Adaptive equalizer for binary signals and method of operating same

Abstract

An adaptive equalizer for high-speed binary signals, operating in baseband, comprises a transversal filter receiving digitized samples of incoming symbols and feeding them to a decision stage. The samples also go to a coefficient computer, in parallel with that filter, which includes a filter simulator, an error calculator and a processor delivering corrective coefficients to the filter. A register in the filter simulator accumulates a predetermined multiplicity of received samples (e.g. 150) which are jointly convoluted with an initial set of coefficients to yield a mean square error supplied by the error calculator to the processor; the latter, for each coefficient of the initial set, selects two collateral values which are successively substituted for that coefficient to yield two further mean square errors. Using an algorithm based upon a parabolic function, the processor computes an optimized coefficient which is rounded to the nearest power of 2 constituting a new coefficient replacing the corresponding coefficient of the initial set. After all coefficients of the initial set have been thus replaced to produce an updated set, the processor determines whether the resulting mean square error is less than that obtained with the initial set and, if so, substitutes the updated set for the initial set in the transversal filter.