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System for determining vehicle speed and presence

  • US 5,455,768 A
  • Filed: 11/06/1992
  • Issued: 10/03/1995
  • Est. Priority Date: 11/06/1992
  • Status: Expired due to Fees
First Claim
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1. A system for monitoring traffic comprising:

  • a magnetic probe to produce an electrical signal in response to changes in magnetic flux in a sensing area caused by a vehicle in the sensing area, the electrical signal having a beginning and an end;

    means for digitizing the electrical signal;

    means for analyzing the digitized signal to determine the duration of the electrical signal by measuring an elapsed time from said beginning of the electrical signal to said end of the electrical signal; and

    means for determining the speed of the vehicle from said duration of the electrical signal wherein the means for determining the speed of the vehicle includes a digital processor having a memory with calibration information, the calibration information including a duration of an electrical signal caused by a vehicle having a known speed for comparison with said determined duration of the electrical signal.

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