Method and apparatus for enhancing the security of a scrambled television signal
US5146496A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 13, 1991 |
| Grant date | Sep 8, 1992 |
| Priority date | — |
| Expiry date | Jun 13, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N7/1693
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
The scrambling security of a sync suppressed television signal is enhanced by eliminating the fixed time relationship between the normal color burst component and synchronization information in successive lines of the television signal. Transmission of a first plurality of television lines is delayed to achieve a cumulative delay corresponding at least to the duration of a color burst component of the television signal. The transmission of a second plurality of television lines is subsequently accelerated to reduce the cumulative delay. By repeating the delaying and accelerating steps, the location of the color burst component is varied within the television signal over time. Derivation of a substitute horizontal synchronization pulse from the color burst component is thereby prevented.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.