Even mark modulation coding method

Details Even mark modulation coding method Even mark modulation coding method

1988-03-18

1989-09-26

Shoop, Jr., William M.

Coded data generation or conversion

Digital code to digital code converters

To or from multi-level codes

341106, H03M 700

Patent

active

048704148

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.

REFERENCES:
patent: 3995264 (1976-11-01), Ouchi
patent: 4413251 (1983-11-01), Adler et al.
patent: 4488142 (1984-12-01), Franaszek
patent: 4502036 (1985-02-01), Furukawa
patent: 4609907 (1986-09-01), Adler et al.
patent: 4688016 (1987-08-01), Fok

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