|[AMRadio] RE:Carrier with one sideband|
k4kyv at charter.net
Fri Feb 8 19:10:09 EST 2008
> I seem to remember that the aircraft radios we used during the 60-80s in
> P-3s/C-130s etc (ARC-94/102 aka 618T) had a
> selection called AME (AM equivalent). It was explained to us (pilots)
> by the techs that it wasn't a
> high level AM, but USB with carrier. It sounded OK, but then again, it
> was designed for communications
> and not "easy listening"! All the airways communication now days is
> SSB, so the AME position rarely
> gets selected.
> Perhaps someone is familiar with that mode and can expand on it.
> 73 Tom/W4OKW
Aircraft VHF radios still use full carrier AM. I have a small Radio Shack
portable with the aircraft band, and there is a lot of AM traffic on it. I
purchased it mainly to use as a tool for sniffing out power line noise. The
reason they use AM instead of FM is the capture effect of FM. With AM, when
a strong signal is on frequency, a weaker one can still be heard under the
stronger one. It would be a catastrophe waiting to happen if aircraft used
FM radios and a stronger signal completely overrode, particularly near a
busy airport. Also, I seem to recall something about SSB being less than
satisfactory due to the shift in frequency due to the Doppler effect, with
high speed jet aircraft.
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