I. P. Smirnov

Modeling of High-Frequency Acoustic Fields Scattered by Bodies in Refractive Waveguides

We study the structure of the high-frequency field scattered by a body (observed object) in a refractive plane-layered waveguide with a curved bottom. The solution of the problem allows one to analyze the possibilities of development of acoustic tomography systems with finite numbers of acoustic sources and receivers located in a limited observation region.

Source localization in a shallow-water channel with a rough surface

The problem of source localization in a shallow-water sea is considered, in which the fully developed sea is the prevailing sound-scattering mechanism. Using the criterion of the signal-to-noise-ratio maximum, we construct robust algorithms for estimating the parameters of partially coherent signals. The results of testing these methods for solving the inverse problem using experimental data obtained on a stationary path in the Barents Sea are presented. It is shown that under real conditions, the corresponding algorithms are serviceable and provide satisfactory quality of reconstructing a source located at a distance of ∼15 km from an antenna array.

Reconstruction of the Sea Bottom Parameters for Coherent Seismoacoustic Sounding: I. Decision Rules

We have developed an algorithm for reconstructing the geoacoustic parameters of bottom layers using parametric models of the formation of signals reflected from a layered halfspace during coherent sounding of the bottom of a sea shelf. We propose a method for layer-by-layer reconstruction that makes it possible to efficiently search for a solution in the multiparameter space with limited a priori data.

Target strength in oceanic waveguides

The structure of the target strength in oceanic waveguides is analyzed. The role of the target strength is discussed as one of the key parameters for designing and estimating the efficiency of promising underwater observation systems.

On optimal acoustic field excitation in oceanic waveguides

We propose criteria and develop methods for stable optimization when synthesizing acoustic fields in the case of their excitation by a finite set of coherent sources in oceanic waveguides. As an example, we consider methods of amplitude-phase focusing of the field of a vertical emitting array to a given point of a refractive waveguide. We show that the problem of optimal field focusing can be approximately reduced to that of focusing of the most powerful and stable wave components. We use the ray representation of the field.

Reconstruction of Sea Bottom Parameters for Coherent Seismoacoustic Probing: II. Analysis of Robustness

We solve the problem of layer-by-layer reconstruction of the parameters of bottom layers using parametric models of the formation of signals reflected from a layered half-space for coherent probing of the sea shelf. We use a decision rule based on the sequential application of the MUSIC projection algorithm. We study the operability and stability of the search and decision-making algorithms with limited a priori data.

Source Localization by a Partially Calibrated Array in an Uncertain Transmission Channel

A robust Capon-type algorithm is constructed for source localization by a partially calibrated array operating in an uncertain environment. Results of statistical modeling are presented to determine the accuracy of source localization and the probability of correct source detection. Experimental testing of the proposed method is carried out to demonstrate its performance in Ladoga Lake.

Study of the Coherence of Acoustic Fields of High-Frequency Noise Sources in a Randomly Inhomogeneous Ocean

A model is been developed for the coherence of high-frequency hydroacoustic fields of noise sources in a randomly inhomogeneous ocean. We analyze the dependences of the coherence of hydroacoustic fields of noise sources on the mutual position of the source and receiver system, the type of waveguide, and the parameters of random inhomogeneities of an oceanic waveguide. We discuss the possibilities of underwater acoustic observation.