Apparatus for correcting the time base of information recovered from a movable information storage medium
US4353089A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 11, 1980 |
| Grant date | Oct 5, 1982 |
| Priority date | — |
| Expiry date | Aug 11, 2000 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2220/20
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Method and apparatus for recovering information from an information storage medium, such as a disc-shaped record carrier, and for correcting time base variations in the recovered information. The disc includes a plurality of substantially parallel information tracks arranged in a spiral or in concentric circles, and information recorded thereon includes a pilot signal having a predetermined frequency. The apparatus includes means for comparing the phase angle of the recovered pilot signal with the phase angle of a locally generated reference signal, to produce an error signal for controlling a variable delay for correcting time base variations of the recovered information. The pilot signal includes an equal integral number of cycles on each information track, so its phase angle is aligned on adjacent tracks and the apparatus can continue to operate even when the information recovering device is traversing the disc from one track to another or is not critically positioned with respect to an individual information track.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.