Maximum likelihood sequence estimator and maximum likelihood sequence estimating method

摘要

When a maximum likelihood sequence estimator according to the present invention is used as an equalizer or the like for a receiver, a Viterbi algorithm processing portion 331 in the maximum likelihood sequence estimator estimates a transmission symbol Ea.sub.n with a reception signal y.sub.n and an estimated impulse response {Eh.sub.k } corresponding to Viterbi algorithm so as to estimate a maximum likelihood sequence corresponding to a soft decision regardless of a modulating method. A transmission logic code decoder 34 converts a transmission symbol Ea.sub.n into hard decision data Eb.sub.m with a value "1" or "0". An envelope detector 333 that is a transmission line quality evaluating means detects an envelope level p.sub.n of the reception signal y.sub.n. A soft decision value converting portion 334 converts the envelope level p.sub.n received from the envelope detector 333 corresponding to the value "1" or "0" of the hard decision data Ebm received from the transmission logic code decoder 34 so as to obtain soft decision value output data q.sub.m.