Browsing by Subject "Acoustic propagation"
Now showing items 1-20 of 153
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A conversational processing system of acoustic data for use on land and at sea: SPADA
(NATO. SACLANTCEN, 1972/05) -
A fast field model for three-dimensional wave propagation in stratified environments based on the global matrix method
(NATO. SACLANTCEN, 1986/03)A three-dimensional fast field program (FFP) model based on the global matrix method will be presented. Compared to traditional propagator matrix methods, the global matrix method allows for a more efficient, and, furthermore, ... -
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 ... -
A note on attenuation and dispersion in marine sediments
(NATO. SACLANTCEN, 1989/04)From the more recent investigations reported ill the literature, -
A note on convergent zones
(NATO. SACLANTCEN, 1962/02)An exact solution for ray paths near a sound channel with parabolic velocity profile is given for rays crossing the sound channel axis at small angles. The convergent zone for such rays for a source on axis is compared ... -
A relation between multipath group velocity, mode number, and ray cycle distance
(CMRE, 2014/01)Weston's ray invariant or "characteristic time" in a range-dependent environment is exactly equivalent to the Wentzel-Kramers-Brillouin phase integral for ducted normal modes. By considering a ray element it is shown that ... -
A review of some developments in ray tracing at the Naval Air Development Center
(NATO. SACLANTCEN, 1971/12)The Naval Air Development Center has a comprehensive ray-tracing program which has been extensively used for a number of years not only by our own laboratory, but also by other naval activities and private contractors . ... -
A solution of of the wave sound equation in shallow water for real speed profiles and solid bottom under sediment
(NATO. SACLANTCEN, 1975/10)The wave equation has been solved by using normal mode theory. The medium is assumed to be horizontally stratified. A closed form solution has been found in the case of GANS - PEDERSEN types of density and sound-speed ... -
A technique of comparative analysis of underwater sound transmission loss curves
(NATO. SACLANTCEN, 1975/10)A procedure has been developed for the analysis of transmission loss curves in which received power is known or expressible as a linear function of range. The procedure separates each curve into a sum of three components ... -
A theoretical method for the prediction of underwater explosion pulses at caustics
(NATO. SACLANTCEN, 1971/12)Our concern [Refs. 1 and 2J is with the effect of refraction on the long range propagation of underwater explosion shock waves. Here, as with acoustic sources, ray tracing can be used to predict refraction effects. From ... -
A wave-theoretic method for estimating the effects of internal tides on acoustic wave transmission
(NATO. SACLANTCEN, 1975/10)The effect of the first mode semidiurnal internal tide on a ducttype sound speed profile was approximated by varying the minimum velocity of the parabolic profile in a sinusoidal fashion with a period of 12.42 hours. The ... -
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 ... -
Acoustic effects of internal microstructure
(NATO. SACLANTCEN, 1975/10) -
Acoustic impact of upper ocean models
(NATO. SACLANTCEN, 1989/12)The upper mixed-surface layer of the ocean, with its homogeneous vertical temperature profile, provides a somewhat special acoustic propagation environment where the sound speed will increase (due to pressure) down to the ... -
Acoustic propagation models as viewed by the sonar systems designer
(NATO. SACLANTCEN, 1971/12)The purpose of this paper is to consider the efforts performed in the development of ray acoustic propagation analyses from the viewpoint of advanced sonar system design. In particular, those parameters required of such ... -
Acoustic propagation through oceanic fronts
(NATO. SACLANTCEN, 1971/12)A resume was given of recent experiments in the Mediterranean, East of Malta, designed as a preliminary test of the effect of oceanic fronts on acoustic propagation. It was apparent that in certain circumstances the ... -
Acoustic properties of the sea floor: a review
(NATO. SACLANTCEN, 1975/10) -
Acoustic signal dispersion and distortion by shallow undersea transmission channels
(NATO. SACLANTCEN, 1997)The undersea littoral is an adverse medium for acoustic signal transmission to horizontal ranges of many water depths. Reflections and scattering in the bounded, nonhomogeneous channel disperse the arrivaj of received ... -
An acoustic, high resolution, sediment profiler
(NATO. SACLANTCEN, 1966/11)An acoustic sediment profiler is described that utilizes short 50 kHz pulses to achieve a high range resolution. In trials in shallow water, penetration depths of about 9 m and resolution of about 25 cm were obtained. ... -
An experimental verification of a geometric acoustic approximation
(NATO. SACLANTCEN, 1971/12)This paper sets out to show that a very simple ray treatment may be used to give a surprisingly good estimate of a sound field, even in conditions where the criteria for the use of geometric acoustics are apparently not fulfilled.
