VOICE QUALITY ASSURANCE SYSTEM FOR PRIVATE BRANCH EXCHANGE IN CONNECTION OF PUBLIC LINE AND PRIVATE LINE

摘要

PURPOSE: To attain more excellent voice communication by providing an automatic gain controller and an echo canceller into an office line trunk of a PBX. ;CONSTITUTION: An office line trunk 4 connecting to a public network 1 incorporates a 2/4-wire conversion circuit 8, an echo canceller 6 connected to be send/receive a signal converted into a 4-wire system by the circuit 8, and an automatic gain controller 7 connected to receive a signal outputted from the canceller 6. Since the automatic gain controller 7 and the echo canceller 6 are provided in a private branch of exchange (PBX) 3 in this way, a speech level of a voice signal attenuated in the public network 1 is compensated by the automatic gain controller 7 and an echo generated through loopback by 2/4-wire conversion circuits 8, 10 is cancelled by the echo canceller 6.;COPYRIGHT: (C)1993,JPO&Japio