"Michael Black" wrote in message
mple.net...
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

You may be right. GE did a lot of early work on SSB and
DSB. GE had a very fine research department until John
Welsch killed it.



-- Richard Knoppow
Los Angeles
WB6KBL

"MoiInAust" wrote in message
...
Diversity is certainly not a new concept. It was present
in the RCA AR88 designed about 1938-9!

I've seen pictures of AR-88s in triple diversity
set-ups. I don't know if that was ever used at the big RCA
Communications stations but at least one of the on-line
service manuals for the AR or CR 88 has a catalogue sheet
and photo of one in the back.


--
Richard Knoppow
Los Angeles
WB6KBL