analysis TS/SF.

Overview

PDF is equivalent to a normalized histogram. A histogram shows how the amplitude of a signal is distributed between its maximum and minimum values. Amplitude is displayed on the X-axis, and number of counts on the Y-axis.

The number of averages for a histogram determines the number of counts in the histogram; in other words, how many records are measured—the records are not "averaged". If averaging is off or if exponential averaging is selected, the measurement continues indefinitely. Keep in mind that the accuracy of the histogram is dependent on the frequency span and number of averages (if averaging is on).

PDF trace data is normalized by multiplying the number of averages by the number of points in the time record, then dividing this value by the ΔV spacing on the X-axis. The probability of a signal falling between two points is equal to the integral of the curve between those points.

PDF trace data displays the number of points used in its computation above the trace (Pts:). It also displays the average level (Avg:) above the trace.

See also

Ch1 Trace Data

About Trace Data TD-SCDMA


Ch1 Analysis Spec Trace Data  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Overall > Analysis Spec

Overall Analysis Spec trace data is the spectral display of the pre-demodulated Time data for the selected Sub-frame (SF) and Timeslot (TS). The Time data is Windowed and FFTed to create the Spectrum display.

If averaging is on, Spectrum trace data is the averaged Instantaneous Spectrum trace data. When averaging is set to zero, the Spectrum trace data is equal to the Inst Spectrum trace data.

Tip

Analysis Timeslot and Analysis Sub-frame parameter entry shortcut:  Right click on the desired Timeslot in the Overall Time trace data display, then select Copy Marker to Analysis TS/SF.

See also

Ch1 Trace Data

About Trace Data TD-SCDMA


Ch1 Analysis Timeslot Trace Data   (TD-SCDMA)

When TD-SCDMA demodulation is enabled, the Analysis Timeslot trace data shows the pre-demodulation time record data for the specified timeslot and sub-frame. The entire Result Length can be viewed with the Overall Time trace data display.

Note

Analysis Timeslot data is unaffected by time averaging.

VSA signal flow (see Digital Demodulation Block Diagram):

See also

Ch1 Trace Data

About Trace Data TD-SCDMA


Ch1 Correction Trace Data  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 > Correction

Shows the correction trace derived by the analyzer from the calibration data. The correction trace is applied to the acquired data to compensate for phase and magnitude anomalies in the analyzer's hardware and software signal processing.

See also

About Calibration

Ch1 Trace Data

About Trace Data TD-SCDMA


Ch1 Inst Analysis Spec Trace Data   (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Overall > Error Summary

Overall Inst Analysis Spec trace data is the spectral display of the pre-demodulated Time data for the selected Sub-frame (SF) and Timeslot (TS).  It uses the non-averaged time data and is not affected by averaging.

Averaging

Averaging does not affect the Overall Inst Analysis Spec trace data.  Use the Overall Analysis Spec trace data to apply averaging to the spectral display.  When averaging is set to OFF, the Overall Analysis Spec trace data is equal to the Overall Analysis Inst Spectrum trace data.

Tip

Analysis Timeslot and Analysis Sub-frame parameter entry shortcut:  Right click on the desired Timeslot in the Overall Time trace data display, then select Copy Marker to Analysis TS/SF.

See also

Ch1 Trace Data

About Trace Data TD-SCDMA


Inst Raw Spectrum Trace Data   (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Inst Spectrum

Instantaneous Spectrum trace data is the spectral display of the Raw Main Time data. The Time data is Windowed and FFTed to generate the Instantaneous Raw Spectrum display.

If averaging is on, the Instantaneous Raw Spectrum does not show the effects of averaging. To see the effects of averaging, use the Ch1 Raw Spectrum trace data (TD-SCDMA).

Since the windowing (unless it is Uniform) has the effect of emphasizing some parts of the time record more than others, the contributions of the different timeslots to this spectrum will vary.  They will even vary from measurement to measurement if the Raw Time is not synchronized to the TD-SCDMA sub-frames, as in a non-triggered measurement.  Therefore, amplitude readings from this trace should not be depended upon for absolute accuracy.  For more accurate spectral measurements of an individual timeslot, use the Analysis Spec (and Inst Analysis Spec).

VSA signal flow (see Digital Demodulation Block Diagram):

See also

VSA Concepts (Windowing and FFTing)

Ch1 Trace Data

About Trace Data TD-SCDMA


Ch1 Raw Main Time Trace Data   (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 > Raw Main Time

Raw Main Time is the raw data read from the input hardware or playback file. For more information about this data, See Raw Main Time (Digital Demod) trace data topic.

VSA signal flow (see Digital Demodulation Block Diagram):

See also

Ch1 Trace Data

About Trace Data TD-SCDMA


Ch1 Raw Spectrum Trace Data    (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 > Spectrum

Raw Spectrum trace data is the spectral display of the Raw Main Time data. The Raw Main Time data is Windowed and FFTed to generate the Raw Spectrum display.

If averaging is on, Raw Spectrum trace data is the averaged Instantaneous Raw Spectrum trace data. When averaging is set to zero, the Raw Spectrum trace data is equal to the Inst Raw Spectrum trace data.

Since the windowing (unless it is Uniform) has the effect of emphasizing some parts of the time record more than others, the contributions of the different timeslots to this spectrum will vary.  They will even vary from measurement to measurement if the Raw Time is not synchronized to the TD-SCDMA sub-frames, as in a non-triggered measurement.  Therefore, amplitude readings from this trace should not be depended upon for absolute accuracy.  For more accurate spectral measurements of an individual timeslot, use the Analysis Spec (and Inst Analysis Spec).

VSA signal flow (see Digital Demodulation Block Diagram):

See also

VSA Concepts (Windowing and FFTing)

About Averaging

Ch1 Trace Data

About Trace Data TD-SCDMA


CDE Composite Trace Data  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP > CDE Composite

Shows the Code Domain Error (CDE) value for each active code channel for all code layers (Spread Code Lengths) at the specified sub-frame number and timeslot. Also the CDE value for each inactive code channel at the lowest code layer is provided.  The CDE of a particular code channel is a measure of the error power in a code channel relative to the total signal power.

Display Format

The data is shown in a multi-color format that assigns a unique color to each code layer and then fills each related active code channels with the same color. This makes it easy to visually identify and distinguish the active code channels for a given code layer (Spread Code Length). The colors are also user definable (See Display Appearance).

Tip

You can use the CDE Layer trace data display to view only one code layer (Spread Code Length or Symbol Rate) at a time.

See also

CDE Layer trace data

CDP Composite trace data

Available Ch1 CDP trace data

About Trace Data TD-SCDMA


CDE Layer Trace Data  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP > CDE Layer

Shows the Code Domain Error (CDE) value for each code channel within the specified sub-frame, timeslot and code layer (Spread Code Length).  The CDE of a particular code channel is a measure of the error power in a code channel relative to the total signal power.

Display Format

The data is shown in a multi-color format that assigns a unique color to each code layer and related active code channels. This makes it easy to visually identify and distinguish the active code channels (Code Length) for a given code layer (Spread Code Length). The colors are also user definable (See Display Appearance).

Selecting a Code Layer

You select the desired code layer by selecting a Spread Code Length from the CDP Layer Spread Code Length drop-down list (MeasSetup > Demod Properties.. > Channel/Layer tab).

See also

Available Ch1 CDP trace data

About Trace Data TD-SCDMA


CDP Composite Trace Data  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP > CDP Composite

Shows the Code Domain Power trace data for the composite signal for the specified sub-frame and timeslot.  Code Domain Power (CDP) is an analysis of the distribution of signal power across the set of code channels normalized to the total signal power.

TIP

You can view CDP trace data as absolute power by clearing the Normalize check box (MeasSetup, Demod Properties, Format tab).

Display Format

The data is shown in a multi-color format that assigns a unique color to each code layer and related active code channels. This makes it easy to visually identify and distinguish the active code channels (Code Number) for a given code layer (Spread Code Length). The colors are also user definable (See Display Appearance).

The y-axis shows the power level and the x-axis shows the Code channel. The x-axis annotation and marker location are based on the lowest symbol rate (ksyms/sec), or equivalently, the highest spread code length. You can also use the code order format parameter to rearrange the placement the displayed Code Channels (See Code Order)

This example Ch1 Composite CDP display Trace A Marker shows the following:

SF0	Sub-frame 0
TS2	Timeslot 2
Symbol Rate:	160 Ksyms/s
Spread Code Length:	8
Code Channel:	1
Relative Power Level:	-5.357 dB
Asterisk *:	The asterisk (*) indicates that the marker is positioned on an active channel.
Tip

You can use the CDP Layer trace data display to view only one code layer (Spread Code Length) at a time.

See also

Available Ch1 CDP trace data

About Trace Data TD-SCDMA


CDP Layer Trace Data  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP > CDP Layer

Shows the Code Domain Power trace data for all code Channels within the specified code layer (Spread Code Length) for the selected sub-frame and timeslot.

Display Format

The data is shown in a multi-color format that assigns a unique color to each code layer and related active code channels. This makes it easy to visually identify and distinguish the active code channels (Code Length) for a given code layer (Spread Code Length). The colors are also user definable (See Display Appearance).

Selecting a Code Layer

You select the desired code layer by selecting the Spread Code Length in the CDP Layer Spread Code Length drop-down list (MeasSetup, Demod Properties.., Channel/Layer tab).

See also

Available Ch1 CDP trace data

About Trace Data TD-SCDMA


Inst CDE Composite Trace Data  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP > Inst CDE Composite

Shows the Instantaneous Code Domain Error trace data for the composite signal. Inst CDE Composite trace data is the non-averaged CDE Composite trace data (see CDE Composite Trace Data).

Note

Inst CDE Composite is not affected by averaging.

See also

Available Ch1 CDP trace data

About Trace Data TD-SCDMA


   Inst CDE Layer Trace Data  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP > Inst CDE Layer

Shows the Instantaneous Code Domain Error trace data for all active Code Channels within the specified code layer (Spread Code Length). Inst CDE Layer trace data is the non-averaged CDE Layer trace data (see CDE Layer Trace Data).

Note

Inst CDE Layer trace data is not affected by averaging.

See also

Available Ch1 CDP trace data

About Trace Data TD-SCDMA


Inst CDP Composite Trace Data  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 CDP

Shows the Instantaneous Code Domain Power trace data for the Composite signal. It is the non-averaged CDP Composite trace data (see CDP Composite trace data).

Note

Inst CDP Composite trace data is not affected by averaging.

See also

Available Ch1 CDP trace data

About Trace Data TD-SCDMA


Inst CDP layer Trace Data   (TD-SCDMA)

Shows the Instantaneous Code Domain Power trace data for all active Code Channels within the specified code layer (Spread Code Length or Symbol Rate). It is the non-averaged CDP Layer trace data (see CDP Layer trace data).

Note

Inst CDP Layer trace data is not affected by averaging.

See also

Available Ch1 CDP trace data

About Trace Data TD-SCDMA


Chan Error Summary Trace Data  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan > Error Summary

When TD-SCDMA Demodulation is enabled, selecting Ch1 Chan Error Summary trace data shows the channel symbol table trace data. The symbol table provides the signal quality error information and the binary bits for each symbol for the specified code channel and code layer. The bottom half of the display shows the symbol data bits and the upper half shows the error summary data.

For more information see the following topics:

•	See About Chan Symbol Table trace data

•	See About Chan Error Summary trace data

•	See Available Chan Error Summary Data

There is also Composite Error Summary trace data (Trace > Data > Ch1 Comp > Error Summary)  and Overall Error Summary trace data (Trace > Data > Ch1 Overall > Error Summary) .

See also

Ch1 Chan Trace Data

About Trace Data TD-SCDMA


Chan Error Vector Time Trace Data  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Chan > Error Vector Time

When TD-SCDMA Demodulation is enabled, the Error Vector Time trace data shows the time-domain error vector trace data results for the specified code channel and code layer (Spread Code Length).  Error Vector Time trace data is the computed error vector between corresponding symbol points in the I/Q measured and I/Q reference signals.  You can view the data results as Error Vector Magnitude, Error Vector Phase, only the I component or only the Q component (see Trace Data Formats below).

If normalization is OFF, the analyzer shows the instantaneous magnitude for each point. If normalization is ON, the analyzer shows the error vector as a percentage (see IQ normalize for an explanation of how this percentage is derived).

Trace Data Formats

It is important to remember that the Error Vector Time trace is a time record made up of complex, time-domain data. Each point in the time record has two components: I and Q. To make sense of the data, you must select an appropriate trace data format (Trace > Format > Format: drop--down list).

•	Linear Mag :  Shows the EVM (Error Vector Magnitude).

•	Real(I) :  Shows the I component of the error vector.

•	Imag(Q) :  Shows the Q component of the error vector.

•	Wrap Phase:  Shows the Error Vector Phase error.

For example, to see the error-vector magnitude, select the Linear Mag trace format (Trace > Format > Format: Linear Mag). Selecting Linear Mag computes the square root of the sum of the squares for each complex pair of points in the time record, which is the error-vector magnitude (EVM):

See also

Ch1 Chan Trace Data

About Trace Data TD-SCDMA


Chan IQ Mag Error and IQ Phase Error Trace Data   (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path:	Trace > Data > Ch1 Chan > IQ Mag Error

or	Trace > Data > Ch1 Chan > IQ Phase Error

When TD-SCDMA Demodulation is selected, the Chan  IQ Mag Error and Chan IQ Phase Error trace data show the vector error between the I/Q measured and the I/Q reference trace data at the sampled symbol times for the specified code channel and code layer (Spread Code Length).

Chan  IQ Mag Error trace data shows the magnitude error and Chan IQ Phase Error trace data shows the phase error for the specified code channel.

Selecting the Code Channel and Code Layer

Select the code channel with the Despread Channel - Code Channel text box  (MeasSetup > Demod Properties > Channel/Layer tab).  Select the code layer with the Despread Channel - Spread Code Length drop-down list (MeasSetup > Demod Properties > Channel/Layer tab).

Concepts

This trace data is determined just like it is for the IQ Mag Error and IQ Phase Error trace data for Digital Demodulation, see IQ Mag Error and IQ Phase Error (Digital Demod) trace data topic.

See also

Ch1 Chan Trace Data

About Trace Data TD-SCDMA


Chan IQ Meas Time and IQ Ref Time Trace Data  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path:	Trace > Data > Ch1 Chan > IQ Meas Time

or	Trace > Data > Ch1 Chan > IQ Ref Time

When TD-SCDMA Demodulation is enabled, the IQ Meas Time and IQ Ref Time traces are the demodulated time data results, sampled at the symbol times, for the specified code channel (Code Length) and code layer (Spread Code Length).  IQ Meas Time is the data results for the measured input signal.  IQ Ref Time trace data is the data results that would be derived from an ideal input signal (reference signal).

Concepts

The analyzer's demodulator produces two signals: I/Q Measured and I/Q Reference.

IQ measured signal

The IQ measured signal is the result of resampling the data to one point per chip and applying carrier locking, symbol locking, IQ origin offset and burst amplitude-droop compensation, filtering, system gain normalization and dispreading to the incoming signal.

IQ reference signal

IQ reference signal is the ideal signal that the analyzer generates from the IQ measured signal demodulated data bits.  The analyzer detects bits from the measured IQ signal and reconstructs a sequence of ideal I and Q states. These are then treated as ideal impulses and are baseband filtered according to the reference filter and added together to form the IQ reference signal. The resultant IQ reference signal is then used compare and analyze against the IQ measured signal.

Tip

Online help for Digital Demodulation includes a block diagram that shows how I/Q measured and I/Q reference data are generated.

Compensation

Demodulation is performed with carrier lock and chip lock. In addition, the analyzer compensates for I/Q origin offset and burst amplitude-droop.

Time-Domain Displays

The analyzer's demodulator produces time-domain data. If you select IQ Meas Time, the analyzer shows the I/Q measured signal in the time domain. Likewise, if you select IQ Ref Time, the analyzer shows the I/Q reference signal in the time domain.

The data can be displayed in a variety of trace data formats, including I-Q, Constellation, Q-Eye, I-Eye, and Trellis-Eye formats (see Trace Formats (Digital Demodulation)) topic.

If normalization is OFF, the analyzer shows the instantaneous magnitude. If normalization is ON, the analyzer scales the IQ measured and IQ reference traces to map them onto the unit circle, which yields a unitless y-axis.

Hint

For further details about normalization, see online help for IQ Normalize.

See also

Ch1 Chan Trace Data

About Trace Data TD-SCDMA


Comp Error Summary Trace Data  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Summary

See About Composite Error Summary data.

There is also Chan Syms/Error Summary trace data (Trace > Data > Ch1 Chan > Error Summary)  and Overall Error Summary trace data (Trace > Data > Ch1 Overall > Error Summary) .

See also

Ch1 Comp Trace Data

About Trace Data TD-SCDMA


Comp Error Vector Spec Trace Data  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Vector Spec

When TD-SCDMA Demodulation is enabled, the composite Error Vector Spec trace data shows the spectrum of the Composite Error Vector Time trace data. In other words, the analyzer derives the composite Error Vector Time trace data, and then windows and FFTs the data to produce the composite Error Vector Spectrum trace data.

Trace Data Results

The trace data is computed from data for the specified Analysis Sub-frame, Timeslot within the measurement Result Length.

Marker Frequency Correction

The analyzer's demodulator removes carrier-frequency error. Therefore, in the composite error vector spectrum display, you must add the carrier-frequency error to marker readouts to obtain exact frequency information. The carrier-frequency error (Freq Err) is shown in the Composite Error Summary (FreqErr) Table.

See also

Ch1 Comp Trace Data

About Trace Data TD-SCDMA


Comp Error Vector Time Trace Data  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Error Vector Spec

When TD-SCDMA Demodulation is enabled, the Ch1 Comp Error Vector Time trace data shows the time-domain error vector data results for the composite signal for the specified Time Slot and Sub-frame.

The Midamble field of the traffic timeslot is not included in the data analysis and is set to zero in the trace display.  In addition, for filter settling reasons, 4 chips at the start and end of the timeslot are ignored, resulting in data results that are 8 chips shorter than the full traffic timeslot length (not including the GP).

Measurement Concepts

Error Vector Time trace data is the computed error vector between corresponding chip points in the I/Q measured and I/Q reference signals.  You can view the data results as Error Vector Magnitude, Error Vector Phase, only the I data results or only the Q data results (see Trace Data Formats below).

Normalized data results

If normalization is OFF, the analyzer shows the instantaneous magnitude for each point. If normalization is ON, the analyzer shows the error vector as a percentage (see IQ normalize for an explanation of how this percentage is derived).

Trace Data Formats

It is important to remember that the Error Vector Time trace is a time record made up of complex, time-domain data. Each point in the time record has two components: I and Q. To make sense of the data, you must select an appropriate trace data format (Trace > Format > Format: drop--down list).

•	Linear Mag :  Shows the EVM (Error Vector Magnitude).

•	Real(I) :  Shows the I component of the error vector.

•	Imag(Q) :  Shows the Q component of the error vector.

•	Wrap Phase:  Shows the Error Vector Phase error.

See also

Ch1 Comp Trace Data

About Trace Data TD-SCDMA


Comp IQ Mag Error and IQ Phase Error Trace Data  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path:	Trace > Data > Ch1 Comp > IQ Mag Error

or	Trace > Data > Ch1 Comp > IQ Phase Error

When TD-SCDMA Demodulation is enabled, the Ch1 Comp IQ Mag Error and Ch1 Comp IQ Phase Error traces show the error between the I/Q measured and the I/Q reference signals for the composite signal.

Ch1 Comp IQ Mag Error shows the magnitude error and Ch1 Comp IQ Phase Error shows the phase error for the composite signal.

Note

The Midamble field of the traffic timeslot is not included in the data analysis and is set to zero in the trace display.  In addition, for filter settling reasons, 4 chips at the start and end of the timeslot are ignored, resulting in data results that are 8 chips shorter than the full traffic timeslot length (not including the GP).

Concepts

This trace data is determined just like it is for the IQ Mag Error and IQ Phase Error trace data for Digital Demodulation, see IQ Mag Error and IQ Phase Error (Digital Demod) trace data topic.

See also

Ch1 Comp Trace Data

About Trace Data TD-SCDMA


Comp IQ Meas Spec and IQ Ref Spec Trace Data  (TD-SCDMA)

Vector Signal Analyzer application only)

Menu Path:	Trace > Data > Ch1 Comp > IQ Meas Spec

or	Trace > Data > Ch1 Comp > IQ Ref Spec

When TD-SCDMA Demodulation is enabled, the Ch1 Comp  IQ Meas Spec and Ch1 Comp  IQ Ref Spec traces show you the spectrum of the Comp IQ Meas Time and Comp IQ Ref Time signals respectively. The analyzer produces the spectrum by windowing and FFTing the Comp I/Q Measured or Comp I/Q Reference signal.

Note

The analyzer's demodulator removes carrier-frequency error. Therefore, in the error vector spectrum display, you must add the carrier-frequency error to marker readouts to obtain exact frequency information. The carrier-frequency error (Freq Err) is shown in Composite Error Summary Table (FreqErr).

The spectrum represents the signal AFTER filtering.

Hint

By default, the analyzer shows the log(dB) magnitude when you select IQ measured spectrum. The same is true for I/Q reference.

See also

Ch1 Comp Trace Data

About Trace Data TD-SCDMA


Comp IQ Meas Time and IQ Ref Time Trace Data  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path:	Trace > Data > Ch1 Comp > IQ Meas Time

      or	Trace > Data > Ch1 Comp > IQ Ref Time

When TD-SCDMA Demodulation is enabled, the Comp IQ Meas Time and Comp IQ Ref Time trace data are the time data results of TD-SCDMA demodulation for the composite signal.  Comp IQ Meas Time is the data results for the measured input signal.  Comp IQ Ref Time trace data is the data results that would be derived from an ideal input signal (reference signal).

Concepts

The analyzer's demodulator produces two signals: I/Q Measured and I/Q Reference.

IQ measured signal

The IQ measured signal is the result of resampling the data to one point per chip and applying carrier locking, symbol locking, IQ origin offset compensation, filtering and system gain normalization to the incoming signal.

IQ reference signal

IQ reference signal is the ideal signal that the analyzer generates from the IQ measured signal demodulated data bits.  The analyzer detects bits from the measured IQ signal and reconstructs a sequence of ideal I and Q states. These are then treated as ideal impulses and are baseband filtered according to the reference filter and added together to form the IQ reference signal. The resultant IQ reference signal is then used compare and analyze against the IQ measured signal.

Tip

Online help for Digital Demodulation includes a block diagram that shows how I/Q measured and I/Q reference data are generated.

Time-Domain Displays

The analyzer's demodulator produces time-domain data. If you select Comp IQ Meas Time, the analyzer shows the composite IQ measured signal in the time domain. Likewise, if you select Comp IQ Ref Time, the analyzer shows the composite IQ reference signal in the time domain.

Note

The Midamble field of the traffic timeslot is not included in the data analysis and is set to zero in the trace display.  In addition, for filter settling reasons, 4 chips at the start and end of the timeslot are ignored, resulting in data results that are 8 chips shorter than the full traffic timeslot length (not including the GP).

The data can be displayed in a variety of trace data formats, including I-Q, Constellation, Q-Eye, I-Eye, and Trellis-Eye formats (see Trace Formats (Digital Demodulation)) topic.

If normalization is OFF, the analyzer shows the instantaneous magnitude. If normalization is ON, the analyzer scales the composite IQ measured and composite IQ reference traces so that the RMS level is one, which produces a unitless y-axis.

Hint

For further details about normalization, See IQ Normalize.

Composite Ref Time Display

The 89600 TD-SCDMA demodulation software uses an advanced multi-parameter estimator to synthesize the reference waveform. This algorithm adjusts reference code domain timing and phase dynamically.  As a result, the magnitude of the Composite Reference Time waveform is not absolutely flat.  If the y-axis annotation is "LinMag", the trace will not be perfectly flat and the marker readout Chip Magnitude values will not be identical.

See also

Ch1 Comp Trace Data

About Trace Data TD-SCDMA


Comp Inst Error Vector Spec Trace Data (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Comp > Inst Error Vector Spec

When TD-SCDMA Demodulation is enabled, the Composite Inst Error Vector Spec trace shows the instantaneous spectrum of the Composite Error Vector Time trace. It is the non-averaged Comp Error Vector Spec trace data.

See also

Ch1 Comp Trace Data

About Trace Data TD-SCDMA


Comp Inst IQ Meas Spec and IQ Ref Spec Trace Data  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path:	Trace > Data > Ch1 Comp > Inst IQ Meas Spec

or	Trace > Data > Ch1 Comp > Inst IQ Ref Spec

When TD-SCDMA Demodulation is enabled, the Ch1 Comp Inst IQ Meas Spec and Ch1 Comp Inst IQ Ref Spec traces show you the instantaneous spectrum of the Comp IQ Meas Time or Comp IQ Ref Time signals. It is the non-averaged Comp IQ Meas Spec and IQ Ref SpecComp IQ Meas Spec and IQ Ref Spec Trace Data  (TD-SCDMA) trace data.

See also

Ch1 Comp Trace Data

About Trace Data TD-SCDMA


Overall Error Summary Trace Data   (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Overall > Error Summary

See About Overall Error Summary data .

See also

Ch1 Overall Trace Data

About Trace Data TD-SCDMA


Overall Filtered Time Trace Data  (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Overall > Filtered Time

When TD-SCDMA demodulation is enabled, the Filtered Time trace shows the pre-demodulation filtered time record data. The Result Length parameter determines the amount of time data that is analyzed and displayed.

Note

Overall Time data is unaffected by time averaging.

VSA signal flow (see Digital Demodulation Block Diagram):

Display Format

The data is shown in a multi-color alphanumeric format that identifies the detected active timeslots within each measured sub-frame including the uplink and downlink pilot time slots. The active Marker timeslot used for data analysis is also highlighted.  The colors can be changed and redefined using the Display Appearance Color dialog box (See Display Appearance).

Interpreting the Overall Filtered Time trace data results.

See the Overall Time trace data topic.

See also

Ch1 Overall Trace Data

About Trace Data TD-SCDMA


Overall Time Trace Data   (TD-SCDMA)

(Vector Signal Analyzer application only)

Menu Path: Trace > Data > Ch1 Overall > Time

When TD-SCDMA demodulation is enabled, the Time trace shows the pre-demodulation time record data. The Result Length parameter determines the amount of time data that is analyzed and displayed.

Note

Overall Time data is unaffected by time averaging.

VSA signal flow (see Digital Demodulation Block Diagram):

Display Format

The data is shown in a multi-color alphanumeric format that identifies the detected active timeslots within each measured sub-frame including the uplink and downlink pilot time slots. The active Marker timeslot used for data analysis is also highlighted.  The colors can be changed and redefined using the Display Appearance Color dialog box (See Display Appearance).

Interpreting the Overall Time trace data results.

Active Data Timeslots:	The numbers 0 and 1 show that Timeslot 0 and Timeslot 1 are active timeslots within the measured sub-frame.   Timeslot 0 is colored in translucent white to show that it's an active timeslot but not selected for data analysis. Timeslot 1 is highlighted to show that it was selected by the Marker and used for the data analysis and trace data results.
Downlink pilot timeslot:	The letter "P" and green color show that the DwPTS pilot timeslot is an active timeslot.
Uplink pilot timeslot:	The letter "P" and red color show that the UpPTS pilot timeslot is an active timeslot.
Marker Readout	Marker Location: 1.28359 mSec after the start of the sub-frame. Power Level: -14.606 dBVpk
	Notes:    Colors shown with default settings.
Tip

Analysis Timeslot and Analysis Sub-frame parameter entry shortcut:  Right click on the desired Timeslot and select Copy Marker to Analysis TS/SF.

See also

Ch1 Overall Trace Data

About Trace Data TD-SCDMA