Method and apparatus for precision attitude determination and kinematic positioning
First Claim
1. A method for determining the relative position of a secondary receiving antenna with respect to a reference receiving antenna in a satellite-based positioning system, the method comprising the steps of:
- making carrier phase measurements based on the reception of a carrier signal from each of a plurality N of satellites, where N is the minimum number of satellites needed to compute the relative position of the secondary antenna;
deriving from the carrier phase measurements an initial set of potential solutions for the relative position, wherein the initial set of potential solutions all fall within a region of uncertainty defined by a sphere having a radius equal to the maximum distance between the two antennas, and wherein multiple potential solutions arise because of whole-cycle ambiguity of the carrier signal;
making redundant carrier phase measurements based on the reception of a carrier signal from an additional (N+1)th satellite; and
eliminating false solutions from the initial set of potential solutions, based on a comparison of the redundant carrier phase measurements with the initial set of potential solutions, to reduce number of potential solutions to close to one, whereby the number of potential solutions is not reduced by use of the redundant carrier phase measurements.
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Abstract
A technique for resolving whole-cycle ambiguity that is inherent in phase-angle measurements of signals received from multiple satellite-based transmitters in a global positioning system. The relative position of a secondary receiving antenna with respect to a reference antenna is approximately known or approximately initially determined and then measurements from a minimum number of satellites are used to determine an initial set of potential solutions to the relative position of the secondary antenna that fall within a region of uncertainty surrounding the approximate position. Redundant measurements are taken from one or more additional satellites and used to progressively reduce the number of potential solutions to close to one. Even if the number of potential solutions is not reduced to one true solution, the number can be further reduced by using additional measurements taken at different time intervals, at which different satellite geometries prevail. The disclosed technique produces rapid elimination of false solutions and permits realtime computation of relative position in kinetic positioning applications, and of angular orientation in attitude determination applications.
110 Citations
32 Claims
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1. A method for determining the relative position of a secondary receiving antenna with respect to a reference receiving antenna in a satellite-based positioning system, the method comprising the steps of:
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making carrier phase measurements based on the reception of a carrier signal from each of a plurality N of satellites, where N is the minimum number of satellites needed to compute the relative position of the secondary antenna; deriving from the carrier phase measurements an initial set of potential solutions for the relative position, wherein the initial set of potential solutions all fall within a region of uncertainty defined by a sphere having a radius equal to the maximum distance between the two antennas, and wherein multiple potential solutions arise because of whole-cycle ambiguity of the carrier signal; making redundant carrier phase measurements based on the reception of a carrier signal from an additional (N+1)th satellite; and eliminating false solutions from the initial set of potential solutions, based on a comparison of the redundant carrier phase measurements with the initial set of potential solutions, to reduce number of potential solutions to close to one, whereby the number of potential solutions is not reduced by use of the redundant carrier phase measurements. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for determining the angular attitude of a line of fixed length between a reference receiving antenna and a secondary receiving antenna, from the relative position of the secondary receiving antenna with respect to the reference receiving antenna as determined in a satellite-based positioning system, the method comprising the steps of:
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making carrier phase measurements based on the reception of a carrier signal from each of two satellites, where two is the minimum number of satellites needed to compute the relative position of the secondary antenna; deriving from the carrier phase measurements an initial set of potential solutions for the relative position, wherein the initial set of potential solutions all fall within a region of uncertainty defined by the surface of a sphere having a radius equal to the fixed distance between the two antennas, and wherein multiple potential solutions arise because of wholecycle ambiguity of the carrier signal; making redundant carrier phase measurements based on the reception of a carrier signal from a third satellite; and eliminating false solutions from the initial set of potential solutions, based on a comparison of the redundant carrier phase measurements with the initial set of potential solutions, to reduce number of potential solutions to close to one, whereby the number of potential solutions is not reduced by use of the redundant carrier phase measurements. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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21. Apparatus for determining the relative position of a secondary receiving antenna with respect to a reference receiving antenna in a satellite-based positioning system, the apparatus comprising:
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means for making carrier phase measurements based on the reception of a carrier signal from each of a plurality N of satellites, where N is the minimum number of satellites needed to compute the relative position of the secondary antenna; means for deriving from the carrier phase measurements an initial set of potential solutions for the relative position, wherein the initial set of potential solutions all fall within a region of uncertainty defined by a sphere having a radius equal to the maximum distance between the two antennas, and wherein multiple potential solutions arise because of whole-cycle ambiguity of the carrier signal; means for making redundant carrier phase measurements based on the reception of a carrier signal from an additional (N+1)the satellite; and means for eliminating false solutions from the initial set of potential solutions, based on a comparison of the redundant carrier phase measurements with the initial set of potential solutions, to reduce number of potential solutions to close to one, whereby the number of potential solutions is not reduced by use of the redundant carrier phase measurements. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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32. Apparatus for determining the angular attitude of a line of fixed length between a reference receiving antenna and a secondary receiving antenna, from the relative position of the secondary receiving antenna with respect to the reference receiving antenna as determined in a satellite-based positioning system, the apparatus comprising:
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means for making carrier phase measurements based on the reception of a carrier signal from each of two satellites, where two is the minimum number of satellites needed to compute the relative position of the secondary antenna; means for deriving from the carrier phase measurements an initial set of potential solutions for the relative position, wherein the initial set of potential solutions all fall within a region of uncertainty defined by the surface of a sphere having a radius equal to the fixed distance between the two antennas, and wherein multiple potential solutions arise because of whole-cycle ambiguity of the carrier signal; means for making redundant carrier phase measurements based on the reception of a carrier signal from a third satellite; and means for eliminating false solutions from the initial set of potential solutions, based on a comparison of the redundant carrier phase measurements with the initial set of potential solutions, to reduce number of potential solutions to close to one, whereby the number of potential solutions is not reduced by use of the redundant carrier phase measurements.
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Specification