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DETECTION SYSTEM

  • US 3,810,172 A
  • Filed: 07/18/1972
  • Issued: 05/07/1974
  • Est. Priority Date: 07/18/1972
  • Status: Expired due to Term
First Claim
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1. A system for detecting the presence of a resonant target in a field of interest comprising:

  • means for generating a signal containing the resonant frequency of the target to be detected;

    antenna means coupled to said generating means for radiating the electromagnetic energy in the predetermined resonant frequency into a field of interest;

    means for periodically gating said generator on and off;

    means for receiving electromagnetic energy in the field as radiated by said antenna means;

    detector means coupled to said receiving means for detecting the presence of the predetermined frequency in the field of interest;

    means for enabling said detector means at a time interval following the termination of transmission of energy by said generator;

    alarm means responsive to the detection of electromagnetic energy in the field of interest after termination of transmission by said generator;

    wherein said generator means produces a plurality of discrete frequencies each in timed sequence and including means for sequentially gating those frequencies for introduction into the transmitting antenna.

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