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Self-monitoring line interface circuit

  • US 5,881,129 A
  • Filed: 08/07/1996
  • Issued: 03/09/1999
  • Est. Priority Date: 05/10/1996
  • Status: Expired due to Term
First Claim
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1. A line interface circuit having self-contained, self-testing circuit elements for providing battery feed, over-voltage protection, ring insertion, supervision, coding/decoding and hybrid (BORSCHT) functions for a subscriber'"'"'s loop, said line interface circuit comprising:

  • a. a feed resistor network connectable to said loop;

    b. a dual voltage regulated current source connected to said network;

    c. line driving and receive amplifier means connected to said feed resistor network, andd. a microprocessor/DSP for controlling the application of power to said current source and to said line driving and receive amplifier means while said line interface circuit is connected to said loop to enable said circuit elements to provide said BORSCHT functions and for selectively denying power to said line driving and receive amplifier means to place said means in a high impedance state so as to isolate or include said amplifier means in circuit for testing purposes while said circuit is connected to said loop.

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