On Sat, 7 Nov 2009, Richard Knoppow wrote:

Around the 1950s Leonard Kahn and others worked out
means of combining the sidbands of a conventional AM or
double sideband suppressed carrier signal using a
synchronous detector. In effect this was a sort of frequency
diversity. It also reduced distortion due to selective
fading since it regenerated the carrier locally.

Wasn't it Webb at GE that was doing the work on DSB? That's the name on
the synchronous detector article in "CQ" in the late fifties, and that was
either preceeded or followed by an article about DSBsc in general.

And John Costas of course came up with the Costas Loop for receiving AM,
and I see he was at GE in the fifties when he came up with the Loop.


Michael VE2BVW