JAMMING by Rimantas Pleikys

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OLEG MAKSIMENKO REMEMBERS

According to Oleg Maksimenko, former shift-leader of the Vilnius jammer ("Object No. 600"), the twelve KV-5 transmitters that were in operation at the jamming station until 1976, were divided into two groups of six transmitters each. Each group of transmitters was controlled by one operator. The operators were managed by the shift-leader. Two other operators worked at the control and correction post and were assigned control of each transmitter group. CCP and the jammer were connected by two direct link (dedicated) telephone cables, approx. 7 km in length, with two terminals on each end. CCP issued orders to the jammer operators to switch on a particular transmitter to a particular frequency. The jammer operators never had a chance to listen to what they jammed. After it was tuned in, the transmitter stayed in heat-up (nakal) mode and the transmitter's RF stage was controlled remotely from the CCP. According to other sources, the technicians used to put a jammer on a particular frequency while listening to the frequency's performance at the control post: the relevant zero-beat audio signal was supplied to them from a communications receiver via a telephone line from the CCP (It is quite possible that this system was used until the mid 1970's when the old KV-5 transmitters were replaced with new VIAZ type transmitters with synthesised exciters). The Vilnius jammer CCP was headquartered one floor above the Central Food Market, Gedimino str., and later in the premises of the State Radio Frequencies Inspectorate (Žvėrynas district, Vytauto Street 20) until 1980 when it was moved to the administration building of the Radio and Television Center (Karoliniškės district, at the TV tower). The Kaunas CCP was on the 6th floor of the Central Post Office and later was moved to the long-distance telephone exchange.

The staff of the Radio and Television Center usually referred to the jammer as the "transmitting department". The call signs of the jammer were transmitted to each transmitter currently in operation two times per minute and twice each time. The Morse signal was produced by a simple device: a disk driven by an electric motor which connected particular contacts into a short-circuit every 30 seconds. The jammer personnel called it a "mashinka". The letters also referred to as ID-codes were assigned to the jammers in order to enable the CCP operators to identify each individual transmitter (or jamming station) and to gauge its performance. In the Soviet Union, groundwave jammers had the ID codes assigned in a two-letter or a-letter-and-a-numeral format (rarely encountered). All the transmitters had the same ID-code. The transmitters of the Vilnius jammer had the "BL" ID-code initially, and was later replaced with the "LM" ID-code (15 transmitters, of 5 kW power each). Long distance skywave jammers possibly also had the ID-codes assigned to individual transmitters (within the range of 20-200 kW). The frequencies to be jammed were communicated from Moscow via teletype (acording to O. Maksimenko, the HF RTTY point to point link was also used for this purpose). The final decision concerning the jamming of a particular frequency was adopted by the relevant CCP. It depended on the actual audibility of the target station in Vilnius. "Object No. 600" employed a staff of 25 persons.

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