Encoder/decoder of information upon/from a video signal
US5386240A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 21, 1992 |
| Grant date | Jan 31, 1995 |
| Priority date | — |
| Expiry date | Aug 21, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N7/081
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An encoder/decoder can insert and demodulate an information signal without affecting a video signal, the information signal being not analyzed, modified and deleted easily. The non-inverted and inverted information signals are inserted into two horizontal lines having a strong correlation in the same field or different fields separated by at least one field of the video signal. A difference of the inserted information signals is obtained by a combination of a delay circuit and a subtracter. Field difference signals Sx and Sy are applied to a band pass filter and are generated by a PSK generation circuit. Generated output signals Qx and Qy are converted into unit information by a majority decision logic circuit and are stored in a memory. A unit information group consisting of a predetermined number of stored bits is used to generate the meaningful information. The inserted information signal has a low level and is inserted in the video period and the unit information is generated by the field difference. Thus, the information signal cannot be analyzed, modified and deleted easily.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.