Back to IndexBack to Tones PageOne Into Fourthe story of how ABC Radio split itself into four distinct networks.ABC Radio |
In 1966, ABC Radio Network used a single
2030Hz signal ahead of news alerts, bulletins and other critical information of
interest to its affiliates. A notch filter was inserted across the output of
the channels feeding the AT&T network.
In time for split network service in 1968, a FSK duo tone service
was installed. A low pass filter was inserted above 4500 Hz to allow these two
tones to be sent without interference from voice and music programming. Prior to moving over to satellite and multiple channels, I removed the low pass filter and replaced it with two notch filters for the fsk 'pulses.' With some affilliates capable of receiving audio out to 8 khz courtesy of AT&T's 'upgrade' to T-carrier program channel gear, this slight tweak in audio performance helped many east coast stations and those that were conneted from satellite point to point trunks in Chicago, LA and other west coast links. We also reduced the 'chirp' level to about 20 db below +8 operating level (memory might off on the exact drop) following our transition to satellite and PCM audio. Eventually, the chirp was dropped altogether and replaced by a more efficient and higher capacity digital cue system. The system is still in service today and available to both ABC affiliates and to some extent to ABC's channel service customers. The warning was transmitted at 10 seconds prior to all ABC shows. It was generated from an oscillator operating at 400 Hz @ +8. I changed it to 440 Hz ("the key of A"). The time beep on the hour was turned off because many stations put the news in delay and the signal proved somewhat inconvenient. I didn't want it to go. But programming always wins out over sentimentality. That's why I love the CBS 'bong.' Awesome!! Bob Donnelly
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