Mathematical relations between traces can be used to compare different traces, correct traces, re-design measurements or create new measurements. Trace mathematics is always based on linear, complex trace data (irrespective of the actual trace format).
Comparing
two traces displayed in dB Mag format
Suppose you have created a channel no. 1 with two traces named Trc1 and Mem2[Trc1] and that you wish to compare the magnitudes of the two traces.
Display the traces in a common diagram area using the default trace format dB Mag (see example of two traces with approx. constant magnitude difference).
Click Trace – Trace Select – Add Trace to add a new trace to the diagram area. The new trace is automatically assigned a trace name (e.g. Trc3) and selected as the active trace.
Click Channel – Trace Funct – User Def Math to open the User Def Math for Trc3 dialog and enter the following mathematical relation for the new trace: Trc1/Mem2[Trc1]. Click OK to confirm your definition and close the dialog
Select Trace – Trace Funct – Math = User Def to display Trc3 as a mathematical trace.
The mathematical relation Trc1/Mem2[Trc1] is applied to the linear trace data. In logarithmic representation, the effect is a subtraction of the two traces. The mathematical trace shows the difference of the dB Mag values of Trc1 and Mem2[Trc1]. In our example the difference trace is approximately constant.
