| 摘要 |
PROBLEM TO BE SOLVED: To reduce the scale of circuit without having any effect on the results of decoding. SOLUTION: The decoder comprises an addition/comparison/selection circuit 60 for determining a correction term being added to provide a logarithmic likelihood and represented by one-dimensional function of variables and calculating a logarithmic likelihood by adding a predetermined value to the correction term such that the positive and negative identification codes of logarithmic likelihood is unified. The addition/comparison/selection circuit 60 stores the relation between absolute value data|P-Q|, i.e., the variables of the function, and the sum of the correction term and the predetermined value in an ROM 66 in the form of a table. The absolute value data|P-Q|fed from an absolute value calculating circuit 65 is read out as an address signal and a value for the absolute value data|P-Q|is read out by a difference unit 67 as data Z.
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