[BC] Mono Expands on the FM Band

[Robert Orban]

>From: "Hershberger, Dave" <DHershberger at axcera.com>
>
>
>USB ONLY Stereo penalty with USB receiver = 12.49  dB
>DB improvement with USB receiver= 10.52  dB
>
>Over 10 dB improvement in SNR! Now we're talking. Too bad it isn't
>compatible.
>
>Bob would probably point out the difficulties of audio processing for SSB
>(L-R) signals - Hilbert transforms are involved.

Dave -- Thanks for running the full set of numbers. I only computed 
the peak modulation increase without also computing the S/N advantage 
of putting more energy where the modulation index is higher.

And yes, the audio processing becomes more challenging because the 
acceptable peak level in the L and R channels depends on the nature 
of the L-R signal. Anyone interested might want to take a look at my 
old US patent 4,674,122 (for FMX encoding and modulation control). It 
describes a look-ahead technique that could probably be adapted to 
peak limiting such a system.

Bob Orban