Computing long term orbit and clock models with variable time-horizons
First Claim
1. A method for generating time-horizons for long term orbit models for at least one satellite within a global navigation satellite system (GNSS) comprising:
- computing a predicted orbit parameter in an orbit parameter prediction model;
producing an indicia of accuracy by comparing the predicted orbit parameter to a current orbit parameter;
if the indicia of accuracy indicates at least a predefined level of accuracy, setting a time-horizon for the orbit parameter prediction model at a first value; and
if the indicia of accuracy indicates less than the predefined level of accuracy, setting the time-horizon for the orbit parameter prediction model at a second value, where the second value is less than the first value.
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Abstract
A method and apparatus for determining long term orbit (LTO) models using variable time-horizons to improve the orbit and clock model accuracy. The method and apparatus use either historic ephemeris or historic measurements for at least one satellite to produce an orbit parameter prediction model (an LTO model). The parameter predicted by the model is compared to an orbit parameter of a current broadcast ephemeris. The result of the comparison (an indicia of accuracy for the model) is used to establish a time-horizon for the orbit parameter prediction model for that particular satellite. Such a time-horizon may be established in this manner for each satellite within a satellite constellation.
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Citations
25 Claims
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1. A method for generating time-horizons for long term orbit models for at least one satellite within a global navigation satellite system (GNSS) comprising:
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computing a predicted orbit parameter in an orbit parameter prediction model; producing an indicia of accuracy by comparing the predicted orbit parameter to a current orbit parameter; if the indicia of accuracy indicates at least a predefined level of accuracy, setting a time-horizon for the orbit parameter prediction model at a first value; and if the indicia of accuracy indicates less than the predefined level of accuracy, setting the time-horizon for the orbit parameter prediction model at a second value, where the second value is less than the first value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for generating long term orbit models for a plurality of satellites within a global navigation satellite system (GNSS) comprising:
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generating an orbit parameter prediction model for each satellite in the plurality of satellites; and generating a time-horizon, associated with each orbit parameter prediction model, within which the orbit parameter prediction model is accurate, where the time-horizon differs for at least one orbit parameter prediction model compared to the time-horizons associated with other orbit parameter prediction models. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. Apparatus for generating long term orbit models for a plurality of satellites within a global navigation satellite system (GNSS) comprising:
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an orbit prediction module for generating an orbit parameter prediction model for each satellite in the plurality of satellites; and a time horizon prediction module for generating a time-horizon, associated with each orbit parameter prediction model, within which the orbit parameter prediction model is accurate, where the time-horizon differs for at least one orbit parameter prediction model compared to the time-horizons associated with other orbit parameter prediction models.
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Specification