The Duga radar were two over-the-horizon radar installations used by the USSR as early warning systems for incoming missiles. It was known to cause interference on shortwave radio that sounded like a woodpecker pecking wood, thus it was called the "Russian Woodpecker". It was a considerable nuisance at the time for radio operators.

When the western governments asked the Soviet government for the purpose of the antennas they said that they were TV broadcast stations. However everyone knew that it was bullshit because the USSR at the time only had like two or so TV channels.