Two-dimensional separation of wideband raypaths in underwater acoustics

Abstract The ocean acoustic tomography (OAT) is frequently used to the estimation of sound speed variations in the shallow ocean waveguide. As the first step of OAT, acoustic wideband rays along the different paths are exactly separated with two particular parameters of direction of arrival (DOA) and time of arrival (TOA). However, the multipath propagation of ray paths induces interferences between different rays, which makes the OAT impossible to identify these raypaths. In this paper, a two-dimensional wideband grid-free algorithm is proposed for separating acoustic raypaths by using their DOAs and TOAs. Firstly, a continuous formulation of the raypath separation problem is presented. Then, an atomic norm minimization (ANM) problem is designed by exploiting an atomic norm which promotes signal sparsity in the continuous domain. To solve such a ANM problem, an equivalent maximization problem is introduced, which can be solved efficiently with semidefinite programming. Finally, the certain parameters of DOA and TOA achieved through an optimization variable of the maximization problem. The experimental results show that the proposed method obtains more accurate separation performance compared to conventional compressive sensing-based algorithms.