Demodulating An Fm Signal Using The Analyzer As A Fixed Tuned Receiver (Time-Domain) - Keysight N9030A Measurement Manual

Demodulating an FM Signal Using the Analyzer as a Fixed Tuned Receiver (Time-Domain)

Demodulating an FM Signal Using the Analyzer as a Fixed Tuned
Receiver (Time-Domain)
To recover the frequency modulated signal, an analyzer can be used as a manually
tuned receiver. However, in contrast to AM, the signal is not tuned into the passband
center, but to one slope of the filter curve as shown in
Figure 2-7 Determining FM Parameters using FM to AM Conversion
Here the frequency variations of the FM signal are converted into amplitude
variations (FM to AM conversion). The reason we want to measure the AM
component is that the envelope detector responds only to AM variations. There are
no changes in amplitude if the frequency changes of the FM signal are limited to the
flat part of the RBW (IF filter). The resultant AM signal is then detected with the
envelope detector and displayed in the time domain.
33
Concepts
Figure 2-7.