SOFAR Acoustics
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ACOUSTICS

PROPAGATION AND REVERBERATION MODELING
Propagation of sound and seismic waves in the ocean water-column and the sediment is of great importance to ocean engineering and underwater acoustics. It influences the design and the performance of active and passive sonar systems, can be used to determine both fluid and solid oceanographic properties and it provides means of communication with submerged instrumentation platforms. At SOFAR Acoustics we are experienced in carrying out ONR sponsored R & D efforts related to acoustic and structural waves propagation to-and-from scattering objects in range-dependent environments, in addition to having a wealth of experience related to complex sonar systems performance prediction. Our background in propagation modeling spans many of the major numerical simulation approaches  such as: wavenumebr integration, ray-theory, normal modes, finite difference approaches, boundary methods, and finite element methods.


SCATTERING AND STRUCTURAL ACOUSTICS
In mine countermeasures (MCM) applications  resonance of man-made elastic targets is a pivotal concept that distinguishes them from rocks or other clutter that may have a similar mine-like shape.  Nevertheless, burial of an elastic target in the seabed results in a variety of modifications to the scattered response caused by different physical mechanisms, geometric constrains, and intrinsic properties of the sediment. At SOFAR acoustics we have expertise in was to identify, analyze, and explain the fundamental effects of the outer sediment and the proximity of the seabed interface on the scattering of sound from elastic  shells insonified using a mine hunting SONAR. We have a strong background in developing physics-based numerical models used for target scattered field computation, and the interpretation of the physical events taking place. Our numerical simulation capabilities are complemented with the wealth of experimental data processing capabilities based on time of arrival, time-frequency, and array processing methods able of extracting properties of buried target signatures that can be used to classify the targets based on their re-radiated returns.


SONAR SYSTEM DESIGN AND ANALYSIS
Our members have experience in developing computationally efficient reverberation and signal excess models for multi-static active sonar configurations related to diver detection, harbor security applications, and marine mammal detection. They have also worked on aspects of innovative sonar systems design, including careful examination of parameters such as detection range, polar/ azimuthal coverage, source/receiver properties, as well as on beamforming of various array geometries.


EXPERIMENTATION
SOFAR Acoustics also provides know-how related to planning and executing acoustic experiments. Our members have been involved in a number of underwater acoustic tests and experiments related to diver and marine mammal detection and tracking in aggressive acoustic environments, active sonar design testing, and buried mine detection and classification in shallow water using automated underwater vehicles (AUVs).