Browsing Technical Reports by Type "Papers and Articles"
Now showing items 1-16 of 16
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A plane-wave decomposition method for modeling scattering from objects and bathymetry in a waveguide
(NATO. SACLANTCEN, 1996/11)In this paper a straightforward plane-wave decomposition method which can be used for solving object andlor interface scattering problems in a waveguide is described. The method utilizes the free-space scattering matrix ... -
A towed CTD chain for two-dimensional high resolution hydrography
(NATO. SACLANTCEN, 1997/04)The need for accurate two-dimensional datasets of temperature and salinity in the upper ocean led to the development of a new type of towed chain. Low-cost sensors are moulded in fins and may be randomly placed on the tow ... -
An automated instrument for testing and monitoring oceanographic mooring cables and ropes
(NATO. SACLANTCEN, 1997/09)Underwater acoustic experiments at the NATO SACLANT Undersea Research Centre, La Spezia, Italy (SACLANTCEN) are largely dependent on moored and towed instrumentation. Every year up to 500 cable terminations am made and ... -
Application of beam-forming techniques to measurements of acoustic scattering from the ocean
(NATO. SACLANTCEN, 1986/10)Signals from an explosive source backscattered from the seafloor and received at long range by -
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 ... -
Deep-sea circulation in the Alboran sea
(NATO. SACLANTCEN, 1985/04)Alboran Sea circulation between 220 and 1100 m depth is studied. Interaction between three types of water masses in this area causes a complicated flow pattern. Atlantic water flowing as a jet through the Strait of Gibraltar ... -
Delay-Doppler resolution performance of large time-bandwidth product linear FM signals in a multi- path ocean environment
(NATO. SACLANTCEN, 1989/04)Active sonar systems that transmit large time-bandwidth (TW)-product linear frequency modulated (LFM) waveforms and receive echoes from targets of unknow~r~an ge and speed can suffer considerable correlation losses that ... -
Efficient global matrix approach to the computation of synthetic seismograms
(NATO. SACLANTCEN, 1986/05)A numerically efficient global matrix approach to the solution of the wave equation in horizontally stratified environments is presented. The field in each layer is expressed as a superposition of the field produced by the ... -
High-resolution analysis of non-stationary data ensembles
(NATO. SACLANTCEN, 1980/10)Estimation of an unknown parameter of a random data ensemble is usually done by maximizing a certain power estimator by varying the unknown parameter. This method is convenient where the data are a nonlinear function of ... -
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 ... -
Limitations on towed array gain imposed by a non-isotropic ocean
(NATO. SACLANTCEN, 1990/08)This study deals with the limitations imposed by ocean characteristics on hydrophone array gain and on attempts to create a synthetic aperture using towed-array measurements. The multi-element synthetic or physical aperture ... -
Modelling scattering from partially buried cylinders = Acoustic scattering from cylindrical objects embedded between two half-spaces/The computation of the scattered pressure field from a cylinder embedded between two half-spaces = The computation of the scattered pressure field from a cylinder embedded between two half-spaces with different densities
(NATO. SACLANTCEN, 1996/12)1. A boundary integral equation method is presented for the computation of the acoustic field scattered from a cylindrical object which is totally within the water column, totally buried in sediment, or partially buried. ... -
Reverberation suppression
(NATO. SACLANTCEN, 1995/05)We propose a processing methodology for shallow-water reverberation -
Some acoustical characteristics of underwater explosions of hydrogen-oxygen mixtures
(NATO. SACLANTCEN, 1963/02)The acoustic characteristics of a hydrogen-oxygen explosive mixture are investigated in an attempt to find a substitute for solid explosives (e.g. TNT) which will achieve a simple underwater acoustic pulse uncomplicated ... -
The joint SACLANTCEN/USA towed vertically directive source - TVDS
(NATO. SACLANTCEN, 1996/07)This report is the text of a paper presented at Undersea Defence Technology, Cannes, 1995 (UDT 95). It outlines the development of the Towed Vertically Directive Source (TVDS) and the associated ship-handling and winching ... -
Virtual beams from an FFT beamformer and their use to assess the quality of a towed-array system
(NATO. SACLANTCEN, 1983/01)Linear towed arrays with sophisticated signal processing systems have become popular for passive sonar and seismic prospecting. This is due to the ease of mobility and the large spatial gains achievable. However, because ...
