Digital echo canceller for data transmission modem for modulating a carrier

canceller for digital echo data transmission modem for modulation of a carrier at the frequency 1 / T by symbols occurring at instants iT. This echo canceller includes means responsive to each symbol configuration at each instant iT to develop at least a number depending on the amplitude allocated to the carrier at said instant and for directing this number to at least one specified portion of a whole adaptive digital filters whose output signals are combined to form a digital version of the echo copy signal; the coefficients of these filters are adjusted from the error between the echo signal and the echo copy signal, so as to minimize the mean square value of this error signal. Application: data transmission simultaneously Duplex .