Even mark modulation coding method
US4870414A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 18, 1988 |
| Grant date | Sep 26, 1989 |
| Priority date | — |
| Expiry date | Mar 18, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L25/497
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A method termed Even Mark Modulation (EMM) is disclosed for coding input strings for input-restricted (1+D) or (1+D).sup.2 partial response channels that require at least one pair of consecutive signals of one state in order to record or transmit data to a receiving device. EMM provides improved coding gains and is especially suitable for optical recording. An input string is encoded into a binary code string in which all one-state signals (e.g., "1's") are in the form of runs of at least one contiguous pair; however, signals of an opposite state (e.g., "0's") may be of any length or duration. The EMM signals are detected with a maximum likelihood detector using an algorithm based on a three-state trellis structure for (1+D) channels and a five-state trellis structure for (1+D).sup.2 channels adapted to the particular partial response channel. In a preferred embodiment, the coding rate is 2/3 and the coding gain is at least 3 dB unnormalized and at least 2.2 dB when normalized. A finite-state encoder and sliding block decoder are disclosed, together with logic equations for encoder and decoder circuits.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.