R&S FSH
Spectrum Analyzer Mode
Configuring Spectrum Measurements
Operating Manual 1309.6275.12 - 14
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By default, the search limit range is over the whole span.
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Press the "Search Limits" softkey
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Select the "Lower Limit" menu item.
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Confirm the selection with the ENTER key.
The R&S FSH opens an input field to define the lower limit of the search range.
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Enter the lower limit.
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Confirm the entry with one of the unit keys.
If the span is wide enough, the R&S FSH displays a red vertical line to indicate the
lower limit.
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Define the upper search limit the same way.
Deactivating marker search limits
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Press the "Search Limits" softkey.
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Select the "Search Limits On/Off" menu item.
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Confirm the selection.
The "Search Limits" softkey turns grey again and in the "Search Limits" menu, the
[X] is no longer displayed.
2.2.6.7 Using Marker Functions
In addition to the frequency and level readout, the R&S FSH provides several, more
complex, marker functions in spectrum analyzer mode.
Deactivating marker functions
Selecting a marker function again while it is still active turns that marker function off.
Measuring the Noise Power Density
The marker noise function calculates the noise power density at the marker position in
dBm/Hz. The R&S FSH includes several variables in the calculation of the noise power
density, including the trace pixel values, the resolution bandwidth, the detector and the
level display mode (absolute or relative). To stabilize the noise power display, the
R&S FSH uses the pixel the marker is on and four pixels to the right and four pixels to
the left of the marker pixel.
Noise power density can provide useful information when you are measuring noise or
digitally modulated signals. However, you will get valid results only if the spectrum in
the vicinity of the marker has a flat frequency response. When measuring the noise
power density on discrete signals, results are not valid.
