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Moving vehicle identification system

DC
  • US 5,196,846 A
  • Filed: 06/18/1990
  • Issued: 03/23/1993
  • Est. Priority Date: 02/13/1980
  • Status: Expired due to Term
First Claim
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1. A system for the exchange of information via electromagnetic transmission and reception between a fixed location interrogator comprising a data signal processing means and a transponder moving in the vicinity of said interrogator, said system comprising:

  • means at said interrogator for periodically transmitting trigger pulses;

    means, comprising storage means at said transponder, responsive to a first received one of said trigger pulses for transmitting a first data message derived from data contained by said storage means at the time that said first trigger pulse is received;

    means at said interrogator for receiving said first data message and responsive to the receipt thereof for generating and transmitting a second data message;

    means at said transponder for receiving said second data message and for storing data derived from said second data message in said storage means;

    means at said interrogator for transmitting a second trigger pulse a predetermined period of time after said first trigger pulse, the predetermined period of time being of sufficient length to permit the storage in said storage means of data derived from said second message; and

    means at said transponder for transmitting a third data message responsive to said second trigger pulse, said third data message comprising data derived from the data contained by said storage means at the time of said second trigger pulse.

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