Browsing CMRE Publications by Subject "Underwater acoustics"
Now showing items 21-40 of 73
-
Digital analysis working group: proceedings of a conference held at SACLANTCEN on 25-27 May 1971
(NATO. SACLANTCEN, 1972/05) -
Doppler passive fathometry
(CMRE, 2019/05)Passive fathometry is a technique whereby broadband ambient ocean noise received on an array of hydrophones is averaged and cross-correlated to produce a sub-bottom profile [Siderius, Harrison, and Porter (2006). J. Acoust. ... -
Effects of sea-ice ridges on sound propagation in the Arctic Ocean
(NATO. SACLANTCEN, 1975/10)An environmental/acoustic model of sound propagation in the Arctic Ocean, which accounts for reflection losses from ridged sea ice, has been developed. In this model sea-ice ridges are represented as infinitely long, ... -
Experimental data on the refraction of underwater explosion pulses
(NATO. SACLANTCEN, 1971/12)There are several reasons why a researcher in underwater acoustics might be interested in the use of explosion pulses as sources. The most generally recognized reason is that explosions are convenient and powerful sources ... -
Gas bubbles in the sea: a review and model proposals
(NATO. SACLANTCEN, 1975/10)The literature pertaining to both free bubbles (pt 1) and bubbles associated with fish anotomy (pt 2) is reviewed with particular emphasis on their distributions in the sea and influencing factors. An attempt is made to ... -
Geometrical properties of underwater sound propagation
(NATO. SACLANTCEN, 1971/12) -
Hamiltonian methods in hydro-acoustic propagation
(NATO. SACLANTCEN, 1971/12)The investigation that I wish to outline here originated in the military need of forecasting detection p r obabilities of underwater acoustic emitters, in case s in which only a somewhat general idea of the sound speed ... -
High-frequency normal-mode calculations in deep water
(NATO. SACLANTCEN, 1982/10)A method has been developed to perform high-frequency deep-water normal-mode calculations in the multikilohertz region in water depths of the order of 5 km. The results from this technique agree with fast field program ... -
Impulse response of a layered bottom
(NATO. SACLANTCEN, 1967/01)Numerical methods are used for the Fourier inversion of the frequency-dependent loss transfer function. Because of the non-zero finite values of the integrand for an infinite high frequency, the asymptotic value is subtracted ... -
Intensity calculations along a single ray
(NATO. SACLANTCEN, 1974/02)A method is presented for the calculation of sound intensity using only one ray. The sound-velocity profile is assumed to be continuous up to the second derivative and it is supposed that the ray equations are solved ... -
Is power averaging the best estimator for undersea acoustic data?
(NATO. SACLANTCEN, 1982/06)The power average is the statistic which is commonly used in all types of acoustic data processing. It is an excellent estimator for "well behaved" Gaussian distributions when the central or average value is desired. ... -
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 ... -
Measurement of the bubble population in coastal waters using combination frequencies of MHz order
(NATO. SACLANTCEN, 1997)This paper describes the use of a combinatron frequency technique to measure the size distribution of oceanic bubbles. Written between two sea trials, the paper describes how the apparatus cart be adapted to design tests ... -
Methods used in France for the calculation of sound fields
(NATO. SACLANTCEN, 1971/12) -
Noise sources in the ocean - part 1
(NATO. SACLANTCEN, 1975/10)Following a brief historical survey of the development of our knowledge of the origins and characteristics of ambient noise in the ocean, the principal known sources of noise are described. These are: environmental origin, ... -
Noise sources in the ocean - part 2
(NATO. SACLANTCEN, 1975/10)Following a brief historical survey of the development of our knowledge of the origins and characteristics of ambient noise in the ocean, the principal known sources of noise are described. These are: environmental origin, ... -
Numerical simulation of the effects of bathymetry on underwater sound propagation using three-dimensional parabolic models
(NATO. SACLANTCEN, 1998/03)Two different three-dimensional parabolic equation (PE) methods are -
The ocean noise coherence matrix and its rank
(CMRE, 2019/05)An expression for the cross-spectral density matrix of ocean noise naturally separates into a Toeplitz part and a Hankel part [Harrison (2017). J. Acoust. Soc. Am. 141, 2812?2820]. The Toeplitz part is shown to be substantially ...