The intrusion was against 3 television stations including WGN-TV out of Chicago located here.

Max Headroom broadcast signal intrusion

The Max Headroom broadcast signal intrusion was a television signal hijacking in Chicago, Illinois, on the evening of November 22, 1987. It is an example of what is known in the television business as broadcast signal intrusion. The intruder was successful in interrupting two television stations within three hours. Neither the hijacker nor the accomplices have ever been found or identified.

• http://en.wikipedia.org/wiki/Max Headroom broadcast signal intrusion