Duplex system of transmission lines in a loop network.

摘要

Disclosed is a duplex system of transmission lines in a loop network applied, for example, to a local area network. To realize an autonomous recognition of transmission line faults by each communication mode and to enable a rapid and automatic reconstruction of a network, each communication mode comprises a loop back circuit for effecting a loop back operation in response to a predetermined state of signals received from two directions of the duplex loop lines, and a return indication circuit for adding to a sent signal a return indication that a received signal was returned when the received signal could not be passed through the mode.