Systems and methods for synthesizing GPS measurements to improve GPS location availability
First Claim
1. A method for synthesizing global positioning system (GPS) measurements, the method comprising:
- receiving GPS signals from at least four signal sources by a navigation device;
calculating pseudoranges (PRs) and delta pseudo ranges (DPRs) associated with the GPS signals from the at least four signal sources;
identifying a lost signal source when the GPS signals are received from less than four of the at least four signal sources;
estimating PRs and DPRs for the lost signal source based on previously calculated PRs and DPRs of the lost signal source; and
calculating a position fix using the calculated PRs and DPRs, and the estimated PRs and DPRs in a navigation solution.
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Abstract
There are situations where GPS signals are received from less than four satellites. In order to improve the GPS location availability, disclosed here are systems and methods for synthesizing GPS measurements, which, together with fewer than four available real GPS signals, can be used to calculate a position fix. In particular, GPS range measurements for lost satellites, which are satellites that were previously tracked but are now not tracked, are synthesized to improve GPS signal availability. The synthesized measurements are used along with real measurements to enable accurate position fix even when GPS satellite availability is poor. Different synthesized measurement generation schemes, depending on whether an INS/DR aiding system is available, are further described herein.
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Citations
21 Claims
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1. A method for synthesizing global positioning system (GPS) measurements, the method comprising:
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receiving GPS signals from at least four signal sources by a navigation device; calculating pseudoranges (PRs) and delta pseudo ranges (DPRs) associated with the GPS signals from the at least four signal sources; identifying a lost signal source when the GPS signals are received from less than four of the at least four signal sources; estimating PRs and DPRs for the lost signal source based on previously calculated PRs and DPRs of the lost signal source; and calculating a position fix using the calculated PRs and DPRs, and the estimated PRs and DPRs in a navigation solution. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A system for synthesizing global positioning system (GPS) measurements comprising:
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a GPS receiver that is configured to; receive GPS signals from at least four satellites, calculate pseudoranges (PRs) and delta pseudo ranges (DPRs) associated with the GPS signals from the at least four satellites, identify a lost satellite when the GPS signals are received from less than four of the at least four satellites, and estimate PRs and DPRs for the lost satellite based on previously calculated PRs and DPRs of the lost satellite, a server in an Assisted GPS (AGPS) operation mode that is configured to; receive the calculated PRs and DPRs, and the estimated PRs and DPRs from the GPS receiver, calculate a position fix of the GPS receiver based on the received calculated PRs and DPRs, and the received estimated PRs and DPRs, and transmit the position fix to the GPS receiver. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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21. A GPS receiver comprising:
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an antenna that is configured to receive GPS signals from at least four signal sources; and a baseband digital signal processor that is configured to; receive the GPS signals from the antenna, calculate pseudoranges (PRs) and delta pseudo ranges (DPRs) associated with the GPS signals from the at least four signal sources, identify a lost signal source when the GPS signals are received from less than four of the at least four signal sources; estimate PRs and DPRs for the lost signal source based on previously calculated PRs and DPRs of the lost signal source; and calculate a position fix using the calculated PRs and DPRs, and the estimated PRs and DPRs in a navigation solution.
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Specification