Satellite navigation using long-term navigation information and autonomous orbit control
First Claim
1. A method of adjusting a navigation satellite orbit, the method comprising:
- determining a nominal orbital path of the navigation satellite;
transmitting ephemeris data corresponding to the nominal orbital path from the navigation satellite to a plurality of navigation devices;
determining an actual orbital path of the navigation satellite locally at the navigation satellite, wherein the determining an actual orbital path comprises;
measuring non-gravitational disturbance force effects locally at the navigation satellite to determine a relative position of the navigation satellite, wherein the measuring is performed by a drag free sensor of the navigation satellite, andusing the relative position to determine the actual orbital path;
maintaining the drag free sensor substantially at a center of gravity of the navigation satellite;
determining a deviation between the actual orbital path and the nominal orbital path locally at the navigation satellite; and
autonomously adjusting the actual orbital path locally at the navigation satellite to reduce the deviation between the actual orbital path and the nominal orbital path.
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Accused Products
Abstract
An improved approach to satellite-based navigation (e.g., GPS) is provided. In one embodiment, a method includes determining a nominal orbital path of a navigation satellite. The method also includes transmitting ephemeris data corresponding to the nominal orbital path from the navigation satellite to a plurality of navigation devices. The method further includes determining an actual orbital path of the navigation satellite locally at the navigation satellite. In addition, the method includes determining a deviation between the actual orbital path and the nominal orbital path locally at the navigation satellite. The method also includes autonomously adjusting the actual orbital path locally at the navigation satellite to reduce the deviation between the actual orbital path and the nominal orbital path.
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Citations
12 Claims
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1. A method of adjusting a navigation satellite orbit, the method comprising:
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determining a nominal orbital path of the navigation satellite; transmitting ephemeris data corresponding to the nominal orbital path from the navigation satellite to a plurality of navigation devices; determining an actual orbital path of the navigation satellite locally at the navigation satellite, wherein the determining an actual orbital path comprises; measuring non-gravitational disturbance force effects locally at the navigation satellite to determine a relative position of the navigation satellite, wherein the measuring is performed by a drag free sensor of the navigation satellite, and using the relative position to determine the actual orbital path; maintaining the drag free sensor substantially at a center of gravity of the navigation satellite; determining a deviation between the actual orbital path and the nominal orbital path locally at the navigation satellite; and autonomously adjusting the actual orbital path locally at the navigation satellite to reduce the deviation between the actual orbital path and the nominal orbital path. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of adjusting a navigation satellite orbit, the method comprising:
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determining a nominal orbital path of the navigation satellite; transmitting ephemeris data corresponding to the nominal orbital path from the navigation satellite to a plurality of navigation devices; determining an actual orbital path of the navigation satellite locally at the navigation satellite, wherein the determining an actual orbital path comprises; measuring non-gravitational disturbance force effects locally at the navigation satellite to determine a relative position of the navigation satellite, wherein the measuring is performed by a drag free sensor of the navigation satellite, wherein the drag free sensor comprises a proof mass enclosed by a vacuum caging system, and using the relative position to determine the actual orbital path; determining a deviation between the actual orbital path and the nominal orbital path locally at the navigation satellite; and autonomously adjusting the actual orbital path locally at the navigation satellite to reduce the deviation between the actual orbital path and the nominal orbital path.
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9. A navigation satellite comprising:
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a receive antenna adapted to receive ephemeris data from a ground station, wherein the ephemeris data corresponds to a nominal orbital path of the navigation satellite; a memory adapted to store the ephemeris data; a transmit antenna adapted to transmit the ephemeris data to a plurality of navigation devices; a plurality of propulsion actuators; a drag free sensor adapted to measure non-gravitational disturbance force effects locally at the navigation satellite to determine a relative position of the navigation satellite; an assembly adapted to maintain the drag free sensor substantially at a center of gravity of the navigation satellite; and a processor adapted to; determine an actual orbital path of the navigation satellite using the relative position, determine a deviation between the actual orbital path and the nominal orbital path, and command the propulsion actuators to adjust the actual orbital path to reduce the deviation between the actual orbital path and the nominal orbital path. - View Dependent Claims (10, 12)
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11. A navigation satellite comprising:
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a receive antenna adapted to receive ephemeris data from a ground station wherein the ephemeris data corresponds to a nominal orbital path of the navigation satellite; a memory adapted to store the ephemeris data; a transmit antenna adapted to transmit the ephemeris data to a plurality of navigation devices; a plurality of propulsion actuators; a drag free sensor adapted to measure non-gravitational disturbance force effects locally at the navigation satellite to determine a relative position of the navigation satellite, wherein the drag free sensor comprises a proof mass enclosed by a vacuum caging system; and a processor adapted to; determine an actual orbital path of the navigation satellite using the relative position, determine a deviation between the actual orbital path and the nominal orbital path, and command the propulsion actuators to adjust the actual orbital path to reduce the deviation between the actual orbital path and the nominal orbital path.
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Specification