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AUTOMATIC DARK CURRENT COMPENSATION

  • US 20040008984A1
  • Filed: 02/15/2001
  • Published: 01/15/2004
  • Est. Priority Date: 02/15/2001
  • Status: Active Grant
First Claim
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1. A monitoring system receiving a first optical signal tapped from an optical communication channel, comprising:

  • an optical coupler combining said first optical signal received on a first input and a second optical signal received on a second input and producing a combined optical signal;

    a photodiode detecting said combined optical signal and outputting a first electrical signal;

    an analog-to-digital converter receiving said first electrical signal and sampling it to produce a multi-bit second electrical signal;

    an electrical signal generator producing a third electrical signal that is repetitive and has a predetermined harmonic characteristic;

    a light emitting electrical device receiving said third electrical signal and outputting said second optical signal to said second input in an optical band in which said photodiode is responsive; and

    a signal processor receiving said second electrical signal and capable of distinguishing a portion of said second electrical signal according to said predetermined harmonic characteristic.

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