Determining at least one coordinate of an object using intersecting surfaces

• US 8,436,762 B2
• Filed: 03/31/2010
• Issued: 05/07/2013
• Est. Priority Date: 01/31/2008
• Status: Expired due to Fees

• Current Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Original Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Inventors: Yannone, Ronald M.
• Primary Examiner(s): Sotomayor, John B
• Application Number:
  US12/751,875
• Publication Number:
  US 20110227783A1
• Time in Patent Office: 1,133 Days
• Field of Search: 342/29, 342/133, 342139-141, 342/146, 342/147, 342/152, 342/156
• US Class Current: 342/29
• CPC Class Codes: G01S 11/02 using radio waves G01S19/00 takes precedence
• CPC Class Codes: G01S 13/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S13/46
• CPC Class Codes: G01S 7/295 Means for transforming co-ordinates or for evaluating data, e.g. using computers

Abstract

In an embodiment, a coordinate determiner is operable to identify at least first and second surfaces that each approximately intersect an object, and to determine at least two approximate coordinates of the object from the first and second surfaces, where at least one of the surfaces is nonplanar. For example, if the coordinate determiner is disposed on a fighter jet having at least two short-baseline-interferometers (SBIs), then two surfaces may be the surfaces of two cones having two of the SBIs as respective vertices, the object may be a close-in target, and the coordinate determiner may determine the azimuth and elevation of the target from the cone surfaces. Furthermore, the coordinate determiner or another computation unit onboard the jet may determine the slant range of the target from the elevation and the altitude of the jet. The coordinate determiner may at least facilitate ranging of the target quickly enough to allow a pilot sufficient time to evade detection by the target, to destroy the target, or to evade or destroy a projectile fired by the target.

Claims

1. An apparatus, comprising:

a first coordinate determiner configured;

to receive a first signal from a first antenna and a second signal from a second antenna;

to identify, in response to the first and second signals, respective first and second surfaces that each approximately intersect an object, at least one of the surfaces being nonplanar; and

to determine at least two approximate coordinates of the object from the first and second surfaces.

2. The apparatus of claim 1 wherein:

the first surface comprises a surface of a first cone; and

the second surface comprises a surface of a second cone.

3. The apparatus of claim 1 wherein the first coordinate determiner is further configured:

to identify at least one location at which the first and second surfaces approximately intersect each other; and

to determine the at least two approximate coordinates of the object from the at least one location.

4. The apparatus of claim 3 wherein the at least one location includes multiple locations that define a curve.

5. The apparatus of claim 3 wherein the at least one location includes multiple locations that define a curve that lies in a plane.

6. The apparatus of claim 3 wherein the coordinate determiner is configured to identify the at least two coordinates from the at least one location and from an estimate of a third coordinate.

7. The apparatus of claim 3 wherein the coordinate determiner is further configured:

to receive a third signal from one of the first and second antennas;

to identify, in response to the third signal, a third surface that approximately intersects the object;

to identify the at least one location as a location at which the first, second, and third surfaces approximately intersect one another; and

to determine as the at least two approximate coordinates of the object three approximate coordinates of the object from the at least one location.

8. The apparatus of claim 1 wherein the at least two coordinates include an azimuth and an elevation.

9. The apparatus of claim 1 wherein the at least two coordinates include an azimuth, an elevation, and a range.

10. The apparatus of claim 1, further comprising a second coordinate determiner configured to determine a third approximate coordinate from at least one of the at least two coordinates and from an estimate of a fourth coordinate.

11. The apparatus of claim 1 wherein the coordinate determiner is further configured to determine an indication of an error in at least one of the at least two determined coordinates.

12. The apparatus of claim 1, further comprising:

wherein the coordinate determiner is further configured to determine a first indication of an error in at least one of the at least two determined coordinates; and

an error calculator configured to calculate from the first indication of an error a second indication of an error in a third approximate coordinate.

13. The apparatus of claim 1 wherein the first coordinate determiner is configured:

to receive the first signal from a first interferometer; and

to receive the second signal from a second interferometer.

14. The apparatus of claim 1 wherein the first coordinate determiner is configured:

to receive the first signal from a first antenna array; and

to receive the second signal from a second antenna array.

15. The apparatus of claim 1 wherein the first coordinate determiner is configured:

to receive the first signal from a first interferometer having a longitudinal axis;

to receive the second signal from a second interferometer having a longitudinal axis that intersects the longitudinal axis of the first interferometer at an angle of less than 180°

.

16. A vehicle, comprising:

a first coordinate determiner configured;

to receive a first signal from a first antenna and a second signal from a second antenna;

to identify, in response to the first and second signals, first and second surfaces that each approximately intersect an object, at least one of the surfaces being nonplanar; and

to determine at least two approximate coordinates of the object from the first and second surfaces.

17. The system of claim 16 wherein the vehicle includes an airplane.

18. A system, comprising:

a vehicle, including;

a first coordinate determiner configured;

to identify from a first signal a first surface that approximately intersects an object,

to identify from a second signal a second surface that approximately intersects the object, at least one of the first and second surfaces being nonplanar, and

to determine at least two approximate coordinates of the object from the first and second surfaces; and

first and second interferometers secured to the vehicle and respectively configured to generate the first and second signals in response to the object.

19. The system of claim 18 wherein the first and second interferometers are respectively configure to generate the first and second signals in response to a third signal emanating from the object.

20. The system of claim 18 wherein the first and second interferometers are respectively configured to generate the first and second signals in response to a third signal generated by the object.

21. The system of claim 18 wherein:

the first interferometer has a first orientation relative to the vehicle; and

the second interferometer has a second orientation relative to the vehicle.

22. A method, comprising:

receiving from first and second antenna arrays respective first and second signals;

identifying, in response to the first and second signals, respective first and second surfaces that each approximately intersect an object, at least one of the surfaces being three-dimensional; and

determining at least two approximate coordinates of the object from the first and second surfaces.

23. The method of claim 22 wherein determining at least two coordinates includes:

identifying at least one location at which the first and second surfaces approximately intersect; and

determining the at least two approximate coordinates from the at least one location.

24. The method of claim 22 wherein determining the at least two approximate coordinates includes determining the at least two coordinates from a first equation that defines at least a portion of the first surface and from a second equation that defines at least a portion of the second surface.

25. The method of claim 22, further comprising:

receiving the first signal from the object with the first antenna array;

determining a first approximate direction of the object relative to the first antenna array; and

wherein identifying the first surface includes identifying the first surface from the first approximate direction.

26. The method of claim 25, further comprising:

receiving the second signal from the object with the second antenna array;

determining a second approximate direction of the object relative to the second antenna array; and

wherein identifying the second surface includes identifying the second surface from the second approximate direction.

27. The method of claim 22, further comprising:

receiving from a third antenna array a third signal;

identifying, in response to the third signal, a third surface that approximately intersects the object; and

wherein determining the at least two coordinates includes determining three approximate coordinates of the object from the first, second, and third surfaces.

28. A non-transitory computer-readable medium storing program instructions that, when executed by a computing apparatus, cause the computing apparatus or another apparatus under the control of the computing apparatus:

to identify first and second surfaces that each approximately intersect an object in response to respective first and second signals respectively received by first and second antennas, at least one of the surfaces being three-dimensional; and

to determine at least two approximate coordinates of the object from the first and second surfaces.

29. A method, comprising:

receiving first and second signals from respective first and second antennas;

identifying, in response to the first and second signals, respective first and second angles of respective first and second cones having respective first and second surfaces that each approximately intersect an object; and

determining at least two approximate coordinates of the object from the first and second angles.

30. The method of claim 29 wherein the identifying includes:

identifying first and second receive angles at which the first and second antennas receive the first and second signals, respectively; and

identifying the first and second angles of the first and second cones in response to the first and second receive angles, respectively.

31. The method of claim 29 wherein the identifying includes:

identifying first and second receive angles at which the first and second antennas receive the first and second signals relative to the respective boresight axes of the first and second antennas; and

identifying the first and second angles of the first and second cones in response to the first and second receive angles, respectively.

32. An apparatus, comprising:

a coordinate determiner configured;

to receive a first signal from a first portion of an antenna and a second signal from a second portion of an antenna;

to identify, in response to the first and second signals, respective first and second surfaces that each approximately intersect an object, at least one of the surfaces being nonplanar; and

to determine at least two approximate coordinates of the object from the first and second surfaces.