Global navigation satellite system spoofer identification technique based on carrier to noise ratio signatures

• US 10,545,246 B1
• Filed: 07/08/2016
• Issued: 01/28/2020
• Est. Priority Date: 07/08/2016
• Status: Active Grant

• Current Assignee: L3harris Interstate Electronics Corporation (L3Harris Technologies, Inc.)
• Original Assignee: Interstate Electronics Corp. (L3Harris Technologies, Inc.)
• Inventors: Johnston, Ivan L., Sada, Gilberto Isaac, Alexander, Steven B.
• Primary Examiner(s): Nguyen, Chuong P
• Application Number:
  US15/205,866
• Time in Patent Office: 1,299 Days
• Field of Search: 34235759, 342372, 342379, 455296
• CPC Class Codes: G01S 19/21 Interference related issues ; Issues related to cross-correlation, spoofing or other methods of denial of service
• CPC Class Codes: G01S 19/215 issues related to spoofing
• CPC Class Codes: G01S 19/37 Hardware or software details of the signal processing chain
• CPC Class Codes: G01S 5/0036 of measured values, i.e. measurement on mobile and position calculation on base station
• CPC Class Codes: G01S 5/0249 Determining position using measurements made by a non-stationary device other than the device whose position is being determined
• CPC Class Codes: G01S 5/08 Position of single direction-finder fixed by determining direction of a plurality of spaced sources of known location
• CPC Class Codes: G01S 7/2813 Means providing a modification of the radiation pattern for cancelling noise, clutter or interfering signals, e.g. side lobe suppression, side lobe blanking, null-steering arrays specially adapted to secondary radar systems G01S13/762; aerials or aerials systems H01Q21/29, H01Q25/00
• CPC Class Codes: H01Q 1/3233 particular used as part of a sensor or in a security system, e.g. for automotive radar, navigation systems
• CPC Class Codes: H01Q 3/2611 Means for null steering; Adaptive interference nulling
• CPC Class Codes: H04B 1/10 Means associated with receiver for limiting or suppressing noise or interference

Abstract

Disclosed is a technique that can provide one or more countermeasures against spoofers. A beamformer can control an antenna pattern of a CRPA to generate a survey beam. The survey beam is swept across space to determine a characteristic signature based on carrier-to-noise ratios (C/No) for particular space vehicle signals. Matching C/No signatures can be used to identify the existence of spoofers and invoke a countermeasure, such as nulling.

Claims

1. An apparatus comprising:

a beamformer device configured to beam steer one or more survey beams of a controlled reception pattern antenna (CRPA); and

a processor configured;

to cause the beamformer device to generate the one or more survey beams of the CRPA to survey a plurality of directions in space;

to step the one or more survey beams through a plurality of azimuth angles to survey the plurality of directions in space and dwell at each step for a predetermined time and separately average C/No readings taken for a plurality of SV signals in view;

to receive space vehicle (SV) signals that appear to be associated with two or more space vehicles of a global navigation satellite system (GNSS); and

to determine whether or not a spoofer exists, wherein the spoofer is determined to exist when the space vehicle (SV) signals appearing to be associated with two or more space vehicles of the global navigation satellite system (GNSS) have similar carrier-to-noise ratio (C/No) signatures.

2. The apparatus of claim 1, wherein the processor is further configured to step the one or more survey beams through a plurality elevation angles to survey the plurality of directions in space.

3. The apparatus of claim 1, wherein the processor is further configured to step the survey beam through a total of 360 degrees to survey the plurality of directions in space.

4. The apparatus of claim 1, wherein the predetermined time corresponds to a time period between 200 milliseconds and 3 seconds.

5. The apparatus of claim 1, wherein the predetermined time corresponds to a time period of about 3 seconds.

6. The apparatus of claim 1, wherein the signature for a particular SV signal corresponds to the particular SV signal'"'"'s averaged C/No reading per sweep step.

7. The apparatus of claim 6, wherein the processor is further configured to calculate a correlation coefficient between the two or more SV signals to determine that the two or more SV signals have similar C/No signatures when the correlation coefficient is at least a predetermined value.

8. The apparatus of claim 1, wherein the processor is further configured to invoke one or more countermeasures in response to detection of the spoofer.

9. The apparatus of claim 1, wherein the processor is further configured to determine a particular beam angle from a vehicle carrying the CRPA to the spoofer based on one or more of the similar C/No signatures.

10. The apparatus of claim 9, wherein the processor is further configured to cause the beamformer device to generate and steer a null along the particular beam angle to null out signals emanating from the spoofer.

11. The apparatus of claim 10, 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 and/or changes in location of the spoofer.

12. The apparatus of claim 10, wherein the processor is further configured to:

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

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

13. The apparatus of claim 12, wherein the processor is further configured to:

receive vehicle dynamics information from an inertial measurement unit (IMU); and

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

14. The apparatus of claim 1, wherein the processor is further configured to repeatedly survey space with the one or more survey beams to confirm persistance of the spoofer and/or to observe new spoofers.

15. An apparatus comprising:

a beamformer device configured to beam steer one or more survey beams of a controlled reception pattern antenna (CRPA); and

a processor configured;

to cause the beamformer device to generate the one or more survey beams of the CRPA to survey a plurality of directions in space;

to receive space vehicle (SV) signals that appear to be associated with two or more space vehicles of a global navigation satellite system (GNSS); and

to determine whether or not a spoofer exists, wherein the spoofer is determined to exist when the space vehicle (SV) signals appearing to be associated with two or more space vehicles of the global navigation satellite system (GNSS) have similar carrier-to-noise ratio (C/No) signatures,

wherein the processor is further configured to;

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

observe the spoofer at least twice via the C/No signatures; and

determine the location of the spoofer based on observed positions of the vehicle and the observed C/No signatures.

16. The apparatus of claim 15, wherein the processor is further configured to determine the location of the spoofer by computation of the following:

17. The apparatus of claim 15, wherein the processor is further configured to at least temporarily cause the beamformer device 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.

18. The apparatus of claim 15, wherein the processor is further configured to cause the determined location of the spoofer to be transmitted to a base station.

19. The apparatus of claim 15, wherein the processor is further configured to cause the determined location of the spoofer to be provided to a targeting system.

20. An electronically-implemented method of detecting a spoofer, the method comprising:

beam steering, using a beamsteering device, one or more survey beams of a controlled reception pattern antenna (CRPA) to survey a plurality of directions in space;

stepping the one or more survey beams through a plurality of azimuth angles to survey the plurality of directions in space;

dwelling at each step for a predetermined time and separately averaging C/No readings taken for a plurality of SV signals in view;

receiving, using a receiving device, space vehicle (SV) signals that appear to be associated with two or more space vehicles of a global navigation satellite system (GNSS); and

determining, using a processing device, whether or not the spoofer exists, wherein the spoofer is determined to exist when the space vehicle (SV) signals appearing to be associated with two or more space vehicles of the global navigation satellite system (GNSS) have similar carrier-to-noise ratio (C/No) signatures.

21. The method of claim 20, further comprising stepping the one or more survey beams through a plurality of elevation angles to survey the plurality of directions in space.

22. The method of claim 20, further comprising stepping the survey beam through a total of 360 degrees to survey the plurality of directions in space.

23. The method of claim 20, wherein the predetermined time corresponds to a time period between about 200 milliseconds and about 3 seconds.

24. The method of claim 20, wherein the predetermined time corresponds to a time period of about 3 seconds.

25. The method of claim 20, wherein the signature for a particular SV signal corresponds to the particular SV signal'"'"'s averaged C/No readings per sweep step.

26. The method of claim 25, further comprising calculating a correlation coefficient between the two or more SV signals and determining that the two or more SV signals have similar C/No signatures when the correlation coefficient is at least a predetermined value.

27. The method of claim 20, further comprising invoking one or more countermeasures in response to detection of the spoofer.

28. The method of claim 20, further comprising determining a particular beam angle from a vehicle carrying the CRPA to the spoofer based on one or more of the similar C/No signatures.

29. The method of claim 28, further comprising causing the beamformer device to generate and steer a null along the particular beam angle to null out signals emanating from the spoofer.

30. The method of claim 29, 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 and/or changes in location of the spoofer.

31. The method of claim 29, further comprising:

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

causing the beamformer device to steer the null such that the null remains pointed towards the spoofer despite changes in attitude of the CRPA induced by vehicle dynamics.

32. The method of claim 31, further comprising:

receiving vehicle dynamics information from an inertial measurement unit (IMU); and

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

33. The method of claim 20, further comprising repeatedly surveying space with the one or more survey beams to confirm persistance of the spoofer and/or to observe new spoofers.

34. An electronically-implemented method of detecting a spoofer, the method comprising:

beam steering, using a beamsteering device, one or more survey beams of a controlled reception pattern antenna (CRPA) to survey a plurality of directions in space;

receiving, using a receiving device, space vehicle (SV) signals that appear to be associated with two or more space vehicles of a global navigation satellite system (GNSS); and

determining, using a processing device, whether or not the spoofer exists, wherein the spoofer is determined to exist when the space vehicle (SV) signals appearing to be associated with two or more space vehicles of the global navigation satellite system (GNSS) have similar carrier-to-noise ratio (C/No) signatures;

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

observing the spoofer at least twice via the C/No signatures; and

determining the location of the spoofer based on observed positions of the vehicle and the observed C/No signatures.

35. The method of claim 34, further comprising determining the location of the spoofer by computing the following:

36. The method of claim 34, further comprising at least temporarily causing the beamformer device 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.

37. The method of claim 34, further comprising causing the determined location of the spoofer to be transmitted to a base station.

38. The method of claim 34, further comprising causing the determined location of the spoofer to be provided to a targeting system.

39. An apparatus comprising:

a beamformer device configured to beam steer one or more survey beams of a controlled reception pattern antenna (CRPA) to survey a plurality of directions in space;

a means for stepping the one or more survey beams through a plurality of azimuth angles to survey the plurality of directions in space and dwell at each step for a predetermined time and separately average C/No readings taken for a plurality of SV signals in view;

a means for receiving space vehicle (SV) signals that appear to be associated with two or more space vehicles of a global navigation satellite system (GNSS); and

a means for determining whether or not a spoofer exists, wherein the spoofer is determine to exist when the space vehicle (SV) signals appearing to be associated with two or more space vehicles of the global navigation satellite system (GNSS) have similar carrier-to-noise ratio (C/No) signatures.