Method and apparatus for frustrating vertical interval detection in scrambled television signals.

摘要

In order to defeat pirate descramblers that detect the occurrence of a vertical blanking interval from a gap in timing data provided on the sound carrier of a scrambled television signal, diversionary pulse information is inserted into the sound carrier during the vertical blanking interval. A pirate descrambler that looks for a gap in data transmitted on the sound carrier will then detect a "false" second gap, and incorrectly phase lock its horizontal oscillator to random video instead of to horizontal timing information that is recoverable during the vertical blanking interval. <IMAGE>