The implementation of an adaptive echo canceller for high-speed digital data transmission

A prototype 1.6 Mb/s adaptive echo canceller for high-speed digital data transmission is presented. An analysis of the transmission line characteristics and echo path transfer function is first given, followed by a study of the echo canceller requirements and a description of the hardware and firmware. Finally, the performance of the echo canceller is given. It is shown that this 128-tap FIR (finite impulse response) echo canceller fully converges for a simulated echo path. The echo return loss exceeds 50 dB for a typical loop. Together with the hybrid, this echo canceller can provide the 60 dB of echo return loss required by the proposed system