ADAPTIVE EQUALIZER

摘要

Base-band signals obtained by asynchronously detecting received signals are sampled and the signals, are written in a buffer memory (11) as series of base-band signals samples. A most likelihood sequence estimating section (15) generates a desirerd symbol sequence corresponding to the samples read out from the memory (11) and supplies the symbol sequence to a transversal filter (18) having characteristics estimated from the impulse response of the transmission line at the timings of the samples. A phase error detecting section (23) successively detects the phase errors between estimated received signals obtained and corresponding base-band signal samples. An offset correcting signal generating section (22) calculates an estimated offset angular frequency DELTA omega e from the phase errors, generates an offset correcting signal having an angular frequency in the reverse direction of rotation, whose absolute value is equal to that of the estimated offset angular frequency DELTA omega e, and supplies the offset correcting signal to a multiplier (21) for correction. The multiplier (21) corrects the offset angular frequency so as to cancel the angular frequency offset by multiplying the samples by the offset correcting signal. A subtractor (14) finds the difference between the corrected samples and estimated signals received from the transversal filter as estimated errors. The estimating section (15) finds the most likelihood information from the estimated errors and discriminates signals by using a most likelihood sequence estimating algorithm based on the most likelihood information.