Timing signal dropout compensation circuit
US4680651A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 19, 1986 |
| Grant date | Jul 14, 1987 |
| Priority date | — |
| Expiry date | Aug 19, 2006 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N5/919
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In video reproduction apparatus in which video information representing a scene is recorded in a plurality of longitudinal tracks on magnetic tape, a timing signal is also recorded in a timing track parallel to the video information tracks. A dropout in the timing signal reproduced from the timing track causes degradation in the reproduced scene. There is disclosed a circuit for compensating for dropouts in the timing signal track to reduce such reproduced image degradation. A phase lock loop circuit produces a video sampling signal which is phase locked to the reproduced timing signal, and which has a frequency that is a multiple of said timing signal. The phase lock loop circuit has a loop bandwidth which tracks variations in frequency produced by flutter. A timing signal dropout detector detects an out of lock condition of the reproduced timing signal and produces a control signal which causes the phase lock loop circuit to continue to produce a video sampling signal during the dropout period of the timing signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.