Estimation of Towed Array Curvature

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Authors
  1. Dosso, S.E.
  2. Collison, N.E.
Corporate Authors
Defence Research Establishment Atlantic, Dartmouth NS (CAN);Victoria Univ, Victoria BC (CAN) Centre for Earth and Ocean Research
Abstract
This report describes a new inversion algorithm developed to estimate the shape of a towed array. The data consist of the relative travel times of acoustic arrivals along direct and reflected paths from sources deployed by two consort ships maintaining station with the moving tow ship (the "dual-shot method"). Previous inversion algorithms applied least-squares methods based on simplifying assumptions, such as straight-line propagation and exact knowledge of the source positions. Here, a regularized inversion is developed based on ray theory, with the source positions included as unknown parameters subject to a priori estimates and uncertainties. In addition, a minimum-structure array shap is determined by minimizing the three-dimensional curavture subject to fitting the dtaa to a statistically meaningful level, thereby reducing spurious fluctuations (roughness) in the solution. Finally, the effect of the survey geometry is investigated by defining a sensor-position error measure based on the a posteriori uncertainty of the inversion. The optimal source configuration is determined by minimizing this error measure with respect to the source positions using an efficient hybrid optimization algorithm. The optimal survey geometry is compared to the standard geometry typically used for the dual-short method. As no field data were available for this contract, the inversion and optimization procedures are illustrated using realistic synthetic examples.
Keywords
Interpolation;Beamforming;Bent arrays;IBF (Interpolation BeamFormer);Curvature;Towed line array;Array element localization;Inversion algorithms;Acoustic source locaization
Report Number
DREA-CR-1999-198 — Contractor Report
Date of publication
01 Sep 1999
Number of Pages
43
DSTKIM No
CA001824
CANDIS No
513692
Format(s):
Hardcopy;Document Image stored on Optical Disk

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