Dynamic antenna platform offset calibration

• US 10,211,508 B2
• Filed: 07/06/2017
• Issued: 02/19/2019
• Est. Priority Date: 07/06/2017
• Status: Active Grant

• Current Assignee: ViaSat Incorporated
• Original Assignee: ViaSat Incorporated
• Inventors: Merrell, Douglas J.
• Primary Examiner(s): Smith, Graham
• Application Number:
  US15/642,808
• Publication Number:
  US 20190013566A1
• Time in Patent Office: 593 Days
• CPC Class Codes: H01Q 1/1257 using the received signal strength
• CPC Class Codes: H01Q 1/18 Means for stabilising antennas on an unstable platform
• CPC Class Codes: H01Q 1/28 Adaptation for use in or on aircraft, missiles, satellites, or balloons
• CPC Class Codes: H01Q 1/288 Satellite antennas
• CPC Class Codes: H01Q 1/42 Housings not intimately mechanically associated with radiating elements, e.g. radome
• CPC Class Codes: H01Q 3/08 for varying two co-ordinates of the orientation
• CPC Class Codes: H04B 7/18545 Arrangements for managing station mobility, i.e. for station registration or localisation

Abstract

Systems and methods are described for supporting dynamic antenna platform offset calibration for an antenna system mounted to a mobile vehicle. In particular, dynamic antenna platform offset calibration can be performed while communicating user data associated with the mobile vehicle (e.g., based at least in part on alignment calibration procedures including measurements of user data signals), with an antenna platform offset being updated when alignment calibration procedures have been performed at suitably separated spatial conditions. Accordingly, antenna platform offset calibration may be performed throughout the operation of the mobile vehicle without requiring that the vehicle be proactively aligned in a particular orientation for a dedicated calibration routine prior to using the antenna for communicating user data during normal operation of the mobile vehicle.

Claims

1. A method, comprising:

communicating, at a mobile vehicle according to a first tracking mode during one or more travel segments of the mobile vehicle, first user data with a target satellite via a beam of an antenna mounted to the mobile vehicle, wherein communicating the first user data according to the first tracking mode comprises;

performing an alignment calibration procedure to determine an antenna pointing offset based at least in part on a difference between;

(1) an estimated pointing direction from the antenna to the target satellite that is determined based at least in part on positional information of the mobile vehicle; and

(2) a peaked pointing direction from the antenna to the target satellite that is determined based at least in part on a measured signal characteristic of the first user data communicated during the alignment calibration procedure;

pointing the beam of the antenna towards the target satellite for subsequent communication of the first user data based at least in part on the positional information of the mobile vehicle and the determined antenna pointing offset; and

repeating the performing and the pointing until determining that the alignment calibration procedure has been performed for a plurality of spatial conditions that satisfy a spatial separation criteria;

determining, for each of the alignment calibration procedures performed for the plurality of spatial conditions, a respective calibration vector set based at least in part on the respective peaked pointing direction associated with the respective one of the plurality of spatial conditions;

determining, based at least in part on determining that the alignment calibration procedure has been performed for the plurality of spatial conditions that satisfy the spatial separation criteria, an antenna platform offset between a reference frame of the antenna and a reference frame of the mobile vehicle based at least in part on the calibration vector sets determined for each of the alignment calibration procedures performed for the plurality of spatial conditions; and

communicating, subsequent to the determining of the antenna platform offset, second user data with the target satellite via the beam of the antenna according to a second tracking mode, wherein communicating the second user data according to the second tracking mode comprises pointing the beam of the antenna towards the target satellite for communicating the second user data based at least in part on the positional information of the mobile vehicle and the determined antenna platform offset.

2. The method of claim 1, wherein communicating the second user data according to the second tracking mode comprises:

performing the alignment calibration procedure to determine a second antenna pointing offset based at least in part on a difference between;

(1) an estimated pointing direction from the antenna to the target satellite that is determined based at least in part on the positional information of the mobile vehicle and the determined antenna platform offset; and

(2) a peaked pointing direction from the antenna to the target satellite that is determined based at least in part on a measured signal characteristic of the second user data communicated during the alignment calibration procedure;

pointing the beam of the antenna towards the target satellite for subsequent communication of the second user data based at least in part on the positional information of the mobile vehicle and the determined second antenna pointing offset; and

repeating the performing and the pointing until determining that the alignment calibration procedure has been performed for a second plurality of spatial conditions that satisfy the spatial separation criteria.

3. The method of claim 2, further comprising:

determining, for each of the alignment calibration procedures performed for the second plurality of spatial conditions, a respective second calibration vector set based at least in part on the respective peaked pointing direction associated with the respective one of the second plurality of spatial conditions; and

determining, based at least in part on determining that the alignment calibration procedure has been performed for the plurality of spatial conditions that satisfy the spatial separation criteria, an updated antenna platform offset between the reference frame of the antenna and the reference frame of the mobile vehicle based at least in part on the calibration vector sets determined for each of the alignment calibration procedures performed for the second plurality of spatial conditions.

4. The method of claim 3, wherein determining the updated antenna platform offset comprises calculating a weighted average of a second antenna platform offset based at least in part on the second calibration vector sets for the second plurality of spatial conditions and the antenna platform offset based at least in part on the calibration vector sets for the plurality of spatial conditions.

5. The method of claim 3, further comprising:

determining that a residual based at least in part on the updated antenna platform offset is above a threshold residual for at least one of the second plurality of spatial conditions;

discarding the second calibration vector set for each of the at least one of the second plurality of spatial conditions; and

determining a new second calibration vector set for each of the at least one of the second plurality of spatial conditions.

6. The method of claim 2, wherein:

for communicating the first user data according to the first tracking mode, repeating the performing and the pointing is conducted at a first periodicity; and

for communicating the second user data according to the second tracking mode, repeating the performing and the pointing is conducted at a second periodicity, the second periodicity being different from the first periodicity.

7. The method of claim 1, wherein determining the antenna platform offset is based at least in part on the antenna platform offset satisfying an offset calibration quality criteria.

8. The method of claim 7, wherein the offset calibration quality criteria comprises a calculated matrix condition number for the antenna platform offset being below a threshold matrix condition number or residuals associated with the determined antenna platform offset for each of the plurality of spatial conditions being below a threshold.

9. The method of claim 1, wherein each of the plurality of spatial conditions comprises an angular direction within one of a plurality of angular ranges.

10. The method of claim 9, wherein the determining a respective calibration vector set comprises:

identifying that a fitness metric associated with a new antenna calibration procedure taken at a new spatial condition within one of the plurality of angular ranges associated with a previously determined calibration vector set exceeds the fitness metric associated with the previously determined calibration vector set; and

replacing the previously determined calibration vector set with a new calibration vector set determined from the new antenna calibration procedure.

11. The method of claim 10, wherein the fitness metric comprises a relationship of the new spatial condition to a nominal direction of the one of the plurality of angular ranges, a quality metric associated with the new antenna calibration procedure, or a combination thereof.

12. The method of claim 1, wherein each of the respective calibration vector sets comprises the estimated pointing direction from the antenna to the target satellite, the peaked pointing direction from the antenna to the target satellite, or both.

13. The method of claim 1, wherein the determining a respective calibration vector set is based at least in part on an angular rate of pointing for the antenna being below a threshold angular rate, a residual error being below a threshold residual error, a servo error being below a servo error threshold, or a combination thereof.

14. The method of claim 1, wherein determining that the alignment calibration procedure has been performed for the plurality of spatial conditions that satisfy the spatial separation criteria comprises:

determining that a number of angular ranges of antenna azimuth direction associated with the plurality of spatial conditions satisfies a threshold number of angular ranges of antenna azimuth direction.

15. The method of claim 1, wherein determining that the alignment calibration procedure has been performed for the plurality of spatial conditions that satisfy the spatial separation criteria comprises:

determining that a maximum angular separation between adjacent pairs of the plurality of spatial conditions is less than or equal to a threshold angular separation.

16. The method of claim 1, wherein the target satellite for each of the alignment calibration procedures performed for the plurality of spatial conditions is the same target satellite.

17. The method of claim 1, wherein the target satellite for the alignment calibration procedures performed for the plurality of spatial conditions comprise two or more different satellites.

18. The method of claim 1, wherein the communicating the first user data comprises transmitting signals from the antenna, receiving signals at the antenna, or a combination thereof.

19. The method of claim 1, wherein each of the antenna pointing offsets comprises offsets along two axes with respect to the reference frame of the antenna.

20. The method of claim 19, wherein the two axes with respect to the reference frame of the antenna correspond to azimuth and elevation.

21. The method of claim 1, wherein the antenna platform offset comprises offsets along three axes with respect to the reference frame of the mobile vehicle.

22. The method of claim 21, wherein the three axes with respect to the reference frame of the mobile vehicle correspond to roll, pitch, and yaw.

23. A system, comprising:

an antenna;

a modem coupled to the antenna operable to process signals communicated via the antenna;

a positioner coupled between the antenna and a mobile vehicle, the positioner positioning the antenna based at least in part on positioning control information; and

an alignment calibration controller operable to cause the positioner to point a beam of the antenna towards a target satellite,

wherein, for a first tracking mode during one or more travel segments of the mobile vehicle, the alignment calibration controller;

estimates a pointing direction from the antenna to the target satellite based at least in part on positional information of the mobile vehicle;

communicates the positioning control information to the positioner for an alignment calibration procedure based at least in part on the estimated pointing direction;

receives, from the modem, a measured signal characteristic of first user data communicated during the alignment calibration procedure via the modem; and

determines an antenna pointing offset based at least in part on a difference between the estimated pointing direction and a peaked pointing direction from the antenna to the target satellite that is determined based at least in part on the measured signal characteristic,

repeats the estimating, the communicating, the receiving, and the determining until the alignment calibration procedure has been performed for a plurality of spatial conditions that satisfy a spatial separation criteria;

determines, for each of the alignment calibration procedures performed for the plurality of spatial conditions, a respective calibration vector set based at least in part on the respective peaked pointing direction associated with the respective one of the plurality of spatial conditions;

determines, based at least in part on determining that the alignment calibration procedure has been performed for the plurality of spatial conditions that satisfy the spatial separation criteria, an antenna platform offset between a reference frame of the antenna and a reference frame of the mobile vehicle based at least in part on the calibration vector sets determined for each of the alignment calibration procedures performed for the plurality of spatial conditions,

and the modem communicates first user data via the antenna positioned according to the positioning control information,

and wherein, in a second tracking mode subsequent to the determining of the antenna platform offset, the alignment calibration controller;

estimates the pointing direction from the antenna to the target satellite based at least in part on positional information of the mobile vehicle and the determined antenna platform offset; and

communicates the positioning control information to the positioner based at least in part on the estimated pointing direction,

and the modem communicates second user data via the antenna positioned according to the positioning control information.

24. The system of claim 23, wherein the alignment calibration controller determines the antenna platform offset based at least in part on the antenna platform offset satisfying an offset calibration quality criteria.

25. The system of claim 23, wherein the alignment calibration controller determines that the alignment calibration procedure has been performed for the plurality of spatial conditions that satisfy the spatial separation criteria based at least in part on determining that a number of angular ranges of antenna azimuth direction associated with the plurality of spatial conditions satisfies a threshold number of angular ranges of antenna azimuth direction.

26. The system of claim 23, wherein the alignment calibration controller determines that the alignment calibration procedure has been performed for the plurality of spatial conditions that satisfy the spatial separation criteria based at least in part on determining that a maximum angular separation between adjacent pairs of the plurality of spatial conditions is less than or equal to a threshold angular separation.

27. An apparatus, comprising:

a processor;

memory in electronic communication with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to;

communicate, at a mobile vehicle according to a first tracking mode during one or more travel segments of the mobile vehicle, first user data with a target satellite via a beam of an antenna mounted to the mobile vehicle, wherein communicating the first user data according to the first tracking mode comprises;

performing an alignment calibration procedure that determines an antenna pointing offset based at least in part on a difference between;

(1) an estimated pointing direction from the antenna to the target satellite that is determined based at least in part on positional information of the mobile vehicle; and

(2) a peaked pointing direction from the antenna to the target satellite that is determined based at least in part on a measured signal characteristic of the first user data communicated during the alignment calibration procedure;

pointing the beam of the antenna towards the target satellite for subsequent communication of the first user data based at least in part on the positional information of the mobile vehicle and the determined antenna pointing offset; and

repeating the performing and the pointing until determining that the alignment calibration procedure has been performed for a plurality of spatial conditions that satisfy a spatial separation criteria;

determine, for each of the alignment calibration procedures performed for the plurality of spatial conditions, a respective calibration vector set based at least in part on the respective peaked pointing direction associated with the respective one of the plurality of spatial conditions;

determine, based at least in part on determining that the alignment calibration procedure has been performed for the plurality of spatial conditions that satisfy the spatial separation criteria, an antenna platform offset between a reference frame of the antenna and a reference frame of the mobile vehicle based at least in part on the calibration vector sets determined for each of the alignment calibration procedures performed for the plurality of spatial conditions; and

communicate, subsequent to the determining of the antenna platform offset, second user data with the target satellite via the beam of the antenna according to a second tracking mode, wherein communicating the second user data according to the second tracking mode comprises pointing the beam of the antenna towards the target satellite for communicating the second user data based at least in part on the positional information of the mobile vehicle and the determined antenna platform offset.

28. The apparatus of claim 27, wherein the instructions to communicate the second user data according to the second tracking mode are executable by the processor to cause the apparatus to:

perform the alignment calibration procedure to determine a second antenna pointing offset based at least in part on a difference between;

(1) an estimated pointing direction from the antenna to the target satellite that is determined based at least in part on the positional information of the mobile vehicle and the determined antenna platform offset; and

(2) a peaked pointing direction from the antenna to the target satellite that is determined based at least in part on a measured signal characteristic of the second user data communicated during the alignment calibration procedure;

point the beam of the antenna towards the target satellite for subsequent communication of the second user data based at least in part on the positional information of the mobile vehicle and the determined second antenna pointing offset; and

repeat the performing and the pointing until determining that the alignment calibration procedure has been performed for a second plurality of spatial conditions that satisfy the spatial separation criteria;

wherein the instructions are further executable by the processor to cause the apparatus to;

determine, for each of the alignment calibration procedures performed for the second plurality of spatial conditions, a respective second calibration vector set based at least in part on the respective peaked pointing direction associated with the respective one of the second plurality of spatial conditions; and

determine, based at least in part on determining that the alignment calibration procedure has been performed for the plurality of spatial conditions that satisfy the spatial separation criteria, an updated antenna platform offset between the reference frame of the antenna and the reference frame of the mobile vehicle based at least in part on the calibration vector sets determined for each of the alignment calibration procedures performed for the second plurality of spatial conditions.

29. The apparatus of claim 27, wherein:

for communicating the first user data according to the first tracking mode, the instructions are executable by the processor to cause the apparatus to repeat the performing and the pointing at a first periodicity; and

for communicating the second user data according to the second tracking mode, the instructions are executable by the processor to cause the apparatus to repeat the performing and the pointing at a second periodicity, the second periodicity being different from the first periodicity.

30. The apparatus of claim 27, wherein the instructions to determine that the alignment calibration procedure has been performed for the plurality of spatial conditions that satisfy the spatial separation criteria are executable by the processor to cause the apparatus to:

determine that a number of angular ranges of antenna azimuth direction associated with the plurality of spatial conditions satisfies a threshold number of angular ranges of antenna azimuth direction.