[GreenKeys] Sheldon and Greg,

[Sheldon Daitch]

Don,

we weren't running full time message traffic, only a
few hours each day, and it was a manual torn tape
operation, full duplex, and our method of telling the
transmitting station was to simply type something to
the distant end.

That would work fine if the message was plain text,
I mean, we would read along with the page copy, so
we could readily see if there were errors, plus if it was
plain text, you could make educated guesses, a garble that
simply misspelled a word was easily correctable, but a
garble in a part number or fiscal data could not be
eye-balled corrected, normally.  At the same time, too,
experienced machine operators could usually detect garbles
just from the rhythm of the machine operations.

Encrypted TTY messages, tho, could not use the educated
guess method, obviously.  As I mentioned earlier, I don't
remember actually being involved in "decoded" the message
with the second tape, but I am sure what I would have done is
to simply have the sending station repeat the traffic for as
many times as I felt necessary to be able to recreate a good tape.
Even if the message text was encrypted, it would have the same
letter/character order for good multiple runs and we would simply
reconstruct it as best as possible.  And if we lost synch, I
suppose we would simply "shift" the decode tape one punched
character at a time until the new section decoded properly.

Our longest paths were NC to Botswana and Greece, so they were
pretty good hauls.

Sheldon

Don Mehl wrote:

>     In WW II we could send a "break" signal which enabled the receiving station to stop the transmiting station.  That was to stop a message that accidentally was being sent in the clear.  If you received garble you could also stop transmission and ask for a repeat. Some messages were very long and HF paths over long distances not always reliable. It made for long nights in the windowless frooms.
>     - I am out of hard cover SIGTOT books but can furnish a soft cover for $20.  I have a hard cover "TOP SECRET COMMUNICATIONS OF WORLD WAR II" that is available for $55, all including  shipping.  It covers SIGTOT and SIGSALY the voice scrambling system and some others.
> Don W5BB
>
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