Recognisable by its signal strength, the unmistakable "rat-tat-tat" sound of 10 pulses per second caused it to be nicknamed "The Woodpecker".
Although the frequency use varied, no part of the shortwave spectrum was free from this incredibly strong signal, much of which was rendered unusable for long periods of time. The use of Direction Finding equipment traced the signals to the area of Gomel, Russia.
Severe interference was caused to both professional and amateur users of the bands, and official complaints were lodged by many countries.
Speculation about the purpose of the signals ranged from submarine communication to weather control, even mind control and mood changing! However, the general consensus finally arrived at a form of Over-The Horizon radar system - something the West was experimenting with too!
Having caused havoc for so long, the signals finally ceased.
FEAR THE WOODPECKER!