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System and methods for detecting change in a monitored environment

  • US 7,733,220 B2
  • Filed: 10/05/2006
  • Issued: 06/08/2010
  • Est. Priority Date: 10/05/2006
  • Status: Active Grant
First Claim
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1. A system for detecting changes in a monitored environment, the system comprising:

  • a plurality of radio frequency (RF) sensors distributed about the monitored environment, each RF sensor configured to respond to an interrogation signal with a unique identifier;

    a radio frequency (RF) interrogator that transmits interrogation sequences of interrogations signals over a plurality of different frequency bands at one or more power levels; and

    a response pattern analyzer that determines response patterns for each of the plurality of RF sensors to the interrogation sequences and transmits a change detection indicator if at least one of the determined response patterns vary outside a predetermined background baseline.

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