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Vehicle communication system using existing roadway loops wherein the physical integrity of the loop is kept intact

  • US 5,198,811 A
  • Filed: 05/16/1991
  • Issued: 03/30/1993
  • Est. Priority Date: 05/08/1987
  • Status: Expired due to Fees
First Claim
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1. A communication system for enabling transfer of information between a vehicle and a stationary information location having a vehicle detector system with a loop antenna, said loop antenna comprising part of a closed loop circuit containing conventional vehicle detector signals normally lying within a given frequency range, said system comprising:

  • stationary transmitter means for enabling transmission of a preselected information signal over a relatively small distance range via the vehicle detector system loop antenna; and

    a vehicle mounted receiver means for receiving said preselected information signal transmitted by said stationary transmitter means when within said distance range, said vehicle mounted receiver means including a loop antenna and means for distinguishing said preselected information signal from the conventional vehicle detector signals present in said vehicle detector system loop antenna which lie within the given frequency range, said transmitter means providing transmission of said preselected information signal in a transmitting frequency range different from said given frequency range of said conventional vehicle detector signals;

    said transmitter means including means for generating a carrier frequency signal lying within a transmitting frequency range different from the frequency range of the conventional vehicle detector signals and containing a preselected information signal, and means for coupling the output of said generating means to said vehicle detector loop antenna without disturbing the physical integrity of said closed loop circuit so that said preselected information signal can be transferred via said vehicle detector loop antenna to the vehicle mounted receiver means without adversely affecting the operation of said vehicle detector system.

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