Why don't voice radio communications use FM?

Mxsmanic wrote:
Dan Luke writes:

******** again. I have a radio that does actively remove noise--it
has a button to turn the feature on and off, and it works quite well.

What kind of noise does it remove, and how does it distinguish noise
from signal?

One proven way to reduce noise is to repeat the signal N times and the
receiver adds up the repetitions and eventually the noise averages to zero
while the signal does not. Of course this is not what is done in practice
in real communications.

(I once wrote software for a Tunneling Electron Microscope (TEM) that did
the above - the target object is repeatedly scanned and the scans are
basically averaged - the noise falls off. Though IIRC, the amplitude of the
noise drops by a factor of 1/sqrt(N) for N scans. I'm too lazy to look it
up so that might not be the correct factor.)

One proven way to reduce noise is to repeat the signal N times and the
receiver adds up the repetitions and eventually the noise averages to zero
while the signal does not. Of course this is not what is done in practice
in real communications.

Actually, doesn't more transmitter power effectively accomplish that?
(the signal is essentially repeated N times, at the same time)

Jose
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Jose wrote:
One proven way to reduce noise is to repeat the signal N times and
the receiver adds up the repetitions and eventually the noise
averages to zero while the signal does not. Of course this is not
what is done in practice in real communications.

Actually, doesn't more transmitter power effectively accomplish that?
(the signal is essentially repeated N times, at the same time)

The unstated assumption is of course that the transmitter is running at
full power output. Once you've done that, the question is what other tricks
are there to increase the range the signals can be detected.

Jose writes:

Actually, doesn't more transmitter power effectively accomplish that?
(the signal is essentially repeated N times, at the same time)

Yes.

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