PRML detector having a viterbi decoder outputting temporary judgement results

摘要

A PRML detector includes a waveform equalizer for equalizing a waveform of a reproduction signal obtained by reproducing marks and non-marks recorded on a recording medium, and a decoder for generating binary-coded data of the reproduction signal based on the waveform equalized by the waveform equalizer. The decoder outputs a temporary data string which is obtained before the binary-coded data is obtained. The waveform equalizer includes an equalizer that includes a delay element that delays propagation of the reproduction signal, a plurality of multipliers that multiply predetermined coefficients by the reproduction signal and the delayed signal from the delay element, and an adder that adds outputs from the plurality of multipliers. A target value judger determines a target value for equalizing based on the temporary data string output from the decoder and a coefficient adaptive controller calculates the predetermined coefficients and adaptively updates the calculated predetermined coefficients for each of a plurality of multipliers.