Use of the vertical blanking interval on BBC distribution
Colin Spicer, Peter William Barlow · 1994
The allocation of VBI lines to local and network noise, Datacast, Ceefax, teletext audio tests, subtitles, the one-line (21/334) Insertion Test Signal and transmission tests is set out and the possible future developments are outlined. A new teletext talkback system is foreshadowed, data distribution and technical security are discussed, and the principle of VBI signal routing in the Regions is explained diagrammatically. >