US 6,211,817 B1 · Differential global positioning system using almanac data for a fast time to first fix

Abstract

A DGPS system using GPS almanac data for determining the locations-in-space and the DGPS corrections for GPS satellites for providing a differentially corrected location of a remote GPS user receiver. A GPS reference receiver determines almanac-based DGPS corrections from the differences between ranges that are measured to GPS satellites and ranges that are calculated to the GPS almanac-based locations-in-space of the GPS satellites from the known location of the GPS reference receiver. The GPS user receiver measures pseudoranges to the GPS satellites. Then, in a first embodiment, the GPS reference receiver radios the DGPS corrections to the GPS user receiver. The GPS user receiver uses almanac-based locations-in-space for the GPS satellites and the almanac-based DGPS corrections for differentially correcting the measured user pseudoranges for providing a differentially corrected user location. In a second embodiment, the GPS user receiver radios the measured user pseudoranges to the GPS reference receiver. The GPS reference receiver uses the measured user pseudoranges, the almanac-based locations-in-space for the GPS satellites, and the almanac-based DGPS corrections for providing the differentially corrected user location.

Claims12

Dependent claims

A method in a differential global positioning system (DGPS) system, comprising steps of:

computing an almanac-based location-in-space of a GPS signal source from GPS almanac data pertaining to said GPS signal source;
at a GPS user receiver, determining a user pseudorange between said GPS signal source and said GPS user receiver;
and
using said almanac-based location-in-space, said user pseudorange, and an almanac based DGPS range correction for calculating a differentially corrected user location of said GPS user receiver, said almanac-based DGPS range correction based upon said GPS almanac data pertaining en said GPS signal source.

1 more element

A global positioning system (GPS) reference receiver, comprising:

a reference processor;
a reference GPS source location code for execution by the reference processor for computing an almanac-based location-in-space of a GPS signal source from GPS almanac data pertaining to said GPS signal source;
a reference range measurement code for execution by the reference processor for measuring a measured reference range from said GPS signal source to the GPS reference receiver;
a reference range calculation code for execution by the reference processor for calculating an almanac-based calculated reference range from almanac-based location-in-space to a pre-determined reference location of the GPS reference receiver;
and
a reference differential correction code for determining an almanac-based DGPS range correction from a difference between said measured reference range and said almanac-based calculated reference range.

3 more elements

Dependencies are inferred from the claim text.

Differential global positioning system using almanac data for a fast time to first fix

Life of this patent

Differential global positioning system using almanac data for a fast time to first fix

Life of this patent

Abstract

Claims12