Abstract: A method and apparatus for disabling the effect of copy-protect signals placed in a recording video signals which is based on differences in the characteristics of television and VCR circuitry. Copy-protect signals include pseudo-sync pulses and/or added AGC pulses in the blanking interval of a video signal. The specific method described includes altering the level of the video signal during the vertical blanking interval, e.g., level-shifting, so as to render the copy-protect signals ineffective to prevent unauthorized copying by a VCR. A circuit for achieving the method includes a sync separator for detecting the vertical blanking interval, pulse generating circuits for producing pulses of predetermined widths during this interval, and a summing circuit for summing the predetermined pulses with copy-protect signals thereby to shift their level.

Abstract: A method and apparatus for disabling the effect of copy-protect signals added to a video signal using differences in the characteristics of television and VCR circuitry. Copy-protect signals as described include pseudo-sync pulses and/or added AGC pulses in the vertical blanking intervals of a video signal. The specific method described includes increasing the effective frequency of the copy-protect signals during the vertical blanking intervals so as to achieve attenuation and/or low-pass filtering in the VCR circuitry to thereby render the signals ineffective in preventing copying. A circuit for achieving this method comprises pulse narrowing and/or pulse multiplication circuitry which effectively increases the high-frequency content of the pseudo-sync and/or AGC pulses.

Abstract: A method and apparatus for disabling the effect of copy-protect signals placed in a recording video signals which is based on differences in the characteristics of television and VCR circuitry. Copy-protect signals include pseudo-sync pulses and/or added AGC pulses in the blanking interval of a video signal. The specific method described includes altering the level of the video signal during the vertical blanking interval, e.g., level-shifting, so as to render the copy-protect copy protection signals ineffective to prevent in preventing unauthorized copying by a VCR. A circuit for achieving the method includes a sync separator for detecting the vertical blanking interval, pulse generating circuits for producing pulses of predetermined widths during this interval, and a summing circuit for summing the predetermined pulses with copy-protect signals thereby to shift their level.