Global positioning system using almanac data for a fast time to first fix
First Claim
1. A global positioning system (GPS) method for a fast time to first fix, comprising:
- measuring user pseudoranges from GPS signals transmitted by GPS signal sources;
determining a coarse GPS-based user location from said measured user pseudoranges and coarse orbital parameters including one of (i) almanac and (ii) non-current ephemeris data;
recalculating user pseudoranges from said coarse GPS-based user location and the same said coarse satellite orbital parameters; and
computing a more accurate GPS-based user location from said recalculated user pseudoranges.
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Abstract
A system using coarse GPS orbital parameters for providing a precise GPS location. The system includes a GPS reference receiver and a GPS user receiver. Coarse locations-in-space of GPS satellites are computed from almanac or old ephemeris data. In a first embodiment the GPS user receiver uses DGPS corrections based upon the same coarse orbital parameters for providing a precise DGPS user location. In a second embodiment the GPS user receiver computes a coarse location from the coarse orbital parameters; and the GPS reference receiver recalculates the user pseudoranges using the same coarse orbital parameters and then uses the recalculated user pseudoranges for providing a more accurate user location.
35 Citations
18 Claims
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1. A global positioning system (GPS) method for a fast time to first fix, comprising:
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measuring user pseudoranges from GPS signals transmitted by GPS signal sources;
determining a coarse GPS-based user location from said measured user pseudoranges and coarse orbital parameters including one of (i) almanac and (ii) non-current ephemeris data;
recalculating user pseudoranges from said coarse GPS-based user location and the same said coarse satellite orbital parameters; and
computing a more accurate GPS-based user location from said recalculated user pseudoranges. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A system having a fast time to a first global positioning system (GPS) fix, comprising:
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a range code for measuring user pseudoranges from GPS signals transmitted by GPS signal sources;
a user coarse location code for determining a coarse GPS-based user location from said measured user pseudoranges and coarse orbital parameters including one of (i) almanac and (ii) non-current ephemeris data;
a pseudorange recalculation code for recalculating user pseudoranges from said coarse GPS-based user location and the same said coarse satellite orbital parameters; and
a recalculated pseudorange location code for computing a more accurate GPS user location from said recalculated user pseudoranges. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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Specification