Decisive modulo and metric value threshold decisive device null of metric value threshold of Viterbi synchronous decision

摘要

PROBLEM TO BE SOLVED: To provide a Viterbi synchronous deciding circuit which synchronizes with a correct encoding ratio when more than two kinds of encoding ratios exist in an input signal of a Viterbi decoding circuit. ;SOLUTION: A 1st encoding ratio setting part 16 sets an encoding ratio in which metric value threshold is sought, and a 2nd encoding ratio setting part 12 sets an encoding ratio except that. While a synchronous/asynchronous monitoring part 18 monitors the synchronization/asynchronization, of a Viterbi decoder 17, a metric value threshold setting part 20 successively lowers metric value threshold from the maximum value and finds the minimum value (limit value that is decided as asynchronous) of metric value threshold which is not perfectly synchronous, and the value is made the metric value threshold of the encoding ratio.;COPYRIGHT: (C)1998,JPO