Video scrambling by segmenting video information lines
US4736420A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Sep 19, 1986 |
| Grant date | Apr 5, 1988 |
| Priority date | — |
| Expiry date | Sep 19, 2006 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N7/1696
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A system for scrambling a video signal having a plurality of horizontal lines, each of which includes a video information portion and a non-video information portion. The scrambling system includes a memory; means for storing the video information portion of each video signal line in the memory; and means for forming scrambled horizontal lines by retrieving each of a plurality of said stored video information lines in a plurality of segments preceded by a non-video segment and separated by non-video segment(s). The retrieval means include means for varying the respective durations of the retrieved video information segments in individual scrambled horizontal lines in accordance with an encryption keystream; and means for varying the total duration of the non-video segments for individual scrambled horizontal lines in accordance with a predetermined timing pattern. A complementary descrambling system also is disclosed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.