| 摘要 |
PROBLEM TO BE SOLVED: To provide an error correction circuit and an error correction method, that can use a trellis decoder in n kinds of states, that is, a trellis decoder capable of conducting decoding in a plurality of different kinds of states, so as to decode data without producing coset. SOLUTION: A branch metric production circuit 201 generates each branch metric, with respect to each code data. An ACS circuit 202 sums each range metric and a path metric in each state, compares the sums, and selects the smallest sum for a new path metric in each state and stores data, corresponding to the selected path in each state to a path memory. A trace back processing circuit 204 traces back a predetermined cut-off path length along a surviving path, which contains a state whose new path metric is smallest, so as to determine data Y2 Y1 (4-states) or data X2 X1 (8-states). Using the configuration above, decoder can decode data using one 4-state and 8-state which are common use trellis.
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