Magnetic disk sampled amplitude read channel employing interpolated timing recovery for synchronous detection of embedded servo data
US5726818A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 5, 1995 |
| Grant date | Mar 10, 1998 |
| Priority date | — |
| Expiry date | Dec 5, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2007/047
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A sampled amplitude read channel reads user data and embedded servo data stored on a magnetic medium by detecting digital data from a sequence of discrete time interpolated sample values. A write frequency synthesizer generates a write clock for writing digital data to the magnetic medium at a predetermined baud rate for a selected zone, and upon read back, a read frequency synthesizer generates a fixed sampling clock at a frequency slightly higher than the write frequency at the outer zone. A sampling device samples the analog read signal at this fixed sampling rate across the data zones and servo wedges to generate a sequence of discrete time channel samples that are not synchronized to the baud rate. Before sampling, an analog receive filter processes the read signal to attenuate aliasing noise without having to adjust its spectrum across data zones or servo wedges. A discrete time equalizing filter equalizes the channel samples according to a predetermined partial response (PR4, EPR4, EEPR4, etc.). An interpolating timing recovery circuit, responsive to the equalized channel samples, computes an interpolation interval .tau. and, in response thereto, generates interpolated sampl…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.