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Identification of vehicles

  • US 3,996,555 A
  • Filed: 09/09/1975
  • Issued: 12/07/1976
  • Est. Priority Date: 09/17/1974
  • Status: Expired due to Term
First Claim
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1. A vehicle adapted to cooperate with a roadway loop having a predetermined resonant frequency, said vehicle having an insulated multi-turn vehicle loop arranged on the vehicle to form a transformer with the roadway loop when said vehicle loop is in proximity to the roadway loop;

  • means for tuning the vehicle loop to form a vehicle loop circuit resonant at a first frequency which is substantially the resonant frequency of the roadway loop; and

    means for modulating the vehicle loop circuit at a second frequency;

    different from said first frequency whereby, when said loops are in proximity to one another, a signal modulated at said second frequency is induced from the vehicle loop into said roadway loop for the identification of said vehicle.

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