Patent ID: 6947553

Claim:
A communication system having a time-division switch; a plurality of two-wire/four-wire hybrid circuits coupled to the time-division switch, the two-wire/four-wire hybrid circuits producing respective echos; a plurality of two-wire type transmission paths respectively coupled to the two-wire/four-wire hybrid circuits; an echo canceller coupled to the time-division switch to suppress the echos produced by the two-wire/four-wire hybrid circuits; and a four-wire type transmission path coupled to the echo canceller, the communication system comprising: a control device operable to control the time-division switch to selectively couple one of the plurality of two-wire type transmission paths to the four-wire type transmission paths to establish a communication path in the communication system; a training signal source operable to output a training signal to permit the echo canceller to perform and complete a training operation; and a switching circuit operable to be acted upon by the control device to selectively switch a signal to be fed to the echo canceller between an ordinary signal and the training signal, the control device being operable to control the switching circuit to feed the training signal to the echo canceller every time a new communication path is established through the line communication system.