[GreenKeys] AN/FGC-38 Torn-Tape Relay Equipment

Mon Aug 28 10:36:24 EDT 2017

Hi Paul:

In a tape relay, no one ever bothered to physically measure how long a tape was.
There was too much of it, and we were too busy. It is possible that some tapes were
more than a hundred feet in length sometimes......some of those military units 
transmitted some really long-winded messages. Specifically, Intel Summaries were
often very long; JAFPUB changes (Joint Army, Navy, Air Force Routing Indicator
publication changes) were lengthy; Exercises, Deployments, and Simulated War traffic
were longish, and of course, the traffic volume was extensive. If there was a real-world
crises ongoing, lots and lots of message traffic followed, often of "high" precedence
which was "Flash" and "Immediate" in nature (these had to do with handling times
from writer to reader, so the tape relay and CommCenter folks had to hustle).

Yes, sometimes, one or two of the perforators would run out of tape in mid-message.
This happened every now and then, but most ops paid attention to tape and generally
changed tape reels long before a roll of tape ran out......usually, during a lull in traffic
on a given circuit. Normally, at the end of tape, the tape would turn pink, around the 14
foot end; the last 4 feet or so, the tape would turn dark purple and then you knew 
you were out of tape.

If a perforator ran out of tape - while it was still receiving, no biggie, no problem. You
simply changed the tape reel while the peforator was still running (receiving). Most
ops were very fast at changing a tape reel....could be done in about 30 seconds
or less. Either way, you lost the incoming message (incomplete) as a result. The
fix was to immediately send a "ZFX" Service Message to the sending end so they
could "reprotect" (resend) the lost message at their next opportunity. This is 
why tape relays always had a few ASRs on the floor as well -- for Service Message
work. A "ZFX" is a "Z" Signal (ACP-131) which tells a station that a message
Channel Number (message) is "open", "unaccounted for", or that a "message was
not received". The receiving station to whom the ZFX service was sent is then
obligated to protect (reprotect) the lost message.....

Example of a ZFX Message sent from the tape relay:

VZCZCFMA100       (Sending relay's Channel Number)
OO RUFMAE           (OO = Immediate Precedence to the receiving station)
DE RUFMCM           (DE - "This Is"...From relay Svc Section, RUFMCM)
ZNR UUUUU           (Security Redundancy or Security Warning Line)
BT                            (BT = Break (Break for Text)
UNCLAS SVC ZFX AEA099 IMI ZEA099            (Message Content)
BT                            (BT = Break (Break from Text_

8 Line feeds here

NNNN                      (End of Msg (EOM)...("Nothing Follows").

So, RUFMCM (Floor Service Section of tape relay RUFM sends a ZFX to station RUFMAE
telling them that Channel Number AEA099 is "open" or "missing" and repeats the Channel
Number (IMI means "repeating"). Channel Numbers themselves were usually the last two
Routing Indicator lettters of the sending stations Routing Indicator, plus the number of
channels if more than one channel or circuits to that station, in this case "A" (Alpha).

The tape relay root routing was RUFM for a Major or Primary Tape Relay, and consisted
of 4 letters. For a Minor Relay, it would be 5 letters, e.g. RUFDZ, RUFMW, etc.

A Channel Check from RUFM would look like this:

VZCZCFMA102
PP RUFM
DE RUFM
ZNR UUUUU
BT
UNCLAS CHANNEL CHECK RYRYRYRYRYRYRYRYRYRYRYRYRYRYRYRYR
BT

NNNN

(A Channel Check was essentially a short test msg only. Text could be anything or nothing.
Sometimes: "THE QUICK BROWN FOX JUMPS OVER THE LAZY DOGS BACK 1234567890 TIMES

(Note that this sentence contains all the letters of the alphabet; important to make sure
all pallets on the teletypes were in fact working properly).

Also: "NOW IS THE TIME FOR ALL GOOD MEN TO COME TO THE AID OF THEIR COUNTRY"

Or: "OF ALL THE SHIPS AT SEA, THE ONE SAILING FOR HOME IS THE ONE FOR ME"

Or: "OF ALL THE FISHES IN THE SEA, THE MERMAID IS THE ONE FOR ME"....

(Note: the "RY" moved all the selector levers on most teletype printers. We sometimes also used "SG")

Usually self-addressed and sent out by the relays when no traffic had been received
for 20 minutes or more. Receiving stations were then obligated to return the same 
Channel Check to the relay with their outgoing Channel Number affixed.

A tributary station could also send out a channel check if none was received from the relay. The
relay was obligated to return it.....and Channel Checks were logged on SEND/RECEIVE logs.

Channel Checks insured 3 things:

a. that the circuit was still there and had not dropped out and that the crypto gear
(KW-26s, KW-7s), had not lost set or synch (as they sometimes did, quietly!).

b. that all equipment at both ends was still working (equipment integrity)

c. that all Channel Numbers (and therefore all messages) were accounted for,
and no Channel Numbers were open, missing or unaccounted for (and thus, no messages
were lost).

Hope this helps. If you have more questions, feel free to ask! Love talking tape relay
with anyone who will listen.....

Dave

# # #

-----Original Message-----
From: Paul Birkel <pbirkel at gmail.com>
To: 'David F' <nnn7dxb at aol.com>; greenkeys <greenkeys at mailman.qth.net>
Sent: Mon, Aug 28, 2017 2:39 am
Subject: RE: [GreenKeys] AN/FGC-38 Torn-Tape Relay Equipment

Thanks Dave.  More great info!  A “couple of hundred feet” would seem to be a real challenge to get from the receiver to another transmitter without a snarl-up.  What’s to preclude “over-running” the pink tape-end-coming-soon indicator and having a tape run-out before a message completes?  Just monitor the receipt, accept that sometimes this will happen (like various categories of receiver mechanical problems) and ask for a retransmit should that happen?  Did the sectioning policy manage to avoid this, by keeping the tape-length for a section less than the pink-length?  Under heavy traffic conditions how long would a tape-roll last and how did you manage to avoid running out of tape mid-message?

(And, alas, I was never able to get my Morse Code proficiency up to the point of passing a radio license exam as a kid.  Now it’s all “ancient history” …)

One aspect of all of this has been the realization (understanding) of why USMTF looks the way it does, SCREAMING CAPS :->.  I grew up with a 33ASR (and minicomputers) in the 70’s and simply didn’t know of the earlier Baudot era.  Store-n-forward packet-switching was the new-thing for computer-communications then.  Its heritage from an earlier technology was either unreported, or I simply missed it in my education.

This whole earlier era is an eye-opener for me.  I’m pleased to report that I’ve recently become the proud recipient of an M15 and table that was passed along from another list member, so it’s no longer “just academic” :->.  I’ve not yet gotten to the point of putting it into service, but it’s an absolutely amazing piece of equipment to examine close up.  Had a bit of show-n-tell with my adult daughter last month.  Even as a “still life”.

Thank heaven for Greenkeys!

From: David F [mailto:nnn7dxb at aol.com] 
Sent: Sunday, August 27, 2017 9:49 AM
To: pbirkel at gmail.com; greenkeys at mailman.qth.net
Subject: Re: [GreenKeys] AN/FGC-38 Torn-Tape Relay Equipment

Hi Paul: 

During the tape relay era, there was NO set length on how "long" a tape could be.

Actually, length was as long as the message was, and tape lengths ranged from

maybe 8 to 10 inches for an hourly "Channel Check" tape, to maybe a hundred

feet or more.

The governing factor in military messages was found the message preparation

regulation (in the case of the Army, AR 105-31 Message Preparation), which

dictated teletype messages be no more than 6 pages in length. Consider then,

that a 6 page teletype message had 20 lines of text per page and pages were

normally numbered, and there were 4 line feeds to separate pages. Heading

and Routing information did count as part of a page.

So, if you had a message longer than 6 pages, and we often did, the message(s)

were sent in Sections and number "Section 1 of -----". Sometimes, we would

have 26 or 30 Sections in some messages. These kinds of messages were

common from certain senders. In addition, the entire military establishment

sent and received message traffic all day long, so the traffic flow was unending,

except on Christmas, New Years and on Sundays, when things slowed way

down. On Christmas, for example, you might have no traffic at all -- just the

hourly Channel Checks to make sure the equipment was still working or that

the circuit was still there (sometimes, circuits dropped out, so the hourly

Channel Checks were sent to and from distant stations to insure circuit

availabilty and equipment intregrity.

Print-on-tape was a technical innovation. Siemens, Kleinschmidt and Lorenze

offered printing on tape, and this came in handy for tape relay operators who

prior to printing, had to learn to read the holes in the tape. Most of learned certain

letters and machine functions very quickly and easily...so, "reading" tape was

never an issue and no harder than learning the Morse Code....

Kleinschmidt equipment used the wider tape and thus printed on the outside

edge of the tape, making reading easy. Siemens printed in the middle of their

narrower tape along the TD guide holes. Easy reading here too.

Bear in mind, a tape relay was essentially a message factory. Message traffic

was prolific and continuous and never ending most of the time. Tape relays

were often very warm, or hot, because all those machines put out a lot of heat!

We (in the Army) took off our fatigue uniform shirts and just wore T-shirts in the relay,

as it was so hot at times. We sometimes had large floor fans, but they often 

tended to blow tapes everywhere!

Tape relay equipment had to be cleaned and wiped down every day, usually

by each shift. The Army was a nit picker on appearance. Likewise, the teletype

repair guys maintained the equipment on each shift...cleaning, oiling, adjusting,

etc....drinking, eating and smoking on the relay floor was not permitted.

DAve

# # #

-----Original Message-----
From: Paul Birkel <pbirkel at gmail.com>
To: greenkeys <greenkeys at mailman.qth.net>
Sent: Sun, Aug 27, 2017 4:41 am
Subject: Re: [GreenKeys] AN/FGC-38 Torn-Tape Relay Equipment

A fascinating thread (for me, anyway :->).  What sorts of tape-lengths would one expect to typically encounter?  Feet, tens-of-feet, hundreds-of-feet?  Were there any maximum message-length strictures in place?

I now understand the purpose (or at least one purpose) for the M14 typing reperforator :->.

What were the other reasons for print-on-tape capability?  Simple avoidance of learning to sight-read Baudot :->?

From: greenkeys-bounces at mailman.qth.net [mailto:greenkeys-bounces at mailman.qth.net] On Behalf Of Dave F via GreenKeys
Sent: Sunday, August 27, 2017 1:26 AM
To: greenkeys at mailman.qth.net
Subject: Re: [GreenKeys] AN/FGC-38 Torn-Tape Relay Equipment

…

We had a few TGC-1s in Europe in the early 60s. Operators did not

normally get in each others way, since an operator was often assigned

to a "bank" of about 3 or 4 Chesters to work. Rather than one op moving

from one Chester to another to send or receive tapes, it was common

practice to toss tapes from one op to another. In order to do this, tapes

were hand-rolled into a figure eight and either handed to a bank op by

an expediter (an expediter is a person who moved traffic within the relay

bay), or tapes were sometimes just tossed back and forth if the working

ops were in close proximity. When tapes were handled by an expediter,

they were NOT rolled into the figure eight; he wore them around his neck

bandolier style as he moved from position to positon or operator to operator. 

As he moved around the relay bay, he read the Routing Indicators to where the tape(s)

were destined and then delivered the tape(s) to the appropriate operator,

or hung it on the tape holder for that circuit. (Routing Indicators == Sort of

like a Call Sign in the tape relay world consisting of a series of letters (no numbers

or figures unlike ham radio Call Signs). See ACP-121 to understand Routing

Indicator formulation and ACP-117 Routing Indicator Lists.

…

Dave

# # #

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