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R&S FSH
Spectrum Analyzer Mode
Configuring Spectrum Measurements
Operating Manual 1173.6275.12 - 30
105
3.2.4 Configuring and Triggering the Sweep
You can find all necessary settings to configure the sweep itself in the sweep menu. To
access it, press the SWEEP key.
3.2.4.1 Setting the Sweep Time
The sweep time is the time it takes the R&S FSH to get the results that are contained
in one trace.
In the frequency domain (span > 0), the sweep time is the time it takes the R&S FSH to
measure the spectrum in the specified span. To avoid the display of spurs in the
spectrum, the sweep time has to meet some conditions.
● The sweep time depends on the resolution bandwidth. If the sweep time is too
short, the resolution filter has no time to settle. In that case, the displayed levels
will be too low. For more information see "
Setting the Resolution Bandwidth
● The sweep depends on the span. If you increase the span, you also have to
increase the sweep time.
In its default state, the R&S FSH couples the sweep time to the span and the
resolution bandwidth to avoid invalid settings. If the coupling is active, the R&S FSH
always sets the shortest possible sweep time to make sure that the display of the
spectrum is correct and valid.
The R&S FSH requires a minimum sweep time of 20 ms for every 600 MHz of span. If
you increase the span, the R&S FSH will also increase the sweep time.
In the time domain (span = 0), the R&S FSH shows the video voltage over time. The
horizontal axis becomes a time axis that starts at 0 s and ends at the sweep time that
you selected. The range of the sweep time in the time domain is from 200 µs to 1000 s.
► Press the SWEEP key.
In the default state, "Auto SWP Time" is active.
► Press the "Manual SWP Time" softkey.
The R&S FSH opens an input field to set the sweep time.
► Enter the sweep time you need.
If the video bandwidth is no longer coupled to the span or the resolution bandwidth,
the R&S FSH puts a red dot at the "SWT" hardware setting (
).
3.2.4.2 Selecting the Sweep Mode
The sweep mode is the way the R&S FSH performs the measurement.
In its default state, the R&S FSH measures continuously. In this mode, the R&S FSH
automatically repeats the sweep in the defined range of the horizontal axis (frequency
or time) and updates the trace accordingly after it has finished with one sweep.