Steel Yard OTH
The Soviet Union began work on over-the-horizon [OTH] radar in the late 1950s, given the potential of this techology to surpasss the range of conventional early warning radars. The focus was on backscatter radars that would provide warning of missile launches by detecting alterations in ionosphere propogation caused by the depletion of ions by missile exhaust plumes. These radars had to reliably detect group and mass launches of intercontinental ballistic missiles from the territory of the US. The radars are reportedly known as STEEL YARD or STEEL WORKS by the Western intelligence community, the code name derived from their large intricate girder construction.
The Duga-2 experimental model over-the-horizon radar, designed in 1970 by Chief Designer F. Kuzmin, was successfully tested using launches of domestic ballistic missiles from the Far East and Pacific Ocean to the testing ground on Novaya Zemlya. The radar, built near Nikolaeyev [Nikolaev] near the Black Sea in Ukraine [almost certainly not in the Caucasus mountains, as suggested by one source] included 26 huge transmitters (each one the size of a two-story building) assembled by the Dnepropetrovsk machine building plant. The transmitting antenna was 210 meters wide and 85 meters high. The receiving antenna was 300 meters wide and 135 meters high. The antenna field housed 330 transmitters of about 15 meters each. This over-the-horizon radar became operational on 07 November 1971. Some sources report that a new radar was built at Nikolayev in the early 1980s to monitor Chinese missile tests, though it is unclear what if any relationship this installation has with the prototype tested in the early 1970s. Some reports suggest that this installation, said to be smaller and lower-power than the radars at other sites, may never have gone on line.
This facility was apparently located at 47°04'30"N 31°39'00"E, about 20 km Northwest of the major city of Nikolaeyev [46°58'N 32°02'E].
The positive results of the initial tests were achieved for a middle-latitude route and in a relatively quiet ionosphere. The development program faced a number of challenges, including the limitations of Soviet computer technology for signal processing. The operational requirement that the system detect American ICBM launches mandated backscatter propatation across north pole, where the Aurora Borealis induces substantial fluctuations in ionospheric properties.
The Steel Yard OTH began operations in 1975-1976. The exact location of this radar is obscure. Many sources report that it was located "near Kiev" while others state that it was "at Gomel, Belarus" [52°26'30"N 030°59'00"E], or "Gomel in Belarus near Chernobyl, approximately 175 mi (150 nm; 280 km) SE of Minsk" or "at Minsk." One source claimed it was located "at a distance of less than 10 km from the operational Chernobyl reactors" [51°16'N 030°14'E] and others claiming it is "near Chernigov" [Chernihiv PPL 51°30'00"N 31°18'00"E]. Some reports claim that the use of Direction Finding equipment traced the signals to the area of Gomel, Russia, or to "a site southeast of Minsk".
Transmitting on frequencies variouly reported as being between 3.26 and 17.54 megahertz and 4 to 30 MHz, with the actual frequency depending on the maximum-usable-frequency (MUF) for propagation. Typically, at dawn the transmissions were between 14 and 22MHz and by 3 PM. they were at 14MHz or lower.
The radar is variously reported as having output power between 20 to 40 MW [though some sources suggest rather less plausibly a power level of 2 MW]. The signal is pulse-modulated at a rate of several times a second [most sources state 10 pulses per second], sounding like a woodpecker. The radar was observed using three repetition rates: 10 Hz, 16 Hz and 20 Hz. The most common rate was 10 Hz, while the 16 Hz and 20 Hz modes were rather rare. The pulses transmitted by the woodpecker had a wide bandwidth, typically 40 kHz.
This powerful Soviet radar signal was quickly dubbed the "Russian Woodpecker." When it first began operations, the transmitter interfered with several communications channels, including emergency frequencies for aircraft on transoceanic flights. Subsequently the operational practice was modified so that the radar skipped these critical frequencies as it moved across its operational spectrum. Noise limiters installed by shortwave ham operators eliminated the "Russian Woodpecker" interferrence.
Such noise blankers, designed to cope with interference such as the Russian 'woodpecker' that was common in the 1980s, cleans up most forms of pulse noise.
When the transmissions were first detected in the West, some suggested that the Soviets were developing a new radio system for communicating with strategic submarines. Others suggested that it was designed to detect and track low-flying aircraft or missiles. Far less plausible theories extended to suggestions the Soviets were trying to modify the weather; experimenting with radio waves to control human behavior; or developing a weapon to shoot down nuclear-tipped missles.
This installation was reportedly abandoned after but was put out of service by the Chernobyl nuclear reactor explosion in 1986, though other reports claim it has remained operational.
Another over-the-horizon radar of this type was built at Komsomolsk-na-Amure [certainly not Nikolayevsk-na-Amur as reported by some sources -- the NIMA GeoNet NameServer is unaware of the "Nikolayevsk-na-Amur" placename]. Along with the facility at Kiev, the other Steel Yard located at Komsomolsk-na-Amure provided complementary coverage of the United States. According to some reports, the Komsomolsk-na-Amure installation was taken off combat alert duty in November 1989, and some of its equipment was subsequently scrapped.
By 1980 the Russians were reportedly operating three OTHR transmitters, including two OTHR transmitters near Kiev and Minsk, and a third transmitter in Siberia focused on their northern flank which became operational in 1979. By the mid-1990s at least the two radars located in Ukraine appeared to have been deactivated, since their continued maintenance did not figure in the negotations between Russia and Ukraine over the active early warning radars at Mukachevo and Sevastopol.
A fourth OTH-B of a different design was reportedly constructed in the 1980s Nakhodka [sometimes incorrectly spelled Nakhoda] on the coastal of the Sea of Japan. It is unclear which location this refers to, since there are several places with this name, including Nakhodka [51°35'40"N 157°48'30"E] on the Pacific coast of the Kamchatka Peninsula, but the most probable locations seems to be Nakhodka 42°50'49"N 132°57'39"] near Vladivostok. This radar was reportedly intended to monitor shipping, aircraft and ballistic missile movements in the area between the coast of China and the island of Guam. The location and ascribed mission of this radar strongly suggest that it unrelated to the STEEL YARD family, but is rather the much smaller "Irida" Over-The-Horizon Surface Wave (OTH-SW) radar. This radar is capable of surface vessel detection at ranges of 280-300 km, depending on sea state and size of vessel. The transmitter complex has a maximum pulse power output of 64 kW in the HF frequency range, with separate transmit and receive complexes positioned 500 to 1,500 m apart.
Gomel' PPL 55°19'00"N 028°47'00"E
Gomel' PPLA 52°26'30"N 030°59'00"E
Gomel', Gorod ADM2 52°26'30"N 030°59'00"E
Gomel'skiy Rayon ADM2 52°20'00"N 031°00'00"E
Gomel-Pokolyubichi AIRF 52°31'32"N 031°00'49"E
Gomel' Severnyy RSTN 52°27'00"N 030°58'00"E
Gomel', Stantsiya RSTN 52°26'00"N 031°00'00"E
Chernobyl' PPL 51°16'00"N 030°14'00"E
Sources and Methods
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