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Chapter 1 67
Making Basic Measurements
Demodulating FM Signals
Figure 1-57 Determining the Offset
Demodulate the FM Signal
1. Connect an antenna to the analyzer INPUT.
2. Perform a factory preset by pressing Preset, Factory Preset (if
present).
3. Tune the analyzer to a peak the peak of one of your local FM
broadcast signals, for example 97.7 MHz by pressing FREQUENCY,
Center Freq, 97.7, MHz.
4. Set the span to 1 MHz by pressing SPAN, Span, 1, MHz.
5. Press AMPLITUDE, Ref Level, and use the front-panel knob to bring
the signal peak to the reference level.
6. Press Scale Type (Lin) to place the analyzer in linear scale mode.
7. Tune above or below the FM signal by the offset noted above in
step 12, in this example 151 kHz. Press
FREQUENCY, CF Step, 151,
kHz, then press Center Freq and use the step-up key (↑) or step-down
key (↓).
8. Set the resolution bandwidth to 100 kHz, by pressing BW/Avg, Res
BW
, 100, kHz.
9. Set the span to zero by pressing SPAN, Zero Span.
10.Turn off the automatic alignment by pressing System, Alignments,
Auto Align, Off.
11. Listen to the demodulated signal through the speaker by pressing
Det/Demod, Demod, AM, Speaker (On), then adjust the volume using
the front-panel volume knob.