Fast acquisition of GPS signal
First Claim
1. An apparatus, comprising:
- a receiver in receipt of a signal having a plurality of pseudo noise codes with each of the pseudo noise codes of the plurality of pseudo noise codes that originate from a plurality of GPS transmitters;
a clock with an error of less than 0.5 ms relative to a GPS time; and
a decoder connected to the receiver and the clock that identifies four pseudo range equations for at least four GPS transmitters from the plurality of GPS transmitters, and determines a location of the receiver by simultaneously solving the four pseudo range equations.
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Accused Products
Abstract
Upon reception of four GPS signals from GPS satellites and determining four pseudo ranges, along with ephemeris data previously stored in the GPS receiver, the location of the GPS receiver and real time clock time error is determined. The GPS receiver is in possession of four pseudo ranges and determines four unknown coordinate values (x, y, x, and time) identifying the location of the GPS receiver and real time clock error. The process of solving for four pseudo range formulas simultaneously with each pseudo range formula having an unknown “x”, “y” “z”, and time coordinates of the GPS receiver, results in identification of the coordinates and time of the GPS receiver. In a similar process, the GPS receiver receiving four GPS signals from four GPS satellites is able to determine four pseudo ranges. Using the four pseudo ranges, four pseudo range equations unknown values for “x”, “y”, “z” and time can be solved for simultaneously. The resulting values are then used to verify that the calculated positions of the GPS satellites are within 0.5 ms of the previous solution. If the GPS satellites are within 0.5 ms range of the prior solution then the real time clock error is estimated. Thus, using ephemeris data, the location of the GPS receiver is determined in a fraction of the time it takes to acquire the GPS satellites using conventional approaches.
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Citations
15 Claims
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1. An apparatus, comprising:
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a receiver in receipt of a signal having a plurality of pseudo noise codes with each of the pseudo noise codes of the plurality of pseudo noise codes that originate from a plurality of GPS transmitters;
a clock with an error of less than 0.5 ms relative to a GPS time; and
a decoder connected to the receiver and the clock that identifies four pseudo range equations for at least four GPS transmitters from the plurality of GPS transmitters, and determines a location of the receiver by simultaneously solving the four pseudo range equations. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method, comprising:
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receiving at a receiver a signal generated at a plurality of GPS transmitters;
identifying at least four pseudo noise codes in the signal at the receiver;
calculating time with a clock having an error of less than 0.5 ms relative to a GPS time;
deriving at least four pseudo range equations from each of the at least four pseudo noise codes; and
locating the receiver by solving the at least four pseudo range equations simultaneously. - View Dependent Claims (8, 9)
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10. An apparatus, comprising:
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means for receiving at a receiver a signal generated at a plurality of GPS transmitters;
means for identifying at least four pseudo noise codes in the signal at the receiver;
means for calculating time with a clock having an error of less than 0.5 ms relative to a GPS time;
means for deriving at least four pseudo range equations from each of the at least four pseudo noise codes; and
means for locating the receiver by solving the at least four pseudo range equations simultaneously. - View Dependent Claims (11, 12)
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13. A machine-readable signal bearing medium containing instructions that cause a controller to perform a method for fast satellite acquisition, the method comprising:
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receiving at a receiver a signal generated at a plurality of GPS transmitters;
identifying at least four pseudo noise codes in the signal at the receiver;
calculating time with a clock having an error of less than 0.5 ms relative to a GPS time;
deriving at least four pseudo range equations from each of the at least four pseudo noise codes; and
locating the receiver by solving the at least four pseudo range equations simultaneously. - View Dependent Claims (14, 15)
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Specification