Method of cancelling echoes in full-duplex data transmission system

摘要

A first difference signal is obtained by subtracting an echo replica from a mixed signal which consists of a received signal and an echo. The echo replica is produced in an adaptive digital filter using an error signal. The first difference signal includes the received signal and a residual echo, and is delayed in a manner to produce a delayed first difference signal. The delayed first difference signal is subtracted from the first difference signal to obtain a second difference signal. Thereafter, a polarity of the residual echo included in said second difference signal is detected. The error signal is obtained based on the detected polarity, and then is applied to the adaptive digital filter.