Defect detection and compensation apparatus for use in an FM signal translating system
US4001496A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 9, 1975 |
| Grant date | Jan 4, 1977 |
| Priority date | — |
| Expiry date | Jul 9, 1995 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N9/882
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In playback of a video record (e.g., in video disc form) employing a FM carrier recording format, a defect compensation system is provided which substitutes delayed video signals for current video signals when a defect is encountered. The current video signals are obtained from the output of the player's pickup-responsive FM detector (illustratively of the zero-crossing detector type) via appropriate frequency responsive circuitry comprising a low pass filter (encompassing the recorded video signal bandwidth: e.g., 0-3 MHz.). To detect the occurrence of a defect, the FM detector output is also supplied to additional frequency responsive circuitry having a wideband response which desirably extends from DC to an upper frequency limit (e.g., 0-6 MHz.) well above the highest frequency of the video signal subject to recording. The wideband circuit output is supplied to pair of voltage level comparators, one supplying an output pulse of a given polarity whenever the wideband circuit output voltage level exceeds a level representative of the FM detector output for the maximum frequency of the FM carrier deviation range employed in recording, and the other supplying an output pulse of the …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.