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Automotive vehicle classification and identification by inductive signature

  • US 6,417,784 B1
  • Filed: 12/02/1997
  • Issued: 07/09/2002
  • Est. Priority Date: 12/03/1996
  • Status: Expired due to Fees
First Claim
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1. A system for inductive vehicle detection comprising:

  • at least one inductive sensor situated in a traffic-lane having a width, said inductive sensor being a wire-loop dimensioned to substantially extend across the width of the traffic-lane and situated at an angle to the flow of traffic, said wire-loop having a common terminal, a charging terminal, and an intrinsic resistance; and

    an inductance measuring device in electrical communication with said wire-loop, said inductance measuring device including a capacitor having two terminals, each said terminal of said capacitor in electrical communication with a corresponding said terminal of said wire-loop thereby forming an LCR circuit which generates an output signal;

    a first control signal generator for generating a first control signal;

    a second control signal generator for generating a second control signal;

    a current source having a common terminal and a power terminal, said current source common terminal in electrical communication with said wire-loop common terminal;

    a first switch in electrical communication with said first control signal, said first switch for electrically connecting and disconnecting said current source power terminal to said wire-loop charging terminal in response to said first control signal;

    a reference-signal generator for generating a reference-signal;

    an instrumentation amplifier having a first input terminal, a second input terminal, and an output terminal, said LCR circuit output signal being delivered to said instrumentation amplifier first input terminal and said reference-signal generator in electrical communication with said instrumentation amplifier second input terminal; and

    a sample-and-hold amplifier having an analog input terminal, an analog output terminal, and a logic input terminal, said instrumentation amplifier output terminal in electrical communication with said analog input terminal and said second control signal generator in electrical communication with said logic input terminal.

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