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The pilot is there for stereo decoding, it has nothing to do with the ability to tune to an FM station. https://wiki.analog.com/university/courses/electronics/
by lrasinen 2y ago
The pilot is there for stereo decoding, it has nothing to do with the ability to tune to an FM station.
https://wiki.analog.com/university/courses/electronics/electronics_lab_fm_detectors https://wiki.analog.com/university/courses/electronics/elect... has some of the analog approaches collected.
- jasonjayr 2y agoYou're right -- after reading some of the peer responses, I realized that (I think...) my response is just how the Broadcast FM signal modulates the parts of the signal, and not how it actually 'locks on'. I'm still learning!
- lrasinen 2y agoI got an RTL-SDR this summer and brushed up my DSP skills playing with FM signals. PLLs are marvellous beasts; you can do a slapdash job in "designing" one and it'll still probably lock on just fine. Might not be optimal but will still lock. Another fun one, when you have IQ samples, is the polar discriminator: calculate x[t] * x*[t-1] where x* is the complex conjugate, and take the angle with arctan. Feels a bit like magic ("is that all?") but is justified by the theory.