[GreenKeys] 1939 Commercial RTTY?

[Jim Haynes]

I don't know, and I wish I did, so I'm hoping someone who knows will 
answer the question.

Something that seems to have been used quite a bit, and I don't know
much about, is the use of high speed Morse, with transmission from
punched tape at speeds up to 500 wpm and reception on an ink recorder.
Then the inked tape was passed to multiple operators to transcribe with
typewriters.  I remember reading somewhere that RTTY was not very
attractive by comparison, being limited to 60 wpm or so.  When they
developed effective multiplexing than RTTY could begin to compete with
high speed Morse, since it replaced all those receiving operators.

Press Wireless seems to have been an early adopter of RTTY.  RCA was
using RTTY with a 3 out of 7 code for error detection in the 1930s,
but this was probably on point-to-point circuits.  I have an article
titled "Teletype Now used on Radio Circuits to Hawaii by R.C.A.
Communications, Inc. for All Its Messages" dated October 1, 1932.

I suspect there was little if any use of RTTY on ships until 1945 or so.
There were experiments done long before, but putting Teletype machines on
ships for operational use would have lots of limitations.  You need
somebody trained to repair the machines, and a stock of spare parts;
because you probably aren't going to find that in random ports around
the world.  Machines like the Model 15 did not do well on ships because
of that massive carriage assembly getting slung around as the ship
pitches or rolls.  That's why the U.S. Navy got the entire output of
Model 28 equipment in the beginning.  Since a ship has to keep a radio
operator on board anyway, you might as well use him as a Morse operator
until the volume of traffic gets too high.