Trellis codes with algebraic constraints for input restricted partial response channels
US5485472A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 16, 1994 |
| Grant date | Jan 16, 1996 |
| Priority date | — |
| Expiry date | May 16, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M13/31
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A method for constructing trellis codes and an apparatus for providing trellis codes with increased minimum distance between output sequences of partial response channels with constrained inputs. A Viterbi detector expands a conventional trellis structure for the channel incorporating additional states interconnected such that a preselected function associates each state in the trellis with an algebraic evaluation of a polynomial at a particular element of a finite field. The detector trellis is time-varying such that only certain values of the preselected function are allowed every m bits. The time-variation assures that there are no minimum distance extensions of erroneous sequences beyond a predetermined length in the trellis. Reliability of storage channels is desirably increased, because more noise is required to overcome the additional distance and cause an error in distinguishing the correct encoded sequence.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.