A method and apparatus for removing the effects of copy protection signals within the video signal

摘要

The circuit, to counter copy protection signals in a video signal, includes a protection detection circuit and a generic modification circuit. The copy protected video signal (12) is input to a correction circuit (14) and to a detector. This has a chroma band pass amplifier (16) to separate the chrominance and the luminance signals. An envelope detector (20) senses the lines containing the colour bursts, and triggers a one-shot circuit (22) having a period of about 52 microseconds, which is less than one TV line period. A second trigger circuit generates a 70 microsecond pulse. These triggers are applied to an AND circuit whose output causes the correction circuit to counter the copy protect signals.