Agilent Technologies Signal Analyzer N9030a - Manual (Page 1458)

6 RLC Swept SA Measurement Front-Panel & SCPI Reference
View/Display
Representation of Time
In the Spectrogram view, zero time is the point where the first trace started, meaning that each
subsequent trace point is at a positive time that represents when that point was gathered, relative
to the start point. Each trace is time stamped as it starts, and this time is remembered for each
trace. As successive traces appear their start times get successively larger, relative to the start
time of the oldest trace. If a marker is placed on the live trace and its readout is set to Time, the
time of this marker will increment by about the sweep time for every new sweep. See the diagram
below for a graphical representation of how this will appear to the user:
Each trace point has a time value; the value of the start time of the trace is accurately time
stamped, but each point within the trace is the start value plus the proportion of sweep time
represented by that position in the trace. This means the time value of the points within a trace
will not be as accurate as the start point, which is actually the case even in the Normal View,
when you use a Time readout for Markers in the frequency domain. This problem is particularly
acute with the Sweep Type set to FFT, since the calculated nominal FFT sweep time estimate can
be off by a large percentage. Therefore, in FFT sweeps, to prevent overlaps of time on traces, and
to make the Sweep Type of FFT consistent with Swept, the end time for each trace is calculated to
yield a continuous functional Z axis time value for each position on the trace. Since any
1458 Remote Language Compatibility Measurement Application Reference