Method and apparatus for disabling anti-copy protection system in video signals using pulse narrowing
US5157510A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 20, 1990 |
| Grant date | Oct 20, 1992 |
| Priority date | — |
| Expiry date | Dec 20, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N2005/91314
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.