SYSTEM AND METHOD FOR USING DATA PHASE TO REDUCE POSITION AMBIGUITIES
First Claim
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1. A method for determining a location of a mobile terminal, comprising:
- receiving, via a communication satellite, a communication from a mobile terminal that includes a code phase measurement and a data phase measurement for at least one GPS satellite signal;
determining a first range distance from said mobile terminal to said communication satellite;
identifying a range intersection curve, said range intersection curve representing a first arc on the surface of the earth that is defined by a known position of said communication satellite and said determined range distance;
identifying a code/data phase intersection curve, said code/data phase intersection curve representing a second arc on the surface of the earth that is defined by a known position of a GPS satellite and a second range distance that is consistent with said code phase measurement and said data phase measurement;
determining an intersection point between said range intersection curve and said code/data phase intersection curve;
identifying an initial position point based on said determined intersection point; and
determining a final position of said mobile terminal using said initial position point.
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Abstract
A geographic tracking system with minimal power and size required at the mobile terminal collects observation data at the mobile terminal and forwards the data to a processor, which calculates the position. The mobile terminal is configured to measure both code phase and data phase of a GPS satellite signal. The code phase and data phase information enables the processor to reduce the number of candidate points to be considered.
11 Citations
14 Claims
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1. A method for determining a location of a mobile terminal, comprising:
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receiving, via a communication satellite, a communication from a mobile terminal that includes a code phase measurement and a data phase measurement for at least one GPS satellite signal; determining a first range distance from said mobile terminal to said communication satellite; identifying a range intersection curve, said range intersection curve representing a first arc on the surface of the earth that is defined by a known position of said communication satellite and said determined range distance; identifying a code/data phase intersection curve, said code/data phase intersection curve representing a second arc on the surface of the earth that is defined by a known position of a GPS satellite and a second range distance that is consistent with said code phase measurement and said data phase measurement; determining an intersection point between said range intersection curve and said code/data phase intersection curve; identifying an initial position point based on said determined intersection point; and determining a final position of said mobile terminal using said initial position point. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for determining a location of a mobile terminal, comprising:
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receiving a communication from a mobile terminal that includes a code phase measurement and a data phase measurement of a GPS satellite signal; determining an initial position point using said code phase measurement and said data phase measurement; and performing an iterative calculation process on said initial position point to produce a final position solution for said mobile terminal. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A mobile terminal, comprising:
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a locating system module that is designed to receive a plurality of GPS satellite signals, wherein for at least one received GPS satellite signal, said locating system module measures a code phase and data phase for said GPS satellite signal; and a satellite modem for sending a report to an operations gateway via a communication satellite, said report including said code phase measurement and said data phase measurement, which are usable by said operations gateway in determining a position of said mobile terminal.
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Specification