User Manual

The Spectrum Application
R&S
®
FPC
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(whichever is larger). Otherwise, the power the R&S FPC shows is too low
because there are spectral components within the frequency range covered by the
pixel that do not originate from the signal you want to observe (e.g. noise).
To get the true power, the video bandwidth (VBW) should also be greater than the
resolution bandwidth (RBW). Otherwise, an averaging effect caused by video
bandlimiting comes into play before the RMS value is calculated.
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"Sample "
The sample detector shows the last level that was measured in the frequency
range covered by a pixel.
The sample detector is useful for measurements in the time domain (span = 0 Hz)
as it provides the only way to represent the timing of the video signal correctly.
In the frequency domain, the sample detector is a good way to measure noise
power because noise usually has a uniform spectrum with a normal amplitude dis-
tribution.
Signals can get lost if you are using the sample detector for measurements with a
span that is greater than RBW*1183 (number of display points).
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"Auto Detector"
The auto detector selects one of the detectors automatically, depending on the
selected trace mode.
For more information, see Chapter 12.8.1, "Trace Mode", on page 109.
Selecting the detector
1. Press the "Trace" key to open the trace menu.
2. Select the "Detector" menu item to open the detector menu.
The R&S FPC opens a submenu to select the detector mode.
3. Select the detector you want to work with.
12.8.3 Memory Traces
Working with memory traces
You can save the image of both traces to the memory of the R&S FPC and later
restore it, compare it to a live trace or apply trace mathematics. The memory trace has
a different shade of color to distinguish it from the live traces. In the spectrum applica-
tion, the R&S FPC supports three memory traces.
When you save a data set, the R&S FPC also stores the associated trace in the trace
memory. If you restore it later, you can display the memory trace as if it is a normal
trace.
1. Press the "Trace" key to open the trace menu.
2. Select the trace you want to store in the trace memory with the "Select Trace"
menu item.
The R&S FPC saves the selected trace.
3. Select the "Memory Traces" menu item.
Trace Configuration