System for passing two color TV signals through non-linear path
US4120001A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 17, 1976 |
| Grant date | Oct 10, 1978 |
| Priority date | — |
| Expiry date | Dec 17, 1996 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N7/20
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
When two color television signals are transmitted over a common non-linear path, such as a transponder in a communications satellite, the two color subcarriers at slightly different frequencies intermodulate each other and produce a disturbing flickering of color on the screens of monitors and receivers. The crosstalk is made invisible in the present system by translating the flicker to fluctuations occurring at too high a frequency to be seen. At the transmitting terminal, alternate lines of one of the television video signals are delayed by half the period of the color subcarrier, and at the receiving terminal, intermediate lines of the same television video signal are delayed by half the period of the subcarrier. The fluctuations may be made invisible to signal-monitoring instruments by passing both the delayed and undelayed television video signals through chroma averaging circuits at the receiving terminal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.