GPS multipath mitigation using a multi-element antenna array

• US 6,421,000 B1
• Filed: 06/08/2000
• Issued: 07/16/2002
• Est. Priority Date: 06/08/2000
• Status: Expired due to Term

• Current Assignee: Rockwell Collins, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Rockwell Collins, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: McDowell, Charles E.
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Marc, McDieunel, Marc, McDieunel
• Application Number:
  US09/591,099
• Time in Patent Office: 768 Days
• Field of Search: 342/375.02, 342/359, 342/352, 342/424, 342/725, 342/757, 342/357.06, 342/357.01, 342/386, 342/457, 342/357.08, 375/343, 375/355, 375/367, 375/137, 375/130, 375/145, 375/147, 375/150, 455/65, 455/296, 701/215, 702/5
• US Class Current: 342/357.59
• CPC Class Codes: G01S 19/11 wherein the cooperating elements are pseudolites or satellite radio beacon positioning system signal repeaters
• CPC Class Codes: G01S 19/22 Multipath-related issues
• CPC Class Codes: G01S 19/26 involving a sensor measurement for aiding acquisition or tracking
• CPC Class Codes: G01S 19/36 relating to the receiver frond end

Abstract

A method and apparatus for mitigating multipath signal distortion using a multi-element antenna array is provided. The multi-element antenna array is used to discriminate between the desired signal and its multipath components based on spatial angle of arrival. A reference signal, provided by the positioning system receiver, is used to compute element weightings that are utilized to null out the multipath components before they reach the receiver.

Claims

1. A method for mitigating multiple distortion in a navigation/positioning system signal, comprising:

receiving a positioning system signal including a direct path component and at least one multipath component utilizing a multi-element antenna having at least three antenna elements wherein each antenna element yields an element path signal based on the received positioning system signal;

multiplying each element path signal by a complex weight; and

summing the weighted element path signals for generating an antenna pattern, each antenna pattern corresponding to a positioning system signal source.

2. The method as claimed in claim 1, further comprising deriving each complex weight by correlating a reference signal returned from a positioning system receiver and the element path signal from each antenna element.

3. The method as claimed in claim 2, further comprising delaying the reference signal by a multiple of one chip relative to the direct path component of the positioning system signal.

4. The method as claimed in claim 3, further comprising generating a correlation matrix (R) using the equation

5. The method as claimed in claim 4, wherein each complex weight is determined from the equation

6. The method as claimed in claim 3, comprising delays at least one of 1 chip and 2 chips.

7. The method as claimed in claim 6, further comprising generating a correlation matrix (R) using the equation

8. The method as claimed in claim 7, wherein each complex weight is determined from the equation

9. A system for mitigating multipath distortion in a positioning system signal, comprising:

a multi-element antenna array capable of receiving a positioning system signal including a direct path component and at least one multipath component, said multi-element antenna array having at least three antenna elements wherein each antenna element yields an element path signal based on the received positioning system signal; and

a signal processing section capable of multiplying each element path signal by a complex weight and summing the weighted element path signals for generating an antenna pattern, each antenna pattern corresponding to a positioning system signal source.

10. The system as claimed in claim 9, wherein the signal processing section further comprises a positioning system receiver, a correlator, and a processor suitable for deriving each complex weight by correlating a reference signal returned from a positioning system receiver and the element path signal from each antenna element.

11. The system as claimed in claim 10, further comprising at least one delay for delaying the reference signal by a multiple of one chip relative to the direct path component of the positioning system signal.

12. The system as claimed in claim 11, wherein the processor generates a correlation matrix (R) using the equation

13. The system as claimed in claim 12, wherein each complex weight is determined from the equation

14. The system as claimed in claim 11, comprising delays of 1 chip and 2 chips.

15. The system as claimed in claim 11, wherein the processor generates a correlation matrix (R) using the equation

16. The system as claimed in claim 15, wherein each complex weight is determined from the equation

17. A navigation/positioning system receiver capable of mitigating multipath distortion in a global positioning system signal, comprising:

a multi-element antenna array capable of receiving a positioning system signal including a direct path component and at least one multipath component, said multi-element antenna array having at least three antenna elements wherein each antenna element yields an element path signal based on the received positioning system signal; and

a signal processing section capable of multiplying each element path signal by a complex weight and summing the weighted element path signals for generating an antenna pattern, each antenna pattern corresponding to a positioning system signal source.

18. The navigation/positioning system receiver as claimed in claim 17, wherein the signal processing section further comprises a positioning system receiver, a correlator, and a processor suitable for deriving each complex weight by correlating a reference signal returned from a positioning system receiver and the element path signal from each antenna element.

19. The navigation/positioning system receiver as claimed in claim 18, further comprising at least one delay for delaying the reference signal by a multiple of one chip relative to the direct path component of the positioning system signal.

20. The navigation/positioning system receiver as claimed in claim 19, comprising delays of 1 chip and 2 chips.

21. A method for mitigating multipath distortion in a navigation/positioning system signal, comprising:

receiving a positioning system signal including a direct path component and at least one multipath component utilizing a multi-element antenna having at least three antenna elements wherein each antenna element yields an element path signal based on the received positioning system signal;

delaying a reference signal returned from a positioning system receiver by at least one of one chip and two chips relative to the direct path component of the positioning system signal;

deriving a complex weight for the element path signal of each antenna element by correlating the reference signal and the element path signal;

multiplying each element path signal by its complex weight; and

summing the weighted element path signals for generating an antenna pattern, each antenna pattern corresponding to a positioning system signal source.

22. The method as claimed in claim 21, further comprising generating a correlation matrix (R) using the equation

23. The method as claimed in claim 22, wherein each complex weight is determined from the equation

24. A system for mitigating multipath distortion in a positioning system signal, comprising:

a multi-element antenna array capable of receiving a positioning system signal including a direct path component and at least one multipath component, said multi-element antenna array having at least three antenna elements wherein each antenna element yields an element path signal based on the received positioning system signal; and

a signal processing section including a correlator and a processor for deriving a complex weight for the element path signal from each antenna element by correlating a reference signal returned from a positioning system receiver and the element path signal, the signal processing section including at least one delay for delaying the reference signal by a multiple of one chip relative to the direct path component of the positioning system signal,

wherein the processor generates a correlation matrix (R) using the equation

25. The system as claimed in claim 24, wherein each complex weight is determined from the equation

26. The system as claimed in claim 24, comprising delays of one chip and two chips.

27. The system as claimed in claim 26, wherein each complex weight is determined from the equation