R&S FSH
Spectrum Analyzer Mode
Performing Spectrum Measurements
Operating Manual 1309.6275.12 - 14
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2.1.2.5 Changing the Span
Usually, the span the R&S FSH sets yields optimal results. But sometimes you also
need to see the spectrum outside the current span to detect other signal components
that you need to include in the measurement. Therefore, you can adjust the span to up
to ten times the channel bandwidth and still be able to see the spectrum outside the
measurement channel.
M
Press the SPAN key.
In the default configuration, "Auto Span" is active. The R&S FSH automatically sets
the optimal span for the channel power measurement.
M
Press the "Manual Span" softkey.
The R&S FSH opens an input field to define the span manually.
M
Enter the span you need.
The largest possible span for the channel power measurement is ten times the
channel bandwidth. At larger spans, the result of the channel power measurement
would be increasingly imprecise, because too few points of the trace occur in the
channel to be measured.
M
Press the "Auto Span" softkey.
The R&S FSH again calculates the span automatically.
2.1.3 Power Measurements on TDMA Signals
When TDMA (time division multiple access) methods are used, e.g. for GSM, several
users share a channel. Each user is assigned a period of time or timeslot. With the
TDMA power measurement, you can determine the power over one of the timeslots.
The TDMA power measurement is a measurement in the time domain (span = 0 Hz).
You can start it on an external or video trigger and specify the power measurement
time.
To prevent incorrect power measurements in the time domain, make sure that the
whole signal is within the selected resolution bandwidth. If the resolution bandwidth is
too small, the displayed power will be lower than the actual power.
M
Press the MEAS key.
M
Press the "Meas Mode" softkey.
The R&S FSH opens the measurement menu.
M
Select the "TDMA Power" menu item.
The R&S FSH starts to measure the TDMA power.
Two vertical lines define the measurement range.
