Method and system for circular polarization correction for independently moving GNSS antennas

• US 7,504,995 B2
• Filed: 08/11/2004
• Issued: 03/17/2009
• Est. Priority Date: 08/11/2004
• Status: Active Grant

• Current Assignee: Novariant Incorporated (Kubota Corporation)
• Original Assignee: Novariant Incorporated (Kubota Corporation)
• Inventors: Lawrence, David Gary, O'Connor, Michael L.
• Primary Examiner(s): Tarcza; Thomas H
• Assistant Examiner(s): Nguyen; Nga X
• Application Number:
  US10/916,198
• Publication Number:
  US 20060033657A1
• Time in Patent Office: 1,679 Days
• Field of Search: 34235701-35717, 342/361, 342/381, 701/4, 701/215, 701/216, 244/171
• US Class Current: 342/357.37
• CPC Class Codes: H01Q 1/1257 using the received signal strength

Abstract

A system and method for compensating for changes in relative antenna attitude in a single-receiver position detection system, such as a differential carrier phase GPS system, utilizes sensor input to detect changes in the relative attitude of at least two antennas or an antenna positioner, such as an motorized actuator or operator, that orients or re-orients the antennas to a predetermined orientation. The changes in the detected relative carrier phase due to the right hand circular polarized nature of the carrier signals are thus corrected. In this way, the high positional accuracy associated with kinematic GPS systems, for example, can be achieved even when the system'"'"'s antennas are not constrained by a common rigid body, for example.

Claims

1. A position detection system, comprising:

a first antenna for receiving carrier signals;

a second antenna for receiving the carrier signals, the second antenna being subject to changes in attitude relative to the first antenna;

an antenna attitude compensator for providing carrier phase correction induced by the changes in relative attitude between the first antenna and the second antenna; and

a receiver for processing carrier signal information from the first antenna and the second antenna in response to a common clock signal and the antenna attitude compensator.

2. A position detection system as claimed in claim 1, wherein the antenna attitude compensator comprises an antenna attitude sensor for detecting changes in relative attitude for the antennas, the receiver determining the position in response to the relative attitude of the antennas.

3. A position detection system as claimed in claim 1, wherein the antenna attitude compensator comprises an antenna positioner that controls an attitude of at least one of the antennas to avoid changes in relative attitude for the antennas.

4. A position detection system as claimed in claim 1, wherein the antenna attitude compensator uses the receiver to determine changes in relative attitude between the first set and the second set of antennas by processing the carrier signals from the antennas using the common clock signal.

5. A position detection system as claimed in claim 1, further comprising a carrier information transmission line for transmitting carrier information from at least one of the first antenna and second antenna to the receiver.

6. A position detection system as claimed in claim 5, wherein a timing delay of the carrier information transmission line is used by the receiver to process the carrier signal information.

7. A position detection system as claimed in claim 1, wherein the antenna attitude actuator points a first one of the antennas to match an attitude of a second one of the antennas.

8. A position detection system as claimed in claim 1, wherein:

the first antenna is part of a first set of antennas; and

the second antenna is part of a second set of antennas.

9. A system as claimed in claim 2, wherein the antenna attitude sensor directly measures changes in the relative attitude of the antennas.

10. A system as claimed in claim 2, wherein the antenna attitude sensor is a magnetic sensor.

11. A system as claimed in claim 2, wherein the antenna attitude sensor is an inertial sensor.

12. A system as claimed in claim 2, wherein the antenna attitude sensor indirectly measures changes in the relative attitude of the antennas by monitoring control instructions indicating changes to the relative attitude.

13. A system as claimed in claim 1, wherein the antenna attitude sensor comprises two or more antennas, having a common attitude relative to each other, that receive the carrier signals, the receiver processing the carrier signal information from the two or more antennas in response to the common clock signal to determine the common attitude of the two or more antennas.

14. A system as claimed in claim 1, wherein the carrier signals are generated by a global positioning system.

15. A system as claimed in claim 14, wherein the global positioning system is the Global Navigation Satellite System.

16. A system as claimed in claim 14, wherein the global positioning system is the Global Orbiting Navigation Satellite System (GLONASS).

17. A system as claimed in claim 14, wherein the global positioning system is the Galileo System.

18. A system as claimed in claim 1, wherein the antennas are mounted on different platforms capable of relative angular motion.

19. A system as claimed in claim 1, wherein the common clock is formed by synchronizing multiple clock signals for multiple clocks for processing the carrier signals that are received by the antennas.

20. A system as claimed in claim 1, wherein the antennas are mounted on a vehicle, with a first one of the antennas rigidly mounted relative to a frame of the vehicle and a second one of the antennas mounted on a part of the vehicle that moves relative to the frame.

21. A system as claimed in claim 20, wherein the antenna attitude sensor is mounted on the part of the vehicle that moves relative to the frame.

22. A system as claimed in claim 20, wherein the part is a blade of the vehicle.

23. A system as claimed in claim 1, wherein the antennas are mounted on units that move relative to each other, at least one of the units having the antenna attitude sensor.

24. A system as claimed in claim 23, wherein both units have an antenna attitude sensor.

25. A system as claimed in claim 3, wherein the positioner comprises an operator.

26. A system as claimed in claim 3, wherein the positioner comprises an actuator.

27. A system as claimed in claim 3, wherein the positioner comprises an antenna attitude sensor for detecting an attitude of the at least one antenna, and the positioner orients said antenna in response to the attitude sensor.

28. A system as claimed in claim 1, wherein the common clock is formed by synchronizing multiple clock signals for multiple clocks for processing the carrier signals that are received by the antennas.

29. A system as claimed in claim 1, wherein the antennas are mounted on a vehicle, with a first one of the antennas rigidly mounted relative to a frame of the vehicle and a second one of the antennas mounted on a part of the vehicle that moves relative to the frame.

30. A system as claimed in claim 1, wherein the antennas are mounted on separate survey units that move relative to each other, at least one of the units having the antenna attitude sensor.

31. A system as claimed in claim 1, further comprising a user interface indicating a protocol for aligning the antennas to an operator.

32. A system as claimed in claim 1, further comprising a user interface, which an operator uses to indicate that the antennas have been aligned.

33. A system as claimed in claim 1, further comprising two or more mobile antennas.

34. A system as claimed in claim 1, further comprising a manual specifying a protocol for aligning the antennas for an operator.

35. A system as claimed in claim 34, wherein the manual instructs the operator to avoid phase wind up during placement of the base antenna and the mobile antenna.

36. A position detection system as claimed in claim 1, wherein the antenna attitude compensator provides the carrier phase correction induced by the changes in relative attitude between the first antenna and the second antenna by correcting for polarization of the carrier signals.

37. A position detection system as claimed in claim 1, wherein the antenna attitude compensator provides the carrier phase correction induced by the changes in relative attitude between the first antenna and the second antenna by correcting for right hand circular polarization of the carrier signals.

38. A position detection system as claimed in claim 1, wherein the antenna attitude compensator determines antenna yaw angle and direction to the position detection system and the position detection system uses the yaw angle and direction to determine a position solution for the antennas.