Patent ID: 7911899
Filing Date: 2011-03-22
Classification: G11B

Abstract:
1. An optical disc reproducing apparatus comprising: an analog-to-digital (A/D) converter which converts an analog signal obtained from an optical disc to a digital signal; an asymmetry compensator which detects and corrects an offset of the digital signal; a phase locked loop (PLL) which estimates a clock of the digital signal and compensates for a frequency error; a binary module which converts the digital signal to binary data; an equalizer which equalizes a particular frequency of the digital signal; and a channel identifier which detects a reference level of the binary module, based on an input signal of the equalizer, wherein the asymmetry compensator comprises: a zero crossing detector detecting a zero crossing point by comparing each sign of two consecutive sample signals with respect to the digital signal; a decimal asymmetry detector computing a jitter value necessary for an asymmetric waveform level compensation of the digital signal; and a count determinator determining a coefficient quantity by using a sign bit of a sample signal according to the zero crossing point, the jitter value, and a predetermined system clock cycle.