Method and system for determining time in a satellite positioning system
First Claim
Patent Images
1. A method of receiving an estimate of time in a satellite signal receiver comprising:
- receiving the estimate of time from a server using a time transfer protocol;
receiving ephemeris data relating to a satellite constellation;
computing pseudoranges to a plurality of satellites of the satellite constellation using the ephemeris data;
compensating for error in a clock in the satellite signal receiver using the estimate of time; and
using an output of the error compensated clock as an input for an a-priori estimate of absolute time to a mathematical model to compute a position of the satellite signal receiver and the absolute time, wherein the mathematical model relates the absolute time to the computed pseudoranges based on rates of change of the computed pseudoranges relative to the absolute time.
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Abstract
Method and apparatus for receiving an estimate of time in a satellite signal receiver receives an estimate of time from a server and compensates for error of a clock in the satellite signal receiver using the estimate of time. The output of the compensated clock is used when computing a position of the satellite signal receiver. The estimate of time is received using a network time protocol (NTP), a simple network time protocol (SNTP), or by one-way broadcast from the server.
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Citations
21 Claims
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1. A method of receiving an estimate of time in a satellite signal receiver comprising:
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receiving the estimate of time from a server using a time transfer protocol; receiving ephemeris data relating to a satellite constellation; computing pseudoranges to a plurality of satellites of the satellite constellation using the ephemeris data; compensating for error in a clock in the satellite signal receiver using the estimate of time; and using an output of the error compensated clock as an input for an a-priori estimate of absolute time to a mathematical model to compute a position of the satellite signal receiver and the absolute time, wherein the mathematical model relates the absolute time to the computed pseudoranges based on rates of change of the computed pseudoranges relative to the absolute time. - View Dependent Claims (2, 3)
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4. A method of receiving an estimate of time in a satellite signal receiver comprising:
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requesting and receiving an estimate of time from a server using a time transfer protocol, wherein said request for the estimate of time is periodic; compensating for error in a clock in the satellite signal receiver using the estimate of time; using, an output compensated clock as an input for an a-priori estimate of absolute, time to a mathematical model to compute a position of the satellite signal receiver and the absolute time, wherein the mathematical model relates the absolute time to measured pseudoranges based on rates of change of the measured pseudoranges relative to the absolute time; comparing the computed absolute time with an output of the error compensated clock; and determining whether the computed absolute time is valid based on the comparison. - View Dependent Claims (5, 6, 7, 8, 9)
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10. A method of receiving the estimate of time in a satellite signal receiver comprising:
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determining a time of last compensation of a clock of the satellite signal receiver; comparing the time of last compensation with a threshold; requesting and receiving an estimate of time from a server in response to the time of last compensation exceeding the threshold; compensating for error in a clock in the satellite signal receiver using the estimate of time; and using, an output of the error compensated clock as an input for an a-priori estimate of absolute time to a mathematical model to compute a position of the satellite signal receiver and the absolute time, wherein the mathematical model relates the absolute time to measured pseudoranges based on rates of change of the measured pseudoranges relative to the absolute time. - View Dependent Claims (11)
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12. A method for determining a position of a satellite signal receiver comprising:
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computing pseudoranges that estimate a range of the satellite signal receiver to a plurality of satellites in a satellite constellation; receiving an estimate of time from a server using a time transfer protocol; compensating for error in a clock in the satellite signal receiver using the estimate of time; using an output of the error compensated clock as an input for an a-priori estimate of absolute time to a mathematical model to compute the position of the satellite signal receiver and the absolute time wherein the mathematical model relates the absolute time to the computed pseudoranges based on rates of change of the computed pseudoranges relative to the absolute time. - View Dependent Claims (13, 14)
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15. A method for determining a position of a satellite signal receiver comprising:
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computing pseudoranges that estimate a range of the satellite signal receiver to a plurality of satellites in a satellite constellation; requesting and receiving an estimate of time from a server using a time transfer protocol, wherein said request for the estimate of time is periodic; providing an a-priori estimate of absolute time from a time source; compensating for error in a clock in the satellite signal receiver using the a-priori estimate of absolute time; using an output of the error compensated clock as an input for the a-priori estimate of absolute time to a mathematical model to compute the position of the satellite signal receiver and the absolute time, wherein the mathematical model relates the absolute time to computed pseudoranges based on rates of change of the computed pseudoranges relative to the absolute times; comparing the computed absolute time with the estimate of time; and determining the computed absolute time is valid based on the comparison. - View Dependent Claims (16)
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17. A system for determining a position of a mobile device comprising:
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a mobile device having a satellite signal receiver and a wireless transceiver; and a server being in wireless communication with the mobile device, wherein the satellite signal receiver receives an estimate of time from the server using a time transfer protocol, compensates for error in a local clock in the satellite signal receiver using the estimate of time, uses an output of the error compensated local clock as an a-priori estimate of absolute time to a mathematical model, and computes using the mathematical model a position of the satellite signal receiver and the absolute time, wherein the mathematical model relates the absolute time to computed pseudoranges based on rates of change of the computed pseudoranges relative to the absolute time. - View Dependent Claims (18, 19, 20, 21)
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Specification