control of electromagnetic radiation การใช้

• Short for Control of Electromagnetic Radiation, it existed from 1951 to 1963 as a way of shifting the broadcast frequencies of AM stations to prevent enemy aircraft from homing in on radio signals for navigation.
• In 1951, CONELRAD, or Control of Electromagnetic Radiation, became the precursor to EBS . CONELRAD tests required all radio stations to go off the air, except for stations that broadcast over 640 AM and 1240 AM . " That's because we didn't want Russian missiles to home in on any frequencies, " said Ralph Swisher, spokesman for the Federal Emergency Management Agency.