Browsing Reprints by Subject "Acoustic reverberation"
Now showing items 1-20 of 25
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A shallow water system for maximizing echo to reverberation ratio
(NATO. SACLANTCEN, 1993/08)A method for increasing incident energy on mid-depth targets while at the same range reducing boundary reverberation for shallow water ducts has been devised. The basis of the approach is couched in range dependant normal ... -
A theoretical model for doppler spread of backscattered sound from a composite roughness sea surface
(NATO. SACLANTCEN, 1975/10)For calculating the Doppler spread of acoustical reverberation from the sea surface, good results are achieved by applying a composite-roughness model. The small wavelets primarily responsible for the backscattering are ... -
Acoustic characterization of a shallow water site
(NATO. SACLANTCEN, 1993/08)Results are presented from an exercise aimed at providing a low frequency active sonar environmental characterization of a specific shallow water site in the Gulf of Mexico. Downward refracting acoustic transmission and ... -
Application of ray tracing with horizontal gradient to monostatic boundary reverberation
(NATO. SACLANTCEN, 1971/12)Presented is the current work being done at the Naval Research Laboratory (NRL) on the development of a series of computer programs to predict long range, low frequency, monostatic boundary reverberation. The emphasis is ... -
Calculation of reverberation and average intensity of broadband acoustic signals in the ocean by means of the RAIBAC computer model
(NATO. SACLANTCEN, 1976/04)Based on the conventional ray-tracing principle, a fast numerical algorithm is developed that calculates averaged propagation loss and reverberation of underwater sound. The averaging is performed by summing incoherently ... -
Comparison of measured reverberation on the transmission loss data with modelled results on the West Florida continental shelf
(NATO. SACLANTCEN, 1993/08)Acoustic data from the September, 1992 Area Characterization Test (ACT I) are compared to ADAM (Advanced Development Acoustic Model) output. Conduct of harsh shallow water acoustic exercises, and data interpretation mandates ... -
Effect of different bandwidths for the detection of extended targets in reverberation
(NATO. SACLANTCEN, 1993/08)In this paper, firstly the theoretical background of bandwidth effects on detection in noise and reverberation is presented in some detail, and secondly the relevant results of sea. trials with a low frequency active sonar ... -
Effects of sea bed structure on high frequency acoustic reverberation in shallow water
(NATO. SACLANTCEN, 1997)Although undoubtedly sea bed structures, patterns, and composition affect the reverberation of high-frequency acoustic energy, the extent of their influence is not well known. The effects of varying selected bedform ... -
High resolution feature extraction from reverberation data
(NATO. SACLANTCEN, 1997)A new method of signal approximatzon is presented which has the capability to model complex active returns due to reverberation. The method explored herein is data adaptive in the sense that high resolution processing is ... -
Measurements and modelling of high-frequency acoustic scattering by a rough seafloor and sea surface
(NURC, 2009/12)Acoustic scattering by a rough, possibly dynamic interface is experimentally studied by insonifying the seabed and the sea surface at high frequency at various incidentangles. A directional source working at 300 kHz was ... -
Model-aided data adaptive suppression of reverberation
(NATO. SACLANTCEN, 1993/08)We propose a processing methodology which is based on the piece-wise modeling, adaptive estimation, and removal of reverberation components. An important feature of this approach is that backscatter models and information ... -
Modeling range-dependent, high-frequency, shallow-water torpedo reverberation data
(NATO. SACLANTCEN, 1997)The high-frequency, forward bottom losses predicted by a lossy Rayleigh and a Biot poroelastic sediment model are substantially different. These differences will accumulate and become measurable in multiple bottom bounce ... -
Multistatic bottom reverberation in shallow water
(NATO. SACLANTCEN, 1997)A wavenumber integration approach to modeling of the full multistatic reverberant field produced by small-scale bottom roughness in stratified shallow water waveguides has been developed. A perturbation approach to rough ... -
Ocean-basin reverberation from large underwater explosions: part 1: source-level and propagation-loss modelling
(NATO. SACLANTCEN, 1975/10)Predicting the reverberant returns from ocean basin reflectors requires describing acoustic source levels for large, conventional underwater explosions, defining the two way propagation loss and signal spreading from the ... -
Ocean-basin reverberation from large underwater explosions: part 2: computer model for reverberation
(NATO. SACLANTCEN, 1975/10)Following detonation of an underwater explosion, sound reverberates from the ocean surface and bottom and from scatterers within the medium. In addition, the boundaries of the ocean basin and obstructions within it, such ... -
Position and shape of the surface shadow zone
(NATO. SACLANTCEN, 1971/12)From surface reverberation studies conducted by SACLANTCEN's Target Classification Group"C , it has been found necessary to know before any sea experiment the precise position of the first surface shadow zone. Since normal ... -
Separability of scattering and reflection parameters in reverberation inversion
(NURC, 2007/11)A premise of reverberation inversion is that one can separate geoacoustic reflection properties from scattering properties since their effects on reverberation are distinguishable. Some doubt has been cast on this premise ... -
Separability of seabed reflection and scattering properties in reverberation inversion
(NURC, 2007/02)Separation of scattering properties (Lambert's mu) from reflection properties (the reflection loss angle derivative alpha) presents difficulties in the geoacoustic inversion of long range reverberation in isovelocity ... -
Shallow water reverberation modeling using an autoregressive range-scattering function approach
(NATO. SACLANTCEN, 1997)The primary limitation on system performance for active sonars is reverberation - the reradiation of acoustic energy back to the receiver from inhomogeneities in the physical properties of the medium and its boundaries. A ... -
Some comments on ray theory with examples from current NUC ray trace models
(NATO. SACLANTCEN, 1971/12)Three topics were covered in this paper: 1. Ray Sweep-out Method - a technique for calculating sound intensities at a large number of receiver points in range and depth . 2. Bi-static Reverberation Model - a technique based ...