Signal quality measuring scheme

摘要

A phase region deciding unit decides the phase region in which the signal point falls and a counter unit counts the number of signal points in each phase region. A weighted average calculating unit calculates a weighted average using the previous weighted average and a result of counting in the counter unit. A likelihood calculating unit calculates likelihood of the weighted average of phase distribution calculated weighted average using the phase-distribution table stored in a phase-distribution table storing unit for each phase-distribution model, detects a maximum likelihood phase-distribution model, and outputs the signal quality corresponding to the detected phase-distribution model as the estimated signal quality.