Data recording/reproducing apparatus with two-dimensional equalizer for

Abstract

An equalizer apparatus is applied to a DBF disk recording medium in which a sampling clock is reproduced from clock pits recorded on the disk recording medium. A fixed coefficient equalizer includes an analog to digital converter, a memory and a two-dimension equalizer. The fixed coefficient equalizer suppresses interference from adjacent tracks and reduces the error rate of the reproduced data caused by crosstalk even in the case of a narrow track pitch. Further, by adding to the equalizer a sign detector, a FIR low-pass filter and a coefficient control circuit to form a variable coefficient equalizer, interference fluctuation attributed to the linear recording density, recording power irregularity, light spot shape, tracking error, etc., can be automatically compensated to suppress the equalization error caused by such fluctuation. Further, using the variable coefficient equalizer, clocking timing errors and fluctuations can be automatically and efficiently compensated.