REVERSIBLE CONVERSION OF BINARY SEQUENCES INTO RUN-LENGTH LIMITED CODED SEQUENCES BETWEEN TRANSITIONS (I, K) WITH TWO/THREE RATIO AND MAXIMAL TRANSITION DENSITY LIMIT

摘要

FIELD: conversion of binary sequences transferred over recording channels of memory devices for optical communication subsystems. SUBSTANCE: run- length limited coded binary sequences between transitions (RLL) (i, k) with 2/3 ratio and maximal density limit of transitions are converted. State transition table for ordered pairs is determined and saved in processor memory. Each pair is indexed with respect to first table coordinate according to current state and with respect to second table coordinate according to vector of current bit pair and desired number of anticipatory bit pairs. State-to-state transitions are limited so as to ensure that mark-to-space ratio of any respective continuous sequence of RLL-coordinate three-bit values were below 50%. Table access is made by means of mentioned processor in compliance with sequence of vectors. State-independent decoding table incorporating list of binary-sequence bit pairs and indexed by means of vector generated around current RLL-coordinate three-bit values and preset number of anticipatory RLL-coordinate three-bit values is determined and saved in mentioned processor memory. Device has finite state machine designed for shaping RLL-coded three-bit characters of both first current state function out of plurality of internal states of finite state machine and mentioned vector. EFFECT: reduced noise level and rate of errors and failures. 4 cl, 15 dwg, 2 tbl