MANY-VALUED RECORDING MODULATOR/DEMODULATOR

摘要

PROBLEM TO BE SOLVED: To improve the recording density of a recording medium. SOLUTION: Encoding efficiency greater than 1 is achieved by realizing ternary recording to the recording medium. For this purpose, the binary data words of 8 bit are converted to ternary code words of 5 symbols. A look-up table 31 stores a modulation and demodulation table for defining the correspondence relation of the binary data words (8B) and the ternary code words (5T). A table forming circuit 31 forms a modulation and demodulation table to be stored into the look-up table 31 so as to satisfy the respective restrictions assigned by the plural parameters. If a PRML(Partial Response Maximum Likelihood) system is combined with the 8B5T codes obtained in the manner described above, a signal-to-noise ratio is improved.