I was reading the Wikipedia entry for an episode of Doctor Who I was watching last night when I happened upon this anecdote (new to me but apparently well-known) about the broadcast of the story on Chicago station WTTW being interrupted by a pirate transmission.
The first occurrence of the signal intrusion took place during then-independent station WGN-TV’s live telecast of its primetime newscast, The Nine O’Clock News. During Chicago Bears highlights in the sports report, the station’s signal was interrupted for about half a minute by a video of a person wearing a Max Headroom mask, moving around in front of a sheet of corrugated metal, which imitated the background effect used in the Max Headroom TV and movie appearances. There was no audio other than a buzzing noise. (…)
Later that night, around 11:15 p.m. Central Time, during a broadcast of the Doctor Who serial ‘Horror of Fang Rock’, PBS member station WTTW’s signal was hijacked using the same video that was broadcast during the WGN-TV hijack, this time with distorted audio.
As Chris Knittel and Alex Pasternack’s comprehensive account of this infamous ‘broadcast intrusion’ concludes, ‘there was no clear motive, no clear message, and thirty years on, no clear perpetrator’.