[GreenKeys] Differences between US Army & Navy TTY communications

[Nick England]

Yes big differences between Army and Navy ops at the unit level. Big
message processing centers were more alike.

When the Navy ran full duplex it was to separate TTYs, one for transmit and
another for receive. Nobody tried to type on the machine that was printing,
except for cutting tape which functioned via direct mechanical keyboard to
perf connection and didn’t interfere with printing. Then when it was your
turn to transmit, you would run that tape through the TD.

The UGC-6 (28ASR) was used in duplex systems as a transmitting TTY while
another TTY was printing (or punching tape).

Mainly, ships received the fleet broadcast on TTY printers. There was no
transmission back from the ship, just reception of messages from shore
stations.

Ships also participated in nets, but that wasn’t full duplex.

Even a smaller ship might have 10 TTY units aboard (counting TD, ROTR, KSR,
ASR)
https://www.navy-radio.com/ships/images/ship-75a.JPG

Disclaimer- this is from what I have read and studied. I have no first-hand
operational experience.


On Sat, Apr 8, 2023 at 7:38 PM Duncan Brown <duncanancy at earthlink.net>
wrote:

> In digging into a M28 ASR, I think I have stumbled across some of the
> differences between Army & Navy TTY communications.  All the schematics for
> M28 KSR & ASR units that I have seen, show just one loop, tying the TX & RX
> circuits together. (Aux reperf in a M28 ASR typically has its own loop.)
> M28s are wired such that they are very flexible and can be wired to
> separate TX & RX circuits, but that is typically not how they are shown on
> system drawings.  Th AN/UGC-6 (M28ASR w/aux reperf) schematic (fig 12-38
> from the Navy manual ) does not show an option for full duplex (separate TX
> & RX loops) operation.
>
> Nick says that full duplex was not used much (if any) in the Navy TTY
> comms, but his page, https://www.navy-radio.com/circuits.htm does mention
> full-duplex operation.
>
> In 1950, the Army (and Army-Air Force) started buying Kleinschmidt
> equipment exclusively (although they did buy some  M28s later.)  All the
> Kleinschmidt units, TT-4, TT-76, TT-98, AN/FGC-25 were set up for full
> duplex operation with separate cables or jacks for TX & RX. The standard
> Army wire-line modems (TH-5 & TH-22) used with the TTYs were capable of
> both simplex (2-wire) and full duplex (4-wire) operation.  Mobile RTTY huts
> (AN/GRC-26, -46, -122) could all be operated full duplex, though simplex
> was the norm. (the AN/GRC-142 is a simplex GRC-122.)
>
> I was a TTY repairman in the Army Security Agency. In Viet Nam in 1967. I
> was in the 337th Radio Research Co., supporting the 1st Infantry Division.
> We were located near the Division HQ and had outstations (AN/GRC-46 huts)
> positioned with the forward located 1st ID Brigades.  We also had a link to
> our battalion HQ and that link carried a lot of traffic; so much so that it
> was run in full duplex mode, with messages going in both directions,
> simultaneously.
>
> The outstations had tape facilities (TT-76s), but our company comm center
> just consisted of a hut (AN/MSA-?) with four TT-4 printers, 4-5 KW-7 crypto
> units and four TH-5 modems in it. So all outgoing messages had to be typed
> on-line.  Imagine typing a message on a printer while another message is
> being printed!
>
> The Army did have medium-sized comm centers in trailers or vans and big,
> fixed station comm stations, but I never saw them. I did work on a 12
> channel tape-relay center that was in a 38 ft trailer..
>
> So maybe some of the difference between Army & Navy operation was due to
> the Army units being smaller and more spread out; vs. the Navy with
> concentrations of operations on big ships. The Navy's use of multiplexed
> RTTY may have given them enough channels that they did not need to operate
> full-duplex.
>
> Just some thoughts.
>
> Have fun,
>
> Duncan
> K2OEQ
> 31J30
>
>
>
> On 08-Apr-23 16:24, Nick England wrote:
>
> See also
> https://www.navy-radio.com/circuits.htm
>
>
> On Sat, Apr 8, 2023 at 4:13 PM Nick England <navy.radio at gmail.com> wrote:
>
>> They just weren’t used in full duplex (except if the aux typing reperf
>> was independently connected). Normal installation was to the C-1004 box
>> that you manually switched from CFS REC to CFS SEND. (The TONE position was
>> for hookups that automatically keyed the xcvr, usually UHF).
>> https://www.navy-radio.com/rtty/c1004.htm
>>
>> I guess I just don’t understand when you would run full duplex using a
>> single TTY.
>> If you wanted to receive while transmitting you just used an additional
>> TTY printer or reperf.
>>
>> Read more about the Navy’s view of RATT
>> https://www.navy-radio.com/journal.htm
>>
>> And
>> https://www.navy-radio.com/commsta/circuit/THE20GOLF20SYSTEM.jpg
>>
>>
>>
>>
> --
Nick England K4NYW
www.navy-radio.com
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