Adaptive equalizer for controlling a step size in proportion to an

Abstract

An adaptive equalizer increases the estimation accuracy of a channel, and prevents the modulation characteristics from degrading. A sampling circuit generates a sampled sequence from a received signal. The sampled sequence is supplied from a buffer to an equalizing circuit, a channel estimating circuit and a delay amount estimating circuit. The equalizing circuit obtains an estimated transmitted symbol sequence from the sampled sequence and an estimated impulse response sequence. The channel estimating circuit obtains the estimated impulse response sequence from the sampled sequence, estimated transmitted symbol sequence and the estimated error. The delay amount estimating circuit supplies an estimated delay amount to a step-size control circuit. An error extracting circuit obtains the estimated error. The step-size control circuit controls a step-size parameter in response to the delay amount, and a tap coefficient update circuit updates the tap coefficients by the estimated transmitted symbol, estimated error e.sub.n and step-size parameter.