GPS correction methods, apparatus and signals
First Claim
1. A method for synthesizing GPS satellite measurements for a declared location, comprising:
- a. receiving network correction data for an epoch comprising;
i. Satellite ephemeris data;
ii. Satellite clock corrections;
iii. Satellite ephemeris corrections;
iv. Atmospheric parameters; and
v. residual error corrections derived from one or more reference stations located within a vernier-cell region;
b. determining whether the declared location is within the vernier-cell region; and
c. applying the network correction data to determine, for each of a plurality of satellites during an epoch;
estimated L1 and L2 pseudorange measurements from the satellite to the declared location; and
estimated phase delays for L1 frequency, for L2 frequency, and for a frequency representing a frequency difference between the L1 frequency and the L2 frequency.
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Abstract
Methods and apparatus are described and illustrated for producing GPS corrections, comprising: collecting measurements from a plurality of network reference stations; determining network corrections from the measurements; determining residual errors at one or more vernier-cell reference stations; and preparing vernier-cell corrections to compensate the residual errors within a vernier-cell region. Network correction streams are described and illustrated which contain network corrections derived from a plurality of network reference stations and residual error corrections derived from one or more vernier-cell reference stations. Methods and apparatus are described for employing such network correction streams in a virtual reference station to produce corrections and/or virtual measurements for use in a GPS receiver.
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Citations
27 Claims
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1. A method for synthesizing GPS satellite measurements for a declared location, comprising:
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a. receiving network correction data for an epoch comprising;
i. Satellite ephemeris data;
ii. Satellite clock corrections;
iii. Satellite ephemeris corrections;
iv. Atmospheric parameters; and
v. residual error corrections derived from one or more reference stations located within a vernier-cell region;
b. determining whether the declared location is within the vernier-cell region; and
c. applying the network correction data to determine, for each of a plurality of satellites during an epoch;
estimated L1 and L2 pseudorange measurements from the satellite to the declared location; and
estimated phase delays for L1 frequency, for L2 frequency, and for a frequency representing a frequency difference between the L1 frequency and the L2 frequency. - View Dependent Claims (2, 3, 4, 5, 6)
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7. Apparatus having a processor far synthesizing GPS satellite measurements for a declared location and further comprising:
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a. a port for receiving network correction data for an epoch comprising;
i. Satellite ephemeris data;
ii. Satellite clock corrections;
iii. Satellite ephemeris corrections;
iv. Atmospheric parameters; and
v. residual error corrections derived from one or more reference stations located within a vernier-cell region;
b. software instructions to determine whether the declared location is within the vernier-cell region;
c. software instructions to apply the network correction data to determine, for each of a plurality of satellites during an epoch;
estimated L1 and L2 pseudorange measurements from the satellite to the declared location; and
estimated phase delays for L1 frequency, for L2 frequency, and for the frequency difference between the L1 and L2 frequencies. - View Dependent Claims (8, 9, 10, 11, 12)
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13. Apparatus for synthesizing GPS satellite measurements for a declared location, comprising:
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a. means for receiving network correction data for an epoch comprising;
i. Satellite ephemeris data;
ii. Satellite clock corrections;
iii. Satellite ephemeris corrections;
iv. Atmospheric parameters; and
v. residual error corrections derived from one or more reference stations located within a vernier-cell region;
b. means for determining whether the declared location is within the vernier-cell region;
c. means for applying the network correction data to determine, for each of a plurality of satellites during an epoch;
estimated L1 and L2 pseudorange measurements from the satellite to the declared location; and
estimated phase delays for the GPS L1 frequency, for the GPS L2 frequency, and for a frequency representing a frequrency difference between the GPS L1 frequency and the GPS L2 frequency. - View Dependent Claims (14, 15, 16, 17, 18)
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19. A method of determining a corrected GPS position fix, comprising:
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a. obtaining network corrections determined from measurements taken at a plurality of GPS reference stations and residual error corrections derived from one or more reference stations located within a vernier-cell region;
b. for each of a plurality of satellites in view at a navigator location, receiving GPS ephemeris data and obtaining GPS receiver measurements;
c. determining, from the GPS ephemeris data and the network corrections and the residual error corrections, calculated corrections appropriate to the navigator location for each of the plurality of satellites;
d. applying the calculated corrections to the GPS receiver measurements to obtain corrected measurements; and
e. computing a position fix from the corrected measurements. - View Dependent Claims (20, 21)
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22. Apparatus for determining a corrected GPS position fix, comprising:
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a. a GPS receiver to receive GPS ephemeris data and to obtain GPS receiver measurements for each of a plurality of satellites in view at a navigator location; and
b. a navigation processor, responsive to network corrections determined from measurements taken at a plurality of OPS reference stations and residual error corrections derived from one or more reference stations located within a vernier-cell region, to i. Determine, from the GPS ephemeris data and the network corrections and the residual error corrections, calculated corrections appropriate to the navigator location for each of the plurality of satellites;
ii. Apply the calculated corrections to the GPS receiver measurement to obtain corrected measurements; and
iii. Compute a corrected GPS position fix from the corrected measurements. - View Dependent Claims (23, 24)
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25. Apparatus for determining a corrected GPS position fix, comprising:
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a. receiver means for receiving GPS ephemeris data and obtaining GPS receiver measurements for each of a plurality of satellites in view at a navigator location;
b. processor means, responsive to network corrections determined from measurements taken at a plurality of GPS reference stations and residual error corrections derived from one or more reference stations located within a vernier-cell region, for i. Determining, from the GPS ephemeris data and the network corrections and the residual error corrections, calculated corrections appropriate to the navigator location for each of the plurality of satellites;
ii. Applying the calculated corrections to the GPS receiver measurement to obtain corrected measurements; and
iii. Computing a corrected GPS position fix from the corrected measurements. - View Dependent Claims (26, 27)
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Specification