"Henry Kolesnik" wrote in message
...
I know that Hallicrafters made a dual diversity set up and RCA used three
AR-88s in a trioka, selecting the best signal with a tone decoder that
switched in the best and let the other/s idle or squelched. I've heard that
Collins used the R 390 (51J or 51S?) , and Hammarlund the Super Pros ( only
600s or others?). It seems like three antennas spaced about 1000 feet apart
on an equilateral triangle was a 100% solution. Did the Brits use it a
Bletchley? But I don't see anything these days and have to wonder if
diversity reception was made obsolete by SSB or the news & financial
services using wire for TTY. I also know that Telstar was the final nail.
Was the primary use for RTTY or was it used to voice well as CW? Anyone
have some real personal experience to offer?
Thanks
Hank WD5JFR
Years ago at Collins we used a frequency diversity system that sent the same
signal on upper and lower sideband. Additional improvement was achieved by
delaying one sideband a few milliseconds, then doing the inverse delay at
the receiving end. The time delay approach worked well, but never caught on
commercially.

Additionally, separate antennas were deployed for space diversity. I have
forgotten the siting guidelines.

The frequency diversity system was used for RTTY, and antenna space
diversity for voice/data.

Wayne wrote:
"The time deay approach werked well, but never caught on commercially."

Our receiver selection boxes were made by Crosby or Pioneer if I
remember, but it`s been a half century.

Best regards, Richard Harrison, KB5WZI

"Richard Harrison" wrote in message
...
Wayne wrote:
"The time deay approach werked well, but never caught on commercially."

Our receiver selection boxes were made by Crosby or Pioneer if I
remember, but it`s been a half century.

Best regards, Richard Harrison, KB5WZI

Heh heh. Yeah, long time.
We made our own time delay box under Navy funding. In a prototype, we
provided the time delay by recording the RTTY signal on tape and playing it
back soon afterwards on a different tape head. The original and delayed
were then sent on different sidebands. Noise was simulated with recorded
static, and the noise audio was injected at the receiving end before
deconstructing the delay with another tape deck.

IIRC, we found combinations that gave about a 3-5 db improvement. Fun
project that would be even more fun with modern circuitry.

Wayne wrote:
"In a prototype, we provided the time delay by recording the RTTY signal
on a tape and playing it back soon afterwards on a different tape head."

That is a technique used to add echo to a recording without a long audio
chamber or worse yet springs stretched between transducers.

Best regards, Richard Harrison, KB5WZI