Browsing Technical Reports by Title
Now showing items 258-277 of 322
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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 ... -
Silent ship research applications and operation: proceedings of a conference held at SACLANTCEN on 2-4 October 1984 - volume 2: unclassified papers
(NATO. SACLANTCEN, 1985/01)Introduction: The project to construct an acoustically quiet research ship for the SACLANT ASW Research Centre provided a reason for SACLANTCEN to organize a conference on silent ships, their operation and applications. ... -
Simple instrumentation for measuring temperature gradients at the sea-air interface, including the results of Winter 1964/65 measurements
(NATO. SACLANTCEN, 1965/07)Very little information is available on the temperature differences in the first several centimetres of air above the sea surface and the first few centimetres of water below the sea surface. Data of this kind are important ... -
Single mode excitation, attenuation and backscatter in shallow water
(NATO. SACLANTCEN, 1995/10)Normal mode theory is used to illustrate that a vertical array of weighted sources driven in an -
Single ping clutter reduction: segmentation using Markov random fields
(NATO. SACLANTCEN, 1999/03)The use of low frequency active sonar in shallow water leads to large numbers of clutter detections. This high false alarm rate can overload automatic tracking and classification algorithms. Traditional detection algorithms ... -
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 ... -
Sound attenuation between 200 and 10,000 cps measured along single paths
(NATO. SACLANTCEN, 1965/09)In the deep Mediterranean basins, the water is perfectly isothermal below 400 m, and the deep refracted ray gives clear signals up to 40 km, with a spreading loss free from any frequency-dependent effect. Exploiting this ... -
Source localization in shallow water using multi-frequency processing of shot data
(NATO. SACLANTCEN, 1996/07)Multi-frequency processing methods are applied to real data generated by explosives to examine the -
Spectral integral representations of monostatic backscattering from three dimensional distributions of sediment volume inhomogeneities
(NATO. SACLANTCEN, 2001/03)A theory is developed for generating short time, monostatic reverberation realizations caused by three dimensionally distributed volume inhomogeneities in stratified media. A spectral integral approach to treating the ... -
Spectral integral representations of scattering from volume inhomogeneities
(NATO. SACLANTCEN, 1999/07)In-situ measurements of scattering strength can be obtained by analyzing the early-time, high angle reverberation from bottom and sub-bottom features. In order to provide insight into the mechanisms which cause bottom ... -
Statistical characteristics of large-scale bottom reverberation
(NATO. SACLANTCEN, 1995/07)Simulation results from a statistical characterization of large-scale bottom reverberation from broadband signals are presented. The seafloor profile is parametrized via the surface root-mean-square height and correlation ... -
Statistical evaluation of 80 kHz shallow-water seafloor reverberation
(NATO. SACLANTCEN, 1997/09)Knowledge of the background reverberation environment is a prerequisite for the design of any target detection scheme. While the problem of understanding and predicting high-frequency background reverberation level or mean ... -
Statistical normalization of non-Rayleigh reverberation
(NATO. SACLANTCEN, 2000/02)Low-frequency active sonar systems operating in shallow water are primarily limited by reverberation. -
Studies on information mechanics
(NATO. SACLANTCEN, 1987/04)Related issues connected with the transmission of information in a command and control environment -
Sub-sea floor buried reflectors imaged by low frequency active sonar
(NATO. SACLANTCEN, 1996/06)Low Frequency Active Sonar (LFAS) utilizes low-frequency acoustic -
SUPREMO: a multistatic sonar performance model
(NATO. SACLANTCEN, 2002/11)Multistatic sonars introduce new problems to the modeller such as mutual interference from multiple sources and variable target aspect in a background of range-dependent bistatic reverberation. A multistatic sonar performance ... -
Surface measurements made during the Icelandic Current Experiment (ICE 89) from the R/V Alliance
(NATO. SACLANTCEN, 1991/10)Measurements of surface meteorology and sea temperature taken during the GIN '89A cruise of the research vessel Alliance are presented in the form of time-series plots. The cruise was in the southern Icelandic and Norwegian ... -
Surface measurements made from the R/V ALLIANCE during the Mediterranean aircraft-ship transmission experiment (MASTEX), June 1990
(NATO. SACLANTCEN, 1992/12)Measurements of sea-surface temperature, surface meteorology and atmospheric profiles taken during the June 1990 cruise of the R/V Alliance in the Aegean and Ionian Seas are presented in graphical form. True winds, net ... -
Target detection using a three-layered neural network trained by supervised back-propagation
(NATO. SACLANTCEN, 1990/05)In any sonar system a detection process has to be performed at -
Target localization with multiple sonar receivers
(NATO. SACLANTCEN, 2000/01)Deployable Underwater Surveillance Systems (DUSS) are a network of small multistatic transmitter/receiver sonar nodes. This study analyzes the contact localization capabilities of DUSS in term of range, time and bearing ...