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Passive microwave fire and intrusion detection system

  • US 7,724,134 B2
  • Filed: 10/31/2007
  • Issued: 05/25/2010
  • Est. Priority Date: 06/15/2007
  • Status: Active Grant
First Claim
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1. A method for detecting at least one of a fire and an intruder using passive reception of microwave radiation, comprising:

  • passively receiving a first microwave radiation signal at a first receiver, said first receiver including a first antenna, a first frequency of said first passively received microwave radiation signal being indicative of a temperature of a source of said first passively received microwave radiation signal;

    passively receiving a second microwave radiation signal at a second receiver, said second receiver including a second antenna, a second frequency of said second passively received microwave radiation signal being indicative of a temperature of a source of said second passively received microwave radiation signal, wherein said first and second frequencies are within a range of microwave frequencies protected from active transmission in a geographic area encompassing a location of said first and second receivers;

    comparing said first frequency with said second frequency to determine a presence of at least one of a fire and an intruder; and

    transmitting said first and second passively received microwave radiation signals to a signal processor;

    said first passively received microwave radiation signal being converted to a first voltage signal;

    said second passively received microwave radiation signal being converted to a second voltage signal;

    said first voltage signal being subtracted from said second voltage signal to provide a resulting voltage signal; and

    said presence of said at least one of said fire and said intruder being determined based on said resulting voltage signal.

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