US 4,006,320 AGranted

Fault locating system and method for transmission lines and repeater stations

AssigneeTekade Felten & Guilleaume Fernmeldeanlagen GmbH

InventorGeorg Markl

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Abstract

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.

Claims20

Dependent claims

A method of locating a fault in a four-wire two-way communications system comprised of a supervisory station, a four-wire transmission path leading away from the supervisory station, and a plurality of repeater stations spaced along the transmission path, the plurality of repeater stations being comprised of a lesser number of first repeater stations and a greater number of second repeater stations, the first repeater stations being interspersed among the second repeater stations, the method comprising, in combination, the steps of:

at each first repeater station connecting between the outgoing and incoming lines a respective one of a plurality of first coupling networks each having the same first transfer function;
at each second repeater station connecting between the outgoing and incoming lines a respective one of a plurality of second coupling networks each having the same second transfer function, different from the first transfer function;
producing a waveform comprised of first pulses and distinguishable second pulses, the first pulses being interspersed among the second pulses in correspondence to the interspersing of the first repeater stations among the second repeater stations, the producing of the first pulses comprising applying a single test pulse to the outgoing line at the supervisory station and deriving all the first pulses from such single test pulse by permitting the single test pulse to travel from the supervisory station along the outgoing line to the individual first repeater stations, through the associated first coupling networks and back to the supervisory station along the incoming line with the different travel times of the single test pulse from and back to the supervisory station via the different ones of the first repeater stations accounting for the spacing of the first pulses within said waveform, the producing of the second pulses comprising applying a single test pulse to the outgoing line at the supervisory station and deriving all the second pulses from such single test pulse by permitting the single test pulse to travel from the supervisory station along the outgoing line to the individual second repeater stations, through the associated second coupling networks and back to the supervisory station along the incoming line with the different travel times of the single test pulse from and back to the supervisory station via the different ones of the second repeater stations accounting for the spacing of the second pulses within said waveform, the fewer first pulses serving to facilitate counting of pulses in the waveform, the number of first and second pulses in the waveform being equal to the number of first and second repeater stations when no faults are present, when a fault is present the pulses missing from the waveform indicating which repeater stations are located beyong the fault.

In a four-wire two-way communications system comprised of a supervisory station, a four-wire transmission path leading away from the supervisory station, and a plurality of repeater stations spaced along the transmission path, the plurality of repeater stations being comprised of a lesser number of first repeater stations and a greater number of second repeater stations, the first repeater stations being interspersed among the second repeater stations, an arrangement for locating faults in the system, the arrangement comprising, in combination, at each first repeater station and connected between the outgoing and incoming lines a respective one of a plurality of first coupling networks each having the same first transfer function;

at each second repeater station and connected between the outgoing and incoming lines a respective one of a plurality of second coupling networks each having the same second transfer function, different from the first transfer function;
and waveform-producing means operative for producing a waveform comprised of first pulses and distinguishable second pulses, the first pulses being interspersed among the second pulses in correspondence to the interspersing of the first repeater stations among the second repeater stations, the waveform-producing means comprising means for producing all the first pulses from a single test pulse and all the second pulses from a single test pulse by applying such test pulse to the outgoing line at the supervisory station and permitting such test pulse to travel from the supervisory station along the outgoing line to the individual repeater stations, through the associated coupling networks and back to the supervisory station along the incoming line with the different travel times of such single test pulse from and back to the supervisory station via the different ones of the first repeater stations and via the different ones of the second repeater stations respectively accounting for the spacing of the first pulses within said waveform and for the spacing of the second pulses within said waveform, the fewer first pulses serving to facilitate counting of pulses in said waveform, the number of first and second pulses in the waveform being equal to the number of first and second repeater stations when no faults are present, when a fault is present the pulses missing from the waveform indicating which repeater stations are located beyond the fault.

Dependencies are inferred from the claim text.