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Intrusion detection system

  • US 4,991,146 A
  • Filed: 11/30/1989
  • Issued: 02/05/1991
  • Est. Priority Date: 11/30/1989
  • Status: Expired due to Fees
First Claim
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1. A system for detecting intrusions into an area to be monitored, the system comprising:

  • means for periodically directing a transmit signal into the area so that a plurality of echo signals will be reflected from objects intruding into the area;

    means for receiving echo signals reflected by an object or objects in the area;

    means for generating a signature data array derived by cumulatively processing an initial set of signature echo signals, the means for generating a signature data array comprising means for generating and storing an initial signature data array having a plurality of data bits corresponding to segments of the echo signals, and means for comparing each signature echo signal segment to a signature threshold value and for replacing a corresponding initial data bit value with a flag value if said segment exceeds the threshold value; and

    means for comparing non-signature data representing non-signature echoes received after reception of said signature echo signals to the signature data array and for generating an alarm signal when the non-signature data differs from signature data.

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