In a data communication system having a channel with time-varying impairments and further having a transmitter with a precoder, a method and apparatus for updating the precoder coefficients. The method and apparatus is based on the arrangement of a duplicate precoder and correction filter in the receiver, where the correction filter generates incremental coefficients. The incremental coefficients are sent via a back channel to the transmitter and added to the current values of the precoder coefficients. The method and apparatus provide DFE-like performance and do not have the delay problems associated with DFEs.