Global navigation satellite system beam based attitude determination

• US 10,031,234 B1
• Filed: 04/03/2015
• Issued: 07/24/2018
• Est. Priority Date: 04/03/2015
• Status: Active Grant

• Current Assignee: L3harris Interstate Electronics Corporation (L3Harris Technologies, Inc.)
• Original Assignee: Interstate Electronics Corp. (L3Harris Technologies, Inc.)
• Inventors: Alexander, Steven B.
• Primary Examiner(s): Gregory, Bernarr E
• Application Number:
  US14/678,768
• Time in Patent Office: 1,208 Days
• Field of Search: 34235759
• CPC Class Codes: G01S 19/215 issues related to spoofing
• CPC Class Codes: G01S 19/36 relating to the receiver frond end
• CPC Class Codes: G01S 19/53 Determining attitude

Abstract

Disclosed is a technique to estimate at least a portion of an attitude, such as an azimuth angle from true North, based on beam angles from a controlled reception pattern antenna (CRPA) to space vehicle locations. Other attitude information such as roll and/or pitch can also be estimated. The at least portion of the attitude can be provided with or without an additional sensor, such as a compass or magnetometer, an inertial measurement unit (IMU), or the like. An attitude estimate can be useful because oftentimes the attitude of an object can vary from its track or velocity direction.

Claims

1. An apparatus for determining at least one of a heading, roll, or pitch of an attitude of an object based on signals received by a controlled reception pattern antenna (CRPA) that is attached, directly or indirectly, to the object, the apparatus comprising:

a digital beamformer configured to generate one or more antenna patterns for digital baseband received signals corresponding to signals received by the CRPA; and

a processor configured;

to associate instances of observed signal strength of signals at various observed beam angles of the CRPA with physical locations of a plurality of space vehicles, wherein the plurality of space vehicles comprise sources of the signals; and

to determine the at least one of the heading, roll, or pitch of the attitude of the object based at least partly on the orientation of the object with respect to the observed beam angles;

a plurality of low noise amplifiers (LNAs) operatively coupled to a plurality of antenna elements of the CRPA, wherein the LNAs are configured to generate amplified signals;

a plurality of radio frequency (RF) downconverters operatively coupled to the plurality of LNAs, the RF downconverters configured to downconvert received signals from RF to baseband to generate baseband received signals; and

a plurality of analog-to-digital converters (ADCs) configured to receive the baseband received signals and to generate the digital baseband received signals;

wherein the digital beamformer is configured to combine the digital baseband received signals to generate the one or more antenna patterns.

2. The apparatus of claim 1, wherein the processor is further configured to determine the orientation of the object by conversion of the orientation from a first reference frame to a second reference frame, wherein the first reference frame is relative to beamforming angles and the second reference frame is global.

3. The apparatus of claim 1, wherein the observed signal strength is based on at least one of a carrier to noise ratio, signal to noise ratio, signal to interference plus noise ratio, carrier power to noise ratio, carrier power to interference plus noise ratio, or a raw power.

4. The apparatus of claim 1, wherein the apparatus comprises a global positioning system (GPS) receiver.

5. The apparatus of claim 1, wherein the beamformer is further configured to null one or more spoofers when spoofing is detected.

6. An apparatus for determining at least one of a heading, roll, or pitch of an attitude of an object based on signals received by a controlled reception pattern antenna (CRPA) that is attached, directly or indirectly, to the object, the apparatus comprising:

a digital beamformer configured to generate one or more antenna patterns for digital baseband received signals corresponding to signals received by the CRPA; and

a processor configured;

to associate instances of observed signal strength of signals at various observed beam angles of the CRPA with physical locations of a plurality of space vehicles, wherein the plurality of space vehicles comprise sources of the signals; and

to determine the at least one of the heading, roll, or pitch of the attitude of the object based at least partly on the orientation of the object with respect to the observed beam angles,

wherein each space vehicle broadcasts a unique pseudorandom noise (PRN) code, wherein the processor is further configured to identify which unique PRN code bearing signal experiences an increase in signal power when a main lobe of an antenna pattern of the beamformer is directed to a particular instance of observed signal strength to determine which space vehicle corresponds to the instance of observed signal strength.

7. The apparatus of claim 6, wherein the signal power comprises at least one of a carrier power to noise ratio, signal to noise ratio, signal to interference plus noise ratio, carrier power to noise ratio, carrier power to interference plus noise ratio, or a raw power.

8. An apparatus for determining at least one of a heading, roll, or pitch of an attitude of an object based on signals received by a controlled reception pattern antenna (CRPA) that is attached, directly or indirectly, to the object, the apparatus comprising:

a digital beamformer configured to generate one or more antenna patterns for digital baseband received signals corresponding to signals received by the CRPA; and

a processor configured;

to associate instances of observed signal strength of signals at various observed beam angles of the CRPA with physical locations of a plurality of space vehicles, wherein the plurality of space vehicles comprise sources of the signals; and

to determine the at least one of the heading, roll, or pitch of the attitude of the object based at least partly on the orientation of the object with respect to the observed beam angles,

wherein the processor is further configured to determine the physical locations of a space vehicle of the plurality of space vehicles from ephemeris data for the space vehicle.

9. An apparatus for determining at least one of a heading, roll, or pitch of an attitude of an object based on signals received by a controlled reception pattern antenna (CRPA) that is attached, directly or indirectly, to the object, the apparatus comprising:

a digital beamformer configured to generate one or more antenna patterns for digital baseband received signals corresponding to signals received by the CRPA; and

a processor configured;

to associate instances of observed signal strength of signals at various observed beam angles of the CRPA with physical locations of a plurality of space vehicles, wherein the plurality of space vehicles comprise sources of the signals;

to determine the at least one of the heading, roll, or pitch of the attitude of the object based at least partly on the orientation of the object with respect to the observed beam angles,

generate hypothetical beam angles from the CRPA to the space vehicles based on a reference hypothetical orientation of the object and the positions of the space vehicles; and

rotate the hypothetical orientation of the object and generate new hypothetical beam angles based on the hypothetical orientation until a match is found between the observed beam angles from the CRPA and the hypothetical beam angles in order to determine the at least one of the heading, roll, or pitch of the attitude.

10. An electronically-implemented method of determining at least one of a heading, roll, or pitch of an attitude of an object, the method comprising:

surveying at least a portion of space to observe instances of radio frequency (RF) signal strength relative to a line of sight of a main lobe of an antenna pattern of a controlled reception pattern antenna (CRPA), wherein the main lobe is generated by a beamformer, wherein the CRPA is attached, directly or indirectly, to the object;

associating instances of observed signal strength of signals at various observed beam angles of the CRPA with physical locations of a plurality of space vehicles, wherein the plurality of space vehicles comprise sources of the signals; and

determining the at least one of the heading, roll, or pitch of the attitude of the object based at least partly on the orientation of the object with respect to the observed beam angles;

amplifying signals from a plurality of antenna elements of the CRPA with a plurality of low noise amplifiers (LNAs) to generate amplified signals;

downconverting the amplified signals from radio frequency (RF) to baseband to generate baseband received signals, wherein downconverting is performed by a plurality of RF downconverters; and

converting the baseband received signals from analog to digital to generate digital baseband received signals, wherein converting is performed by a plurality of analog-to-digital converters;

wherein the beamformer is configured to combine the digital baseband received signals to generate the main lobe of the antenna pattern of the CRPA.

11. The method of claim 10, further comprising performing the method in a global positioning system (GPS) receiver.

12. The method of claim 10, further comprising nulling one or more spoofers with the beamformer when spoofing is detected.

13. An electronically-implemented method of determining at least one of a heading, roll, or pitch of an attitude of an object, the method comprising:

surveying at least a portion of space to observe instances of radio frequency (RF) signal strength relative to a line of sight of a main lobe of an antenna pattern of a controlled reception pattern antenna (CRPA), wherein the main lobe is generated by a beamformer, wherein the CRPA is attached, directly or indirectly, to the object;

associating instances of observed signal strength of signals at various observed beam angles of the CRPA with physical locations of a plurality of space vehicles, wherein the plurality of space vehicles comprise sources of the signals;

determining the at least one of the heading, roll, or pitch of the attitude of the object based at least partly on the orientation of the object with respect to the observed beam angles;

wherein each space vehicle broadcasts a unique pseudorandom noise (PRN) code, further comprising identifying which unique PRN code bearing signal experiences an increase in signal power when the main lobe of the antenna pattern of the CRPA is directed to a particular instance of observed signal strength to determine which space vehicle corresponds to the instance.

14. The method of claim 13, wherein the signal power comprises a carrier power to noise ratio.

15. An electronically-implemented method of determining at least one of a heading, roll, or pitch of an attitude of an object, the method comprising:

surveying at least a portion of space to observe instances of radio frequency (RF) signal strength relative to a line of sight of a main lobe of an antenna pattern of a controlled reception pattern antenna (CRPA), wherein the main lobe is generated by a beamformer, wherein the CRPA is attached, directly or indirectly, to the object;

associating instances of observed signal strength of signals at various observed beam angles of the CRPA with physical locations of a plurality of space vehicles, wherein the plurality of space vehicles comprise sources of the signals;

determining the at least one of the heading, roll, or pitch of the attitude of the object based at least partly on the orientation of the object with respect to the observed beam angles;

wherein determining the at least one of the heading, roll, or pitch of the attitude further comprises;

initially determining a relative heading of the object in a first reference frame that is relative to beam steering angles; and

converting the relative heading from the first reference frame to a second reference frame to generate a global heading, wherein the second reference frame is relative to a coordinate system of ephemeris data.

16. An electronically-implemented method of determining at least one of a heading, roll, or pitch of an attitude of an object, the method comprising:

surveying at least a portion of space to observe instances of radio frequency (RF) signal strength relative to a line of sight of a main lobe of an antenna pattern of a controlled reception pattern antenna (CRPA), wherein the main lobe is generated by a beamformer, wherein the CRPA is attached, directly or indirectly, to the object;

associating instances of observed signal strength of signals at various observed beam angles of the CRPA with physical locations of a plurality of space vehicles, wherein the plurality of space vehicles comprise sources of the signals;

determining the at least one of the heading, roll, or pitch of the attitude of the object based at least partly on the orientation of the object with respect to the observed beam angles;

electronically beam steering the CRPA in a plurality of observed beam angles to perform surveying;

observing signal strength for the plurality of steered observed beam angles; and

storing indications of the signal strength for the plurality of steered observed beam angles in a computer-readable medium.

17. An electronically-implemented method of determining at least one of a heading, roll, or pitch of an attitude of an object, the method comprising:

surveying at least a portion of space to observe instances of radio frequency (RF) signal strength relative to a line of sight of a main lobe of an antenna pattern of a controlled reception pattern antenna (CRPA), wherein the main lobe is generated by a beamformer, wherein the CRPA is attached, directly or indirectly, to the object;

associating instances of observed signal strength of signals at various observed beam angles of the CRPA with physical locations of a plurality of space vehicles, wherein the plurality of space vehicles comprise sources of the signals;

determining the at least one of the heading, roll, or pitch of the attitude of the object based at least partly on the orientation of the object with respect to the observed beam angles; and

determining the physical location of a space vehicle of the plurality of space vehicles from ephemeris data for the space vehicle.

18. An electronically-implemented method of determining at least one of a heading, roll, or pitch of an attitude of an object, the method comprising:

surveying at least a portion of space to observe instances of radio frequency (RF) signal strength relative to a line of sight of a main lobe of an antenna pattern of a controlled reception pattern antenna (CRPA), wherein the main lobe is generated by a beamformer, wherein the CRPA is attached, directly or indirectly, to the object;

associating instances of observed signal strength of signals at various observed beam angles of the CRPA with physical locations of a plurality of space vehicles, wherein the plurality of space vehicles comprise sources of the signals;

determining the at least one of the heading, roll, or pitch of the attitude of the object based at least partly on the orientation of the object with respect to the observed beam angles;

generating hypothetical beam angles from the CRPA to the space vehicles based on a reference hypothetical orientation of the object and the positions of the space vehicles; and

rotating the hypothetical orientation of the object and generating new hypothetical beam angles based on the hypothetical orientation until a match is found between the observed beam angles from the CRPA and the hypothetical beam angles in order to determine the at least one of the heading, roll, or pitch of the attitude.