Actually, the test pattern as pictured here has nothing to do with the Emergency Broadcast System (now known as the Emergency Alert System). 'Bars' (or SMPTE bars) as this test pattern is known in the TV industry are present at the beginning of most recordings so that the master control operator at a station can make sure what they are putting out over the airwaves is true in color. 'Tone' is the audio portion of what is sent out while 'bars' are present and 'tone' does sound very much like the 'alert signal' sent out during an EBS test. Bars and tone are what went out over the air after hours, when a station had concluded it's broadcast day, back when the networks did not air programs overnight.