Echo control for two-wire duplex data circuits - has monitor and control circuits to terminate correlation computation at specific value or time

摘要

The control uses an adaptive filter on the 4 wire side of a local hybrid plus a control circuit measuring the error correlation during several frames to determine the most suitable adaption characteristic. The design provides a faster adaption than previously. The adaptive digital filter has a 16 segment delay line transversal filter coupled to a multiplexar, coefficient store and accumulator to give output Yn for each digital Sn input. The appts has a monitor and control circuit for monitoring the computation of the correlation summation and terminating it when a specific value or given number of frames has been reached.