PR4 sampled amplitude read channel for detecting user data and embedded servo data
US6115198A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 29, 1997 |
| Grant date | Sep 5, 2000 |
| Priority date | — |
| Expiry date | Oct 29, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2220/2516
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A partial response class-IV (PR4) sampled amplitude read channel is disclosed for detecting user data and embedded servo data. The detected servo data is encoded using a novel servo code capable of accurately decoding detected codewords representing servo track address during seek operations, even when the recording head flies between two adjacent tracks, and capable of correcting errors in the detected codedwords caused by noise in the read signal, such as inter-symbol interference. In one embodiment, the servo code corrects certain minimum distance error events, such as a bit shift error event, associated with a trellis type sequence detector. To achieve the equivalent effect of a conventional Gray code, the codewords are arranged such that adjacent track addresses differ by a number of bits relative to the minimum distance error events corrected. In this manner, when the recording head spans two adjacent tracks during a seek operation, the ambiguity in the detected codeword will be resolved in favor of one of the adjacent track addresses. To further increase performance, the servo data PR4 sample values are converted into an EPR4 response and detected with a sliding threshold de…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.