Determination of scrambling mode of a television signal
US6072872A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 27, 1998 |
| Grant date | Jun 6, 2000 |
| Priority date | — |
| Expiry date | Jan 27, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N7/1713
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A signal such as an analog scrambled television signal in a cable television network has first scrambling mode data which is compatible with a first decoder population, but not a second decoder population. The scrambled television signal is processed to determine the scrambling mode without recovering the first scrambling mode data. Second scrambling mode data which is compatible with the second decoder population is then provided in the scrambled television signal, for example, in the vertical blanking interval or on an audio subcarrier. During processing to determine the scrambling mode, the television signal is delayed, e.g., by digitizing it and temporarily storing it in memory. The delay compensates for the time required to determine the scrambling mode. The television signal is recovered in the analog domain prior to inserting the second scrambling mode data. The system is compatible with various scrambling modes, including sync suppression and inversion of the active video as well as with dynamic scrambling mode changes.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.