About Math Functions

Math functions create mathematical expressions that operate on trace data. Use math functions to:

Perform mathematical operations on trace data.
Create a mathematical expression that you can apply as a filter to a waveform.
Manipulate data in the data registers.

All math operations are performed on linear data, even when the trace data is logarithmic magnitude. For log traces, math operations are performed before the trace data is converted from linear to log values.

Trace titles of math functions have a prefix of "Fn", followed by the name of the math function. For example, "Fn ChanImpResp" is the trace title of a math function named ChanImpResp.

Trace Blanking and Math

Math attempts to track trace blanking from the operand to the result. Trace blanking occurs when the Group Delay trace format is selected (see Group Delay Aperture) or when the start frequency or stop frequency is set outside the valid values.

Time stamps and 3D Trace Mapping

The time stamp of a result of a math function is determined by the leftmost data operand. This means that the time stamp can be constant even though the result of the math function may change with every measurement sweep.

The following are two examples which produce the exact same result, but with different time stamps.

Variable time stamp: Data('Main Time1') - Data('D1')
Constant time stamp: -1*Data('D1') + Data('Main Time1')

The time stamp of the underlying trace data determines how the VSA updates 3D Trace Mapping that is applied to a trace.