FEDS FINGER SHORTWAVE JAMMERS AGAIN Copyright 1989 by Bob Parnass, AJ9S Shortwave broadcasters in the United States, the United Kingdom, Israel, and West Germany have long been subjected to intentional interference (jamming). To identify the jammers, an intensive investigation was conducted in 1984 and 1985 under the auspices of the Inter- national Frequency Registration Board of the International Telecommunication Union (ITU). A 318 page report was issued after the investigation,1 and I summarized the report in an earlier article2. Since the original study, closer East/West relations have led to a decrease in jamming. The Russians have stopped jamming Radio Liberty's broadcasts aimed at the Soviet Union, ending a 35 year long tradition. Another study was conducted in July 1988, and this article summarizes that report.3 Jamming Characteristics Foreign language programs, particularly those in languages spoken in Iron Curtain countries, are the primary targets of the jammers. Jamming installations fall into two categories: 1. Ground wave jammers are used for localized jamming, directed toward the immediate vicinity (up to 100 km) of the jammer. They are situated close to the people who are to be prevented from hearing the broadcast, and are effective in blanketing high population regions with strong signals. 2. Sky wave jammers are used to prevent people far away from the jammer from hearing the targeted broadcast. The jamming transmitters monitored in this operation were assumed to run 250 KW power and antennas with 10 dB gain. Jammers need not provide a signal with the same field strength as the broadcast signal in order to be disruptive to the the targeted transmission. By using appropriate modulation schemes, a jamming signal can obtain 10 to 15 dB relative gain compared to a broadcast signal. Sometimes, several different jamming transmitters are used at the same time to interfere with a single broadcast fre- quency. About 90% of the jamming signals observed during the study were accompanied by a 2 character Morse Code identifier, which presumably allows the offender's field monitoring stations to determine the effectiveness of each jamming transmission. Monitoring Stations Jammers were monitored between July 4 and 24, 1988, in a cooperative effort by monitoring stations in West Germany, the United Kingdom, Norway, Sweden, Canada, South Korea, Japan, Italy, and the United States, The American locations were FCC field monitoring sites, and most employed fixed monopole (Wullenweber) antenna systems with goniometers. Most European monitoring stations employed Adcock antennas, and Korean and Japanese stations used log periodic anten- nas. Findings The July 1988 study uncovered an entirely new set of mark- ers (Morse Code identifiers), different from those recorded in earlier studies. Monitors reverified their assumption that each marker transmitted from only one location. Although the markers heard in 1988 were different than those in 1984, the general locations of the jammers did not change drastically. The 1984 surveillance traced the source of most jamming to the USSR. In 1988, 61 of the 69 jammers monitored were again located in the western USSR, with a large grouping around Moscow. Four jammers were located in Czechoslovakia and three in Bulgaria. Most jammers in the USSR were aimed against Russian and Russian dialect broadcasts, with the exception of a few Bulgarian and Czechoslovakian language jammers. Russian jamming of Polish language broadcasts stopped, even though they were consistently jammed in 1984. Jamming of Radio Liberty stopped, although it was jammed more than any other broadcaster observed in the 1984 operation. ______________________________________________________ | Participating U.S. Monitoring Stations | | | | Location Antenna Type | |_____________________________________________________| | Anchorage, AK fixed monopoles with goniometer| | Belfast, ME fixed monopoles with goniometer| | Douglas, AZ fixed monopoles with goniometer| | Ferndale, WA fixed monopoles with goniometer| | Vero Beach, FL fixed monopoles with goniometer| | Grand Island, NE rotating Adcock type | | Kingsville, TX fixed monopoles with goniometer| | Laurel, MD fixed monopoles with goniometer| | Livermore, CA fixed monopoles with goniometer| | Powder Springs, GA fixed monopoles with goniometer| | Sabana Seca, PR fixed monopoles with goniometer| | Honolulu, HI fixed monopoles with goniometer| |_____________________________________________________| ______________________________________________________________ | Participating Foreign Monitoring Stations | | | |Location Antenna Type | |____________________________________________________________| |Ft. Smith, Alberta, Canada (no bearing information) | |Langley, B.C., Canada (no bearing information) | |St. Remy, Quebec, Canada (no bearing information) | |Bockhacken, W. Germany Adcock | |Berlin, W. Germany Adcock | |Darmstadt, W. Germany Adcock | |Munchen, W. Germany Adcock | |Itzehoe, W. Germany Adcock | |Konstanz, W. Germany Adcock | |Krefeld, W. Germany Adcock | |Norway (4 stations) Adcock | |Enkoping, Sweden Adcock | |Baldock, U.K. fixed monopoles with goniometer| |Crowsley Park, U.K. (bandwidth measurement only) | |Rome, Italy Adcock | |Tokyo, Japan log periodic | |Seoul, S. Korea log periodic | |Rusan, S. Korea log periodic | |Kwangcu, S. Korea log periodic | |Kangnung, S. Korea log periodic | |____________________________________________________________| ___________________________________________________ | Jammer Jammer | Jammer Jammer | | cw id Location | cw id Location | |________________________|_________________________| | A5 Bulgaria | MU USSR | | AL USSR | MX USSR | | AR USSR | NA USSR | | B1 Czechoslovakia| ND USSR | | BF USSR | NI USSR | | BN USSR | NK USSR | | BS USSR | NU USSR | | CB USSR | PF USSR | | DK USSR | R9 Czechoslovakia| | DP USSR | RA USSR | | DW USSR | RD USSR | | FG USSR | RP USSR | | FI USSR | RQ USSR | | FL USSR | RT USSR | | G3 Bulgaria | S5 Czechoslovakia| | GA USSR | SF USSR | | GD USSR | SU USSR | | GF USSR | TF USSR | | GL USSR | TK USSR | | GS USSR | TU USSR | | GU USSR | U7 Czechoslovakia| | GV USSR | UA USSR | | HD USSR | UD USSR | | HP USSR | UR USSR | | IL USSR | VL USSR | | IR USSR | VN USSR | | KM USSR | WA USSR | | KU USSR | WQ USSR | | KV USSR | WU USSR | | L4 Bulgaria | WV USSR | | LK USSR | XD USSR | | LR USSR | Z3 Czechoslovakia| | LU USSR | ZA USSR | | M3 USSR | ZK USSR | | MB USSR | ZN USSR | | MG USSR | ZT USSR | | ML USSR | | |________________________|_________________________| __________ 1. Monitoring of Harmful Interference to the HF Broadcasting Service: I. Results of the October 1984 and March/April 1985 Coordinated Monitoring Periods, by M. W. Sowers, G. R. Hand, and C. M. Rush, U.S. Department of Commerce, NTIA, Institute for Telecommunications Sciences. NTIA Report 85-187, December 1985. PB86163011/AS. 2. Shortwave Jammers Identified, by Bob Parnass in The Radio Enthusiast, June 1987. 3. Monitoring of Harmful Interference to the HF Broadcasting Service: I. Results of the July 1988 Coordinated Monitoring Period, by M. W. Sowers, G. R. Hand, and C. M. Rush, U.S. Department of Commerce, NTIA, Institute for Telecommunications Sciences. NTIA Report 89-244, June 1989. PB89231732. -- ============================================================================ Bob Parnass, AJ9S - AT&T Bell Laboratories - att!ihuxz!parnass (708)979-5414