The source of the interference would not become clear until after the fall of the Berlin Wall. The culprit was found to be an enormous, 700 metre long, 240 metre tall over-the-horizon radar, a type of cold war era early warning system nestled in dense forest in the shadow of the now infamous town of Chernobyl. Its purpose was to detect an intercontinental ballistic missile within minutes of its launch. It was one of a pair of radar systems. Duga-2 faced east, in the direction of China while Duga-1 watched suspiciously over the west.
The radar system was ingenious in its simplicity. It worked by bouncing radio signals off of the stratosphere back towards earth, therefore allowing it to reach beyond the horizon which would otherwise limit the range of conventional radar systems. For the system to function it required an enormous radio signal, hence the size of the structure and hence the droll humming heard across the globe in the late 1970’s.
Luckily neither Duga-1 nor Duga-2 ever picked up the type of signal they were intended to. Duga-2 to the east was destroyed while Duga-1 now lies derelict and rusting. It is now part of the Chernobyl Nuclear Exclusion Zone but some still venture there due to the photo opportunities offered by the abandoned structure. Below are a series of compiled images of Duga-1 radar installation and its surroundings.