Circuitry for accomplishing digital echo suppression for a plurality of two-way transmission circuits is disclosed. Analogue signal levels on each line of each associated transmit-receive pair are periodically converted into pcm codes and applied to common time-shared circuitry, which includes a time-divided memory, in the time slot allocated for that pair. The common circuitry translates the pulse codes into echo suppressor control signals by combining them with code signals representing the past signal bearing statuses of the lines and timing signals stored in the time-divided memory to determine if the respective present activity statuses of the line pair are such that echo suppression is required.
COMMON CONTROL DIGITAL ECHO SUPPRESSION