U.S. Naval Cryptologic Veterans Association

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In-Port Time

While the DEs were tied up at Pearl Harbor the ships’ crews performed normal maintenance and training. Groups of CTs from TGU would board the ship during the day to train on and maintain the telemetry intercept equipment. The Telemetry room was laid out like as shown in the figure at the end of this chapter.
The telemetry intercept positions were arrayed along one side of the compartment. A comfortable chair was bolted to the deck in front of each position. The chairs had to be bolted down because the ship would roll as much as 30 degrees in heavy seas.

Each telemetry position looked much like the example in the NSA Cryptologic Museum exhibit on Telemetry Intercept. The primary radio receivers are at the bottom of the position. The oscilloscopes above the receivers were used to display the signal characteristics. The operator could also recognize various type of telemetry signals by the sound made when the signals were routed from the receiver through an AM or FM detector and played through headphones.

One test given to new operators was to set up the position to intercept and display a standard TV signal. This could be done because the Tektronix oscilloscopes at the position were very versatile instruments. You could set up the vertical scan to match the 60Hz TV vertical sweep. You could then set the horizontal sweep to match the horizontal scan rate of the TV signal. An FM detector in the position was used to generate a signal proportional to the TV luminance signal. That signal was fed into the Z-axis or brightness input of the oscilloscope. When everything was set up properly, you got an intelligible TV picture in shades of CRT green.

It took me several hours of practice before I could pass this test. The most difficult part was the setting of the sweep triggers to achieve a stable picture without rolling or tearing. I was the first division officer to pass the test. After I passed the test and showed some general competence with other pieces of equipment, the Chief presented me with my very own tweaker. (A tweaker is a small screwdriver used to adjust some of the maintenance settings of the equipment). This was a rare honor. A common question at the time was “What is the most destructive thing on any warship?” The answer was “An ensign with a screwdriver”.