SSM - 33 |
The SSM-33 was a newer version of the 131B2 table. It consisted of a gray interface/mixer box about the size of a desktop tower computer, a special Model 14 tape reader (TD), and a Model 14 KTR (Keyboard Typing Reperforator) . SSM-33 was issued to the Koreans fighting in the Vietnam war.This system used a special "one time tape reader" which was also used with several crypto mixing machines.( e SSM-33, 131B-2). The distributor head is different than a regular Model 14 Transmitter Distribution. It has a clutch control magnet that was "stepped" by the crypto device in conjunction with a classified traffic message. This system was called "SIGTOT".
The distributor commutator of the special TD is made up of two concentric conducting rings mounted on an insulated disk. The outer ring is divided into five large and 10 small segments as compared to seven on the corresponding ring of a regulator TD. It's important to notice these two differences in TD distributor segments, as it indicates that the mixing (Crypto) unit was clocked to produce a cipher tape.
The SSM-33 external Teletype gear could be configured in a number of different ways. In Communications Centres, this was usually done via a teletype patch panel. One specific configuration might have a KTR14, a normal TD, a special TD hooked up to the SSM-33 along with a Teletype page printer for set up and to read what the distant station was sending you.
A punched, plain language (P/L) tape would be produced on the KTR14. Next, the P/L tape would be mounted on the normal 14TD while the special 14TD would have the keytape mounted and ready to go. When the operator initiated transmission, the P/L tape was “mixed (Boolean Exclusive OR function) with the keytape and the ciphered message was sent across the link to the far end.
Components of the SSM-33 tape system were never classified. This equipment is referenced in document TM 11-2222. When the manual talks about a "Receiving" TD, that's means the device local to the operator and *not* the far end.
Some parts of an SSM-33
cryptosystem with a spare synchronous TD motor. At the top is
the 14 KTR teleprinter (Keyboard Typing Reperforator). This unit
normally would be used to prepare a clear text copy of traffic
to be transmitted into the SSM-33 for encryption and
transmission. The clear text would be printed on the tape as the
holes were being punched, so the operator could check the data
stream.
Almost all traffic was punched up on tape so an operator could check it and also circuit time was at a premium. Once the operator established the circuit, clear text tapes would be fed into the SSM-33 and encrypted. Rather the special TD, a normal TD is depicted in the photo. A normal TD has two cables and it also has a tight-tape stop lever coming out of it’s left side which a special TD does not have. |