Mis-detection of a video switchover key signal
US4881253A · kind A · utility
4Cited by
4References
6Claims
0Family size
Assignees
Inventors
Key dates
| Filing date | Jun 8, 1988 |
| Grant date | Nov 14, 1989 |
| Priority date | — |
| Expiry date | Jun 8, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N7/148
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A television telephone system utilizes a tone signal of a predetermined duration. The tone signal has a plurality of frequencies and is positioned at the starting portion of a transmission signal. The tone signal reduces the possibility of mis-detection of signals during reception and allows video signals to be transmitted more satisfactorily.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.