SYSTEM AND METHOD FOR ADAPTABLE APERTURE PLANAR PHASED ARRAY

• US 20100175474A1
• Filed: 01/09/2009
• Published: 07/15/2010
• Est. Priority Date: 01/09/2009
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Underbrink, James R.
• Granted Patent: US 8,009,507 B2
• Time in Patent Office: Days
• US Class Current: 73/618
• CPC Class Codes: G01N 29/14 using acoustic emission techniques echo of particles G01N29/046; measuring mechanical vibrations or acoustic waves in solids in general G01H1/00
• CPC Class Codes: G01N 29/262 by electronic orientation or focusing, e.g. with phased arrays phased arrays per se G10K11/34
• CPC Class Codes: G01S 15/8927 using simultaneously or sequentially two or more subarrays or subapertures

Abstract

A system for an adaptable aperture planar array for maintaining source resolution is provided. The system includes a first nested array defining a first aperture responsive to a first range of frequencies. The first aperture is sized based on an angle between the array and the source, and includes a first subset of sensor elements. The system includes a second nested array defining a second aperture responsive to a second range of frequencies that is less than the first range of frequencies. The second aperture is sized based on the angle between the array and the source, and includes a second subset of sensor elements. The first aperture and second aperture change in size as the angle changes, which results in a change in the sensor elements within the first subset and the second subset to maintain the source resolution for the array.

Claims

1. A system for an adaptable aperture planar array for maintaining source resolution as the array moves relative to a source comprising:

a first nested array defining a first aperture responsive to a first range of frequencies, the first aperture sized based on an angle between the array and the source, the first aperture including a first subset of sensor elements;

a second nested array defining a second aperture responsive to a second range of frequencies that is less than the first range of frequencies, the second aperture sized based on the angle between the array and the source, the second aperture including a second subset of sensor elements; and

the first aperture and the second aperture change in size as the angle between the array and the source changes, which results in a change in the sensor elements within the first subset and the second subset so that the source resolution for the array remains substantially the same as the angle changes.

2. The system of claim 1, further comprising:

a third nested array defining a third aperture responsive to a third range of frequencies that is less than the first range of frequencies and the second range of frequencies, the third aperture sized based on the angle between the array and the source, the third aperture including a third subset of sensor elements.

3. The system of claim 2, wherein the third subset of sensor elements includes at least one of the sensor elements associated with the first subset and at least one of the sensor elements associated with the second subset, and the second subset of sensor elements includes at least one of the sensor elements associated with the first subset.

4. The system of claim 2, wherein the third aperture is larger than the first aperture and the second aperture, and the second aperture is larger than the first aperture.

5. The system of claim 2, further comprising:

a fourth nested array defining a fourth aperture responsive to a fourth range of frequencies that is less than the first range of frequencies, the second range of frequencies and the third range of frequencies, the fourth aperture sized based on the angle between the array and the source, the fourth aperture larger than the third aperture, and the fourth aperture including a fourth subset of sensor elements that includes at least one of the sensor elements associated with the first subset, at least one of the sensor elements associated with the second subset and at least one of the sensor elements associated with the third subset.

6. The system of claim 1, wherein the source is a mobile platform.

7. The system of claim 1, wherein the first aperture and second aperture are sized based on a look angle measured between a line drawn from a center point of the array to a center point of the source and a normal to the center point of the array.

8. The system of claim 7, wherein the array is formed of a plurality of sensor elements, and each sensor element of the plurality of sensor elements has an x-coordinate and y-coordinate location within the array.

9. The system of claim 8, wherein each of the first aperture and the second aperture define a boundary for the first nested array and the second nested array, and the sensor element is selected to be within the first subset, second subset or combination thereof based on whether the x-coordinate and y-coordinate location of the sensor element is within the boundary defined by the first aperture of the first nested array, the second aperture of the second nested array or combination thereof.

10. The system of claim 9, wherein the boundary of the first aperture and the boundary of the second aperture are defined to include a plurality of locations having x and y coordinates, and the first aperture and the second aperture are resized as a function of the cosine of the look angle.

11. The system of claim 1, wherein the first aperture and the second aperture change in size as the array moves in a second direction parallel to the longitudinal axis of the source, which results in a change in the sensor elements within the first subset and the second subset so that the source resolution for the array remains substantially the same during the movement of the array in the second direction.

12. A method of maintaining source resolution for an adaptable aperture planar array movable relative to a source comprising:

providing a plurality of sensor elements that each include a coordinate location in the array;

determining a position of the array relative to the source;

computing a first nested array responsive to a first range of frequencies based on the position of the array, the first nested array including a first subset of the plurality of sensor elements;

computing a second nested array that is larger than the first nested array, the second nested array including a second subset of the plurality of sensor elements that includes at least one sensor element associated with the first subset;

acquiring data associated with the first range of frequencies with the first subset of the plurality of sensor elements;

acquiring data associated with the second range of frequencies with the second subset of the plurality of sensor elements;

determining that the position of the array relative to the source has changed;

recomputing the first nested array based on the changed position of the array; and

recomputing the second nested array based on the changed position of the array, with the recomputing of the first nested array and the second nested array maintaining the source resolution for the array.

13. The method of claim 12, wherein determining a position of the array relative to the source further comprises:

receiving a user input that indicates a look angle measured between a line drawn from a center point of the array to a center point of the source and a normal to the array.

14. The method of claim 13, wherein computing the first nested array and second nested array further comprises:

determining a first aperture for the first nested array based on a look angle of zero degrees;

determining which of the plurality of sensor elements have coordinate locations within the first aperture to define the first subset;

determining a second aperture for the second nested array based on a look angle of zero degrees, with the second aperture being larger than the first aperture; and

determining which of the plurality of sensor elements have coordinate locations within the second aperture to define the second subset.

15. The method of claim 14, wherein recomputing the first nested array and the second nested array when the position of the array relative to the source has changed further comprises:

recomputing the first aperture for the first nested array based on a function of the cosine of the look angle;

determining which of the plurality of sensor elements have coordinate locations within the recomputed first aperture;

associating at least one of the plurality of sensor elements within the recomputed first aperture to define a recomputed first subset;

recomputing the second aperture for the second nested array based on a function of the cosine of the look angle;

determining which of the plurality of sensor elements have coordinate locations within the recomputed second aperture; and

associating at least one of the plurality of sensor elements within the recomputed second aperture to define a recomputed second subset.

16. The method of claim 15, further comprising:

acquiring data associated with the first range of frequencies with the recomputed first subset of the plurality of sensor elements when the position of the array relative to the source has changed; and

acquiring data associated with the second range of frequencies with the recomputed second subset of the plurality of sensor elements when position of the array relative to the source has changed.

17. A system for an adaptable aperture planar array for maintaining source resolution as the array moves relative to a source comprising:

a source having a longitudinal axis;

a plurality of sensor elements each having a coordinate location within the array;

a first nested array defining a first aperture responsive to a first range of frequencies, the first aperture sized based on an angle between the array and the source, the first aperture including a first subset of the plurality of sensor elements, with each of the plurality of sensor elements within the first subset having coordinate locations within the first aperture;

a second nested array defining a second aperture responsive to a second range of frequencies that is less than the first range of frequencies, the second aperture larger than the first aperture and including a second subset of the plurality of sensor elements that includes at least one of the plurality of sensor elements associated with the first nested array, with each of the plurality of sensor elements within the second subset having coordinate locations within the second aperture;

a third nested array defining a third aperture responsive to a third range of frequencies that is less than the first range of frequencies and the second range of frequencies, the third aperture larger than the first aperture and the second aperture and including a third subset of the plurality of sensor elements that includes at least one of the plurality of sensor elements associated with the first subset and at least one of the plurality of sensor elements associated with the second subset, with each of the plurality of sensor elements within the third subset having coordinate locations within the third aperture; and

a control module that resizes the first aperture, the second aperture and the third aperture based on the position of the array relative to the source, and changes the plurality of sensor elements associated with the first subset, the second subset and the third subset based on the coordinate locations of the plurality of sensor elements within the resized first aperture, second aperture and third aperture to maintain the source resolution of the array.

18. The system of claim 17, wherein the first aperture, second aperture and third aperture are changed in size in the x-direction by a factor of the cosine cubed of the angle, and are changed in size in the y-direction by a factor of the cosine of the angle.

19. The system of claim 17, wherein the first aperture, second aperture and third aperture are changed in size in the x-direction by a factor of the cosine of the angle and are changed in size in the y-direction by a factor of the cosine cubed of the angle.

20. The system of claim 17, wherein the array is at a fixed location and the first aperture, second aperture and third aperture are resized based on movement of the source relative to the array.

21. The system of claim 17, wherein the array is at a fixed location and the first aperture, second aperture and third aperture are resized based on the location in the source region around the source at which the array is looking.