MODULATOR, MODULATION METHOD, DEMODULATOR, DEMODULATION METHOD, AND RECORDING MEDIUM

摘要

<P>PROBLEM TO BE SOLVED: To perform recording and reproduction at a high linear density. Ž<P>SOLUTION: A DSV (Digital Sum Value) control bit determination/insertion unit 11 inserts a DSV control bit for DSV control into an input data sequence to be output to a modulation unit 12. The modulation unit 12 converts data having a basic data length of 2 bits into a variable-length code having a basic code length of 3 bits on the basis of a conversion table and outputs it to an NRZI (NonReturn to Zero Inverted) encoding unit 13. The conversion table of the modulation unit 12 includes a replace code for limiting the number of consecutive minimum runs to a predetermined value or less, and a replace code for conforming to run-length control. The replace code has replace limitation added thereto, and has a conversion rule where both a remainder obtained by dividing the number of '1' in the elements of a data sequence by 2 and a remainder obtained by dividing the number of '1' in the elements of a code word sequence by 2 are the same, "1" or "0". Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž