Telecommunication system with a line for digital duplex traffic, comprising an arrangement for tapping the digital duplex traffic, and arrangement to be used in the telecommunication system

摘要

In prior-art telecommunication systems a two-wire line carrying digital duplex traffic is tapped by inserting, at a line interruption, two mutually coupled hybrid circuits which convert the two-wire line to a four-wire connection, a traffic stream in one direction being conveyed by two of the four wires and a traffic stream in the other direction being conveyed by the further two of the four wires. A disadvantage for this is that the line is to be interrupted. In the telecommunication system according to the invention the tapping is performed by way of discrimination means and echo cancelling means coupled thereto. The invention is based on the recognition that the traffic stream having the larger amplitude can be discriminated from the digital duplex traffic by way of the discrimination means and that, subsequently, the other traffic stream can be discriminated from the digital duplex traffic by way of the echo cancelling means which echo cancelling means are supplied with both the digital duplex traffic coming from the line and the traffic stream that has the larger amplitude coming from the discrimination means.