Patent Document ID: 20030231762
Application ID: 10459227
Patent Flag: 0

Claim One:
1. A communication system comprising a two-wire/four-wire hybrid circuit and an echo canceller being placed on a four-wire type transmission path to suppress an echo occurring in said two-wire/four-wire hybrid circuit, and having functions of connecting a plurality of paths and changing said paths through a two-wire type line and four-wire type line by switching control on a time-division switch to be exerted by a control device, said communication system comprising: a training signal source to output a training signal to said echo canceller; a switching circuit to do switching of a signal to be fed to said echo canceller between an ordinary signal and said training signal; and wherein said control device exerts control on connection and changing of said paths and on switching of said switching circuit to have said training signal source feed said training signal to said echo canceller such that said echo canceller may perform and complete a training operation.