Adaptive signal processing method using PRML for high density optical disks

Numerous types of DVD recording equipment have emerged on the market, and there is much demand for such optical storage systems with high speed and large capacity for digital high definition broadcasts. However, it becomes difficult to maintain data reliability with increasing recording speed and density, because the signal to noise ratio degrades and recording control of the phase changed mark becomes difficult. To improve the error rate of reproduced data, PRML (partial response maximum likelihood) decoding is expected to be used. We have developed a more advanced method of PRML, where the difference of the reproduced waveform is analyzed and the PRML decoder is compensated. In this paper we report the analysis of the reproduced waveform and the effect of the developed PRML algorithm.