An adaptive filter convergence method for echo cancellation and decision feedback equalization

This paper proposes a new convergence method for adaptive digital filters applied to echo cancellation and decision feedback equalization. The proposed method, using Disturbing Signal Canceler (DSC), saves adaptive filters from falling into a deadlock. DSC takes advantage of a line code property, wherein the number of symbol waveforms is limited and each waveform has both polarities. Since DSC is realized simply with an adder and a delay element, it is suitable for LSI implementation. Theoretical analyses were carried out to show the convergence characteristics and the convergence condition. Computer simulations prove that both an echo canceler and a decision feedback equalizer based on the proposed method, employing DSC, possess satisfactory performance.