Unsuitable programme editing method for TV and VTR

摘要

The method involves using the audio band of a television broadcast. Typically, a 2.0 kHz signal of 250 ms duration is transmitted at the beginning of a programme deemed to be unsuitable for children while a similar 2.2 kHz signal is transmitted to indicate the beginning of advertisements. Both signals are transmitted to beat at 200 Hz and reset the system. The televisions and VTRs used can either come ready equipped with receivers for these signals and existing sets already in use can use have the receiver coupled via their SCART connector.