RE: [Discuss-gnuradio] NBFM

[Matthew Francey]

Marcus Leech asked:

>In the analog world, do they implement squelch using
>  detected RF power levels (i.e. prior to FM demod), or
>  something else?

I think early receivers used an AGC level.  Modern receivers use the noise:  
once the high frequency (above the expected voice bandwidth) content of the 
demodulated audio drops below a some value, the squelch is disabled.