Agilent Technologies 89400 Series Command Reference Manual page 112

Command Reference
query is that of the most recent trace.
If the number of traces displayed has reached the buffer depth, the value returned is the
buffer depth.
Related Commands:
To set the buffer depth, use DISP:WIND:TRAC:BUFF.
To turn on the spectrogram/waterfall trace-analysis feature, use CALC:MARK:TRAC.
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