| 摘要 |
A communication system has at least one supervisory station and a large number of repeater stations spaced along a four-wire two-way transmission line. A number of repeater stations are selected at equal intervals along the line to have a coupling network coupling test signals from the first pair of wires in the transmission line to the second pair of wires which differs from the coupling network of the remainder of the repeater stations. To locate a fault, test signals in the form of pulses are sent from the supervisory station to the repeater stations. At each repeater station, if operative, the received test signals are coupled to the second pair of wires for retransmission back to the supervisory station. In view of the differences in the coupling networks, the test signals returned from the selected repeater stations will have a difference in, for example, amplitude which, when the returned test signals are displayed at the supervisory station can serve as markers to divide the repeater stations into groups and to determine the group containing the repeater station or line segment having a fault. The group containing the repeater station or line segment having a fault can then be displayed on the oscillograph on an expanded scale allowing ready determination of the segment or repeater station having the fault. |
