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SPREAD-SPECTRUM POSITION MONITORING SYSTEM

  • US 3,714,573 A
  • Filed: 05/06/1970
  • Issued: 01/30/1973
  • Est. Priority Date: 05/06/1970
  • Status: Expired due to Term
First Claim
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1. A position monitoring system in which a plurality of mobile transmitters transmit modulated spread-spectrum signals asynchronously and wherein said signals are received at a remote location for use in identifying and locating the transmitters and thereby monitoring their positions, said system comprising:

  • at least one mobile transmitter for transmitting spread-spectrum signals to a remote location for use in monitoring said transmitters'"'"''"'"' position, said transmitter comprising;

    means for generating a modulating signal having a predetermined code unique to said transmitter for use in supplying information from said transmitter;

    means responsive to said modulating signal for generating a modulated, spread-spectrum signal, said modulated signal having modulation components which are decodable for use in supplying information from and locating said transmitter; and

    means for transmitting said modulated-spread spectrum signal asynchronously with respect to other transmitters in said system; and

    signal receiving apparatus at said remote location for receiving a spread-spectrum signal, having unique decodable modulation components, from each of said transmitters, said receiving apparatus comprising;

    a plurality of means, each at a different station and each for receiving the signals from said transmitters;

    signal compression means responsive to the received signals for developing a coded signal representative of the decodable components of each of said received spread-spectrum signals, all signals received from the same transmitter having decodable components unique to that transmitter;

    means responsive to the coded signals for generating timing signals, said timing signals being representative of the difference in the time of arrival, at pairs of said receiving stations, of the signal received from each transmitter; and

    means responsive to the timing signals and the coded signals for processing said signals to determine the position of each transmitter and information supplied from each transmitter.

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