The Russian Woodpecker

Not an avian at all, the Russian Woodpecker was the vast, faceless and distant enemy of most of the users of shortwave radio in the Western World for eight or nine years, beginning in 1976. Folks were going about their electronic business in North America one day (July 4, 1976. Bathe in the snark), talking to airplanes, ships, each other - and all of a sudden, an enormous stuttering noise slammed down onto an entire range of frequencies. The signal was monstrously powerful, and was heard on wide bands (up to 40 KHz across) on several frequencies in the shortwave bands. It manifested as a harsh, rapid clicking or tapping.

Andy Clark, call sign W4IYT, was at the time working for a commercial aeronautics radio company. It maintained communications links between commercial aircraft and their owners, allowing airlines and the like to speak directly to their airplanes while aloft. In a 1999 interview with the Miami Herald, he claims that he named the phenomenon 'woodpecker' for the sound. While talking to his home office, he asked if they, too were getting an awful loud 'woodpecker' noise on their airwaves. They confirmed it.

What was it determined to be at the time?

The 'woodpecker' was fairly quickly tracked back via RDF to two sites inside the Soviet Union. Analysis of the pulses, as well as the behavior of the signal (times of day, attentuation, etc.) indicate that the 'woodpecker' was the signal of an extremely large OTH-B radar system. This system was, presumably, being used by the Soviets as a long-distance air-search radar to warn them of inbound bomber and cruise missile attack travelling over the North Pole.

It was tracked to two sites because, like many extremely powerful radar systems, processing the radar return data was much easier if the transmission and reception points were widely separated, rather than having to filter the full strength of the emissions from an adjacent transmitter. The sites were near Minsk and Nicolaev, and were likely operated by PVO Strany as early warning systems.

Why was it a problem?

It was a problem for Western operators because the Soviets had chosen to use a set of frequencies which had been set aside for civilian use by international agreement. They didn't care, of course. Hams and companies pushed the U.S. Government (and the British Government, and the Canadian government) into formally protesting to the U.S.S.R. about the woodpecker's presence. However, the Soviet Union would never even officially acknowledge the presence of the woodpecker, much less that it was their doing - in much the same way the U.S. government refuses to acknowledge the existence of Area 51. Since they wouldn't own up, protests were pointless.

'The Russian Woodpecker,' as it came to be known, would appear when the atmospheric conditions over the northern hemisphere were conducive to shortwave relaying - shortwaves travel around the world (rather than straight into space) by bouncing off the ionosphere and then the ground, 'rebounding' their way around the world. These did the same thing. Not only did it invade voice transmissions, but harmonics caused pulsing static on television signals, made more problematic by the lack of modern filtering electronics on most television sets at the time. For a while, electronics companies in the West even began selling 'Woodpecker Killers' - damping and filtering devices that would, when connected inline with commercial radio and television antennae, damp out the characteristic steady pulsing of the woodpecker's signal. These worked with varying degrees of success, as the woodpecker was wily, and jumped around a bit as the Soviets adjusted the system for best resolution. Eventually, the Soviets did modify the operating parameters of the radar to avoid the most commonly used aircraft emergency frequencies, which didn't calm down the ham community.

What Did the Signal Look Like?

Lots of folks in the civilian ham radio community hauled out oscilloscopes and wideband receivers and had a good gander at the woodpecker. Some did so out of curiousity, some did so while finding ways to damp it out. A few, however, did so with an eye to defeating it (more on that in a moment). So doing, they left us with fairly good data on what the signal looked like. The majority of this data is from an article reprinted on the web from the ham radio magazine "Monitoring Times", and was originally published in 1985.

At the grossest level, the signal varied in its pulse rate - not the frequency it travelled on, but the rate of the signal pulses heard. Although it was observed at 10, 16 and 20 Hz, it operated nearly all of the time in a 10 Hz mode. The pulses were centered around four different frequencies at any given time; typically, it wandered around the low MHz range. The example given in the article has it observed using 16390, 16450, 16490 and 16570 KHz.

There were two observed main 'operating modes', named 'static' and 'dynamic' by western observers. In static mode, the woodpecker would transmit four pulses, one on each of the four operating frequencies, in four adjacent 7 ms windows. The pulses themselves were of unknown shape and length, as they were hashed by the bounces and the like, but their observed length varied between 3 and 6 ms. Then there would be a 72 ms silent period, and the cycle would begin again. This produced the 10 Hz pulse - 7ms + 7ms + 7ms + 7ms + 72ms = 100ms, or one-tenth of a second. So it was actually producing four separate 10 Hz pulses, offset by approximately 7 ms in time and a few tens of KHz.

In 'dynamic mode', the woodpecker would step through four different frequency-to-window assignment patterns over a six-second cycle. That is, if we label the operating frequencies of the moment A, B, C and D then the cycle might look like this:

seconds 1-6:
(window 1) A (window 2) B (window 3) C (window 4) D
seconds 7-12:
(window 1) B (window 2) C (window 3) D (window 4) A
seconds 13-18:
(window 1) C (window 2) D (window 3) A (window 4) B
seconds 19-24:
(window 1) D (window 2) A (window 3) B (window 4) C

Some dedicated listeners eventually became able to determine what operating mode the Woodpecker was in just by The Mark One Earhole, but even so the modes and frequencies would change at random, occasionally to previously-unseen ones. This tended to drive operators crazy, since it was just not possible to 'stake out' a quiet frequency for use when the Woodpecker was out and about.

Vigilante EW

We don't know what, if anything, the U.S. military did about it, although it's likely the woodpecker didn't have much of an impact on the spectrum they used. Western hams, however, did what most disgruntled North Americans would do if a woodpecker started in on their patch - they shouldered shotguns (virtual ones, in this case) and started laying in wait.

Since the operating principle of a radar is to listen for reflected radio energy from its targets, these hams reasoned that they could probably interfere with the proper operation of the Woodpecker if they used their own sets to send back carefully timed pulses of their own which would interfere with any actual reflected radio energy. This they did; for a time, the airwaves and newsletters were rife with people trading ideas, analysis and techniques for 'jamming the woodpecker.' Did it work? To some degree, we can say it did: The woodpecker would react when intefered with, usually by switching modes or frequencies.

This was a truly inspiring find, because it meant that dedicated, frustrated lone radio hams, hunched over their sets at the height of the Cold War, could do what the U.S. Government seemed unwilling to do - stick it to the USSR on their own turf. Spoofing the Woodpecker was a delicious means of personal catharsis, since a single ham with a moderately powerful radio could cause major annoyance to an entire enormous Soviet early warning organization. Better yet, groups of hams could, with coordination, drive the woodpecker off the air entirely! It was found that if enough hams staked out frequencies in its known range, and instantly began to spoof it when pulses appeared on their freqs, the woodpecker would (after a time) shut down entirely, briefly. No one was sure why - hypotheses ranged from Soviet operators doing manual-instructed systems tests, to their efforts being interpreted as massive weather interference, or even just plain frustration. Whatever the reason, 'Russian Woodpecker Hunting Clubs' sprang up in the ham community as groups organized to 'peck back.'

The irony of it all was too good to miss, anyhow. Shortwave hams were used to being targeted as the sources of whatever strange interference their neighbor's TV ran into, no matter that they were nowhere near that frequency. In this case, they were actively out to interfere, and not just with a TV but with the Soviet military - and, of course, the Soviets couldn't do anything about it since they refused to admit the signal was theirs in the first place!

Eventually, of course, the Woodpecker was shut down, for whatever reason. Although occasional bursts of interference still fly out of the former Soviet Union, their adoption of standards and Western electronics means that the ability of the Russian military to blithely invade the spectrum is somewhat hampered.

So what was it really?

Turns out that the signals were produced by two massive radar installations which NATO ended up codenaming STEEL WORKS and STEEL YARD, apparently due to their massive, open-framework construction. They were known to the Soviets as S-225 ABM-2 systems. They were built to serve as missile launch warning radars. When the exhaust plume of a boosting ICBM hits the ionosphere it causes a localized depletion of ions, which changes the reflectivity of the layer. Hence, the 'backscatter' - i.e. those signals which were reflected back towards the USSR by ground features and objects - would change signal characteristics enough to gather data on said missile plumes.

Global Security says that sources put the power of the radar's transmitters at between 20 and 40 megawatts, which would explain why it caused so many people so much annoyance. The Minsk facility, which may have already been shut down, was abandoned after the 1986 Chernobyl disaster.

As with any potentially fun and interesting enigma, there were (and are) no end of conspiracy theory games that surround it. At times, the Russian Woodpecker has been deemed by the tinfoil-hat set to be a Russian weather-control system, a Mind Control device, a surveillance (as in, listening to your living room) device, beacons for aliens, and of course (since they're electromagnetic and powerful) brainchildren of the late, great Nikola Tesla. That latter might make them death rays, Tesla Globe generators, versions of Wardenclyffe, who knows. Some of the nonsense is fun to read, but most of it's junk. A great deal of these so-called 'experts' seem to confuse the pulse frequency with the actual signal frequency, leading to statements like this: "The Russian signals are primarily pulsed at the very dangerous 10 Hertz Extreme Low Frequency (ELF)." (from a member's site on Tesla) Sigh. Google mind control and russian woodpecker together, see what you get.


  • "Radio hams do battle with 'Russian Woodpecker.'" Miami Herald, 1982. Reprinted on the web at
  • "The Russian Woodpecker." David Wilson, Monitoring Times newsletter, 1985. Reprinted on the web at
  • Personal experience in 1980-82, during ham instruction by Mark (KA2MRE) and as a licensed ham (KA1KTP)
  • Documents and texts of the ABM treaty at FAS:
  • Global Security online, at

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