An echo canceler having a predictive filter that generates an echo replica signal
and an adder that subtracts the echo replica signal from a send input signal also
has a receive input amplifier and a clipping circuit. The clipping circuit clips
the input to the predictive filter at a threshold level determined by increasing
the receive input amplifier gain until distortion of the echo component causes
echo cancellation performance to degrade. Alternatively, the echo canceler may
have a send input amplifier, a send output amplifier, and an echo replica amplifier
that amplifies the predicted echo replica signal. The gain of the send input amplifier
is increased to determine the gain at which echo cancellation performance begins
to deteriorate due to echo amplification, and the gain of the echo replica amplifier
is set to compensate for the echo amplification.
