Patent ID: 8160241

Claim:
A communication terminal device with an echo canceller for removing a true echo in communication, the true echo being generated by a hybrid circuit that outputs a signal to a telephone set, comprising: a pseudo signal generating circuit having the same or substantially the same characteristic as a characteristic of the hybrid circuit, the pseudo signal generating circuit generating a pseudo echo for canceling out the true echo, the pseudo echo having a phase opposite to a phase of the true echo, wherein the pseudo signal generating circuit includes: a phase inverter for inverting the phase of the same signal as a signal input to the hybrid circuit, a pseudo telephone set having the same or substantially the same electric impedance as the electric impedance of the telephone set, and a pseudo hybrid circuit for generating the pseudo echo, the pseudo hybrid circuit having the same or substantially the same characteristic as a characteristic of the true echo from the signal inverted by the phase inverter, the pseudo hybrid circuit outputting a signal to the pseudo telephone set.