Duga, known as the Russian Woodpecker, was a Soviet over-the-horizon radar system used as part of the early warning network of detectors during the cold war. Comprised of two sites it operated between July 1976 to December 1989. The nickname woodpecker originated from a distinctive 10Hz tapping noise generated by the antennas.
Many controversies and conspiracy theories arose around this site. The powerful 10MW signal would often disrupt amateur radio operations, TV broadcasts and aviation communications at a considerable distance leading to some speculations, the most prominent theory being that Duga was a part of a secret Soviet mind-control experiment.
Today only the Duga-1 site within the Chernobyl Exclusion zone remains. Duga-2 located in Eastern Siberia was reportedly disassembled and scrapped several years ago.