Phase lock loop for sector servo system
US5208556A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 4, 1992 |
| Grant date | May 4, 1993 |
| Priority date | — |
| Expiry date | Sep 4, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B5/59616
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A phase lock loop for a sector servo system. A servo phase lock loop oscillator provides the control timing function of the servo. Initially, the PLO is locked in frequency to a frequency reference obtained from a counter/timer in a digital signal processor (DSP) used to control the servo system. Subsequent to acquisition of the nominal operation frequency, the PLO is caused to lock in turn to gap and frame character markers derived from the digital information encoded into the servo burst. Transition between PLO reference sources is commanded by the microprogram running in the DSP, based upon microprogram assessment of servo PLO status. The PLO outputs timing control tags to the servo control logic and PES demodulator, a reference clock to the file read/write channel, and interrupt pulses to the DSP to synchronize DSP operation with the servo hardware, and initiate periodic DSP computation of the control algorithm.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.