| 摘要 |
A non-copiable videotape recording system includes a synchro signal separator adapted to separate a horizontal and a vertical synchro signal from a synchro signal section of a video signal, a first-pulse generator adapted to generate a first pulse while the video signal is in the duration of the back porch which follows the horizontal synchro signal, wherein the first pulse has a narrower width than that of the back porch, a second-pulse generator adapted to generate a second pulse having a lower level than that of the first pulse while the video signal is in the duration of the back porch following the horizontal synchro signal, wherein the second pulse has a narrow width than that of the back porch and has a substantially equal pulse-area to that of the first pulse, and means for adding the first pulse and the second pulse alternately to the back porch of the video signal at predetermined time intervals.
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