Video inversion detection apparatus and method
US5930361A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 31, 1996 |
| Grant date | Jul 27, 1999 |
| Priority date | — |
| Expiry date | Dec 31, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N7/1716
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An apparatus/method for descrambling a TV cable system transmission that been scrambled using an unknown scrambling algorithm. Insertion apparatus inserts a known visual/electrical characteristic into the TV transmission prior to scrambling by the unknown scrambling algorithm. The scrambled TV transmission, the scrambled insert-characteristic, and an encrypted message that defines the unscrambled insert-characteristic, are sent to all set-tops within the cable system. A set-top descrambler at each system-authorized set-top operates to descramble the scrambled insert-characteristic. The encrypted message is decrypted at each system-authorized set-top, to thereby reproduce the unscrambled insert-characteristic. Comparing apparatus compares the reproduced unscrambled insert-characteristic with the descrambled insert-characteristic, and thereby generates a control signal that is used to control the set-top descrambler to descramble the scrambled TV transmission in a manner that is compatible with the unknown scrambling algorithm.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.