An improved echo cancellation technique may be employed by a server modem in a
digital communication system. The disclosed echo cancellation technique provides
not only for the cancellation of echo signals imparted on the received signals
of a modem but also for the cancellation of various non-linearities that are present
in a transmit circuitry. The echo canceler resident in the server modem may be
initially trained to account for the echo signals imparted by an echo channel present
in the communication system. In the preferred embodiment, the echo canceler samples
an analog output signal of the transmit circuitry and produces an output signal
representative of the echo signals and the non-linearities. In the context of the
echo cancellation, a compensated digital signal is produced by subtracting the
output signal of the echo canceler from an impaired digital signal to be received
by the server modem, wherein the echo signals and non-linearities are substantially
eliminated from the impaired digital signal.