[AMRadio] RE:Carrier with one sideband

D. Chester 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.

Don k4kyv 

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