Echo cancelling device with frequency sub-band filtering

Abstract From the Canadian patent

An echo cancelling device for use between a line receiving an incoming signal and a line transmitting an outgoing signal, for cancelling out echo comprising a, plurality of processing channels connected in parallel relation and assigned to successive mutually adjacent sub-bands of the spectral band of the outgoing signal each channel having: a first analysis band-pass filter receiving the echo-affected signal to be transmitted whose output is connected to the additive input of a subtractor; a second analysis band-pass filter identical to the first filter, receiving the incoming signal and feeding an adaptive filter delivering an estimated echo value in the sub-band to the subtractive input …