FM Signal demodulator with defect detection
US4203134A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 2, 1978 |
| Grant date | May 13, 1980 |
| Priority date | — |
| Expiry date | Oct 2, 1998 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N9/882
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In the playback of a video disc record employing an FM carrier recording format, a defect compensation system is provided which substitutes delayed video signals for current video signals when a defect is encountered. A phase locked loop including a phase detector and a voltage controlled oscillator is employed in FM detection circuits. A defect detector compares the phase between the oscillator output signal and a signal corresponding to the recovered signal. When the phase difference between these two signals exceeds a certain value, a defect signal is generated to disable the normal signal path of the recovered signal so that the delayed version of the video may be substituted for the current video for the duration of the occurrence of the defect.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.