Precise absolute time transfer from a satellite system
First Claim
1. A method of transferring precise absolute time from a satellite to a device, the method comprising:
- receiving data from a messaging channel, wherein the data has a frame structure;
using the data to identify the satellite and a position of the satellite;
correcting for signal time of flight using the satellite identity and the position of the satellite;
using the data as a time reference to align a receiver clock to the frame structure;
with the receiver clock aligned to the frame structure, receiving a precision time signal from the satellite, wherein the precision time signal comprises a periodic repeating code;
determining a timing phase of the code; and
using the timing phase to determine a precise absolute time.
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Abstract
Various techniques are provided for obtaining a precise absolute time using a satellite system. In one example, a method of transferring precise absolute time from a satellite to a device includes receiving data from a messaging channel, wherein the data has a frame structure. The method also includes using the data to identify the satellite and a position of the satellite, correcting for signal time of flight using the satellite identity and the position, and using the data as a time reference to align a receiver clock to the frame structure. The method also includes, with the receiver clock aligned to the frame structure, receiving a precision time signal from the satellite, wherein the precision time signal comprises a periodic repeating code. The method also includes determining a timing phase of the code and using the timing phase to determine a precise absolute time.
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Citations
19 Claims
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1. A method of transferring precise absolute time from a satellite to a device, the method comprising:
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receiving data from a messaging channel, wherein the data has a frame structure; using the data to identify the satellite and a position of the satellite; correcting for signal time of flight using the satellite identity and the position of the satellite; using the data as a time reference to align a receiver clock to the frame structure; with the receiver clock aligned to the frame structure, receiving a precision time signal from the satellite, wherein the precision time signal comprises a periodic repeating code; determining a timing phase of the code; and using the timing phase to determine a precise absolute time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A receiver unit adapted for use in attenuated or jammed environments, comprising:
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an antenna adapted to receive a signal from a satellite acquisition channel or a messaging channel; a processor; a receiver clock; and a memory for storing a plurality of machine readable instructions which when executed by the processor cause the receiver unit to; receive data from the acquisition channel or the messaging channel, wherein the data has a frame structure, use the data to determine an identity of the satellite and a position of the satellite, correct for signal time of flight using the identity of the satellite and the position of the satellite, use the data as a time reference to align the receiver clock to the frame structure, with the receiver clock aligned to the frame structure, receive a precision time signal from the satellite, wherein the precision time signal comprises a periodic repeating code, determine a timing phase of the code, and use the timing phase to determine a precise absolute time. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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Specification