System and method for model-base compression of GPS ephemeris
First Claim
1. A method for propagating ephemeris data for a satellite in Earth orbit comprising:
- receiving orbital positional data for a first time period of a satellite'"'"'s Earth orbit;
propagating orbital positional data for the satellite'"'"'s Earth orbit during a second time period extending beyond the first time period;
fitting a Keplerian ephemeris model to the propagated orbital positional data to estimate model coefficients; and
sending the estimated model coefficients to receivers for determination of receiver position at a time during the second time period.
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Abstract
A method for propagating ephemeris data for a satellite in Earth orbit is provided. The method includes the steps of receiving orbital positional data for a first time period of a satellite'"'"'s Earth orbit, propagating orbital positional data for the satellite'"'"'s Earth orbit during a second time period extending beyond the first time period, fitting a Keplerian ephemeris model to the propagated orbital positional data to estimate model coefficients, and sending the estimated model coefficients to receivers for determination of receiver position at a time during the second time period.
46 Citations
24 Claims
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1. A method for propagating ephemeris data for a satellite in Earth orbit comprising:
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receiving orbital positional data for a first time period of a satellite'"'"'s Earth orbit;
propagating orbital positional data for the satellite'"'"'s Earth orbit during a second time period extending beyond the first time period;
fitting a Keplerian ephemeris model to the propagated orbital positional data to estimate model coefficients; and
sending the estimated model coefficients to receivers for determination of receiver position at a time during the second time period. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A reference station for providing compressed data to represent a propagated ephemeris comprising:
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a receiver for receiving orbital positional data for a first epoch of a satellite ephemeris;
an orbit propagator for propagating orbital positional data for a second epoch of an ephemeris for the satellite corresponding to the received orbital positional data;
an ephemeris compressor for fitting an ephemeris format to the propagated orbital positional data of the second epoch to generate compressed data for representing the second epoch of the satellite ephemeris; and
a transmitter for sending the compressed data to satellite receivers for computing a receiver location from a satellite position represented by the compressed data. - View Dependent Claims (16, 17, 18, 19)
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20. A method for reacting to planned satellite maneuvers, comprising the steps of:
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receiving notification of planned satellite maneuvers from public or private sources including the government;
deleting ephemerides generated for satellites for time subsequent to the time of a planned maneuver; and
generating a warning message to be distributed with the ephemerides that indicates that time of a planned maneuver.
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21. A method for verifying that satellite maneuvers would not affect the navigation of a navigation receiver, comprising the step of:
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receiving notification of transmitted time of planned satellite maneuvers from public or private sources including the government;
comparing the transmitted time of planned satellite maneuvers to time that satellites are used in navigation; and
verifying that the transmitted time of planned satellite maneuvers is not prior to the time that satellites are used in navigation and will not affect the navigation of a navigation receiver.
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22. A method for receiving ephemeris data for a satellite in Earth orbit at a navigation receiver, comprising the steps of:
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receiving estimated model coefficients of orbital positional data for a second time period of a satellite'"'"'s Earth orbit, the second time period extending beyond a first time period, the estimated model coefficients based on propagating orbital positional data for the first time period of a satellite'"'"'s Earth orbital positional data, the model coefficients obtained from fitting a Keplerian ephemeris model to the propagated orbital positional data to estimate the model coefficients; and
determining the receiver position at a time during the second time period, based at least partially on the estimated model coefficients. - View Dependent Claims (23, 24)
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Specification