Now showing items 85-104 of 882
-
Acoustic models at SACLANTCEN
(NATO. SACLANTCEN, 1995/03)The Environmental Modelling Group at SACLANTCEN maintains a suite of computer codes to model sound propagation in the ocean. This suite contains numerical models to cover all environmental conditions and acoustic frequencies ... -
Acoustic noise models
(NATO. SACLANTCEN, 1975/10)The question of modeling the vertical directionality of ambient noise in the ocean is considered. The problem of converting from a description in terms of directional density function to a description in terms of 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 scattering from rough surfaces
(NATO. SACLANTCEN, 1975/10)A review of scattering from the ocean bottom and ocean ice cover is given. Areas of deficiency are cited. -
Acoustic scintillations of acoustic waves
(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 ... -
Acoustic source characteristics of merchant ships
(NATO. SACLANTCEN, 1982/06)Merchant ships are sources of broadband acoustic noise which can interfere with and confuse ocean surveillance. The purpose of this discussion is to review: the status of research on and measurements of merchant ship ... -
Acoustic source-level measurements for a variety of merchant ships
(NATO. SACLANTCEN, 1988/07)This report describes a set of 50 source spectra obtained from merchant ships of opportunity near Genova, Italy. These spectra were obtained from radiated-noise spectra measured on a towed array and a transmission-loss ... -
Acoustical characteristics of the sea floor: experimental techniques and some examples from the Mediterranean Sea
(NATO. SACLANTCEN, 1974/11)The acoustical properties of the sea floor are primarily determined by the physical properties of the sediments, layering in the sediments, and the roughness of the bottom and sub-bottom. Over the last decade many cores ... -
Acoustical probing for microbubbles at sea
(NATO. SACLANTCEN, 1975/10)Free gas bubbles have been indicted for many physical processes at sea including: scavenging detritus and chemicals from the ocean volume; generating droplets whose salts affect thunderstorm activity over the sea; providing ... -
Active contours for synthetic aperture sonar snippet registration
(CMRE, 2019/06)In mine-hunting operations, there is currently a strong focus on using autonomous systems in order to remove personnel and ships from the minefield. These systems must perform their missions effectively, and the collected ... -
Active detection enhancement in coastal areas
(NURC, 2006/08)The processing chain used for active detection analysis in association with measures of performance that allow real time performance monitoring is presented. Real life examples demonstrating environmental volatility ... -
Active signal detection in shallow water using the Page test
(NATO. SACLANTCEN, 1996/11)The use of active sonar in shallow water results in received echoes that may be considerably spread in time compared to the transmitted wave form. The duration and structure of the spreading and the time of occurrence of ... -
Adaptive autonomous underwater vehicles for littoral surveillance: the GLINT10 field trial results
(NURC, 2012/05)Autonomous underwater vehicles (AUVs) have gained more interest in recent years for military as well as civilian applications. One potential application of AUVs is for the purpose of undersea surveillance. As research into ... -
An adaptive cross-layer routing protocol for underwater acoustic networks
(2019/05)This short paper presents an adaptive cross-layer routing protocol for Underwater Acoustic Networks (UANs). The proposed solution, termed NADIR for Network Aware aDaptIve Routing, is fully distributed and self-adaptive. ... -
Adaptive filter of seabed clutter onboard the AUVs of an active multistatic sonar network
(CMRE, 2019/05)This work aims at reducing the false alarm rate of a multistatic active sonar working in coastal, shallow waters. The sonar system is implemented through a heterogeneous manned-unmanned network including autonomous underwater ... -
Adaptive filtering of imprecisely time-stamped measurements with application to AIS networks
(CMRE, 2019/06)Driven by real-world issues in maritime surveillance, we consider the problem of estimating the target state from a sequence of observations that can be imprecisely time-stamped. That is, the time between two consecutive ...