System and method for model-base compression of GPS ephemeris
OwnerJames L. Garrison, Brenda E. Eichelinventors
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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.
Claims22
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 the received orbital positional data to generate propagated 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.
A reference station for providing compressed data to represent a propagated ephemeris comprising:
- 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.
A method for receiving ephemeris data for a satellite in Earth orbit at a navigation receiver, comprising the steps of:
- 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.
Dependencies are inferred from the claim text.