Steven Swift wrote:

"Frank Dresser" writes:



I think the fact that the synchrodyne never became at all popular as an AM
radio detector in the tube era means something. If I recall correctly, I
read that synchrodyne detectors would howl until they sync'd. Also, the
phasing would have to be perfect to get good demodulation from normal double
sideband AM.





Frank Dresser



Yes, they howl. But his channel concept eliminates that problem. In a private
email, I asked Jon if his design can use ICs. If you use a couple of ICs to
generate the "synchronized" signal, I think you can get around the complexity.

Jon has a lot of work. Block diagrams are pretty simple. Details are hard.



AM stereo radios use sync detectors to demodulate the L-R signal
(broadcast in quadrature).
Not strictly in quad, but close. The Sony SRF42 has a sync detect chip
that doesn't do the
"envelope" detector correction on the quad signal, and thus I could
shift by 90 degrees the
AM carrier signal feeding its PLL section. Thus creating sync
demodulated main channel
(true mono on non-AM stereo stations). See
http://home.earthlink.net/~wa2ise/im...syncdetmod.jpg
http://home.earthlink.net/~wa2ise/images/cxa1758n.jpg
and 3/4 the way down this page:
http://pw2.netcom.com/~wa2ise/radios/amstmod.html