| 摘要 |
PROBLEM TO BE SOLVED: To correct an error by LDPC in a hologram recording and reproducing system. SOLUTION: A block-like code such as a sparse code is used for a recording and modulating code in a hologram recording and reproducing system. Accordingly, LLR (log-likelihood ratio) cannot be calculated directly with the same means as the conventional LDPC system. Then, such a means is adopted that the LLR is decided to be a value based on amplitude difference between the prescribed pixels in order from a bit the value of which is reversed depending on its sparse decoding result while replacing amplitude order of each pixel of a read-out signal. Thus, even when a balance code is used for a recording and modulating code, the LLR of each bit can be calculated from the read signal. At the time, reduction of the number of times of repeat in LDPC coding processing and further improvement of reproducing performance are achieved by adjusting the value of calculated LLR in accordance with reliability of the read signal. COPYRIGHT: (C)2011,JPO&INPIT
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