Richard Fry wrote:

If you are still thinking of the broadcast television signal, the audio
portion is not a subcarrier -- it is a discrete carrier whose modulation
can be detected by any receiver capable of FM demodulation, and able to
tune to its r-f center frequency.


You've described how it's commonly generated. But is the end result any
different than if it were generated instead by modulation of the main
carrier by an ideal modulation system not having the practical problem
of intermodulation distortion? That is, isn't the end result identical
to a subcarrier?

When I worked in radio broadcasting in the '60s, we generated an FM
(SCA) subcarrier in addition to the stereo subcarrier by modulating the
transmitter. Some stations had multiple SCA subcarriers.

Roy Lewallen, W7EL