In article , "Steve Nosko"
writes:

What's the essence of an AM sync detector? Extract the carrier
(filter/clip/amplify the bajeebers out of it) then product detect the
sidebands ?
--
Steve N, K,9;d, c. i My email has no u's.

Essentially, yes. There's a further step, though, and that is
locking a local mixing oscillator to the carrier frequency and
mixing that with the whole thing.

If the local mixing oscillator is in phase with the received
carrier, the mixing results in just a DC component which can
be removed easily. A carrier in-phase lock allows separate
detection of the sidebands...which could be used to
advantage such as having binaural audio modulation with AM.

That also works out well for a quasi-stereo listening with any
signal that is NOT binaurally modulated. The effect of hearing
through such a detector's audio cannot accurately be described
in words. Nearby-signal splatter can be "heard" as left or right
of the desired signal. Strange sound but does allow the mind's
own spatial filtering to sort-of blot out nearby interference.

That quasi-stereo circuit is a lot more complicated (it's usually
a typical Costas Loop with local mixing oscillator having shifts
for quadrature phasing) than the direct amplify-limit-clip-the-
bejeebers out of the carrier and mix that with whole works...as
was done in the Motorola MC1330P 8-pin DIP IC (now obsolete
but Kits&Parts as a few left).

Len Anderson
retired (from regular hours) electronic engineer person