PROBLEM TO BE SOLVED: To achieve decoding of an arbitrary code through a simple arrange ment. SOLUTION: In a soft output decoding circuit of an element decoder, a circuit 161' for calculating a logarithmic soft output I /1 calculates the sum of logarithmic likelihoods I, I and I corresponding to respective branches on a trellis, selects a relevant branch depending on the I/O pattern of each branch, and calculates a logarithmic soft output I by performing an operation comparable to a tournament. More specifically, the soft output calculating circuit 161' selects a relevant branch depending on the I/O pattern of each branch on the trellis previously from data AGB of thirty two systems through a selection circuit 590, performs log-sum operation through log-sum operating circuits 5911,..., 5918 using the data AGB of selected sixteen systems and outputs the data AGB selectively from seven log-sum operating circuits thus realizing cumulative addition of log-sum operation depending on the input.
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