Browsing by Subject "Acoustic propagation"
Now showing items 21-40 of 153
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Analysis systems for the mesoscale thermal variability in the Greenland-Iceland-Norwegian Sea
(NATO. SACLANTCEN, 1988/07)Mesoscale thermal structure and its spatial variability are very significant for acoustic propagation in the ocean. Therefore ocean thermal analysis procedures are important for the initialisation andverification of ... -
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 ... -
Arctic ambient noise statistical measurement results and their implications to sonar performance improvements
(NATO. SACLANTCEN, 1982/06)Recent analyses of FRAM II arctic data have shown that under ice ambient noise can be at times highly impulsive and non-Gaussian. The analyses included time domain statistical measurements which were consistent with ... -
Assessment techniques for computer models of sound propagation
(NATO. SACLANTCEN, 1975/10)Computer models of sound propagation have exactly three drawbacks: the model only approximates reality,the computer program only approximates the model, and the cost approximates infinity. The only way to assess these ... -
Attenuation of shear waves in near-surface sediments
(NATO. SACLANTCEN, 1997)In situ measurement of compressional and shear speed and compressional attenuation in near-surface marine sediments is a well-developed technology but techniques required to measure shear attenuation have lagged behind. ... -
Beam spreading and loss of spatial coherence in an inhomogeneous and fluctuating ocean
(NATO. SACLANTCEN, 1975/10)A theory has been developed that enables estimates to be made of beam bending, beam spreading and loss of spatial coherence. In this paper we concentrate on the loss of spatial coherence due to scattering. Using a minus ... -
Benchmarking scattering in ocean waveguides
(NATO. SACLANTCEN, 1995/07)Accurate numerical solutions are presented for benchmark problems -
Bottom-interacting ocean acoustics: proceedings of a conference held at SACLANTCEN on 9-13 June 1980
(NATO. SACLANTCEN, 1980/07) -
Broadband acoustic transmission intensity fluctuations in the Tyrrhenian Sea
(NATO. SACLANTCEN, 1996/11)An acoustic propagation experiment was carried out in the Tyrrhenian Sea in October 1985 in which signals from a broadband source were recorded at a range of 5 km with a vertical 62 m hydrophone array over a period of 5 ... -
Calculation of propagation losses in a medium with a velocity profile approximated by a number of Epstein profiles
(NATO. SACLANTCEN, 1971/12)This paper presents a digital ray-theory program, by which the ray trace, travel time and intensity can be calculated for velocity profiles approximated by a number of Epstein functions. -
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 ... -
Celtic Duet - a joint SACLANTCEN/NRL shallow-water sea trial in Celtic Sea during July 1992: data summary
(NATO. SACLANTCEN, 1996/10)In July 1992 a joint shallow-water sea trial was conducted in the -
Channel sensitive processor: real data processing
(NATO. SACLANTCEN, 1998/02)The CSP is applied to data collected during the DUSS97 sea trial. A one-way geometry is used and the transmitted signal propagation time is known a priori. As predicted by analytical and simulation studies, the CSP detector ... -
Comments on the ray theory approximation
(NATO. SACLANTCEN, 1971/12) -
Comparison of CONGRATS ray tracing predictions with MEDUSA measurements of reverberation
(NATO. SACLANTCEN, 1971/12)From the user's point of view, ray tracing is just a computer procedure which is inserted into larger programs of different degrees of complexity . The following table indicates in which kind of programs this procedure is ... -
Comparison of propagation measurements obtained using the MEDUSA system with computer modelled data
(NATO. SACLANTCEN, 1971/12) -
Comparison of ray tracing predictions with wideband propagation measurements
(NATO. SACLANTCEN, 1971/12)The paper gives an illustration of the latest methods which have been developed at SACLANTCEN for the experimental study of sound propagation in deep water. They are based on a high sampling of the sound field produced by ... -
Computer models for underwater sound propagation
(NATO. SACLANTCEN, 1975/10)The state of affairs of computer models for underwater sound propagation loss estimation is discussed from the viewpoints of two segments of the sonar community; i.e., (1) those who develop the models and are primarily ... -
Connection between the solution of the Helmholtz and parabolic equations for sound propagation
(NATO. SACLANTCEN, 1975/10)Using a conformal mapping technique in a rectangular waveguide, we present an exact integral relation between the solutions of the Helmholtz equation whose sound speed c(x,y) varies as a function of both depth y and range ... -
Considerations on numerical and experimental propagation models for two-dimensional variations of medium properties
(NATO. SACLANTCEN, 1971/12)One of the problems the FWG is dealing with is the prediction of sound propagation loss in shallow water. A part of this problem is being treated by bringing measurements and numerical computation into relationship.