Method and apparatus for television signal scrambling using block shuffling
US5321748A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 2, 1992 |
| Grant date | Jun 14, 1994 |
| Priority date | — |
| Expiry date | Jul 2, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N7/1696
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for scrambling video signals to obtain the secure transmission of video information. A block of video lines in a television raster is divided into top and bottom sub-block portions. The top and bottom sub-block portions are switched in position. The sequence of video lines within the sub-blocks are shuffled so that the resulting scrambled video signal contains blocks of video lines which have been block portion switched and shuffled from their original block portion position and their original line sequences. The size of the first block of video lines can grow and/or shrink in time so that the video appears to roll down or up the display. A pseudo-random number of sequence controls the shuffling sequence. A descrambler receives the scrambled video signal and a code identifying the shuffling sequence of the scrambled video for descrambling the video signal and returning the block portions and the video lines to their original sequences.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.