Satellite signal multipath mitigation in GNSS devices

• US 8,717,233 B2
• Filed: 11/21/2011
• Issued: 05/06/2014
• Est. Priority Date: 11/24/2010
• Status: Active Grant

• Current Assignee: Javad GNSS, Inc.
• Original Assignee: Javad GNSS, Inc.
• Inventors: Ashjaee, Javad, Gribkov, Mikhail
• Primary Examiner(s): Phan, Dao
• Application Number:
  US13/301,633
• Publication Number:
  US 20120293365A1
• Time in Patent Office: 897 Days
• Field of Search: 342/357.21, 342/357.25, 342/357.61, 701/468, 701/469, 701/478.5
• US Class Current: 342/357.25
• CPC Class Codes: G01S 19/22 Multipath-related issues
• CPC Class Codes: G01S 19/28 Satellite selection
• CPC Class Codes: G01S 19/35 Constructional details or hardware or software details of the signal processing chain
• CPC Class Codes: G01S 19/485 whereby the further system is an optical system or imaging system

Abstract

A method for mitigating the effects of multipath errors in GNSS devices is provided. Signals from GNSS satellites are received. Image data from an image sensor is received. Orientation data from an orientation sensor is received. The orientation data describes the orientation of the image sensor. Obstruction data is determined based on the image data. The obstruction data includes an obstruction region that indicates the sky in that region is obstructed by a structure. Based on the orientation data, obstruction data, and GNSS satellite location data, the position of GNSS satellites with respect to the obstruction region is determined. The location of the GNSS device is determined based on signals from some of the GNSS satellites and the position of GNSS satellites with respect to the obstruction region.

Claims

1. A method for mitigating the effect of multipath error in a GNSS device, the method comprising:

receiving signals from a plurality of GNSS satellites;

receiving image data from at least one image sensor;

receiving orientation data from at least one orientation sensor, wherein the orientation data comprises inclination data that describes a pitch and roll of the GNSS device with respect to a horizon;

determining obstruction data based on the image data and the orientation data, wherein the obstruction data indicates an obstruction region;

based on the obstruction data, the orientation data, and GNSS satellite location data, determining the position of at least one GNSS satellite of the plurality of GNSS satellites relative to the obstruction region, wherein the GNSS satellite location data describes the location of the at least one GNSS satellite;

determining whether a satellite of the at least one GNSS satellite is an obstructed satellite if its position is within the obstruction region; and

determining the location of the GNSS device based on the signals from the plurality of GNSS satellites, wherein measurements based on signals from obstructed satellites are excluded or de-weighted relative to measurements based on other satellites of the plurality of GNSS satellites.

2. The method of claim 1, wherein the orientation data further comprises magnetic direction data that describes the magnetic direction that the GNSS device is pointing.

3. The method of claim 1, further comprising:

determining whether a satellite of the at least one GNSS satellite is a suspect satellite if its position relative to the obstruction region corresponds to a multipath error higher than a multipath threshold, wherein determining the location of the GNSS device further includes excluding or de-weighting signals from suspect satellites.

4. The method of claim 1, wherein the image data is a combination of image data received from the image sensor at different orientations.

5. A non-transitory computer readable storage medium storing computer executable instructions for:

receiving signals from a plurality of GNSS satellites;

receiving image data from at least one image sensor;

receiving orientation data from at least one orientation sensor, wherein the orientation data comprises inclination data that describes a pitch and roll of a GNSS device with respect to a horizon;

determining obstruction data based on the image data and the orientation data, wherein the obstruction data indicates an obstruction region;

based on the obstruction data, the orientation data, and GNSS satellite location data, determining the position of at least one GNSS satellite of the plurality of GNSS satellites relative to the obstruction region, wherein the GNSS satellite location data describes the location of the at least one GNSS satellite;

determining whether a satellite of the at least one GNSS satellite is an obstructed satellite if its position is within the obstruction region; and

determining the location of the GNSS device based on the signals from the plurality of GNSS satellites, wherein measurements based on signals from obstructed satellites are excluded or de-weighted relative to measurements based on other satellites of the plurality of GNSS satellites.

6. The non-transitory computer readable storage medium of claim 5, wherein the orientation data further comprises magnetic direction data that describes the magnetic direction that the GNSS device is pointing.

7. The non-transitory computer readable storage medium of claim 5, further storing computer executable instructions for:

determining whether a satellite of the at least one GNSS satellite is a suspect satellite if its position relative to the obstruction region corresponds to a multipath error higher than a multipath threshold, wherein determining the location of the GNSS device further includes excluding or de-weighting signals from suspect satellites.

8. The non-transitory computer readable storage medium of claim 5, wherein the image data is a combination of image data received from the image sensor at different orientations.

9. A GNSS device for mitigating the effect of multipath error, the GNSS device comprising:

at least one antenna configured to receive signals from a plurality of GNSS satellites;

at least one image sensor configured to generate image data;

at least one orientation sensor configured to generate orientation data, wherein the orientation data comprises inclination data that describes a pitch and roll of the GNSS device with respect to a horizon; and

a processor configured to;

determine obstruction data based on the image data and the orientation data, wherein the obstruction data indicates an obstruction region;

based on the obstruction data, the orientation data, and GNSS satellite location data, determine the position of at least one GNSS satellite of the plurality of GNSS satellites relative to the obstruction region, wherein the GNSS satellite location data describes the location of the at least one GNSS satellite;

determine whether a satellite of the at least one GNSS satellite is an obstructed satellite if its position is within the obstruction region; and

determine the location of the GNSS device based on the signals from the plurality of GNSS satellites, wherein measurements based on signals from obstructed satellites are excluded or de-weighted relative to measurements based on other satellites of the plurality of GNSS satellites.

10. The GNSS device of claim 9, wherein the orientation data further comprises magnetic direction data that describes the magnetic direction that the GNSS device is pointing.

11. The GNSS device of claim 9, wherein the processor is further configured to determine whether a satellite of the at least one GNSS satellite is a suspect satellite if its position relative to the obstruction region corresponds to a multipath error higher than a multipath threshold, wherein determining the location of the GNSS device further includes excluding or de-weighting signals from suspect satellites.

12. The GNSS device of claim 9, wherein the image data is a combination of image data received from the image sensor at different orientations.