Patent ID: 7068584

Claim:
A signal processor, comprising: an analog filter for removing high-frequency noises of a played-back signal from an optical disk and amplifying a specific frequency band of the played-back signal; an analog-to-digital (A-D) converter for converting the played-back signal from the analog filter into a digital signal; an adaptive equalization filter for performing waveform equalization of the played-back signal from the A-D converter while adjusting a tap coefficient of the adaptive equalization filter so as to reduce a difference between an output of the adaptive equalization filter and a target value; a quality value calculating circuit for calculating an average value of absolute values of the difference between the output of the adaptive equalization filter and the target value within a prescribed time, and outputs the calculated average value as a quality value; and a control circuit for comparing the quality value calculated by the quality value calculating circuit with a predetermined reference value, and conducting a process for improving the quality value according to the comparison result.