Method and apparatus for modifying the color burst to prohibit videotape recording
US4577216A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 14, 1983 |
| Grant date | Mar 18, 1986 |
| Priority date | — |
| Expiry date | Nov 14, 2003 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N2005/91371
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus which modifies a color video signal in such a manner that a conventional television receiver produces a normal color picture from the modified signal, whereas a videotape recording made from the modified signal exhibits annoying color interference. This is achieved by phase modulating the color burst component of the video signal with a noise signal. A videotape recorder interprets the phase variation as a velocity error and alters the chrominance signal, giving rise to color noise in the videotape recording. The characteristics of the noise signal are chosen to preclude interfering with the receiver's subcarrier regenerator.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.