During WWII, Allied bomber crews used the broadcast signals of German radio stations as a giant set of navigation beacons. After the war, the Truman Administration was afraid that the Soviets would use US radio and television stations in the same way and created the CONELRAD (Control of Electromagnetic Radiation) System. Only radio stations on 640 and 1240 AM would remain on the air, alternating in five-minute increments.

With the onset of the ICBM threat, CONELRAD was replaced by the Emergency Broadcast System. The original purpose of the EBS was to find a way for the president to address all of the United States within ten minutes. It eventually morphed into a regional alert system as well for natural disasters.

One of my first duties in television was cutting my station’s EBS audio. I was also in charge of making sure the authentication codes were up to date. In case of a national emergency declared by the president, you put the system on the air only after you matched the code word that was received in a sealed envelope.