Autonomous orbit propagation system and method
First Claim
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1. A method of predicting a location of a satellite, comprising:
- receiving, at an RF antenna of a GNSS device, an ephemeris associated with a satellite, the ephemeris valid for an effective time period;
using the ephemeris, the GNSS device calculating position data and velocities of the satellite for a plurality of time intervals over the effective time period;
the GNSS device calculating, at a time during the effective time period, a plurality of correction acceleration terms for reducing errors between predicted position data and predicted velocities of the satellite and ephemeris-derived position data and velocities of the satellite at each of the plurality of time intervals over the effective time period, the predicted position data and predicted velocities being determined using a plurality of previously calculated orbit state vectors stored in memory of the GNSS device;
the GNSS device calculating a current orbit state vector using force model coefficients adjusted based on the plurality of correction acceleration terms and storing the current orbit state vector in the memory, the current orbit state vector being used as initial state for propagating an orbit of the satellite within a predicted time period, at least a portion of the predicted time period occurring after the effective time period; and
the GNSS device determining the location of the satellite using the orbit.
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Abstract
A method of predicting a location of a satellite is provided wherein the GPS device, based on previously received information about the position of a satellite, such as an ephemeris, generates a correction acceleration of the satellite that can be used to predict the position of the satellite outside of the time frame in which the previously received information was valid. The calculations can be performed entirely on the GPS device, and do not require assistance from a server. However, if assistance from a server is available to the GPS device, the assistance information can be used to increase the accuracy of the predicted position.
49 Citations
20 Claims
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1. A method of predicting a location of a satellite, comprising:
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receiving, at an RF antenna of a GNSS device, an ephemeris associated with a satellite, the ephemeris valid for an effective time period; using the ephemeris, the GNSS device calculating position data and velocities of the satellite for a plurality of time intervals over the effective time period; the GNSS device calculating, at a time during the effective time period, a plurality of correction acceleration terms for reducing errors between predicted position data and predicted velocities of the satellite and ephemeris-derived position data and velocities of the satellite at each of the plurality of time intervals over the effective time period, the predicted position data and predicted velocities being determined using a plurality of previously calculated orbit state vectors stored in memory of the GNSS device; the GNSS device calculating a current orbit state vector using force model coefficients adjusted based on the plurality of correction acceleration terms and storing the current orbit state vector in the memory, the current orbit state vector being used as initial state for propagating an orbit of the satellite within a predicted time period, at least a portion of the predicted time period occurring after the effective time period; and the GNSS device determining the location of the satellite using the orbit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method of predicting a location of a satellite, comprising:
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a GNSS device propagating an orbit of the satellite using an orbit state vector calculated using a force model, coefficients of the force model being calculated at a time during an effective time period of a broadcast ephemeris received by an RF antenna of the GNSS device, the coefficients being calculated to reduce errors, for a plurality of time intervals over the effective time period of the broadcast ephemeris, between a plurality of ephemeris-derived position data and velocities and a plurality of predicted position data and predicted velocities calculated using a plurality of previously calculated orbit state vectors; and when the effective time period has expired, determining the location of the satellite using the orbit. - View Dependent Claims (17, 18)
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19. A GNSS device comprising:
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an RF receiver for receiving an ephemeris comprising position data and velocities associated with a satellite, the position data and the velocities valid for an effective time period; a processor for calculating, at a time during the effective time period, ephemeris-derived position data and velocities of the satellite for a plurality of time intervals over the effective time period, calculating a plurality of correction acceleration terms for reducing error between predicted position data and predicted velocities of the satellite and the ephemeris-derived position data and velocities of the satellite at each time interval over the effective time period, the predicted position data and predicted velocities being determined using a plurality of previously calculated orbit state vectors, and calculating a current orbit state vector using force model coefficients adjusted based on the plurality of correction acceleration terms; and a memory for storing the current orbit state vector and previously calculated orbit state vectors; wherein the current orbit state vector is for propagating an orbit of the satellite within a predicted time period, at least a portion of the predicted time period occurring after the effective time period. - View Dependent Claims (20)
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Specification