Data retrieval
US6970522B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 17, 2000 |
| Grant date | Nov 29, 2005 |
| Priority date | — |
| Expiry date | Apr 17, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2020/1457
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A digital data storage (DDS) system for reading DDS tapes employs a partial response maximum likelihood detection system which utilises redundancy in the 8-10 DC free modulation encoding to reduce low frequency noise. The system incorporates a time-varying trellis decoder which embodies some of the PR1 rules together with the rules regarding the charge state or the digital sum variation (DSV) implicit in 8-10 modulation coding. The decoder operates to reject low frequency noise such as that caused by crosstalk noise between adjacent tracks on the tape. The trellis topography has been considerably simplified by adopting a two step six state trellis which operates on bit pairs and in which the states relate to the current DSV value, and sign of the previous bit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.