Effect Of Averaging On A Trace; Averaging Menu - HP 8753E User Manual

Averaging Menu

The (XjJ key is used to access three different noise reduction techniques: sweep-to-sweep
averaging, display smoothing, and variable IF bandwidth. All of these can be used
simultaneously. Averaging and smoothing can be set independently for each channel, and the
IF bandwidth can be set independently if the stimulus is uncoupled.
The following softkeys are located within the averaging menu:
Averaging
Averaging computes each data point based on an exponential average of consecutive sweeps
weighted by a user-specified averaging factor. Each new sweep is averaged into the trace until
the total number of sweeps is equal to the averaging factor, for a fully averaged trace. Each
point on the trace is the vector sum of the current trace data and the data from the previous
sweep. A high averaging factor gives the best signal-to-noise ratio, but slows the trace update
time. Doubling the averaging factor reduces the noise by 3 dB. Averaging is used for ratioed
measurements: if it is attempted for a single-input measurement (e.g. A or B), the message
CAUTION: AVERAGING INVALID ON NON-RATIO MEASURE is displayed. Figure 6-25 illustrates the
effect of averaging on a log magnitude format trace.
Note
If you switch power ranges with averaging on, the average will restart.
Figure 6-25. Effect of Averaging on a Trace
Application and Operation Concepts 6-61