R&S FSW-K7 User Manual page 173

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R&S FSW-K7
9. Now the RF spectrum shows that part of the FM signal is cut off. The missing sig-
nal parts are not included in the calculated results. Increase the demodulation
bandwidth to 400 kHz to include the entire signal, but no interfering frequencies.
The span is not automatically increased for the wider DBW since it may be useful
to display only a small range from the demodulated bandwidth. However, this
means the RF spectrum will still not show the entire signal.
10. Increase the span manually to show the entire demodulated bandwidth:
a) Select the RF Spectrum window.
b) Press the SPAN key.
c) Select the "Full Span" softkey.
Figure 9-6: RF spectrum with demodulation bandwidth = 400 kHz
11. Once the correct DBW has been determined, you can replace the RF spectrum by
the FM spectrum result display to analyze the spectrum of the FM signal. Select
the "Display Config" softkey and move an "FM Spectrum" window over the "RF
Spectrum" window in the display.
User Manual 1173.9240.02 ─ 23
Measurement Example: Demodulating an FM Signal
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