Browsing Reprints by Title
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Tactical data acquisition experiences
(NATO. SACLANTCEN, 1972/05)The requirements of Tactical Data Acquisition systems are discussed and summarized. Experiences with equipment and their utilization are described including : quantities measured, input signal conditioning, analogue ... -
Tank measurements of elastic scattering by a resin-filled fiberglass spherical shell
(NURC, 2007/12)Acoustic elastic scattering measurements were conducted in a tank on a 6cm radius fibreglass spherical shell filled with a low-shear-speed epoxy resin. Preliminary measurements were conducted also on the void shell before ... -
Tank measurements of scattering from a resin-filled fibreglass spherical shell with internal flaws
(NURC, 2008/09)This paper presents results of acoustic inversion and structural health monitoring achieved by means of low to midfrequency elastic scattering analysis of simple, curved objects, insonified in a water tank. Acoustic elastic ... -
Target detection and location with ambient noise
(NURC, 2008/09)By placing a vertical array in an ambient noise field and forming an upward and a downward beam one obtains two time series which can be cross correlated to reveal a subbottom profile of the seabed [Siderius et al., J. ... -
Target time smearing with short transmmissions and multipath propagation
(NURC, 2012/04)In active sonar the target echo level is often estimated with a propagation model that adds all multipath arrivals. If the (post-correlator) transmitted pulse is short compared to the multipath time spread then there is ... -
Temporal fluctuation of backscattered field due to bioturbatioon in marine sediments
(NATO. SACLANTCEN, 1997)Biological activity in marine sediments creates a time-varying, randomly fluctuating medium. A bio-diffusive model is proposed for predicting the temporal and spatial spectrum of sediment density fluctuations. Perturbation ... -
Temporal modeling of high frequency (30-100 kHz) acoustic seafloor backscatter: shallow water results
(NATO. SACLANTCEN, 1997)A temporal model of high frequency seafloor acoustic backscatter is presented and compared to recorded echoes from terrigenous sediments. Using acoustic properties correlated with mean grain size, the echo shapes and ... -
Terrain mapping with forward looking sonar on unmanned underwater vehicles
(NATO. SACLANTCEN, 1997)In the future, successful reconnaissance operations conducted in shallow water with Autonomous Underwater Vehicles will rely heavily on a high performance, high resolution, forward look sonar coupled with terrain mapping ... -
Texture analysis of sidescan sonar imagery using statistical scattering models
(NATO. SACLANTCEN, 1997)It is shown that the generalised K-distribution provides a good fir to the amplrtude statisttcs of sonar imagery from several different types of seabed sediment. A number of possible explanations for the Ricean nature of ... -
The AP-120B array processor
(NATO. SACLANTCEN, 1979/12)The Floating Point Systems array processor AP 120 B is briefly presented. An overview of the architecture is given. The most important features and the use of the AP software are described -
The application of high-speed processors to propagation experiments using explosives
(NATO. SACLANTCEN, 1979/12)The possibility of analysing explosive signals directly, without an intermediate recording system, offers large improvement~ in the quality and rapid availability of results from acoustic propagation experiments. The ... -
The ARL shipborne computer system
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The continuous gradient ray tracing system (CONGRATS)
(NATO. SACLANTCEN, 1971/12)CONGRATS, an acronym for the Continuous Gradient Ray Tracing System, is an integrated collection of ray tracing programs designed to model acoustic propagation and reverberation. The fundamental programs of the series, ... -
The dynamics of information fusion: synthetic versus misassociation
(NURC, 2006/08)Fusion entails both the association and synthesis of information. If missassociations occur, they obviously undermine the gains won by synthesis, compromising the fusion product. An analytic framework is presented here to ... -
The effect of gravity-forced oscillations at the base of the duct on its effective depth as a channel for acoustic rays
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The effect of suspended particulate matter on the performance of high frequency sonars in turbid coastal waters
(NATO. SACLANTCEN, 1997)Shallow coastal environments are characterised by high levels of suspended mineral particles relative lo the open ocean and such suspensions can have a significant effect on the performance of high frequency sonars operating ... -
The effect of water column stability on acoustic backscatter from the ocean bubble layer
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The effect source movements on shallow water bottom backscatter
(NATO. SACLANTCEN, 1997)The time-evolution model BORIS is used to study the effects of source movements on bottom backscatter. Changes in the backscattend time domain signals as functions of source depth, position and incident angles are simulated ... -
The effectiveness of a system-of-systems for countering asymmetric maritime threats in ports and harbours
(NURC, 2008/09)A small boat loaded with explosives has been used by terrorists to attack military and civilian maritime surface vessels at berth or at anchor. For example, suicide bombers attacked the USS Cole using a small boat while ... -
The fauna of the Strait of Sicily
(NATO. SACLANTCEN, 1972/09)All students of the Mediterranean, both biologists and physical oceanologists, now agree t ·hat the Western and the Eastern basins have rather different features and that the Strait of Sicily is there fore an interesting ...