ECHO CANCELLER BETWEEN SYSTEMS OF COMMUNICATION DEVICE

PROBLEM TO BE SOLVED: To achieve stable convergence of the filter coefficient of an adaptive filter in a training mode and a tracking mode of an echo canceller of each of a plurality of communication devices connected to the same cable.SOLUTION: An echo canceller comprises: an operation mode control unit which commands an operation mode; and a filter control unit which receives its training command to stop updating the filter coefficient of an adaptive filter coping with a near-end crosstalk echo from another communication device and to start updating the filter coefficient of an adaptive filter coping with the transmission echo of a relevant communication device, and starts updating the filter coefficient of each adaptive filter depending on the condition of reception of a tracking mode command and reception of presence of a reference signal.