Patent ID: 7256718
Filing Date: 2007-08-14
Classification: G11B,H03M,H04L

Abstract:
1. A modulation apparatus for converting data having a basic data length of m bits into variable-length code (d, k; m, n; r) having a basic code length of n bits, said modulation apparatus comprising: conversion means for converting input data into codewords in accordance with a conversion table containing conversion codes having a coding rule that the remainder of the number of “1's” in each element of the data sequence divided by two and the remainder of the number of “1's” in each element of the converted codeword string divided by two are equally 1 or 0; minimum-run-length limitation code detection means for detecting a minimum-run-length limitation code from the input data, the minimum-run-length limitation code being contained in the conversion codes of the conversion table and limiting the minimum run length to a predetermined number or less; consecutive-minimum-run replacement means for replacing the codeword string converted by the conversion means so that the minimum run length is limited to the predetermined number or less based on the minimum-run-length limitation code detected by the minimum-run-length limitation code detection means; and modulation information storage means for counting the number of conversions performed by the conversion means based on a specified conversion code of the conversion codes contained in the conversion table and for storing information indicating the conversion count, wherein the minimum-run-length limitation code detection means is controlled to detect the minimum-run-length limitation code from the input data based on the information stored by the modulation information storage means.