Why don't voice radio communications use FM?

On Mon, 04 Sep 2006 19:47:13 +0200, Mxsmanic
wrote:

writes:

You don't seem to understand there is NO quality difference in audio
quality between FM & AM, unless you're equipment is faulty and
introducing distortion. I've used AM & FM with amateur radio and been
a professional Broadcast Engineer for 30 years so believe me you are
wrong!

Odd that FM seems to sweep AM out of so many markets, then. All the
FM transmissions I've heard were superior to AM.

Because it's simple to modulate at low level and generally uses a
wider bandwidth. It is only superior in signal to noise as long as the
receiver detector is limiting but once the signal drops it's useless.
I don't know if you would get much multipath distortion from the
ground to an aircraft but if you do you would get noticable
distortion.

I cannot remember the exact figures but I seem to remember
communication quality AM is about 8db better than the equivalent FM.
SSB is about 13db better than FM. Remember you need also to specify
power.