An improved echo control system has an adaptive controlled echo canceling filter
arrangement in which a background filter updates the filter coefficients of an
echo shaping filter responsive to a normalized least mean square (NLMS) algorithm.
An adaptive control module determines a weighted reference signal for the background
filter in which the weight is proportional to a far signal reference and an estimate
of the norm of an echo canceller error vector, and inversely proportional to en
estimate of a residue of the echo canceller. And a non-linear normalized convergence
term is used in the NLMS algorithm.