Global navigation satellite system spoofer identification technique

1. An apparatus comprising:

a beamformer configured to generate a plurality of antenna patterns to beam steer a main lobe of an antenna pattern of a controlled reception pattern antenna (CRPA);

a processor of a global navigation satellite system (GNSS) receiver configured:

to cause the beamformer to generate and steer the main lobe of the CRPA to survey a plurality of directions in space;

determine that a spoofer exists along a particular beam angle in the surveyed space when signals appearing to be associated with two or more space vehicles of a global navigation satellite system are higher in signal power along the particular beam angle relative to other directions; and

to cause the beamformer to generate and steer a null along the particular beam angle to null out signals emanating from the spoofer such that interfering signals from the spoofer are suppressed.

2. The apparatus of claim 1 , wherein the signal power comprises a carrier power to noise ratio.

3. The apparatus of claim 1 , wherein the processor is configured to actively steer the null such that the null remains pointed towards the spoofer despite changes in attitude induced by vehicle dynamics of a vehicle to which the CRPA is attached and/or changes in location of the spoofer.

4. The apparatus of claim 1 , wherein the processor is further configured to:

reference beam steering and null steering activities to a global reference frame; and

cause the beamformer to steer the null such that the null remains pointed towards the spoofer despite changes in attitude of the CRPA induced by vehicle dynamics of a vehicle to which the CRPA is attached.

5. The apparatus of claim 4 , wherein the processor is further configured to:

receive vehicle dynamics information of a vehicle from an inertial measurement unit (IMU), wherein CRPA and the IMU are attached to the vehicle; and

cause the beamformer to steer the null based at least partly on the vehicle dynamics information.

6. The apparatus of claim 1 , wherein the processor is further configured to estimate a heading of an object based at least partly on beam steering main lobe angles to GNSS space vehicle positions and an orientation of the object with respect to the GNSS space vehicle positions, wherein the CRPA is attached, directly or indirectly, to the object.

7. The apparatus of claim 1 , wherein the processor is further configured to repeatedly survey a plurality of beam angles and determine new beam angles to the spoofer and/or to observe new spoofers.

8. The apparatus of claim 1 , wherein the processor is further configured to:

determine a position of an object with the GNSS signals, wherein the CRPA is attached, directly or indirectly, to the object;

observe the spoofer at least twice; and

determine the location of the spoofer based on observed positions of the object and observed beam angles to the spoofer.

9. The apparatus of claim 8 , wherein the processor is further configured to determine the location of the spoofer by computation of the following:

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wherein s corresponds to the location of the spoofer, i corresponds to an observation index, I corresponds to an identity matrix, v i corresponds to a unit vector having in an i-th observed direction to the spoofer, v i T corresponds to a transpose of the vector v i , and p i corresponds to a position of the object at observation i.

10. The apparatus of claim 8 , wherein the processor is further configured to at least temporarily cause the beamformer to generate and steer the null based at least partly on the determined location of the spoofer, the position of the object, and an attitude of the object.

11. The apparatus of claim 8 , wherein the processor is further configured to cause the determined location of the spoofer to be transmitted to a base station.

12. The apparatus of claim 8 , wherein the processor is further configured to cause the determined location of the spoofer to be provided a targeting system.

13. The apparatus of claim 1 , wherein the processor is configured to determine that the spoofer exists along the particular beam angle when the signal power increases beyond a predetermined threshold amount or by a predetermined threshold ratio for signals appearing to be associated with the two or more GNSS satellites.

14. The apparatus of claim 1 , wherein the processor is configured to determine that the spoofer exists along the particular beam angle when the signal power increases beyond a predetermined threshold amount or by a predetermined threshold ratio for the majority the signals appearing to be associated with the two or more GNSS satellites.

15. An electronically-implemented method of invoking a countermeasure for a global navigation satellite system (GNSS) receiver, the method comprising:

beam steering, by a beamformer of the GNSS receiver, a main lobe of a survey antenna pattern of a controlled reception pattern antenna (CRPA) connected to the GNSS receiver to survey a plurality of directions in space;

determining, by a processor of the GNSS receiver, that a spoofer exists along a particular beam angle in the surveyed space when signals appearing to be associated with two or more space vehicles of a global navigation satellite system are higher in signal power along the particular beam angle relative to other directions; and

steering, by a beamformer of the GNSS receiver, a null of an antenna pattern along the particular beam angle to null out signals emanating from the spoofer such that interfering signals from the spoofer are suppressed.

16. The method of claim 15 , wherein the signal power comprises a carrier power to noise ratio.

17. The method of claim 15 , further comprising actively steering such that the null remains pointed towards the spoofer despite changes in attitude induced by vehicle dynamics of a vehicle to which the CRPA is attached and/or changes in location of the spoofer.

18. The method of claim 15 , further comprising:

referencing the beam steering and null steering to a global reference frame; and

steering such that the null remains pointed towards the spoofer despite changes in attitude induced by vehicle dynamics of a vehicle to which the CRPA is attached.

19. The method of claim 18 , further comprising:

receiving vehicle dynamics information of a vehicle from an inertial measurement unit (IMU), wherein the CRPA and the IMU are attached to the vehicle; and

steering the null based at least partly on the vehicle dynamics information.

20. The method of claim 15 , further comprising estimating a heading based at least partly on beam steering main lobe angles and the position of the GNSS receiver.

21. The method of claim 15 , further comprising repeatedly performing beam steering and determining to obtain new beam angles to the spoofer and/or to observe new spoofers.

22. The method of claim 15 , further comprising:

determining a position of an object with the GNSS signals, wherein the CRPA is attached, directly or indirectly, to the object;

observing the spoofer at least twice; and

determining the location of the spoofer based on observed positions of a object and observed beam angles to the spoofer.

23. The method of claim 22 , wherein determining the location of the spoofer further comprises computing the following:

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wherein s corresponds to the location of the spoofer, i corresponds to an observation index, I corresponds to an identity matrix, v i corresponds to a unit vector having in an i-th observed direction to the spoofer, v i T corresponds to a transpose of the vector v i , and p i corresponds to a position of the object at observation i.

24. The method of claim 22 , further comprising at least temporarily performing further null steering based at least partly on the determined location of the spoofer, the position of the object, and an attitude of the object.

25. The method of claim 22 , further comprising transmitting the determined location to a base station.

26. The method of claim 22 , further comprising providing the location of the spoofer to a targeting system.

27. An apparatus comprising:

a beamformer configured to beam steer a main lobe of a first antenna pattern of a controlled reception pattern antenna (CRPA) for surveying and to steer a null of a second antenna pattern of the CRPA as a countermeasure; and

a means for determining that a spoofer exists along a particular beam angle when signals appearing to be associated with two or more space vehicles of a global navigation satellite system (GNSS) increase in signal power along the particular beam angle relative to other directions, wherein the determining means is part of a GNSS receiver, wherein the determining means is further configured to cause the beamformer to direct the null along the particular beam angle such that interfering signals from the spoofer are suppressed.