I remember it on shortwave back in the 50’s and 60’s.
At some point in 1976, a new and powerful radio signal was detected simultaneously worldwide, and quickly dubbed ‘the Woodpecker’ by amateur radio operators. Transmission power on some Woodpecker transmitters was estimated to be as high as 10 MW equivalent isotropically radiated power.
Even prior to 1976, a similar ‘woodpecker’ interference is remembered by radio amateurs occurring in the high frequencies. As early as 1963, or before, radio amateurs were calling this “the Russian Woodpecker”. Little is known about the power levels or Russian designation but it was probably a forerunner of the Duga radar systems. It was also speculated at that time, at least among radio amateurs, that this was an over-the-horizon radar.
These signals even caused interference on 27 MHz CB radios in the late 60s and early 70s sometimes completely blocking even local communications in Portugal for example, leading to the supposition of several megawatts of RF power transmission.