An echo tail canceller based on adaptive interpolated FIR filtering

A computationally efficient two-stage echo canceller is proposed. The first stage is a direct form adaptive FIR filter to cancel the main part of the echo response. The second stage cancels the tail part of the echo response. The proposed tail canceller is an adaptive version of a previously reported interpolated FIR (IFIR) filter. It is shown that the two-stage canceller meets the 60-dB echo cancellation accuracy for various typical loops. Extensive simulations were carried out to study the effects of the main canceller length as well as the interpolator parameters on the performance of the proposed two-stage echo canceller in the U-interface transceiver for basic rate ISDN. It is shown that the proposed structure compares favorably with a recently reported two-stage canceller