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Object identification system

  • US 4,209,783 A
  • Filed: 03/22/1978
  • Issued: 06/24/1980
  • Est. Priority Date: 03/30/1977
  • Status: Expired due to Term
First Claim
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1. An object identification system comprising:

  • an interrogation circuit including a sweep frequency signal generator for generating a sweep frequency signal;

    a transmitting/receiving duplex circuit connected to said interrogation circuit;

    transmitting/receiving antenna means which is connected to said transmitting/receiving duplex circuit and transmits said sweep frequency signal as an interrogation signal;

    an answer device which includes a plurality of resonators with different resonance frequencies connected in parallel one another and an answer antenna means connected in parallel with said resonators, and which is fixed on an object to be identified and transmits resonance answer signals corresponding to the resonances of said resonators in response to said interrogation signal toward said transmitting/receiving antenna means;

    phase adjusting means which is connected to said transmitting/receiving duplex circuit and said interrogation circuit and adjusts the phases of the sweep frequency signal from said sweep frequency signal generating circuit and said resonance answer signal to have a phase difference of substantially 0 or 180 degrees;

    a detector for detecting a ringing answer signal included in said resonance answer signal from the output of said phase adjusting means;

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