Global navigation satellite antenna systems and methods

• US 20120119951A1
• Filed: 11/17/2010
• Published: 05/17/2012
• Est. Priority Date: 11/17/2010
• Status: Active Grant

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Vollath, Ulrich
• Granted Patent: US 8,669,900 B2
• Time in Patent Office: Days
• US Class Current: 342/357.61
• CPC Class Codes: G01C 15/00 Surveying instruments or accessories not provided for in groups G01C1/00 - G01C13/00
• CPC Class Codes: G01S 19/22 Multipath-related issues

Abstract

A method for reducing multipath when determining a location of a stationary or near stationary position, includes receiving a signal from an antenna moving continuously with respect to the stationary or near stationary position, the signal including a multipath component, processing the received signal including the multipath component, wherein multipath error in the received signal is reduced during the processing and determining a location of the stationary or near stationary position based on the processed received signal with the multipath error reduced.

Claims

1. A method for reducing multipath error when determining a location of a stationary or near stationary position, comprising:

receiving a signal from an antenna moving continuously with respect to the stationary or near stationary position, the signal including a multipath component;

processing the received signal including the multipath component, wherein multipath error in the received signal is reduced during the processing; and

determining a location of the stationary or near stationary position based on the processed received signal with the multipath error reduced.

2. The method as recited in claim 1, wherein the antenna is moved in a circular pattern around the stationary or near stationary position.

3. The method as recited in claim 2, wherein a diameter of the circular pattern is equivalent to at least one GNSS wavelength.

4. The method as recited in claim 3, wherein the diameter is at least 24 cm.

5. The method as recited in claim 1, wherein the antenna is moved in epicycles.

6. The method as recited in claim 1, wherein the antenna is moved in a pattern such that it crosses a minima and maxima of at least one GNSS wavelength.

7. The method as recited in claim 6, wherein the at least one GNSS wavelength is based on a GPS L2 carrier wave frequency.

8. The method as recited in claim 7, wherein the GNSS wavelength is approximately 24 cm.

9. The method as recited in claim 1, wherein the antenna is continuously moved vertically with respect to the stationary or near stationary position.

10. The method as recited in claim 9, wherein the antenna is moved up and down a distance corresponding to at least one GNSS wavelength.

11. The method as recited in claim 10, wherein the at least one GNSS wavelength is approximately 24 cm.

12. The method as recited in claim 1, wherein the determining step comprises determining a location of the antenna and referencing back from there to the location of the stationary or near stationary position.

13. The method as recited in claim 1, wherein the multipath error is averaged out during the processing.

14. The method as recited in claim 1, wherein the multipath error is filtered out during processing.

15. A system for reducing multipath error when determining a location of a stationary or near stationary position, comprising:

a moving platform having an antenna mounted thereto, the moving platform moving the antenna continuously with respect to the stationary or near stationary position;

a receiver for receiving a signal from the continuously moving antenna, the signal including a multipath component;

a processor for processing the received signal including the multipath component, wherein multipath error in the received signal is reduced during the processing; and

a location determining unit for determining a location of the stationary or near stationary position based on the processed received signal with the multipath error reduced.

16. The system as recited in claim 15, wherein the moving platform rotates to move the antenna in a circular pattern around the stationary or near stationary position.

17. The system as recited in claim 16, wherein the circular pattern is centered over the stationary or near stationary position.

18. The system as recited in claim 15, wherein the antenna is mounted on the moving platform a distance corresponding to at least one-half of one GNSS wavelength from the stationary or near stationary position.

19. The system as recited in claim 16, wherein the GNSS wavelength is approximately 24 cm.

20. The system as recited in claim 15, wherein the moving platform moves the antenna in epicycles.

21. The system as recited in claim 15, wherein the moving platform moves the antenna in a pattern such that it crosses a minima and maxima of at least one GNSS wavelength.

22. The system as recited in claim 21, wherein the at least one GNSS wavelength is based on a GPS L2 carrier wave frequency.

23. The system as recited in claim 22, wherein the GNSS wavelength is approximately 24 cm.

24. The system as recited in claim 15, wherein the moving platform continuously moves the antenna vertically with respect to the stationary or near stationary position.

25. The system as recited in claim 24, wherein the antenna is moved up and down a distance corresponding to at least one GNSS wavelength.

26. The system as recited in claim 25, wherein the at least one GNSS wavelength is approximately 24 cm.

27. The system as recited in claim 25 wherein the location determining unit determines a location of the antenna and references back from there to the location of the stationary or near stationary position.

28. The system as recited in claim 15, wherein the multipath error is averaged out during the processing.

29. The system as recited in claim 15, wherein the multipath error is filtered out during processing.

30. A system for reducing multipath error when determining a location of a stationary or near stationary position, comprising:

a plurality of antennas arranged in positions fixed with respect to the stationary or near stationary position;

a combining unit for combining signals from the plurality of antennas and outputting a compound received signal, the compound received signal including a multipath component;

a processor for processing the compound received signal including the multipath component, wherein multipath error in the compound received signal is reduced during the processing; and

a location determining unit for determining a location of the stationary or near stationary position based on the processed compound received signal with the multipath error reduced.

31. The system as recited in claim 30, wherein said combining unit comprises:

a plurality of variable attenuators each receiving a signal from one of the plurality of antennas, each variable attenuator attenuating or amplifying and outputting the received signal; and

a mixer for combining outputs of the variable attenuators and outputting the compound received signal.

32. The system as recited in claim 31, further comprising an attenuation controller for controlling each of the variable attenuators so that each received signal is attenuated or amplified for defined periods of time and output.

33. The system as recited in claim 32, wherein transitions between periods of attenuation and amplification are gradual for each signal.

34. The system as recited in claim 33, wherein only one signal from one of the antennas is output to the mixer at a time except during transitions.

35. The system as recited in claim 34, wherein during transitions, signals from two antennas are gradually mixed by gradually attenuating one while gradually amplifying the other.

36. The system as recited in claim 30, wherein the processor and location determining unit comprise a GNSS receiver.

37. The system as recited in claim 30, wherein the multipath error is averaged out during the processing.

38. The system as recited in claim 30, wherein the multipath error is filtered out during processing.

39. A method for reducing multipath error when determining a location of a stationary or near stationary position, comprising:

receiving signals from a plurality of antennas arranged in positions fixed with respect to the stationary or near stationary position;

combining the signals from the plurality of antennas and outputting a compound received signal, the compound received signal including a multipath component;

processing the compound received signal including the multipath component, wherein multipath error in the compound received signal is reduced during the processing; and

determining a location of the stationary or near stationary position based on the processed compound received signal with the multipath error reduced.

40. The method as recited in claim 39, wherein said combining step comprises:

selectively attenuating or amplifying the received signals; and

combining the attenuated or amplified signals and outputting the compound received signal.

41. The method as recited in claim 40, further comprising attenuating or amplifying each received signal for defined periods of time.

42. The method as recited in claim 41, wherein transitions between periods of attenuation and amplification are gradual for each signal.

43. The method as recited in claim 42, wherein during transitions, signals from two antennas are gradually mixed by gradually attenuating one while gradually amplifying the other.

44. The method as recited in claim 39, wherein the multipath error is averaged out during the processing.

45. The method as recited in claim 39, wherein the multipath error is filtered out during processing.