Attention Signal Next, the Attention Signal was transmitted. Prior to 1976, primary stations would turn their transmitters off for five seconds, back on for five seconds, off for five seconds more, then go back on air and transmit a 1000 Hz tone for 15 seconds to alert secondary stations, as was used by predecessor CONELRAD. Television stations adhered to similar rules, but switched only their sound carriers off. This quick off-and-on became known to broadcast engineers as the "EBS Stress Test", as older transmitters would sometimes fail after the quick cycling on and off.
Attention Signal Next, the Attention Signal was transmitted. Prior to 1976 primary stations would turn their transmitters off for five seconds, back on for five seconds, off for five seconds more, then go back on air and transmit a 1000 Hz tone for 15 seconds to alert secondary stations, as was used by predecessor CONELRAD. Television stations adhered to similar rules, but switched only their sound carriers off. This quick off-and-on became known to broadcast engineers as the "EBS Stress Test", as older transmitters would sometimes fail after the quick cycling on and off.