The Russian woodpecker: the official bird of the Cold War nests in a giant antenna
On July 4, 1976, as Americans celebrated the country’s bicentennial with beer and bottled rockets, a strong signal began to disrupt shortwave, maritime, aeronautical, and telecommunications signals around the world. The signal was a fast 10Hz tapping that sounded like a spike or a helicopter hitting the roof. It had a wide bandwidth of 40 kHz and sometimes exceeded 10 MW.
It was during the Cold War, and many people rushed to the conclusion that it was some kind of Soviet mind control system or time control experiment. But amateur radio operators traced the mysterious signal to a radar antenna above the horizon near Chernobyl, Ukraine (then part of the USSR) and named it the Russian peak. Here is an excerpt from the sound.
The frequency hopping Woodpecker’s signal was so strong that it made communication impossible on some channels and could even be heard on telephone lines when conditions were right. Several countries filed official complaints with the USSR through the UN, but nothing prevented the Russian peak. Russia would not even recognize the existence of the signal, which has since a huge antenna structure which measures nearly half a mile long and at 490 feet, is slightly taller than the Great Pyramid of Giza.
This imposing steel structure stands in the irradiated forest near Pripyat, an idyllic town founded in 1970 to house workers at the Chernobyl nuclear power plant. In the photo above, the transmitter, also known as Duga-1, Chernobyl-2, or Duga-3, depending on who you ask. Located 30 miles northeast of Chernobyl, on old Soviet maps, the area is simply referred to as Camp Scout. Today everything is inside the Chernobyl exclusion zone.
It was such a secret that the government denied its existence, but was heard all over the world. What was this gigantic installation used for?
Remote early warning
The Duga radar was one of two transmitter / receiver pairs built in response to the Distant Early Warning Line (DEW Line), a handful of antennas built above the Arctic Circle as part of a joint effort between the United States and Canada. Like any radar above the horizon, the theory behind the Russian system was that Moscow would have about 25 minutes to respond to ICBMs in kind, rather than just about 10 minutes to dodge and cover and kiss the world goodbye. To get a better idea of how big this thing is, check out Tom Scott’s brief tour in the embedded video below.
Over-the-horizon radar relies on a similar phenomenon that offers such a great range for amateur radio – signals bounce off the ionosphere and thus are able to overcome the curvature of the Earth, allowing it to detect launches much earlier than standard ground radar can.
In the 2015 documentary The russian woodpecker, a film crew led by an artist from Kiev tries to uncover the mysteries of the antenna. He believes the Chernobyl nuclear incident was orchestrated to distract from the structure, which was due for an upcoming inspection that it was never going to pass.
According to the documentary, the Duga antenna cost twice as much as the Chernobyl plant itself – about 7 billion rubles. Putting this cost into a historical context is tricky. Using the Exchange rates declared by the Treasury at June 30, 1976 we find that the exchange rate at the time was 0.7550 rubles to dollars. That puts the 1976 cost at around $ 9.27 billion. Inflation-adjusted is $ 43.16 billion in 2021 value – a mind-boggling amount that makes us question the documentary’s cost estimate (and the accuracy of our own conversion process).
Some sources say the radar system never worked. Other sources claim that this is the case and that they were able to detect every launch of Shuttle with it. And when it was reported that the Woodpecker was interfering with Russian SOS signals, they changed the frequency. But after doing this, it stopped working due to interference from the Northern Lights.
Make Moscow mufflers
Ultimately, businesses and individuals have built suppression circuits to turn off incessant eavesdropping. Conventional interference suppression circuits work by looking for a short pulse duration with a fast rise time and generate a signal to close a gate in the signal path. But these would be useless to drown the peak, as they don’t work on low amplitude pulses.
The problem with the Woodpecker’s signal suppression was that it had high bandwidth and inconsistent pulses. The ionospheric reflection would stretch the impulses and sometimes create echoes, turning it into a mole-kick game. To make matters worse, they often looked like regular signals, which made it even more difficult to isolate the woodpecker from whatever signal you wanted.
A popular device was the Muffler AEA Moscow (PDF), which worked by generating an internal 10 or 16 Hz signal to mask the peak. But if the ionosphere stretched the pulses, the pulse width of the suppressor had to be increased to compensate, which often meant losing the desired signal in the stirring.
Another device, the Datong SRB2, was much more of a set-it-and-forget-it affair (PDF, page 39). The SRB2 worked much like the Moscow squelch, generating an internal clock and comparing it to the Woodpecker signal.
The interesting thing about the SRB2 is that it was automatic. Once he found a match, he matched the blocking pulse to fit by dialing the pulse width, number of suppress pulses, and their ideal positions. Conversely, Moscow’s squelch used fixed-width pulses, so you had to keep playing with it in order to keep the signal masked.
Still standing, silent
The interference of the Russian peak ceased after the fall of the Soviet Union in 1989, when its existence was finally confirmed by the Soviet government. By this time, the Russians had switched to satellites for their early warning needs.
In 2013, a similar signal began to terrorize shortwave, but not as strongly as the original. It is believed to be from a new Russian OTH radar system called Container, who appears to be almost as tall as Duga. If you want to check it out, tune in to 14,270 on shortwave and tell us what you hear!