Method and apparatus for determining the geographic location of a device
View Patent ↗A method and apparatus for determining the location of a device from signals provided by a plurality of satellites. A device receives a first plurality of signals comprising one signal from each of a first plurality of satellites and determines a first location of the device as a function of the first plurality of signals. The device then determines a second location thereof as a function of a second plurality of signals if the first location is not within a predetermined threshold. The second plurality of signals is a first subset of the first plurality of signals.
1. A method for determining the location of a device comprising the steps of:
(a) receiving a first plurality of signals comprising one signal from each of a first plurality of satellites;
(b) determining a first location of the device as a function of the first plurality of signals;
(c) determining a second location of the device as a function of a second plurality of signals if the first location is not within a predetermined threshold; and,
(d) determining a third location of the device as a function of a third plurality of signals if the second location is not within the predetermined threshold,
wherein the second plurality of signals is a first subset of the first plurality of signals, wherein the third plurality of signals is a second subset of the first plurality of signals and wherein a cardinality of the second plurality of signals is the same or greater than a cardinality of the third plurality of signals.
2. The method of claim 1 wherein a cardinality of the second plurality of signals is at least four.
3. In a method for eliminating erroneous satellite signals in a position calculation for a device receiving a first plurality of signals from a first plurality of satellites, the improvement comprising the steps of determining a first position calculation of the device as a function of the first plurality of signals, determining a second position calculation of the device as a function of a second plurality of signals if the first calculation is not within a predetermined threshold, and determining a third location of the device as a function of a third plurality of signals if the second location is not within the predetermined threshold, wherein the second plurality of signals is a first subset of the first plurality of signals, wherein the third plurality of signals is a second subset of the first plurality of signals, and wherein a cardinality of the second plurality of signals is the same or greater than a cardinality of the third plurality of signals.
4. The method of claim 3 wherein the device is receiving signals from a cellular network.
5. The method of claim 4 wherein a position calculation of the device is a function of signals provided by the cellular network.
6. The method of claim 3 wherein the satellites are part of a Global Navigation Satellite System (“GNSS”).
7. The method of claim 6 wherein the GNSS is selected from the group consisting of: Global Positioning System (“GPS”), Galileo, GLONASS, and Quasi-Zenith Satellite System (“QZSS”).
8. The method of claim 3 wherein the device is a mobile unit.
9. The method of claim 8 wherein the mobile unit is selected from the group consisting of: cellular device, text messaging device, computer, portable computer, vehicle locating device, vehicle security device, communication device, and wireless transceiver.
10. The method of claim 3 wherein a cardinality of the second plurality of signals is at least four.
11. A device comprising:
a receiver for receiving a first plurality of signals comprising one signal from each of a first plurality of satellites;
a means for determining a first location of the device as a function of the first plurality of signals;
a means for determining a second location of the device as a function of a second plurality of signals if the first location is not within a predetermined threshold, wherein the second plurality of signals is a first subset of the first plurality of signals; and
a means for determining a third location of the device as a function of a third plurality of signals if the second location is not within the predetermined threshold, wherein the third plurality of signals is a third subset of the first plurality of signals and wherein a cardinality of the second plurality of signals is the same or greater than a cardinality of the third plurality of signals.
12. The device of claim 11 wherein the satellites are part of a Global Navigation Satellite System (“GNSS”).
13. The device of claim 12 wherein the GNSS is selected from the group consisting of: Galileo, GLONASS, and Quasi-Zenith Satellite System (“QZSS”).
14. The device of claim 11 wherein the satellites are Global Positioning System (“GPS”) satellites.
15. The device of claim 11 wherein the predetermined threshold is a function of ephemeris information transmitted by one of the satellites.
16. The device of claim 11 wherein the predetermined threshold is a function of a lowest sum of the squared residuals.
17. The device of claim 11 wherein the device is a mobile unit.
18. The device of claim 17 wherein the mobile unit is selected from the group consisting of cellular device, text messaging device, computer, portable computer, vehicle locating device, vehicle security device, communication device, and wireless transceiver.
19. The device of claim 18 wherein the mobile unit is adaptable to receive signals from a cellular network.
20. The device of claim 19 wherein the predetermined threshold is a function of information received from the cellular network.