| 摘要 |
PROBLEM TO BE SOLVED: To economize hardware and accelerate operation as a whole by decoding an unreliable code word with a decoder having reliability standards being common to each symbol of a code word and decoding an unreliable code word with a 2nd decoder using a proprietary reliability value for each symbol of an unreliable code word when useful results are not obtained. SOLUTION: A hard decoder 32 generates an error pattern from an unreliable word c (J) and gives it to an error pattern reliability calculation circuit 34. Decision logic 33 counts the number of given errors in outputs from the decoder 32 by a circuit 36, and a selector circuit 40 selects one among plural reliability thresholds on the basis of the calculated number of errors. These thresholds are decided by a reliability threshold processor 38. The thresholds are selected by the selector 40 in every unreliable code word and compared with an error pattern reliability output S (42).
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