FAST RECOVERY FROM INCORRECT CARRIER PHASE INTEGER LOCKING

• US 20180074211A1
• Filed: 09/13/2016
• Published: 03/15/2018
• Est. Priority Date: 09/13/2016
• Status: Active Application

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: NIESEN, Urs, GARIN, Lionel Jacques, JOSE, Jubin
• Granted Patent: US 10,274,607 B2
• Time in Patent Office: Days
• CPC Class Codes: G01S 19/23 Testing, monitoring, correcting or calibrating of receiver elements
• CPC Class Codes: G01S 19/426 by combining or switching between position solutions or signals derived from different modes of operation in a single system
• CPC Class Codes: G01S 19/44 Carrier phase ambiguity resolution; Floating ambiguity; LAMBDA [Least-squares AMBiguity Decorrelation Adjustment] method

Abstract

Determining a position of a device using a signal received from a reference emitter includes: receiving the signal; determining a state of a first filter, the state of the first filter including a first carrier phase ambiguity estimate that includes a floating value; determining a state of a second filter, the state of the second filter including a second carrier phase ambiguity estimate that includes a fixed value; determining whether the state of the second filter is consistent with one other filter state or measurement; maintaining the state of the second filter in response to the device determining that the state of the second filter is consistent with the other filter state; changing the state of the second filter to the state of the first filter in response to the device determining that the state of the second filter is not consistent with the other filter state.

Claims

1. A method of determining a position of a device using a signal received from a reference emitter, the method comprising:

receiving, with a receiver of the device, the signal from the reference emitter;

determining a state of a first filter based on the signal, wherein the state of the first filter includes a first carrier phase ambiguity estimate comprising a floating value;

determining a state of a second filter based on the signal, wherein the state of the second filter includes a second carrier phase ambiguity estimate comprising a fixed value;

determining whether the state of the second filter is consistent with at least one other filter state or measurement;

maintaining the state of the second filter in response to the device determining that the state of the second filter is consistent with the at least one other filter state or measurement;

changing the state of the second filter to the state of the first filter in response to the device determining that the state of the second filter is not consistent with the at least one other filter state or measurement; and

determining the position of the device based on the state of the second filter.

2. The method of claim 1, wherein the at least one other filter state is a previous state of the second filter.

3. The method of claim 2, wherein determining whether the state of the second filter is consistent with the at least one other filter state or measurement comprises determining whether a measurement prediction residual based on a current measurement is consistent with the previous state of the second filter.

4. The method of claim 1, wherein the at least one other filter state is the state of the first filter.

5. The method of claim 4, wherein determining whether the state of the second filter is consistent with the at least one other filter state comprises determining whether an estimate from the state of the second filter is consistent with a variance of an estimate from the state of the first filter.

6. The method of claim 1, wherein the first filter is a first Kalman filter and the second filter is a second Kalman filter.

7. The method of claim 1, further comprising fixing the second carrier phase ambiguity estimate by setting a covariance matrix term associated with the second carrier phase ambiguity estimate to be equal to or approximately equal to zero.

8. The method of claim 1, wherein the reference emitter is a satellite.

9. A device for determining a position of the device using a signal received from a reference emitter, the device comprising:

a wireless receiver for wirelessly receiving the signal from the reference emitter; and

a processor, communicatively coupled to the wireless receiver, configured to;

determine a state of a first filter based on the signal, wherein the state of the first filter includes a first carrier phase ambiguity estimate comprising a floating value;

determine a state of a second filter based on the signal, wherein the state of the second filter includes a second carrier phase ambiguity estimate comprising a fixed value;

determine whether the state of the second filter is consistent with at least one other filter state or measurement;

maintain the state of the second filter in response to the processor determining that the state of the second filter is consistent with the at least one other filter state or measurement;

change the state of the second filter to the state of the first filter in response to the processor determining that the state of the second filter is not consistent with the at least one other filter state or measurement; and

determine the position of the device based on the state of the second filter.

10. The device of claim 9, wherein the at least one other filter state is a previous state of the second filter.

11. The device of claim 10, wherein the processor is configured to determine whether the state of the second filter is consistent with the at least one other filter state by determining whether a measurement prediction residual based on a current measurement is consistent with the previous state of the second filter.

12. The device of claim 9, wherein the at least one other filter state is the state of the first filter.

13. The device of claim 12, wherein the processor is configured to determine whether the state of the second filter is consistent with the at least one other filter state by determining whether an estimate from the state of the second filter is consistent with a variance of an estimate from the state of the first filter.

14. The device of claim 9, wherein the first filter is a first Kalman filter and the second filter is a second Kalman filter.

15. The device of claim 9, wherein the processor is configured to fix the second carrier phase ambiguity estimate by setting a covariance matrix term associated with the second carrier phase ambiguity estimate to be equal to or approximately equal to zero.

16. A device for determining a position of the device using a signal received from a reference emitter, the device comprising:

receiving means for wirelessly receiving the signal from the reference emitter;

first filtering means for determining a first state based on the signal, wherein the first state includes a first carrier phase ambiguity estimate comprising a floating value;

second filtering means for determining a second state based on the signal, wherein the second state includes a second carrier phase ambiguity estimate comprising a fixed value;

determining means for determining whether the second state is consistent with at least one other filter state or measurement;

maintaining means for maintaining the second state in response to the device determining that the second state is consistent with the at least one other filter state or measurement;

changing means for changing the second state to the first state in response to the device determining that the second state is not consistent with the at least one other filter state or measurement; and

positioning means for determining the position of the device based on the second state.

17. The device of claim 16, wherein the at least one other filter state is a previous state of the second filtering means.

18. The device of claim 17, wherein the determining means comprises means for determining whether a measurement prediction residual based on a current measurement is consistent with the previous state of the second filtering means.

19. The device of claim 16, wherein the at least one other filter state is the first state.

20. The device of claim 19, wherein the determining means comprises means for determining whether an estimate from the second state is consistent with a variance of an estimate from the first state.

21. The device of claim 16, wherein the first filtering means comprises a first Kalman filter and the second filtering means comprises a second Kalman filter.

22. The device of claim 16, wherein the second filtering means comprises fixing means for setting a covariance matrix term associated with the second carrier phase ambiguity estimate to be equal to or approximately equal to zero.

23. A non-transitory processor-readable storage medium comprising processor-readable instructions configured to cause a processor of a device to:

receive a signal from a reference emitter;

determine a state of a first filter based on the signal, wherein the state of the first filter includes a first carrier phase ambiguity estimate comprising a floating value;

determine a state of a second filter based on the signal, wherein the state of the second filter includes a second carrier phase ambiguity estimate comprising a fixed value;

determine whether the state of the second filter is consistent with at least one other filter state or measurement;

maintain the state of the second filter in response to the device determining that the state of the second filter is consistent with the at least one other filter state or measurement;

change the state of the second filter to the state of the first filter in response to the device determining that the state of the second filter is not consistent with the at least one other filter state or measurement; and

determine a position of the device based on the state of the second filter.

24. The non-transitory processor-readable storage medium of claim 23, wherein the at least one other filter state is a previous state of the second filter.

25. The non-transitory processor-readable storage medium of claim 24, wherein the instructions configured to cause the processor to determine whether the state of the second filter is consistent with the at least one other filter state comprise instructions configured to cause the processor to determine whether a measurement prediction residual based on a current measurement is consistent with the previous state of the second filter.

26. The non-transitory processor-readable storage medium of claim 23, wherein the at least one other filter state is the state of the first filter.

27. The non-transitory processor-readable storage medium of claim 26, wherein the instructions configured to cause the processor to determine whether the state of the second filter is consistent with the at least one other filter state comprise instructions configured to cause the processor to determine whether the state of the second filter is consistent with a variance of an estimate from the state of the first filter.

28. The non-transitory processor-readable storage medium of claim 23, wherein the first filter is a first Kalman filter and the second filter is a second Kalman filter.

29. The non-transitory processor-readable storage medium of claim 23, further comprising instructions configured to cause the processor of the device to fix the second carrier phase ambiguity estimate by setting a covariance matrix term associated with the second carrier phase ambiguity estimate to be equal to or approximately equal to zero.

30. The non-transitory processor-readable storage medium of claim 23, wherein the reference emitter is a satellite.