System and method of using two coefficient banks in an adaptive echo canceller

Abstract

A device has a first echo canceller having a first bank of coefficients to be applied to a reference signal to produce a first echo prediction signal, and a first arithmetic unit to combine the first echo prediction signal with the echo-bearing signal to produce a first echo-cancelled signal. A second echo canceller receives the reference signal and the first echo-canceled signal, and has a second bank of coefficients to be applied to the reference signal to produce a second echo prediction signal. The second bank of coefficients is adapted to improve echo cancellation in the second echo canceller. A second arithmetic unit combines the first echo-cancelled signal with the second echo-prediction signal to produce a second echo-cancelled signal. A third echo canceller receives the second echo prediction signal and has an adaptive gain to be applied to the second echo prediction signal to produce a third echo prediction signal, and a third arithmetic unit to combine the third echo prediction signal with the first echo-cancelled signal to produce a third echo-cancelled signal. The device also has a selector to select one of echo-cancelled signals.