| 摘要 |
PROBLEM TO BE SOLVED: To provide a recording medium reproducing apparatus that applies turbo decoding to a reproduction signal reproduced from a recording medium. SOLUTION: At the preceding stage of a first one of two APP (A Posteriori Probability) decoders that constitute a turbo decoder, there is provided a logarithmic-likelihood computing circuit 42 that creates and outputs logarithmic likelihoods I-(y'i /yi ) of a reproduced signal y'i which is soft information. The first APP decoder has an APP decoding function of receiving logarithmic likelihoods L(y'i /yi ) of the reproduced signal y'i as well as a-priori information as to code data c'i , updating the code data c'i and producing outputs of a- posteriori probabilities according to trellis diagram information that satisfy constraints concerning an RLL(Run Length Limited) modulation. Turbo decoding becomes compatible with the RLL demodulation, and a turbo decoding with high error-correcting capability is usable in reproducing channel data ai recorded onto a recording medium, which allows a recording density of the recording medium to be increased.
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