| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a highly efficient and reliable reproduced signal evaluation method and an optical disk drive using the method since in a large capacity optical disk system with a constraint length of 5 or longer, the circuit size increases exponentially in accordance with an increase in the constraint length of a PRML system when determining the matching of a binarized bitstream with predetermined evaluation bitstreams and calculating the Euclidean distances to evaluate the quality of a reproduced signal. Ž<P>SOLUTION: Assuming that the number of 2T's appearing successively in a predetermined evaluation bit stream is i, the evaluation bitstream is divided into a main bitstream (5+2i) long and sub bitstreams at ends of the main bitstream. A determination process to determine whether a predetermined evaluation bitstream is included in the binarized bitstreams is aggregated with a main bitstream matching determination. This prevents an increase in the circuit scale. At the same time, by separately summing up for each main bitstream the calculated results of Euclidean distance between the reproduced signal and the target signal corresponding to the evaluation bitstream, the scale of an evaluation summing circuit can be reduced. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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