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High power moving object identification system

  • US 5,712,630 A
  • Filed: 07/24/1995
  • Issued: 01/27/1998
  • Est. Priority Date: 07/26/1994
  • Status: Expired due to Fees
First Claim
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1. A system for identifying a moving object comprising:

  • an interrogator transmitting an RF transmission signal indicative of transmission data;

    a transponder adapted to be mounted on said moving object for transmitting an RF answer signal indicative of answer data available at said transponder to said interrogator upon receiving said transmission signal, said transponder including energy storing means which stores energy from said RF transmission signal for powering said transponder;

    said interrogator comprising;

    coding means for providing, from said transmission data, a coded signal in which one logical level of said transmission data is represented by a first series of binary digits and another logical level of said transmission data is represented by a second series of binary digits;

    a carrier wave generator for generating a carrier wave; and

    a modulator for modulating said carrier wave by said coded signal in an amplitude shift keying (ASK) technique to give an ASK modulated signal in which a binary digit "1" of said coded signal is represented by a maximum amplitude of said carrier wave and a binary digit "0" is represented by the absence of said carrier wave, said ASK modulated signal defining said transmission signal;

    said transponder comprising;

    a demodulator for demodulating said ASK modulated signal into a demodulated signal having a sequence of pulses of varying width; and

    decoding means for decoding said demodulated signal into said transmission data;

    wherein, said coding means of the interrogator is configured to provide each said first and second series of binary digits such that a number of binary digit "1" in each series of binary digits is greater than a number of the binary digit "0" in each series of binary digits.

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