Local clock frequency calibration using low earth orbit (LEO) satellites
First Claim
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1. A method of transferring frequency stability from a satellite to a device, the method comprising:
- receiving a signal from the satellite;
determining a code phase from the satellite signal, wherein;
the satellite is a low earth orbit (LEO) satellite having a clock frequency,the signal comprises a plurality of message frames each having an ordinal number, and at least one time transfer structure message having a unique pseudorandom code, andthe code phase corresponds to the ordinal number of the message frame whose time transfer structure message is identified through its unique pseudorandom code;
receiving aiding information; and
calibrating a frequency of a local clock of the device to substantially synchronize the local clock frequency with the satellite clock frequency, wherein the calibrating comprises measuring a frequency of the satellite signal using the code phase and the aiding information.
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Abstract
Various techniques are provided for calibrating a frequency of a local clock using a satellite signal. In one example, a method of transferring frequency stability from a satellite to a device includes receiving a signal from the satellite. The method also includes determining a code phase from the satellite signal. The method further includes receiving aiding information. In addition, the method includes calibrating a frequency of a local clock of the device using the code phase and the aiding information to substantially synchronize the local clock frequency with a satellite clock frequency.
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Citations
15 Claims
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1. A method of transferring frequency stability from a satellite to a device, the method comprising:
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receiving a signal from the satellite; determining a code phase from the satellite signal, wherein; the satellite is a low earth orbit (LEO) satellite having a clock frequency, the signal comprises a plurality of message frames each having an ordinal number, and at least one time transfer structure message having a unique pseudorandom code, and the code phase corresponds to the ordinal number of the message frame whose time transfer structure message is identified through its unique pseudorandom code; receiving aiding information; and calibrating a frequency of a local clock of the device to substantially synchronize the local clock frequency with the satellite clock frequency, wherein the calibrating comprises measuring a frequency of the satellite signal using the code phase and the aiding information. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A receiver unit comprising:
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an antenna adapted to receive a signal from a satellite, wherein; the satellite is a low earth orbit (LEO) satellite having a clock frequency, and the signal comprises a plurality of message frames each having an ordinal number, and at least one time transfer structure message having a unique pseudorandom code; a local clock; an analog-to-digital (A/D) converter adapted to sample data from the time transfer structure message in the satellite signal; a memory adapted to store aiding information; and a computer adapted to determine a code phase using the sampled data, wherein; the code phase corresponds to the ordinal number of the message frame whose time transfer structure message is identified through its unique pseudorandom code, and the computer is further adapted to measure a frequency of the satellite signal using the code phase and the aiding information to determine a frequency correction for the local clock to substantially synchronize the local clock frequency with the clock frequency of the satellite. - View Dependent Claims (12, 13, 14, 15)
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Specification