DECODING CIRCUIT

摘要

PROBLEM TO BE SOLVED: To solve a problem of a conventional decoding circuit that has sometimes selected an erroneous path when the C/N is small because the conventional decoding circuit provides a constant metric independently of the C/N since the metric of decoded information depends on the quantity of the C/N. SOLUTION: The C/N of a signal whose received amplitude is corrected is measured and a value a×mb that results from multiplying a correction value (a) with a branch metric mb is used for a new branch metric, and when the C/N is low, a contribution rate of the branch metric to a state metric is decreased and a weight is provided to a past state metric to select a path.