"Gary Schafer" wrote
However if the TV video signal was an FM modulated signal rather than
AM then the sound sub carrier would not be visible without the main
video carrier if it was generated as a sub carrier.
The same happens with an FM broadcast SCA sub carrier or the stereo
sub carrier on the main signal. The main signal must first be
demodulated in order to demodulate any sub carrier.
_____________

The r-f spectra of TV aural signals and FM SCAs are standalone entities.
Each may be fully demodulated by a suitable FM receiver capable of tuning to
that r-f spectrum. No "main" carrier is needed. Given, this isn't the
conventional practice -- however it would be possible to do.

Likewise, the L-R audio information of an FM stereo transmission is a
standalone entity, and given a suitable r-f receiver and detector, it can be
fully demodulated back to L-R without needing the main carrier. Not
conventional or cost-effective, but possible. Of course, the L+R waveform
conveyed by the main carrier is necessary to matrix with L-R to produce the
L&R channels needed for stereo reproduction by the receiver system.

RF