Method to localize an underwater object

1. A method for locating an acoustic source comprising:

providing a first linear array at a first depth in a plane;

providing a second linear array at a second depth in the same plane as the first linear array;

receiving signals from the acoustic source at each of the first linear array and the second linear array;

resolving signals received at the first linear array into a first cone of possible acoustic source locations;

resolving signals received at the second linear array into a second cone of possible acoustic source locations; and

estimating a contour of possible acoustic source locations at an intersection of the first and second cones of possible acoustic source locations.

2. The method in accordance with claim 1 , wherein the contour of estimated possible acoustic source locations includes a set of ranges, depths, bearing angles, and depression/elevation (DE) angles from a known location to the acoustic source.

3. A method for locating an acoustic source comprising:

providing a first linear array at a first depth in a plane;

providing a second linear array at a second depth in the same plane as the first linear array;

receiving signals from the acoustic source at each of the first linear array and the second linear array;

resolving signals received at the first linear array into a first cone of possible acoustic source locations;

resolving signals received at the second linear array into a second cone of possible acoustic source locations;

estimating a contour of possible acoustic source locations at an intersection of the first and second cones of possible acoustic source locations wherein the estimated location of the acoustic source includes a set of ranges, depths, bearing angles, and depression/elevation (DE) angles from a known location to the acoustic source; and

towing the first linear array and the second linear array by a vessel in a tow direction in a near-field of the acoustic source wherein the known location is a location on the vessel.

4. The method in accordance with claim 3 , wherein the first linear array has a first phase center and the second linear array has a second phase center such that the second linear array is offset from the first linear array along the tow direction of the vessel.

5. The method in accordance with claim 3 , further comprising:

providing a third sonar array positioned on the vessel; and

obtaining a bearing angle and a depression/elevation angle from the acoustic source to the third sonar array.

6. The method in accordance with claim 5 , further comprising estimating the location of the acoustic source as a function of the bearing angle and depression/elevation angle, and the contour of possible acoustic source locations.

7. A method for locating an acoustic source comprising:

providing a first linear array at a first depth in a plane;

providing a second linear array at a second depth in the same plane as the first linear array;

providing a third sonar array on a vessel;

receiving signals from the acoustic source at each of the first linear array, the second linear array, and the third sonar array;

resolving signals received at the first linear array into a first cone of possible acoustic source locations;

resolving signals received at the second linear array into a second cone of possible acoustic source locations;

estimating a contour of possible acoustic source locations at an intersection of the first and second cones of possible acoustic source locations;

obtaining a bearing angle and a depression/elevation angle from the acoustic source to the third sonar array; and

estimating a location of the acoustic source as a function of the third array bearing angle and depression/elevation angle, and the contour of possible acoustic source locations.

8. The method of claim 7 , further comprising providing a controller wherein said steps of receiving signals, resolving signals received at the first linear array, resolving signals received at the second linear array, obtaining a bearing angle and a depression/elevation angle, and estimating the location are performed by the controller.

9. The method of claim 8 , wherein the controller is positioned at the second vessel.

10. The method of claim 8 , wherein the controller is positioned remotely from the second vessel.

11. A method for locating an acoustic source comprising:

providing a first linear array at a first depth in a plane;

providing a second linear array at a second depth in the same plane as the first linear array;

providing a third sonar array on a first vessel;

receiving signals from the acoustic source at each of the first linear array, the second linear array, and the third sonar array;

resolving signals received at the first linear array into a first cone of possible acoustic source locations;

resolving signals received at the second linear array into a second cone of possible acoustic source locations;

estimating a contour of possible acoustic source locations at an intersection of the first and second cones of possible acoustic source locations;

obtaining a bearing angle and a depression/elevation angle from the acoustic source to the third sonar array;

estimating a location of the acoustic source as a function of the third array bearing angle and depression/elevation angle, and the contour of possible acoustic source locations; and

towing the first linear array and the second linear array in a tow direction by a second vessel.

12. The method of claim 11 , wherein the second vessel is a surface vessel.

13. The method of claim 11 , wherein the second vessel is a submarine.

14. The method in accordance with claim 11 , wherein the second linear array is at a deeper depth relative to the first linear array, the first linear array being parallel to the second linear array.

15. The method in accordance with claim 11 , wherein the second vessel is the same vessel as the first vessel.