CBC: As oddly as it started, the widespread problem with some garage doors in the Ottawa region had disappeared by Friday. The powerful radio signal causing the problem stopped transmitting on Thursday afternoon, around the time CBC News contacted the U.S. Embassy to ask if it knew anything about it. The embassy categorically denies that it had anything to do with it. The signal was being transmitted at 390 megahertz, a U.S. military frequency used by the Pentagon’s new Land Mobile Radio System.