Spycraft - Melton [61]
Receiver packages, small enough to be carried under a coat, included a time marker capability so the “rabbit” would push the button when he left the office, then five minutes later, as he took a street to the left, push the button again. Analysis of the marked times and locations were correlated with KGB radio transmissions to determine when the rabbit had surveillance and what frequency was used. Over time, a picture emerged of the type and intensity of surveillance Americans faced and how the KGB coordinated its efforts. Patterns surfaced that defined a standard operating procedure by the KGB, and detailed analysis identified types of behaviors that would likely draw surveillance and which Americans were most closely watched.
Recordings showed that some KGB conversations were in shorthand combinations of terms and numbers. For instance, the term “twenty-one” meant “I have the target in sight,” while some code words described specific people or activities. Brief conversations or even single words would indicate surveillance, while extended silence became a reliable sign they were free of their KGB watchers.
The CIA discovered that their KGB watchers would follow an individual with several different teams. One set would conduct overt surveillance, while the second team would hang back, invisible. Sometimes the surveillants would walk, changing articles of clothing to avoid recognition. At other times, they would rotate colors and models of cars. Surveillance could be in fixed positions located in apartment buildings and offices. “Warming rooms” were provided during winter months where inactive surveillants were put on stand-by should their services be needed.
For the operations officer this meant that surveillance could appear and disappear at almost any time. To know with certainty when one was free of surveillance, even momentarily, was the key to conducting a clandestine act. To take advantage of these transmissions, OTS was tasked to build a concealable, body-worn monitor. Conceptualized by an engineer in the Office of Communications and produced by OTS, the SRR-100 enabled the wearer to eavesdrop on KGB surveillance transmissions.
The first models of the SRR-100 could pick up only a single frequency. To alter frequencies, the TOO had to change out the two-pronged crystal, though once the monitor’s effectiveness was demonstrated, OTS developed a multichannel receiver to keep pace with the KGB’s communication systems. 5
The second half of building an operational receiver for clandestine use was designing the scanner to be covert as well as functional. The scanner had to be small enough not to attract attention on the street when worn under either summer or winter clothing. While transistors could solve this problem by powering a three-quarter-inch-thick receiver that was no larger than a pocket radio, the question remained of how the case officer could covertly hear the transmissions.
Thirty years after the SRR-100’s introduction, it is now commonplace to see the young and elderly walking with headphones and earpieces coupled to devices such as an iPods and cell phones. However, in Moscow, in 1973, an ear bud or headphones—particularly worn by an American—would surely have attracted attention and suspicion. A telltale trace of wiring, no matter how cleverly disguised, trailing from the ear to the shirt pocket of a foreigner on the streets of Moscow would be noticed and reported by the KGB watcher teams.
The solution the techs eventually arrived at was an ingenious use of existing technology, known as an “induction loop.” Based on an electrical phenomenon whose applications may be traced to the mid-nineteenth century, the “induction loop” operates on the principle that electrical currents sent through a wire (loop) generate an electromagnetic field that can be picked up by another nearby wire. Electromagnetic induction is similar to the way vibrations in one prong of a tuning fork cause the other prong to vibrate as well.
Engineers created an induction loop