System and method for locating emitters

• US 6,734,824 B2
• Filed: 08/06/2002
• Issued: 05/11/2004
• Est. Priority Date: 08/06/2002
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Herman, Carl R.
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US10/213,708
• Publication Number:
  US 20040027276A1
• Time in Patent Office: 644 Days
• Field of Search: 342/89, 342/175, 342/176, 342/181, 342/195, 342/385, 342/386-449, 342/368, 342/375, 342/450-465, 342/20
• US Class Current: 342/465
• CPC Class Codes: G01S 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence

Abstract

A method for determining a location of an emitter in a monitored area includes the step of providing an array representative of the monitored area, the array including a plurality of elements. Next, at least one first curve and at least one second curve is provided in the array. The first and second curves are representative of possible locations of the emitter in the monitored area. Then, possible emitter locations are identified at intersections of the first and second curves. The intersections are identified by determining locations in the array where an element having an assigned attribute corresponding to a first curve has a predetermined number of adjacent elements having an assigned attribute corresponding to a second curve.

Claims

1. A method for determining a location of an emitter in a monitored area, said method comprising the steps of:

providing an array representative of the monitored area, said array including a plurality of elements;

providing at least one first curve and at least one second curve in said array, said at least one first and second curves being representative of possible locations of the emitter in the monitored area; and

identifying possible emitter locations at intersections of said at least one first and second curves, said intersections being identified by determining locations in said array where an element having an assigned attribute corresponding to said at least one first curve has a predetermined number of adjacent elements having an assigned attribute corresponding to said at least one second curve.

2. The method as recited in claim 1, wherein said step of providing said at least one first and second curves comprises the steps of:

providing said at least one first curve corresponding to at least one of a constant time delay of arrival value and a constant frequency delay of arrival value associated with an emission of the emitter measured from a first pair of receivers having a known location in the monitored area; and

providing said at least one second curve corresponding to at least one of a constant time delay of arrival value and a constant frequency delay of arrival value associated with an emission of the emitter measured from a second pair of receivers different than said first pair of receivers and having a known location in the monitored area.

3. The method as recited in claim 2, wherein said step of providing said at least one first curve further comprises the steps of monitoring emissions from the emitter with said first pair of receivers and determining time and frequency delays of arrival of emissions from the emitter received at said first pair of receivers, said step of providing said at least one second curve further comprising the steps of monitoring emissions from the emitter with said second pair of receivers and determining time and frequency delays of arrival of said emissions from the emitter received at said second pair of receivers.

4. The method as recited in claim 2, further comprising the steps of:

providing at least one third curve in said array corresponding to at least one of a constant time delay of arrival value and a constant frequency delay of arrival value associated with an emission of the emitter measured from a third pair of receivers different than said first and second pairs of receivers and having known locations in the monitored area; and

identifying possible emitter locations where said at least one third curve intersects said intersections of said at least one first and second curves, said possible emitter locations being identified by determining locations in said array where an element having an assigned attribute corresponding to said at least one third curve is positioned adjacent a predetermined number of elements associated with said intersections of said at least one first and second curves.

5. The method as recited in claim 4, wherein said step of providing said at least one third curve in said array comprises the step of providing said at least one third curve in a graphical image comprising a plurality of pixels having an assignable color attribute, said at least one third curve being provided in said graphical image by assigning a third color to said color attribute of said pixels along said at least one third curve;

said step of identifying possible emitter locations where said at least one third curve intersects said intersections of said at least one first and second curves comprising the step of determining locations in said graphical image where a pixel assigned a color attribute associated with said intersection of said at least one first and second curves has a predetermined number of adjacent pixels assigned said third color attribute.

6. The method as recited in claim 4, wherein said step of providing said at least one third curve further comprises the steps of monitoring emissions from the emitter with said third pair of receivers and determining time and frequency delays of arrival of emissions from the emitter received at said third pair of receivers.

7. The method as recited in claim 1, wherein each of said elements corresponds to a known location in the monitored area;

said step of providing said at least one first and second curves further comprising the steps of assigning a first value to said assignable attribute of said elements in said array that lie along said at least one first curve, and assigning a second value to said assignable attribute of said elements in said array that lie along said at least one second curve;

said step of identifying possible emitter locations further comprising the step of determining whether an element assigned said first value has a predetermined number of adjacent elements assigned said second value.

8. The method as recited in claim 1, wherein said step of providing an array comprises the step of providing a graphical image, said elements comprising pixels having assignable color attribute, each of said pixels corresponding to a known location in the monitored area.

9. The method as recited in claim 8, wherein said step of providing said at least one first and second curves in said array comprises the step of providing said at least one first and second curves in said graphical image by assigning a first color to said color attribute of said pixels along said at least one first curve and assigning a second color to said color attribute of said pixels along said at least one second curve.

10. The method as recited in claim 9, wherein said step of identifying possible emitter locations at intersections of said at least one first and second curves other comprises the step of determining locations in said graphical image where a pixel assigned said first color attribute has a predetermined number of adjacent pixels assigned said second color attribute.

11. A method for determining a location of at least one emitter in a monitored area, said method comprising the steps of:

providing a graphical image including a plurality of pixels having an assignable color, each of said pixels corresponding to a known location in the monitored area;

providing at least one first curve in said graphical image by assigning a first color to the pixels along said at least one first curve, said at least one first curve being representative of possible locations of the emitter in the monitored area;

providing at least one second curve in said graphical image by assigning a second color to the pixels along said at least one second curve, said at least one second curve being representative of possible locations of the emitter in the monitored area; and

identifying possible emitter locations at intersections of said at least one first and second curves, said intersections being identified by determining locations in said graphical image where a pixel assigned said first color is positioned adjacent a predetermined number of pixels assigned said second color.

12. A computer product operative to determine a location of an emitter in a monitored area, said computer product embodied in a computer readable medium and comprising:

a portion for providing an array representative of the monitored area, said array including a plurality of elements;

a portion for providing at least one first curve and at least one second curve in said array, said at least one first and second curves being representative of possible locations of the emitter in the monitored area; and

a portion for identifying possible emitter locations at intersections of said at least one first and second curves, said intersections being identified by determining locations in said array where an element having an assigned attribute corresponding to said at least one first curve has a predetermined number of adjacent elements having an assigned attribute corresponding to said at least one second curve.

13. The computer product recited in claim 12, wherein said portion for providing said at least one first and second curves comprises:

a portion for providing said at least one first curve corresponding to at least one of a constant time delay of arrival value and a constant frequency delay of arrival value associated with an emission of the emitter measured from a first pair of receivers having known locations in the monitored area; and

a portion for providing said at least one second curve corresponding to at least one of a constant time delay of arrival value and a constant frequency delay of arrival value associated with an emission of the emitter measured from a second pair of receivers different than said first pair of receivers and having known locations in the monitored area.

14. The computer product recited in claim 13, wherein said portion for providing said at least one first curve further comprises a portion for monitoring emissions from the emitter with said first pair of receivers and determining time and frequency delays of arrival of emissions from the emitter received at said first pair of receivers, said portion for providing said at least one second curve further comprising a portion for monitoring emissions from the emitter with said second pair of receivers and determining time and frequency delays of arrival of emissions from the emitter received at said second pair of receivers.

15. The computer product recited in claim 13, further comprising:

a portion for providing at least one third curve in said array corresponding to at least one of a constant time delay of arrival value and a constant frequency delay of arrival value associated with an emission of the emitter measured from a third pair of receivers different than said first and second pairs of receivers and having known locations in the monitored area; and

a portion for identifying possible emitter locations where said at least one third curve intersects said intersections of said at least one first and second curves, said possible emitter locations being identified by determining locations in said array where an element having an assigned attribute corresponding to said at least one third curve is positioned adjacent a predetermined number of elements associated with said intersections of said at least one first and second curves.

16. The computer product recited in claim 15, wherein said portion for providing said at least one third curve in said array comprises a portion for providing said at least one third curve in a graphical image comprising a plurality of pixels having an assignable color attribute, said at least one third curve being provided in said graphical image by assigning a third color to said color attribute of said pixels along said at least one third curve;

said portion for identifying possible emitter locations where said at least one third curve intersects said intersections of said at least one first and second curves comprising a portion for determining locations in said graphical image where a pixel assigned a color attribute associated with said intersection of said first and second curves has a predetermined number of adjacent pixels assigned said third color attribute.

17. The computer product recited in claim 15, wherein said portion for providing said at least one third curve further comprises a portion for monitoring emissions from the emitter with said third pair of receivers and determining time and frequency delays of arrival of emissions from the emitter received at said third pair of receivers.

18. The computer product recited in claim 12, wherein each of said elements corresponds to a known location in the monitored area;

said portion for providing said at least one first and second curves further comprising a portion for assigning a first value to said assignable attribute of said elements in said array that lie along said at least one first curve, and a portion for assigning a second value to said assignable attribute of said elements in said array that lie along said at least one second curve;

said portion for identifying possible emitter locations further comprising a portion for determining whether an element assigned said first value has a predetermined number of adjacent elements assigned said second value.

19. The computer product recited in claim 12, wherein said portion for providing an array comprises a portion for providing a graphical image, said elements comprising pixels having assignable color attribute, each of said pixels corresponding to a known location in the monitored area, said portion for providing said at least one first and second curves in said array comprising a portion for providing said at least one first and second curves in said graphical image by assigning a first color to said color attribute of said pixels along said at least one first curve and a portion for assigning a second color to said color attribute of said pixels along said at least one second curve.

20. The computer product recited in claim 19, wherein said portion for identifying possible emitter locations at intersections of said at least one first and second curves comprises a portion for determining locations in said graphical image where a pixel assigned said first color attribute has a predetermined number of adjacent pixels assigned said second color attribute.