Browsing CMRE Publications by Subject "Shallow water"
Now showing items 41-60 of 105
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Geoenvironmental characterization of selected shallow-water sites on the western European continental shelf (SWAP)
(NATO. SACLANTCEN, 1995/04)Geoenvironrnental analyses for four experiment sites on the continental -
High frequency acoustic propagation in coastal waters
(NATO. SACLANTCEN, 1997)High Frequency Acoustic Propagation experiments were performed with bottom-mounted sources and receivers at different coastal sites. A measurement technique has been developed and propagation loss data have been taken using ... -
High frequency matched field processing
(NATO. SACLANTCEN, 1997)Results are discussed from a high frequency (0 9-5 7 kHz), very shallow water (<10 m) experiment exploring the feasibility of carrying out matched field processing in this frequency and water depth regime The data was ... -
High resolution geoacoustic inversion in shallow water: a joint time and frequency domain technique
(NATO. SACLANTCEN, 1998/12)High resolution geoacoustic data are quired for accurate predictions of -
High-resolution characterization of shallow water sea bottom: need and methodology for a ground-truth reference database
(NATO. SACLANTCEN, 1994/12)A systematic approach to underwater observation of high-resolution seabed features has been developed. These include: morphology caused by current, wave, and biological factors and certain engineering geological factors ... -
Highlights of bottom topography inferred from received depression and bearing angles
(NATO. SACLANTCEN, 1975/10)Statistical properties of the acoustic reflection from the ocean floor have been studied for a var i.ety of bottom types including deep, smooth, flat topography thorough, jagged bottom in shallower (~l km) depths. Explosive ... -
Horizontal array gain in shallow water
(NATO. SACLANTCEN, 1980/12)Some results of a comprehensive model study on the use of horizontal hydrophone arrays in shallow water are presented. Well-known signal processing techniques are applied to a shallow-water sound propagation model in order ... -
Impact of uncertain environmental knowledge on the shallow-water transfer function
(NATO. SACLANTCEN, 1992/12)It is assumed that the acoustic channel can be modeled as a linear time-invariant space-variant filter. In this case, from linear systems theory, it is known that the filter output, that is the predicted source signal ... -
Intensity-range relations for shallow-water sound propagation
(NATO. SACLANTCEN, 1976/04)Convincing experimental evidence is presented to show that various "decay laws" for the decrease of sound intensity with increasing range can give high-quality representation for shallow water data. However, while a sequence ... -
Inversion for geometric and geoacoustic parameters in shallow water: experimental results
(NATO. SACLANTCEN, 1994/12)Experimental results on the estimation of both geometric and geoacoustic parameters in shallow water are presented. Genetic algorithms are used for estimation of the forward model parameters, the -
Low-frequency acoustic measurements in a shallow-water area with a rough sea surface
(NATO. SACLANTCEN, 1975/10)Surface wave spectra have been measured in the North Sea simultaneously with acoustic investigations using explosive and CW sources. The goal of these experiments was to determine the influence of surface waves to low-frequency ... -
Measurement and interpretation of angular spreading from multiple boundary interactions in a shallow water channel
(NATO. SACLANTCEN, 1997)The problem of angular spreading of sound that has undergone multiple boundary scattering (both sea surface and sea bed) in a shallow water channel is discussed. Measurements made of the horizontal spatial coherence along ... -
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 ... -
Measurements and predictions of transmission loss at two sites in the Southwest Approaches to the English Channel
(NATO. SACLANTCEN, 1995/12)As part of a continuing series of measurements being made by -
Measurements of correlation loss and time-spreading in linear FM sweeps and pseudo-random noise signals transmitted over long ranges in shallow water
(NATO. SACLANTCEN, 1986/12)The results of some transmission measurements made in shallow water are described. The ranges were about 15 km, 20 km, and 34 km, and the sound source was either suspended about 10 m above the bottom or was on the bottom ... -
Measurements of normal-mode amplitude functions in a nearly-stratified medium
(NATO. SACLANTCEN, 1975/10)In normal-mode treatments of acoustic propagation in nearly-stratified media, calculations are frequently based on the perfectly-stratified medium model, in which symmetry permits separation of the wave equationo In these ... -
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 ... -
Multipath field representation for seabed parameter extraction using backscatter data from shadow zones
(NATO. SACLANTCEN, 1997)Inversion strategies for bottom parameter estimation in shallow water impose stringent requirements on accuracy and speed of acoustic models. We highlight the importance of second order effects as first order determinants ...