Diffraction of sound pulses on a spherical target in an oceanic waveguide covered with ice

pp. 139-144, vol. 19, 2016

Natalie Grigorieva
St. Petersburg State Electrotechnical University (SPbETU), Russia
St. Petersburg State Marine Technical University, Russia

Mikhail Kupriyanov
St. Petersburg State Electrotechnical University (SPbETU), Russia

Dmitriy Ostrovskiy
St. Petersburg State Electrotechnical University (SPbETU), Russia
JSC Concern Oceanpribor, Russia

Daria Stepanova
JSC Concern Oceanpribor, Russia

Key words: diffraction of acoustic waves; ice-covered homogeneous waveguide; normal modes of the waveguide; a pulse with a Gaussian envelope; surface waves: Franz type; Whispering Gallery type

Abstract: This paper is devoted to modeling of the pulse scattering by a spherical target immersed in a homogeneous waveguide covered with ice. For calculating the echo signal in the frequency domain we have followed Hackman and Sammelmann’s general approach. The arising scattering coefficients of a sphere were evaluated with the use of the normal mode method. The amount of normal modes forming the backscattered field is determined by the given directivity of the source. The emitted signal is a pulse with a Gaussian envelope. Computational results are obtained in a wide frequency range 8 12 kHz for water depths equal to several hundreds of m, and distances between the source/receiver and a target from 1 km up to 10 km. The target is assumed to be acoustically rigid or fluid. In particular, the properties of the ice cover and a scatterer may coincide.

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