Method of scrambling and of unscrambling composite video signals, and device for implementation
US5224161A · kind A · utility
26Cited by
7References
8Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jul 8, 1991 |
| Grant date | Jun 29, 1993 |
| Priority date | — |
| Expiry date | Jul 8, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N7/1675
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In order to scramble as effectively as possible pay-television transmissions, the transmitter is made to transmit, at one and the same time, access messages and entitlement messages, all of them crypted and corresponding to a control word periodically loaded into a pseudo-random generator. In each receiver, the decoder comprises a control unit processing the various messages and sending them to a security processor which supplies a control word to the pseudo-random generator controlling the unscrambling.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.