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Terrain mapping with forward looking sonar on unmanned underwater vehicles
(NATO. SACLANTCEN, 1997)
In the future, successful reconnaissance operations conducted in shallow water with Autonomous Underwater Vehicles will rely heavily on a high performance, high resolution, forward look sonar coupled with terrain mapping ...
High frequency acoustic observations of Mediterranean flow into the Black Sea
(NATO. SACLANTCEN, 1997)
The physical behavior of Mediterranean flow entering the Black Sea through the Strat of Istanbul is described using a variety of high frequency acoustic systems. Because of the density difference between salty Meditermnean ...
Statistical evaluation of 80 kHz shallow-water seafloor reverberation
(NATO. SACLANTCEN, 1997)
In this work a comparison is presented between 80 kHz reverberation statistics obtained at shallow water sites around Sardinia and Sicily. The data include measurements from several distinct bottom provinces, including ...
Areal seabed classification using backscatter angular response at 95kHz
(NATO. SACLANTCEN, 1997)
A sediment classification scheme is developed based on the angular response (AR) of the seabed backscatter strength. The AR is characterised based on its mean level and slope over predefined angular sectors, and the presence ...
Seabed sediment characteristics assessed geophysically: results of experiments in the Clyde Sea, Scotland
(NATO. SACLANTCEN, 1997)
Within a research programme aimed at developing in situ sediment classification methodologies, it has been demonstrated that with only limited ground truth information, sub-bottom profiler data can be inverted to produce ...
Estimation of shear wave properties in the upper sea-bed using seismo-acoustical interface waves
(NATO. SACLANTCEN, 1997)
Acoustic interface waves have been recorded with a bottom deployed acoustic array at several locations. High resolution array processing technique (Prony) is used to estimate velocity versus frequency for the interface ...
A noise directionality model including variable bathymetry
(NATO. SACLANTCEN, 1997)
In this paper we investigate the noise directionality due to distributed surface sources m several envtronments with a uniformly sloping sea bed. Of particular interest are frequency dependence and the question of the ...
Seabed characterization by inversion of parametric sonar data: selection of the cost function
(NATO. SACLANTCEN, 1997)
A class of possible cost functions to be used in model-based estimation of bottom parameters from highfrequency backscatter signals is introduced. The cost is based on the properttes of the signal in the wavelettransformed ...
Dynamic attenuation extraction of seafloor sediments from very high resolution acoustic data
(NATO. SACLANTCEN, 1997)
An approach to acquire geophysical information of seabed sediments as derrved from acoustic attenuation rs described. Using thefrequencies corresponding to the signal power spectrum maximum and a point 3 dB below, signal ...
Intensity moments of underwater sound scattered by a Gaussian spectrum corrugated surface: measurements and comparison with a catastrophe theory approximation
(NATO. SACLANTCEN, 1997)
An underwater forward-scattering investigation was undertaken with random rough corrugated pressure release surface manufactured out of Styrofoam. Measured wavefields associated with the reflection caustics agree with ...