Shape calibration for a nominally linear equispaced array

We consider a thin flexible line array of equispaced hydrophones that is towed through the sea and develop a statistical test that allows us to decide whether the array is straight or not. The motion of the towing ship, the ocean currents and other forces induce deformations on the array and affect the performance of spatial processing of the data developed under the assumption that the array is straight. When the ship is maneuvering, the processing is generally turned off for long periods of time, an extremely penalizing situation that can be overcome by applying our scheme. Indeed, if the test-applied to the whole array-decides that it is out of shape, the same test is applied to parts of the array to determine the maximum size of admissible subarrays on which the standard processing can be pursued. By combining the bearings estimated by the different subarrays, we reconstruct a piecewise linear estimate of the shape of the array. The approach allows the handling of quite important deformations with no need for a cooperating source