Hybrid approach for antenna baseline self-survey and line bias calibration using GPS carrier phase

• US 6,061,631 A
• Filed: 07/03/1997
• Issued: 05/09/2000
• Est. Priority Date: 07/03/1997
• Status: Expired due to Term

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Zhang, Qiyue John
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Beaulieu, Yonel
• Application Number:
  US08/887,953
• Time in Patent Office: 1,041 Days
• Field of Search: 701/213-15, 701/200, 701/207, 342/450, 342/1, 342/463, 342/357.01-357.04, 342/357.06, 342/357.17, 342/451, 342/352, 342/350, 343/757
• US Class Current: 701/213
• CPC Class Codes: G01S 19/55 Carrier phase ambiguity resolution; Floating ambiguity; LAMBDA [Least-squares AMBiguity Decorrelation Adjustment] method

Abstract

Methods for estimation of the relative locations (baseline vectors) of two or more GPS signal antennas relative to each other and for estimation of line biases associated with each signal processing channel associated with each GPS signal antenna. Double difference carrier phase signal measurements are formed, using floating integer and fixed integer solutions for the phase integer ambiguities, and baseline vectors between the GPS signal antennas are estimated. Single difference phase integer ambiguities are obtained and approximations for line biases are computed. Single difference carrier phase measurements are used to estimate baseline vectors and line biases, using fixed phase integer ambiguities with the estimated baseline vectors and line biases as initial conditions, and are processed by Kalman filtering or other suitable signal processing. Angular orientation or attitude of a vehicle body on which the GPS signal antennas are placed is determined from the baseline vectors.

Claims

1. A method for determination of the locations of, and line biases for, two or more spaced apart GPS signal antennas in a kinematic or static environment, the method comprising the steps of:

receiving GPS carrier phase signals from at least two GPS signal sources at each of at least two GPS signal antennas and associated GPS signal receivers;

measuring double difference phase signal observations for the carrier phase signals received at the at least two GPS receivers from at least two GPS signal sources and determining fixed value double difference phase integer ambiguities;

computing a single difference range for each of the at least two GPS signal sources and determining single difference phase measurements for the at least two GPS signal sources; and

subtracting the computed single difference range from the single difference phase measurement, identifying the integer part of this difference with a single difference phase integer ambiguity, and identifying the fractional part of this difference with a line bias for a signal processing channel associated with each of the at least two GPS receivers.

2. The method of claim 1, wherein said step of determining fixed value double difference phase integer ambiguities comprises the steps of:

estimating a first value of a baseline vector for a vector separating said at least two GPS receivers, using double difference floating phase integer solutions; and

estimating a second value of the baseline vector, using the first estimated baseline vector, ephemeris data for said at least two GPS signal sources and double difference fixed phase integer solutions.

3. The method of claim 1, further comprising the step of performing extended Kalman filtering on said single difference carrier phase observations with said fixed phase integer ambiguities to obtain a third value of said estimated baseline vector and to determine said line biases, using said estimated second baseline vector and said line biases as initial conditions.

4. The method of claim 3, further comprising the step of using said Kalman filtered single difference carrier phase observations, said line biases and said third value of said estimated baseline vector to estimate an attitude or angular orientation of said at least two GPS antennas relative to each other.

5. The method of claim 4, further comprising the step of using said Kalman filtered single difference carrier phase observations and said third value of said estimated baseline vector to estimate an attitude or angular orientation of said at least three GPS antennas relative to each other.

6. The method of claim 1, further comprising the steps of:

positioning said at least three GPS antennas on a selected vehicle; and

estimating an angular orientation of said at least three GPS antennas relative to a selected body frame of the vehicle.

7. The method of claim 6, further comprising the step of estimating an angular orientation of said vehicle body frame.

8. A method for determination of the locations of, and line biases for, two or more spaced apart GPS signal antennas, the method comprising the steps of:

receiving GPS carrier phase signals from at least two GPS signal sources at each of at least two GPS signal antennas and associated GPS signal receivers;

measuring double difference phase signal observations for the carrier phase signals received at the at least two GPS receivers from at least two GPS signal sources;

estimating a first value of a baseline vector for the vector separating the at least two GPS receivers, using double difference floating phase integer solutions;

determining double difference phase integer ambiguities, using fixed integer constraints, the estimated first baseline vector and ephemeris data for each of the at least two GPS signal sources;

estimating a second value of the baseline vector, using the double difference phase measurements with fixed integer phase solutions;

computing a single difference range for each of the at least two GPS signal sources and determining single difference phase measurements for the at least two GPS signal sources;

subtracting the computed single difference range from the single difference phase measurement, identifying the integer part of this difference with a single difference integer ambiguity, and identifying the fractional part of this difference with a line bias for a signal processing channel associated with each of the at least two GPS receivers; and

performing extended Kalman filtering on single difference phase signal observations with fixed phase integer ambiguities to obtain a third value of the estimated baseline vector and to determine line biases, using the initial values of line biases and estimated second value of the baseline vector as initial conditions.

9. The method of claim 8, further comprising the step of using said Kalman filtered single difference carrier phase observations, said line biases and said third value of said estimated baseline vector to estimate an attitude or angular orientation of said at least two GPS antennas relative to each other.

10. The method of claim 8, further comprising the step of using said Kalman filtered single difference carrier phase observations, said line biases and said third value of said estimated baseline vector to estimate an attitude or angular orientation of said at least three GPS antennas relative to each other.

11. The method of claim 10, further comprising the steps of:

positioning said at least three GPS antennas on a selected vehicle; and

estimating an angular orientation of said at least three GPS antennas relative to a selected body frame of the vehicle.

12. The method of claim 11, further comprising the step of estimating an angular orientation of said vehicle body frame.

13. A computer-usable medium having computer-readable program code embedded therein for causing a computer to determine the locations of, and line biases for, two or more spaced apart GPS signal antennas by performing the steps of:

receiving GPS carrier phase signals from at least two GPS signal sources at each of at least two GPS signal antennas and associated GPS signal receivers;

measuring double difference phase signal observations for the carrier phase signals received at the at least two GPS receivers from at least two GPS GPS signal sources;

estimating a first value of a baseline vector for the vector separating the at least two GPS receivers, using double difference floating phase integer solutions;

estimating a second value of the baseline vector, using the first estimated baseline vector, ephemeris data for the at least two GPS signal sources and double difference fixed phase integer solutions;

computing a single difference range for each of the at least two GPS signal sources and determining single difference phase measurements for the at least two GPS signal sources; and

subtracting the computed single difference range from the single difference phase measurement, identifying the integer part of this difference with a single difference integer ambiguity, and identifying the fractional part of this difference with a line bias for a signal processing channel associated with each of the at least two GPS receivers.

14. The computer-usable medium of claim 13, wherein said computer-readable program code further causes said computer to perform extended Kalman filtering on said single difference carrier phase observations with said fixed phase integer ambiguities to obtain a third value of said estimated baseline vector and to determine said line biases, using said estimated second baseline vector and said line biases as initial conditions.

15. The computer-usable medium of claim 14, wherein said computer-readable program code further causes said computer to use said Kalman filtered single difference carrier phase observations, said line biases and said third value of said estimated baseline vector to estimate an attitude or angular orientation of said at least two GPS antennas relative to each other.

16. The computer-usable medium of claim 14, wherein said computer-readable program code further causes said computer to use said Kalman filtered single difference carrier phase observations, said line biases and said third value of said estimated baseline vector to estimate an attitude or angular orientation of said at least three GPS antennas relative to each other.

17. The computer-usable medium of claim 16, wherein said at least three GPS antennas are positioned on a selected vehicle;

and

wherein said computer-readable program causes said computer to estimate an angular orientation of said at least three GPS antennas relative to a selected body frame of the vehicle.

18. The computer-usable medium of claim 14, wherein said computer-readable program code further causes said computer to estimate an angular orientation of said vehicle body frame.

19. A computer system comprising:

a computer signal processor;

an address and data bus connected the processor;

a computer-readable memory, connected to the processor, that provides processor instructions that allow the processor to perform the steps of;

receiving GPS carrier phase signals from at least two GPS signal sources at each of at least two GPS signal antennas and associated GPS signal receivers;

measuring double difference phase signal observations for the carrier phase signals received at the at least two GPS receivers from the at least two GPS GPS signal sources;

estimating a first value of a baseline vector for the vector separating the at least two GPS receivers, using double difference floating phase integer solutions;

estimating a second value of the baseline vector, using the first estimated baseline vector, ephemeris data for the at least two GPS signal sources and double difference fixed phase integer solutions;

computing a single difference range for each of the at least two GPS signal sources and determining single difference phase measurements for the at least two GPS signal sources; and

subtracting the computed single difference range from the single difference phase measurement, identifying the integer part of this difference with a single difference integer ambiguity, and identifying the fractional part of this difference with a line bias for a signal processing channel associated with each of the at least two GPS receivers.

20. The computer system of claim 19, wherein said processor further performs extended Kalman filtering on said single difference carrier phase observations with said fixed phase integer ambiguities to obtain a third value of said estimated baseline vector and to determine said line biases, using said estimated second baseline vector and said line biases as initial conditions.

21. The computer system of claim 20, wherein said processor further uses said Kalman filtered single difference carrier phase observations, said line biases and said third value of said estimated baseline vector to estimate an attitude or angular orientation of said at least two GPS antennas relative to each other.

22. The computer system of claim 20, wherein said processor further uses said Kalman filtered single difference carrier phase observations, said line biases and said third value of said estimated baseline vector to estimate an attitude or angular orientation of said at least three GPS antennas relative to each other.

23. The computer system of claim 22, wherein said at least three GPS antennas are positioned on a selected vehicle;

and

wherein said processor estimates an angular orientation of said at least three GPS antennas relative to a selected body frame of the vehicle.

24. The computer system of claim 23, wherein said processor estimates an angular orientation of said vehicle body frame.