Help me design a 19kHz FM demodulator

[PalapaGuy]

I am attempting to design a demodulator for commercial FM broadcasts that is optimized to detect only the 19 kHz unmodulated stereo pilot at very low C/N (below ordinary discriminator threshold). I need only the 19 kHz tone, not the program audio. Any help is appreciated.

 

[FvM]

Re: FM Demodulation

I'm not sure, if it matters practically, but from a general signal processing view, a linear receiver would be required, without the usual IF limiting of a FM receiver. It would be able to detect a pilot tone that is partial covered by a stronger FM signal in a neighbour channel, particularly if the detection bandwith can be low. Are you planning a digital receiver or an analog solution?

 

[PalapaGuy]

Re: FM Demodulation

Digital solution is preferred. There will be no adjacent channel problem due to IF filtering, but the 19 kHz pilot of course is in the composite baseband together with random audio. The pilot is protected by guard bands around it. So the receiver's job is relatively straightforward: to detect the unmodulated 19 kHz tone at low values of C/N. I think you're correct that a limiter should not be used.