Subscriber line testing system
AssigneesHitachi, Ltd., Nippon Telegraph & Telephone Public Corporation
InventorsTakafumi Kojima, Kenzo Tamaki, Shiro Yokota
Life of this patent
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Abstract
A system for testing subscriber lines and terminals by leading the subscriber line to the testing system through an associated semiconductor switch of a type driven by a constant current. The system includes a circuit for varying a current fed through the switch from the subscriber line to be tested, a circuit for measuring current values corresponding to the circuit states of the circuit, and a circuit for determining on the basis of the measured values derived from the measuring circuit a current value from which the constant current component for driving the switch is eliminated.
Claims13
A testing system for testing a subscriber line and a terminal equipment connected thereto by leading-in said subscriber line through a switch, comprising:
- a semiconductor switch of a type driven by a constant current for electrically connecting said subscriber line to a testing apparatus;
- and
- said testing apparatus comprising,
- current changing means for changing a current fed from said subscriber line by way of said semiconductor switch, measuring means for measuring the values of current changed by said current changing means, and means for determining on the basis of the results of measurements effected by said measuring means a current value from which the constant current for driving said semiconductor switch is eliminated.
A subscriber line testing system, comprising:
- a plurality of subscriber lines;
- semiconductor switches each driven by a constant gate current and selected for leading a desired one of said subscriber lines for testing;
- change-over means for changing over a value of current flowing through the subscriber line to be tested and introduced through the selected one of said semiconductor switches;
- means for measuring the levels of the current fed through the selected one of said semiconductor switches and changed over by said change-over means, respectively.
Dependencies are inferred from the claim text.