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Methods and apparatus for intrusion detection having improved immunity to false alarms

  • US 5,581,236 A
  • Filed: 07/01/1994
  • Issued: 12/03/1996
  • Est. Priority Date: 01/28/1993
  • Status: Expired due to Term
First Claim
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1. An intrusion detection apparatus comprising:

  • a sensor for detecting an intrusion in a volume of space by a physical phenomenon and for generating a plurality of detection signals in response thereto;

    means for receiving said plurality of detection signals generated during a time period, and for generating an averaged signal based upon a time average of said plurality of detection signals generated during said time period; and

    means for comparing said averaged signal to a threshold signal;

    wherein the result of said comparison is indicative of fault of said apparatus,wherein said comparing means compares said averaged signal to a first threshold signal and wherein said apparatus is deemed to be faulty in the event said averaged signal exceeds said first threshold signal, andwherein said comparing means compares said averaged signal to a second threshold signal and wherein said apparatus is deemed to be faulty in the event said averaged signal is below said second threshold signal.

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