Apparatus for encoding of information
US4396947A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 26, 1980 |
| Grant date | Aug 2, 1983 |
| Priority date | — |
| Expiry date | Mar 26, 2000 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N7/167
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A composite video signal containing an information portion and a synchronization pulse is encoded by shifting the level of the synchronization pulse and also by inverting the information portion. The encoding is switched on and off at a randomly chosen frequency, under the control of random number generator enabled at regular intervals. The encoded signal is transmitted with a data signal representing the random number so that a receiver can decode the received signal. The transmitted data can include details of undesired recipients, to disable their decoders. Applied to a pay TV system, the transmitted data can include the rate to be charged for the program and a billing mechanism at the receiver will meter the appropriate charge.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.