Re: [TenTec] AM, was "Just noticed ..."

["Grant Youngman" <nq5t@comcast.net>]

> Do any of you know whether when running SSB-AM the carrier 
> power has to be the same as it was for DSB-AM in order for a 
> regular AM detector to demodulate the signal properly? 

Yes, the carrier-sideband amplitude ratio matters even if you're only
transmitting one sideband.  The carrier either has to be transmitted or
supplied at the receive end.  One of the problems with simple diode
detectors is that non-linearities increase as modulation percentage gets
close to 100% (actually a good bit less).  You can have too much carrier
with little ill effect, other than the perception that the signal doesn't
have quite enough audio.  But too little buys you distortion unless you're
using a synchronous detector on the receive end.  It's why signals go
unintelligible when selective fading takes out the carrier -- one sideband
or two.

In my opinion, there's quite a lot to be said for the notion of SSB-AM with
a pilot carrier, and an appropriate sync detector in the receiver.

Grant/NQ5T


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