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Method and system for determining a position of a target vehicle utilizing two-way ranging

  • US 5,969,674 A
  • Filed: 02/21/1997
  • Issued: 10/19/1999
  • Est. Priority Date: 02/21/1997
  • Status: Expired due to Term
First Claim
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1. A communication system for monitoring the position and velocity of an aircraft, the system comprising:

  • a control station positioned on earth, the control station having a known position;

    at least three satellites orbiting earth and positioned in multiple planes, each of the at least three satellites having a communication link system communicating through a respective first signal link with the control station, wherein a position of each of the at least three satellites is known such that a range between each of the at least three satellites and the control station is known; and

    an aircraft having a communications transceiver for sending and receiving signals to and from each of the at least three satellites through a second signal link corresponding to a respective first link, each of the corresponding first and second signal links defining a path for carrying a signal between the aircraft and the control station via a respective one of the at least three satellites, wherein each of the paths is a two-way communication between a respective one of the at least three satellites and each of the control station and the aircraft, wherein each signal includes a unique Auslander-Barbano code division multiple access (AB CDMA) signal portion assigned to the aircraft and a data message portion, the data message portion being modulated by a wavelet-based finite-impulse-response (WFIR) waveform with the AB CDMA signal portion;

    wherein the control station includes a dual alpha-beta/extended Kalman-filter tracking loop which processes the signals to determine a range between each of the at least three satellites and the aircraft as a function of time for the signals to travel the paths, the position of the aircraft as a function of the ranges and the known positions of the control station and the at least three satellites, and the velocity of the aircraft as a function of Doppler shift of each of the signals during travel of the paths.

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