Line fault discriminator
First Claim
1. An auxiliary system for determining the existence of an abnormal change in load at the load end of a transmission line, said auxiliary system comprising a remote operating test station at the opposite end of said line and means, interposed in series in said line in proximity to said load and directly responsive to such abnormal change in load, for creating a phenomenon interpretable at said remote operating station as an abnormal change in load, said means responsive to said abnormal change in load including an electronic circuit in said line in series relationship with said load, said electronic circuit including a load side and a line side with said circuit being responsive only to said abnormal change in load occurring on the load side of said circuit.
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Accused Products
Abstract
An auxiliary test system for use with a long transmission line such as one having a telephone at an end thereof whereby from a remote central test station a line may be tested for a short between wires, an open, an abnormal load condition or reversed connections and the relative location of such a fault condition determined.
11 Citations
14 Claims
- 1. An auxiliary system for determining the existence of an abnormal change in load at the load end of a transmission line, said auxiliary system comprising a remote operating test station at the opposite end of said line and means, interposed in series in said line in proximity to said load and directly responsive to such abnormal change in load, for creating a phenomenon interpretable at said remote operating station as an abnormal change in load, said means responsive to said abnormal change in load including an electronic circuit in said line in series relationship with said load, said electronic circuit including a load side and a line side with said circuit being responsive only to said abnormal change in load occurring on the load side of said circuit.
- 5. An auxiliary system for determining the existence of an abnormal change in load at the load end of a transmission line, said auxiliary system comprising a remote operating test station at the opposite end of said line and means, interposed in series in said line in proximity to said load and directly responsive to such abnormal change in load, for creating a phenomenon interpretable at said remote operating station as an abnormal change in load, said means reresponsive to said abnormal change change in load including an electronic circuit in said line in series relationship with said load, said electronic circuit including a load side and a line side with said circuit being responsive only to said abnormal change in load occurring on the load side of said circuit, said electronic circuit including controllable inhibiting means for selectively allowing conduction of current through said circuit unihibited under normal conditions and responding to a abnormal load by periodically inhibiting such current flow to induce a rise and decay of voltage on said line side, whereby said rise and decay of voltage may be detected and interpreted at a remote operating station, said circuit further including means for triggering said inhibiting means to allow current flow through said circuit, said triggering means being responsive to a no-current flow condition in said circuit whereby, said inhibiting means responds to such abnormal load to inhibit current flow through said circuit and responds to said trigger to uninhibit current flow through said circuit, said remote operating station including a DC supply source of power comprising voltage and current, said means for triggering said inhibiting means including capacitance means, means for developing a charge across said capacitance means and a trigger pulse generating means responsive to such charge for generation a pulse to trigger said inhibiting means into conduction, said capacitance means and said trigger pulse generating means including an electrical relationship with said current inhibiting means and said line whereby, when current conduction is inhibited through said circuit, current is directed to said capacitance means, voltage at said capacitance means builds up to the value of said DC supply voltage as said current at said capacitance means approaches zero, a condition is created for said trigger pulse generating means to generate a trigger to which said current inhibiting means responds by uninhibiting current conduction through said circuit to provide a discharge path for said capacitance means until such time as such abnormal load condition again causes said current condition inhibiting means to again inhibit current through said circuit and thus create a cyclic rise and decay of voltage on said line, which may be detected and interpreted at said remote operating station.
- 12. In combination, a transmission line such as for use in a telephone installaion including a telephone on one end thereof, means including an electronic circuit in series in said line in proximity to said telephone and a remote test station including means controllable, via the transmission line, by an operator for determining the existence of a fault with respect to said electronic circuit without interfering with telephone communications over said transmission line, whereby, faults may be tested concurrently with normal telephone use.
Specification