Method and device for transmitting video signals in confined spaces
US5335006A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 26, 1992 |
| Grant date | Aug 2, 1994 |
| Priority date | — |
| Expiry date | May 26, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N7/20
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A UHF carrier signal modulated by a video signal, where the frequency and the format of a line synchronization signal are known, is transmitted in a transmission region in a confined medium by a microwave link. In a reception region, two signals are received along two angularly offset privileged axes, each is frequency-demodulated along identical processing channels, the existence in the signal emitted from one of the channels, the "starting channel", of a periodic signal with the line synchronization frequency is checked and this signal is selected if the check proves positive. If the periodic signal disappears, the test is applied to the other channel; if that check is positive, this other channel is selected until this periodic signal disappears. Such a process is especially applicable in tunnels.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.