Coding system for pay television
US4369462A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 15, 1980 |
| Grant date | Jan 18, 1983 |
| Priority date | — |
| Expiry date | Aug 15, 2000 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N7/1675
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A coding system for use in a television system wherein at least a part of a television signal is inverted by an encoder at a broadcasting station, according to a code signal and the coded television signal is decoded by decoders of specific subscribers to be reproduced on TV sets. The coding system is comprised of a clock oscillation means, a mode generating means for generating signals indicating plural inversion modes, a counter for counting clock signals from the clock oscillation means, a setting means for outputting a predetermined signal based on addresses provided corresponding to the respective inversion modes of the mode generating means and determined by an output from the counter, and a means for inserting the code signal during a vertical blanking period of the television signal. When the output signal of the mode generating means and the output signal of the setting means are in a given relation, the count value of the counter is used as the code signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.