Underwater acoustic positioning using a ray-tracing-based ToA–wavefront database in very shallow water with a non-uniform sound speed profile

Abstract This study proposes an underwater acoustic positioning method designed for very shallow water, where severe multipath propagation and non-uniform sound speed profiles (SSPs) often obscure the direct path and degrade ranging accuracy. The method combines the spatial convergence of backward-propagated synthetic wavefronts from imaginary sources with time-of-arrival (ToA)-wavefront shape database based on ray tracing. The proposed method actively exploits reflections and reconstructs the c