Patent ID: 6175542
Filing Date: 2001-01-16
Classification: G11B,H03M

Abstract:
A demodulation circuit of an optical disc apparatus performing an FSK demodulation by being provided with a binary signal which is obtained by binarizing a signal reproduced from an optical disc on which an FSK modulation signal is previously recorded, said demodulation circuit comprising:edge interval measuring means for measuring an edge interval of said binary signal;subtracting means for obtaining an FSK modulation component from a difference between a measured edge interval value and a previously determined edge interval reference value;first moving average means for obtaining a moving average of said FSK modulation component;demodulation value calculating means for obtaining a demodulation value based on an average value output from said first moving average means;second moving average means for obtaining a moving average of said demodulation value; andcomparing means for comparing an average value output from said second moving average means with a reference value so as to obtain a binary FSK demodulation signal.