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Auto theft detection system

  • US 4,177,466 A
  • Filed: 11/16/1977
  • Issued: 12/04/1979
  • Est. Priority Date: 11/16/1977
  • Status: Expired due to Term
First Claim
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1. A system for locating a selected motor vehicle in a circumscribed geographic area, said selected vehicle being one of a multitude of motor vehicles dispersed randomly throughout said area with each vehicle having a different predetermined vehicle identification code assigned thereto;

  • said system comprising;

    a first transmitter centrally stationed in said geographic area and adapted to broadcast a call signal, encoding means coupled to said first transmitter for modulating said call signal with any selected one of said different codes;

    each of said motor vehicles including at least one transponder inaccessibly concealed thereon, said transponder including a first receiver, a second transmitter adapted to broadcast a continuous predetermined locator signal, a decoder coupled to said first receiver adapted to provide an output signal in response to said call signal when said call signal is modulated with the vehicle identification code characteristic of the vehicle on which the transponder is concealed, and a relay coupled between said decoder and said second transmitter adapted to actuate the latter in response to said output signal;

    at least some of said transponders on different vehicles being adapted to broadcast identical locator signals;

    at least one finder vehicle of transportation adapted to be driver-operated;

    a second receiver mounted on said finder vehicle of transportation; and

    a direction finder on said finder vehicle of transportation responsive to said locator signal picked up by said second receiver to indicate the direction of the source of said locator signal relative to said further vehicle of transportation.

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