Robustness of Holographic Processing of Hydroacoustic Signals in the Presence of Intense Internal Waves

Abstract

The robustness of the holographic processing of hydroacoustic broadband signals with respect to the spatial and temporal inhomogeneities of the ocean medium has been experimentally studied. The experiment was performed in shallow water against the background of intense internal waves (IIWs). The sound source was a towed pneumatic emitter; a single hydrophone played the role of a receiver. The interference patterns and holograms of sound pressure for different instants, when a perturbation of the medium caused horizontal refraction or coupling of acoustic field modes, are presented. It is shown that, in the presence of IIWs (which perturb the source field), holographic processing makes it possible to separate the spectral densities of unperturbed and perturbed fields. This circumstance allows one to reconstruct the hologram and interference pattern of unperturbed source field, thus demonstrating the robustness of holographic processing of hydroacoustic signals in the presence of hydrodynamic perturbations.