Along the same line consider that the envelope of an SSB signal has no
direct relationship to the original modulation the way that an AM
signal does.

This is why you can not use RF derived ALC to control the audio stage
of an SSB transmitter the way you can with an AM transmitter.
Or audio clipping that works on AM but does not work the same on SSB.

Transmit a square wave on an AM transmitter and you see a square wave
in the AM envelope. Do the same with an SSB transmitter and you only
see sharp spikes in the envelope.

73
Gary K4FMX


On Thu, 23 Oct 2003 12:08:31 -0700, "Joel Kolstad"
wrote:

Fred McKenzie wrote:
Perhaps that is what I'm remembering. Now, if you use a filter to
eliminate the other sideband, the higher frequency components and the
carrier, don't you have a nearly identical remainder?

At that point I don't think you could tell the difference since there's no
longer any local phase reference (i.e., the carrier) to compare with. I
suppose this is why your SSB-AM rig is able to (somewhat) receive low
frequency (and thereby presumably narrowband) FM broadcasts; this is what
you were saying in your last post, correct?

I think we are in agreement that you can't recover FM modulation with
just an envelope detector

Yes, at least you can't recover a signal that directly corresponds to what
you transmitted. It does appear that you can recover the signal's square,
however, so this approach might be useful for, e.g., remote command
transmissions. (But probably just for the novelty of having said you did
it... since it's probably not much harder to build the slope detector you
describe!)

---Joel