Copy protection for video signal using narrowed horizontal synchronization signals and amplitude modulation
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United States of America Patent
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-
Apr 1, 2008
Grant Date -
Mar 2, 2006
app pub date -
Aug 16, 2005
filing date -
May 17, 1993
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
Enhancements to a video anticopying process that causes an abnormally low amplitude video signal to be recorded on a illegal copy. The enhancement in one version include a negative going waveform that appears to the television receiver or videotape recorder to be a sync signal, thereby causing an early horizontal or vertical retrace. In another version, selected horizontal sync pulses are narrowed, causing irregular vertical retraces. In another version, post-pseudo sync pulses that have a minimum level above the minimum level of sync pulses are added to enhance anti-copy effectiveness. The post pseudo-sync pulses may be amplitude modulated.
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