Studies On DOA Estimation Of Underwater Short-Range Target Based On UCA

DOA finding of underwater short-range target is one of the key techniques for underwater weapons including sonar, homing torpedo and mobile mine. Weapon's tracking ability and exploding damage to target can be increased by precision detection of target's azimuth and elevation. UCA is array with 360° azimuth scanning ability, and it is of the same resolving power in all directions, meanwhile its aperture can be increased by enlarging the radius to some scale. With all these advantages it is a good choice when used in DOA finding of underwater short-range target compared with ULA and other arrays. This dissertation is devoted to DOA finding of underwater short-range target based on UCA from both array structure research and DOA estimation algorithm analysis. The main work is as follows:Firstly, the space structure of UCA and its narrowband statistical data model are introduced in detail, and also the design parameters of UCA are concluded. The beam bearing character and weighted methods of UCA are researched compared with ULA, and the beam bearing character of UCA with unidirectional elements is also studied. Based on mode-space transform, virtual array and its beam bearing are introduced, including weighted method for virtual array.Secondly, DOA finding methods for underwater short-range target are studied thoroughly including both classical beamforming methods and spatial spectrum high resolution methods. In classical beamforming methods, multi-beam scanning, multi-beam interpolating and beam optimal match in MSE are used in DOA finding and their resolution performance are also compared. In high resolution methods, MUSIC and Mini-Norm are used in UCA DOA finding, and beam-space methods are studied based on UCA.Thirdly, by using mode-space transform, more high resolution DOA methods are taken into UCA which used to fit only array with Vandermonde structure, also classical beamforming methods are used on virtual array. Based on mode-space transform, DOA finding methods of coherent signals using UCA are studied including spatial smoothing, matrix reconstruct, Toeplitz and other methods.Fourthly, after theoretically analysis and simulating studies, the holistic architecture of direction detection system for underwater short-range target is designed based on...