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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. ...
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 ...
Noise measurements during MAPEX 2000
(NATO. SACLANTCEN, 2002/03)
During MAPEX2000 some simultaneous ambient noise measurements with an HLA and satellite SAR images were collected. The aim was to predict shipping and wind noise from the satellite radar and to compare results with acoustic ...
Separation of measured noise coherence matrix into Toeplitz and Hankel parts
(CMRE, 2017/08)
The cross-spectral density of ocean ambient noise is usually estimated from the product of the complex hydrophone signals, each of which already corresponds to the summed responses of sources from all angles. The true ...
Bottom reflection properties deduced from an ambient noise: simulation of a processing technique
(NATO. SACLANTCEN, 2002/11)
A promising new method has already been proposed [SACLANTCEN SM-387] to calculate bottom reflection loss from ambient noise directionality. Although this method has been tried experimentally at more than 11 sites under ...
Geoacoustic inversion using multipath pulse shape
(NURC, 2008/09)
Experimental data, measured in a shallow water region of the Mediterranean Sea, are used to show that the variation of received intensity with time is well described by existing expressions [Harrison and Nielsen, J. Acoust. ...
Signal and reverberation formulae including refraction
(NATO. SACLANTCEN, 2003/04)
Because reverberation is an incoherent process it is possible to base realistic solutions on very simple flux theory. This report extends the closed-form signal and reverberation formulae of an earlier report [SACLANTCEN ...
Multipath pulse shape in a refracting environment
(NURC, 2007/11)
Multiple boundary interactions in shallow water propagation introduce a more or less Gaussian angle distribution at a distant receiver. When all paths are added the result is 'mode-stripping', i.e. the steep rays are ...
Ray convergence in a flux-like propagation formulation
(CMRE, 2014/01)
The energy flux formulation of waveguide propagation is closely related to the incoherent mode sum, and its simplicity has led to development of efficient computational algorithms for reverberation and target echo strength, ...
Multipath pulse shapes in shallow water: theory and simulation
(NURC, 2007/04)
In shallow water propagation the steeper ray angles are weakened most by boundary losses. Regarding the sound intensity as a continuous function of angle it can be converted into a function of travel time to reveal the ...