Quasi-parallel television if suitable for stereo sound reception
US4660088A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 29, 1983 |
| Grant date | Apr 21, 1987 |
| Priority date | — |
| Expiry date | Nov 29, 2003 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N5/607
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A multiplier for multiplying the modulated sound and picture carriers to produce an intercarrier sound signal in a quasi-parallel sound channel of an IF section has a pair of anti-parallel connected diodes in a limiter for generating an amplitude limited version of the picture carrier. It has been discovered that the varying capacitance of the diodes with picture amplitude can cause phase shifts and hence phase modulation interference in the intercarrier signal. The latter is especially troublesome for stereo sound reproduction. To reduce such interference, a low value resistor is shunt coupled to the diodes to inhibit the capacitance variations of the diodes and resulting undesired phase modulation in the intercarrier sound signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.