Anomaly•Registry
AR-0121

The Russian Woodpecker

Later explained
Date July 1976 to 1989
Location Shortwave bands worldwide. The best-known source, the Duga receiving array, stands beside the closed town of Chornobyl-2 in northern Ukraine; its transmitters were near Liubech.
Coordinates 51.3039, 30.0678
Category Sounds and Signals

Summary

From July 1976 a loud, rapid tapping, usually ten pulses a second, spread across the world's shortwave bands and interfered with broadcasters, aviation and shipping communications, and radio amateurs. It was Soviet over-the-horizon radar, called Duga, and it fell silent as the systems were shut down between 1986 and 1989.

Listeners called it the Woodpecker. The Soviet Union described it only as "tests" and "research on radio-wave propagation", and the lack of an admission left room for decades of theories about mind control, weather control and, later, the Chernobyl disaster. The documentary record is less exotic. Radio monitors had the signal's parameters and approximate sources worked out within a few years, and the international body that handles radio interference complaints had asked Moscow to stop it within months.

the signal, the complaints and the shutdowns, 1976 to 1989 one second about 10 pulses a second each about 3 ms long heard from 5 to 28 MHz Jul 1976: first complaint to the FCC Oct 1976: the IFRB asks the USSR to stop Dec 1976: the USSR cites HF tests Apr 1986: Chernobyl system stops 1976 1980 1985 1989 Nov 1977: IFRB finds the stations should "cease operation" Nov 1989: last system stood down ASKED TO STOP IN 1976. STOPPED IN 1989. the pulses were a radar's, and the bearings matched radar sites. Moscow called it "research on radio-wave propagation". the mystery was official silence, not missing evidence.
Figure Drawn by Anomaly Registry from the 1987 Woodpecker Project report of the Association of North American Radio Clubs, which quotes the IFRB and Soviet correspondence of 1976 and 1977, and from GlobalSecurity.org's shutdown dates. The pulse strip is schematic; the timeline shows the complaints and the shutdowns.

What is documented

The first complaint. The earliest known report of the interference is a complaint to the US Federal Communications Commission about the 14,000 to 14,200 kHz band at 03:00 UTC on 12 July 1976, according to the Woodpecker Project report of the Association of North American Radio Clubs (ANARC). The report, prepared by Robert Horvitz and dated 8 January 1987, was distributed at the International Telecommunication Union's 1987 World Administrative Radio Conference on high-frequency broadcasting in Geneva.

The signal. ANARC's monitors found the pulses repeating "nearly always 10 per second", with rates of 7.4 and 17 a second seen rarely, each pulse lasting about 3 milliseconds. The emissions ranged between about 5 and 28 MHz, with most of the power in a band some 16 to 18 kHz wide and sidebands spaced every 10 kHz. The name came from the sound the pulses made on a communications receiver.

Who it hit. The interference affected the fixed, aeronautical mobile, maritime mobile, broadcasting and amateur services, including international broadcasters such as the BBC, the Voice of America and Radio Australia (ANARC).

The official exchange. On 17 September 1976 the International Frequency Registration Board (IFRB), the ITU body responsible for resolving harmful interference, asked six European administrations to monitor the signal. On 25 October 1976 it sent a telex to the Soviet Union asking it to "take the necessary measures to eliminate the interference". The Soviet reply of 3 December 1976 said that "tests are being carried out with radio installations operating in the HF bands", which might cause interference for short periods. A further reply on 5 July 1977 said that steps were being taken. The IFRB issued a formal report on 10 November 1977 finding that the stations should "cease operation" (ANARC). They did not.

The sources. By direction-finding, the FCC placed the first transmitter in the Kiev to Gomel area in 1976. A second site, on the Pacific coast of Siberia in the general area of Sakhalin and Khabarovsk, was detected on 10 April 1979, and a third was suspected near Nikolayev (now Mykolaiv), north of the Black Sea, in May 1980. ANARC noted that the bearings matched over-the-horizon radar installations shown on maps in the US Department of Defense's annual public report Soviet Military Power. In the British trade press the identification was already being made in February 1977, when Wireless World ran an item headed "Mystery Soviet over-the-horizon tests".

The system. The institute NIIDAR, which developed the Soviet Union's long-range radars, lists the Duga over-the-horizon radar system among its achievements. According to a compilation by GlobalSecurity.org, the western system's receiving centre was at Chornobyl-2, with its transmitting centre near Liubech, about 60 kilometres away; the eastern system stood near Komsomolsk-on-Amur, and an experimental installation near Nikolayev. The same compilation records the Chernobyl system as stopped on 26 April 1986, the day of the reactor accident, and the Komsomolsk system as deactivated on 14 November 1989. The Chornobyl-2 array appears, still standing, in the 2015 documentary The Russian Woodpecker.

How well it worked. Over-the-horizon radar bounces high-frequency signals off the ionosphere to see far beyond the horizon, in this case to detect missile launches from the United States. Pavel Podvig, reviewing the Soviet early-warning system in 2002, concluded that the Soviet over-the-horizon radars "failed to live up to their expectations" and played no significant role in early-warning operations.

Leading explanations

Soviet over-the-horizon early-warning radar (Duga). Established.

ANARC's measurements describe short pulses at a steady repetition rate, which its authors ascribed to over-the-horizon radar. The transmitter bearings matched the radar sites shown in US Department of Defense maps. The Soviet Union admitted to HF "tests" in 1976. The institute that built Duga lists it as an over-the-horizon radar system. And the signal ended as the Duga systems were shut down. Nothing in the record requires any other explanation.

Mind control, weather modification and similar theories. Unsupported.

These filled the gap left by Soviet silence. No evidence for any such function appears in the monitoring data or the ITU record, and none has been produced since.

What the popular version gets wrong

"It was a mind-control or weather-control transmitter." These were Cold War speculations, as Paste's reviewer of the 2015 documentary noted. The signal was measured in detail at the time, matched to radar sites, and identified by its own builders as over-the-horizon radar.

"The Chernobyl disaster was staged to hide the radar's failure." This is the theory of Fedor Alexandrovich, the subject of the 2015 documentary: that "the nuclear reactor was purposefully blown to cover up the radar system's functional failings" (as summarised by Paste magazine). The International Atomic Energy Agency's safety advisory group, in its 1992 report INSAG-7, attributed the accident to the physical characteristics of the reactor, the design of its control rods, and the reactor being brought to a state not specified by procedures during a test. Its conclusions identify no radar connection and no deliberate destruction.

"The giant antenna at Chernobyl sent the signal." The towering array beside Chornobyl-2, the one in the photographs, was the receiving centre. The transmitters were near Liubech, about 60 kilometres away (GlobalSecurity.org).

"Nobody knew what it was until the Soviet Union fell." The Soviet government never named it, but it was not a secret for long. The Soviets acknowledged HF tests to the IFRB in December 1976. Wireless World was calling it Soviet over-the-horizon testing by February 1977. By January 1987, FCC bearings on two of the transmitters had been matched to radar sites on published US government maps, and the radio clubs' report ascribed a third to the same maps.

Current status

Later explained. The Woodpecker was the signal of the Soviet Duga over-the-horizon radars, a system that worked poorly, interfered with radio services across the world for more than a decade, and was never identified as radar by the government that ran it. The signal has not been heard since the systems were shut down. The remaining uncertainty is administrative rather than scientific: exact operating dates rest on secondary compilations rather than on released Soviet records.

Sources

  • Horvitz, R. (1987). Woodpecker Project Report: A Preliminary Report. Association of North American Radio Clubs, 8 January 1987. Distributed at the ITU World Administrative Radio Conference on HF broadcasting, Geneva, 1987. Includes the IFRB correspondence of 1976 and 1977.
  • "Mystery Soviet over-the-horizon tests." Wireless World, February 1977, p. 68.
  • NIIDAR (Scientific Research Institute of Long-Distance Radio Communication). Institutional history, niidar.ru.
  • GlobalSecurity.org. "5N32 Duga [Arc] Steel Yard OTH."
  • Podvig, P. (2002). "History and the current status of the Russian early-warning system." Science and Global Security 10: 21 to 60.
  • International Atomic Energy Agency (1992). The Chernobyl Accident: Updating of INSAG-1. Safety Series No. 75-INSAG-7. Vienna: IAEA.
  • Mathews, J. (2015). Review of The Russian Woodpecker. Paste, 21 October 2015.

Last reviewed: September 2026. Records are provisional. Where the evidence changes, the entry changes. Found an error? Tell us.

Related records
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AR-0046 Whistlers and the Dawn Chorus Whistles on telephone lines in the 1880s were lightning, bent by the magnetosphere. The dawn chorus is made in the magnetosphere itself. Recorded since 1886 Later explained
AR-0002 The Wow! Signal A strong narrowband radio signal from Sagittarius, detected once, never repeated. 1977 Unsolved

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