[1] SRAC devices were adopted by Western intelligence agencies during the Cold War in the 1960s, but Eastern Bloc nations possessed and used similar technologies.
The device operated in the upper part of the VHF band and sent high speed bursts of encrypted data from an agent to a receiving station located within a Western diplomatic facility in a hostile country to avoid interception by the adversary signals intelligence service.
[2] A high-grade US intelligence source in Cold War Poland, Colonel Ryszard Kukliński, is believed to have been using an SRAC device shortly before his defection to the West in late 1981.
Former British intelligence officer Richard Tomlinson mentioned SRAC devices of a cigarette pack size in his book The Big Breach: From Top Secret To Maximum Security.
[4] In 2006 Russian authorities accused Britain of conducting spy operations in Moscow and exposed an artificial rock, which housed an electronic dead drop allegedly used by British assets in Russia.