Jitter measurement apparatus detecting amplitude of phase errors between information signal and synchronized clock signal
US5663942A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 27, 1995 |
| Grant date | Sep 2, 1997 |
| Priority date | — |
| Expiry date | Apr 27, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0908
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A read-out information signal read out from an optical disk carrier is digitized, thereby detecting an amplitude of an absolute value of a phase error between the read-out information signal and a synchronized clock signal. The synchronized clock signal is obtained by using a phase locked loop constituted by a phase detector having two outputs, that is, a phase lead and a phase lag, and a VCO operating at an average value of a differential signal representing a difference between the two outputs. A phase error amplitude is detected from a sum signal representing a sum of the two outputs of this phase detector. By appropriately displacing a focus actuator in a state where a focus control is performed, an offset compensation amount where the phase error amplitude becomes minimum is obtained.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.