Method for processing teletext data present in a television signal
US5627593A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 21, 1994 |
| Grant date | May 6, 1997 |
| Priority date | — |
| Expiry date | Dec 21, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N7/0357
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In order to achieve a greater degree of security in the decoder for the control frame of teletext pages, the control frame is initially selected and decoded from the data stream by means of a bit by bit comparison with a frame word. Thereby, the following steps are carried out in dependence on the number of coincidences occurring during the bit by bit comparison with the frame word: PA1 a) if, during the bit by bit comparison, eight coincidences are detected, the control frame is considered to have been identified and the counter is reset; PA1 b) if less than eight coincidences are detected, it is determined whether a particular number ("444") or a multiple of this number ("n 444") has been reached on the basis of the count-state of the clock pulse counter, whereby, in the event that this number has been reached, the control frame is considered to have been identified and the counter is reset.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.