CONELRAD (
Control of Electromagnetic Radiation) was a method of
emergency broadcasting to the public of the
United States in the event of enemy attack during the
Cold War. It was intended to allow continuous broadcast of
civil defense information to the public using radio or TV stations, while rapidly switching the transmitter stations to make the broadcasts unsuitable for
Soviet bombers that might attempt to
home in on the signals (as was done during
World War II, when German radio stations, based in or near cities, were used as beacons by pilots of bombers).