Hi
Frequency division multiplexing for telegraphy goes back quite a ways:
(note the use of tuning forks …)
It was an established approach long before Teletypes came along. The whole
“who worked out what” is very tangled. Folks write papers on just the tangled
part:
It’s a pretty good bet that whatever got used for the early AFSK gear was based on
the tone groups used on this or that FDM wireline setup. They came up with a
mind boggling number of these systems over the years and in various countries.
Once microwaves came along, they appear to have re-invented them all over again.
Some “quality time” spent digging into the various wired systems in use in the 1910
to 1930 range likely would turn up a candidate.
Bob
On Fri, October 8, 2021 4:41 am, Nick England wrote:
AN/FGC-1 block diagram and general description is on this page
https://www.navy-radio.com/rtty-demod.htm
I think I have the manual somewhere and will scan it when I get a chance.
Nick
Thanks! I suspect this is the origin of the tones for amateur radio work.
See paragraph b at
https://www.navy-radio.com/rtty/ww2/FGC1-TM11356-abstract.pdf#page=5 .
--
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