Method and apparatus for mitigating multipath effects at a satellite signal receiver using a sequential estimation filter

• US 8,395,543 B2
• Filed: 07/03/2007
• Issued: 03/12/2013
• Est. Priority Date: 10/27/2005
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Global Locate Incorporated (Broadcom, Inc.)
• Inventors: van Diggelen, Frank, Abraham, Charles, Podshivalov, Sergei
• Primary Examiner(s): Phan, Dao
• Application Number:
  US11/772,927
• Publication Number:
  US 20100019960A1
• Time in Patent Office: 2,079 Days
• Field of Search: 342/357.46, 342/357.51, 342/357.61, 701/213, 701/215, 701/412
• US Class Current: 342/357.61
• CPC Class Codes: G01S 19/22 Multipath-related issues
• CPC Class Codes: G01S 19/25 involving aiding data received from a cooperating element, e.g. assisted GPS
• CPC Class Codes: G01S 19/42 Determining position

Abstract

A method and apparatus for mitigating multipath effects in a satellite signal receiver is described. In one example, measured pseudoranges are obtained from the satellite signal receiver to a plurality of satellites. For each measured pseudorange: an expected pseudorange is derived from a sequential estimation filter in the satellite signal receiver. The measured pseudorange and the expected pseudorange are differenced to compute a pseudorange residual. The measured pseudorange is applied to the sequential estimation filter only if the pseudorange residual is within a window.

Claims

1. A method for mitigating multipath effects in a satellite-signal receiver, comprising:

computing at least one pseudorange residual as a function of a measured pseudorange to a given satellite and an expected pseudorange to the given satellite; and

when the pseudorange residual satisfies a given threshold, applying the measured pseudorange to a filter.

2. The method of claim 1, further comprising:

deriving the expected pseudorange by applying to another filter at least one a-priori parameter for mathematically projecting a pseudorange to the given satellite.

3. The method of claim 1, wherein the measured pseudorange comprises a sub-millisecond pseudorange.

4. The method of claim 1, wherein the filter comprises any of a Kalman filter and a batch filter.

5. The method of claim 1, further comprising:

applying the pseudorange residual to the given threshold.

6. The method of claim 1, farther comprising:

applying the pseudorange residual to the given threshold, wherein the threshold defines a range of values, and wherein the pseudorange residual satisfies the given threshold when the pseudorange residual has a value that is within the range of values.

7. The method of claim 6, further comprising adjusting the range of values.

8. The method of claim 7, wherein adjusting the range of values comprises any of reducing and enlarging the range of values by an amount of values in response to one or more of a number of satellites in view of the satellite-signal receiver, a Dilution of Precision, and a signal quality.

9. The method of claim 6, wherein the range of values comprises a range between about a negative 100 meters and positive 100 meters.

10. An apparatus for mitigating multipath effects in a satellite-signal receiver, comprising:

memory operable to store executable instructions; and

a processor operable to obtain from the memory the executable instructions and execute the executable instructions to;

compute at least one pseudorange residual as a function of a measured pseudorange to a given satellite and an expected pseudorange to the given satellite; and

apply the measured pseudorange to a sequential-estimation filter for solving a navigation-solution problem when the pseudorange residual satisfies a given threshold.

11. The apparatus of claim 10, wherein the processor is further operable to execute the executable instructions to:

derive the expected pseudorange by applying to another sequential-estimation filter at least one a-priori parameter for mathematically projecting a pseudorange to the given satellite.

12. The apparatus of claim 10, wherein the processor is further operable to execute the executable instructions to:

apply the pseudorange residual to the given threshold.

13. The apparatus of claim 10, wherein the processor is further operable to execute the executable instructions to:

apply the pseudorange residual to the given threshold, wherein the threshold defines a range of values, and wherein the pseudorange residual satisfies the given threshold when the pseudorange residual has a value that is within the range of values.

14. The apparatus of claim 10, wherein the processor is further operable to execute the executable instructions to:

adjust the range of values.

15. The apparatus of claim 10, wherein the processor is further operable to execute the executable instructions to:

reduce the range of values by an amount of values when at least one current state of the sequential-estimation filter is known.

16. The apparatus of claim 10, wherein the processor is further operable to execute the executable instructions to:

enlarge the range of values by an amount of values when at least one current state of the sequential-estimation filter is not known.

17. A mobile device, comprising:

a satellite signal receiver operable to process signals from at least one satellite to obtain a measured pseudorange to the satellite; and

a processor operable to compute at least one pseudorange residual as a function of the measured pseudorange to the satellite and an expected pseudorange to the satellite and to apply the measured pseudorange to a sequential-estimation filter for solving a navigation-solution problem when the pseudorange residual satisfies a given threshold.

18. The mobile device of claim 17, wherein the processor is further operable to derive the expected pseudorange by applying to another sequential-estimation filter at least one a-priori parameter for mathematically projecting a pseudorange to the given satellite.