Method and apparatus for secure transmission of video signals
US5555305A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 13, 1994 |
| Grant date | Sep 10, 1996 |
| Priority date | — |
| Expiry date | Jun 13, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N7/17327
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Video signals are sampled at 4Fsc locked onto sub-carrier phase and frequency. The active picture lines of each field are divided into 6 blocks of 47 lines and the active line periods of those lines scrambled on a block by block basis by line order shuffling. The shuffling algorithm is generated by a line shuffling permutator driven by a PRBS generator (controls 36, 38). Active line period samples for one block are written in unscrambled form into a first memory block (32) and samples from the previous block are read out in scrambled form from a second memory block (34) for transmission. The complementary process takes place in the decoder.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.