Passive ranging of a target

• US 9,341,705 B2
• Filed: 02/06/2013
• Issued: 05/17/2016
• Est. Priority Date: 01/31/2008
• Status: Active Grant

• 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): Brainard, Timothy A
• Application Number:
  US13/760,660
• Publication Number:
  US 20150268329A1
• Time in Patent Office: 1,196 Days
• Field of Search: 342/13, 342/126, 342/133, 342/139, 342/140, 342/146, 342/147, 342/417, 342/463
• US Class Current: 1/1
• CPC Class Codes: G01S 11/02 using radio waves G01S19/00 takes precedence
• CPC Class Codes: G01S 19/42 Determining position
• CPC Class Codes: G01S 2205/03 Airborne
• CPC Class Codes: G01S 5/0278 involving statistical or probabilistic considerations G01S5/0252, G01S5/0294 take precedence
• CPC Class Codes: G01S 5/0294 Trajectory determination or predictive filtering, e.g. target tracking or Kalman filtering
• CPC Class Codes: G01S 7/292 Extracting wanted echo-signals
• CPC Class Codes: G01S 7/295 Means for transforming co-ordinates or for evaluating data, e.g. using computers

Abstract

In an embodiment, an apparatus includes a detector and a range finder. The detector is configured to determine a direction to a target in response to a signal received from the target, and the range finder is configured to determine a range to the target in response to the direction and independently of an amplitude of the signal. For example, such an apparatus (e.g., a computer-based apparatus) may be disposed on tactical fighter aircraft, and may be able to range (e.g., azimuth range or slant range) a target passively even if an accurate measure of the amplitude of the signal received from the target is unavailable.

Claims

1. An apparatus, comprising:

a detector configured to determine a direction to a target in response to a signal received from the target; and

a range finder configured to determine a range to the target in response to the direction and independently of an amplitude of the signal;

wherein the range finder is configured to determine the range to the target by;

tracking the target according to a first algorithm;

tracking the target according to a second algorithm;

weighting results of the first and second algorithms; and

determining the range to the target in response to the weighted results of the first and second algorithms.

2. The apparatus of claim 1 wherein the direction includes an azimuth angle.

3. The apparatus of claim 1 wherein the direction includes an elevation angle.

4. The apparatus of claim 1 wherein the detector is configured to determine a direction to a moving target in response to a signal received from the moving target.

5. The apparatus of claim 1 wherein the detector is configured to determine a direction to an approximately stationary target in response to a signal received from an approximately stationary target.

6. The apparatus of claim 1 wherein the detector is configured to determine a direction to a target in response to a signal emitted from the target.

7. The apparatus of claim 1 wherein the detector includes an electronic warfare system.

8. The apparatus of claim 1 wherein

the first algorithm is configured to model a path of the target as being an approximately straight line;

and

the second algorithm is configured to model the path of the target as being a curved line.

9. The apparatus of claim 1 wherein

the first algorithm is configured to model the target as moving at an approximately constant velocity;

and

the second algorithm is configured to model the target as moving at a changing velocity.

10. The apparatus of claim 1 wherein the range finder includes:

a first stage configured to determine a coarse range to the target; and

a second stage configured to determine a fine range to the target in response to the coarse range.

11. The apparatus of claim 1 wherein the first algorithm is configured to model the target as not moving.

12. The apparatus of claim 1 wherein the range finder includes at least one Kalman filter.

13. The apparatus of claim 1 wherein the range finder includes at least one Kalman filter with all velocity component states having values fixed at zero.

14. The apparatus of claim 13 wherein the range finder is configured to prompt an operator of the object to move the object in a manner that increases a speed at which the range finder can determine the range.

15. An apparatus, comprising:

a detector configured to determine a direction to a target in response to a signal received from the target; and

a range finder configured to determine a range to the target in response to the direction and independently of an amplitude of the signal;

wherein the range finder includes;

a first Kalman filter configured to determine a first value of the range to the target; and

a second Kalman filter configured

to receive a seed parameter from the first Kalman filter, and

to determine a second value of the range to the target in response to the seed parameter.

16. An apparatus comprising:

a detector configured to determine a direction to a target in response to a signal received from the target; and

a range finder configured to determine a range to the target in response to the direction and independently of an amplitude of the signal;

wherein the range finder includes;

a first Kalman filter configured to determine a first value of the range to the target; and

a second Kalman filter configured

to receive seed values for filter coefficients and filter variables from the first Kalman filter, and

to determine a second value of the range to the target in response to the seed values.

17. A tangible computer readable medium storing instructions that, when executed by a computing apparatus, cause the computing apparatus to perform, or cause the computing apparatus to cause another apparatus to perform, the following steps:

determining a direction to a target in response to a signal received from the target; and

determining a range to the target in response to only the direction;

wherein the range to the target is determined by;

tracking the target according to a first algorithm;

tracking the target according to a second algorithm;

weighting results of the first and second algorithms; and

determining the range to the target in response to the weighted results of the first and second algorithms.