matt weber wrote:
On Wed, 5 Oct 2005 08:14:49 -0700, "Caveat Lector"
wrote:


What USA commercial broadcasting mode uses double sideband - suppressed
carrier ?

FM stereo transmits the L-R signal at 38Khz with DSB-SC (DSB without
supressed carrier is simply AM).
The signal is recovered by using the 19Khz Pilot carrier on the main
FM transmission to phase lock the 38Khz oscillator for synchronous
detection (If you cannot phase lock the injected carrier, you WILL get
phase distortion, and the stereo signal will sound like cr*p).

That is also why most FM receivers have a deep notch in the audio
section at 19Khz...


Perfectly true, but few, if any, FM receivers can receive above 15kz
and few FM broadcasts ever exceed 15kz, so the notch at 19kz is somewhat
moot.

Tony

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