Brenda Ann wrote:


"David" wrote in message
...
The only thing that keeps us from hearing the digital sidebands is
their symmetry (the digital sidebands are out of phase with each other
and cancel out in the receiver).

I'm still trying to figure out how this is supposed to work.. I understand
the concept, FM stereo does something similar by using phasing to reduce
the bandwidth needed for the L-R signal. The peaks of the L-R fit nicely
into the valleys of the L+R signal and vice versa.

No, this is not how FM works. I suggest you do some google searching. Here
is a start.
http://www.radio-electronics.com/inf...modulation.php
http://www.st-andrews.ac.uk/~www_pa/...t13/page1.html
http://www.fas.org/man/dod-101/navy/docs/es310/FM.htm


But this doesn't seem like it would work as advertised on a store-stock AM
radio, because the ordinary envelope detector does not detect both
sidebands, only one of them. So how does it cancel?


An envelope detector does just what its name implies. It works from the
peaks in the time domain signal. The signal applied to the detector is
everything that comes through the filter; the carrier and both sidebands if
the signal is centered in the filters passband. The only way you can
exclude a sideband is to tune off from the center frequency.

A little bit of google searching can find you these.
http://en.wikipedia.org/wiki/Envelope_detector
http://www.radio-electronics.com/inf...e_am_demod.php
http://www.st-andrews.ac.uk/~jcgl/Sc...rt9/page2.html
http://www.mit.bme.hu/research/chaos...1_04am_dem.pdf