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KW-37

The KW-37, code named JASON, was an encryption system developed In the 1950s by the U.S. National Security Agency to protect fleet broadcasts of the U.S. Navy. Naval doctrine calls for warships at sea to maintain radio silence to the maximum extent possible to prevent ships from being located by potential adversaries using radio direction finding. To allow ships to receive messages and orders, the navy broadcast a continuous stream of information, originally in Morse code and later using radioteletype. Messages were included in this stream as needed and could be for individual ships, battle groups or the fleet as a whole. Each ship's radio room would monitor the broadcast and decode and forward those messages directed at her to the appropriate officer. The KW-37 was designed to automate this process. It consisted of two major components, the KWR-37 receive unit and the KWT-37 transmit unit. Each ship had a complement of KWR-37 receivers that decrypted the fleet broadcast and fed the output to teleprinter machines. KWT-37's were typically located at shore facilities, where high power transmitters were located.

Experiences operating the KWR-37
Typically, fleet units utilizing the KWR-37 units were outfitted with two devices for redundancy. Should one unit fail, the other one would already be online and patches via a high level, 60-milliamp patch panel would quickly be changed around so that the current offline unit could be changed over to online status at a moment's notice, to ensure that there was no interruption of message traffic. Later in their life, when KWR-37 units were aged and worn, sometimes the circuit cards inside had to be reseated with a rubber mallet which helped ensure the cards were seated properly. Other problems with the KWR-37's were related to the startup times. Fleet radiomen, and those stationed in the shore transmitting stations, had to listen to an HF signal for coordinated universal time. Radiomen called this broadcast the "time tick," which gave them a sharp tone, signalling them to press the restart button so that the unit could then start up for "new day" or otherwise known as "HJ's" by the radiomen. This took place after the new day's crypto keylist card was properly inserted into the "crib" or the card reader by securing it onto pins and then firmly closing the card access door and then locking it with a key. Once the unit(s) were restarted, the key was placed back in the safe using two-person integrity (TPI) which was stringently enforced following the Walker spy investigation. In the early nineties when the KWR-37 units were retired from the navy and replaced by the more reliable and modern KWR-46's, fleet Radiomen breathed a sigh of relief because the KWR-37 units were often unreliable and would occasionally fall out of synchronization timing, resulting in a loss of broadcast messages from the various fleet channels. ==Sources==
Source: Wikipedia ↗
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