Browsing Reprints by Title
Now showing items 185-204 of 548
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Dynamic placement of a constellation of surface buoys for enhanced underwater positioning
(CMRE, 2019/06)This paper addresses the challenge of dynamically adapting the location of the nodes in an acoustic network to optimise the localisation performance of Autonomous Underwater Vehicles (AUVs) operating in the area. A dynamic ... -
Dynamic underwater glider for environmental field estimation
(CMRE, 2019/06)A coordinated dynamic sensor network of autonomous underwater gliders to estimate three-dimensional time-varying environmental fields is proposed and tested. Integration with a network of surface relay nodes and asynchronous ... -
Dynamic underwater sensor network for sparse field estimation
(CMRE, 2019/06)A coordinated dynamic network of autonomous underwater gliders to estimate 3D environmental sparse fields is proposed and tested. Field spatial sparsity is exploited in the estimation algorithm. Moreover field measurements ... -
Effect of different bandwidths for the detection of extended targets in reverberation
(NATO. SACLANTCEN, 1993/08)In this paper, firstly the theoretical background of bandwidth effects on detection in noise and reverberation is presented in some detail, and secondly the relevant results of sea. trials with a low frequency active sonar ... -
Effect of ship motion on sonar detection performance
(NATO. SACLANTCEN, 1975/10)For an unstabilized transducer, the effect of ship motion on sonar echoes is twofold: 1. Attenuation caused by the rotational movement of the transducer in the vertical plane. The results show that the different loss figures ... -
Effect of waveform on synthetic aperture sonar performance
(NATO. SACLANTCEN, 1997)This paper describes the main properties of the synthetic aperture sidescan sonar and highlights performances and limitations related to sonar features for mine counter measures. Attention is focused on the theoretical ... -
Effects of sea bed structure on high frequency acoustic reverberation in shallow water
(NATO. SACLANTCEN, 1997)Although undoubtedly sea bed structures, patterns, and composition affect the reverberation of high-frequency acoustic energy, the extent of their influence is not well known. The effects of varying selected bedform ... -
Effects of sea-ice ridges on sound propagation in the Arctic Ocean
(NATO. SACLANTCEN, 1975/10)An environmental/acoustic model of sound propagation in the Arctic Ocean, which accounts for reflection losses from ridged sea ice, has been developed. In this model sea-ice ridges are represented as infinitely long, ... -
Effects of topographic blockage and ocean boundaries on low frequency noise fields
(NATO. SACLANTCEN, 1982/06)Low frequency noise in most ocean areas is dominated by shipping or industrial noise. The composite noise field is the result of radiated energy from each discrete noise source propagating over relatively large distances ... -
Efficient dense sonar surveys with an autonomous underwater vehicle
(CMRE, 2014/01)An algorithm for the in situ adaptation of the survey route of an autonomous underwater vehicle (AUV) equipped with side-looking sonars was recently proposed. This algorithm immediately exploits the through-the-sensor data ... -
Environmental field estimation by consensus based dynamic sensor networks and underwater gliders
(CMRE, 2019/06)A coordinated dynamic sensor network of autonomous underwater gliders to estimate 3D time-varying environmental fields is proposed and tested. Each sensor performs local Kalman filter sequential field estimation. A network ... -
Environmental impact on mobile sonar shallow water operations
(NATO. SACLANTCEN, 1993/08)Shallow Water operations provide unique challenges for mobile sonars. In many cases propagation conditions can be optimized - our studies have shown that sound channeling can occur in approximately 75% of the strategic ... -
Estimating surface orientation from sonar images
(NATO. SACLANTCEN, 1997)A maximum likelihood method for estimating remote surface orientation from multi-static sonar images is presented. It is assumed that the sonar images are corrupted by signal-dependent noise, known as speckle, arising from ... -
Estimation of chirp sonar signal attenuation for classification of marine sediments: improved spectral ratio method
(NATO. SACLANTCEN, 1997)Remote sediment classification through acoustic methods is of great interest for a few years. The attenuation coefficient of the transmitted wave is an important feature to characterize physical sediment layers properties. ... -
Estimation of shear wave properties in the upper sea-bed using seismo-acoustical interface waves
(NATO. SACLANTCEN, 1997)Acoustic interface waves have been recorded with a bottom deployed acoustic array at several locations. High resolution array processing technique (Prony) is used to estimate velocity versus frequency for the interface ... -
The euRathlon 2015 Grand Challenge: the first outdoor multi-domain search and rescue robotics competition - a marine perspective
(CMRE, 2019/06)The euRathlon project was an FP7-funded Coordination and Support Action (2013-2015). Its main aim was to organize outdoor robotics competitions in realistic search and rescue response scenarios for cooperative land, sea, ... -
Evaluation of experimental techniques for determining the plane wave reflection coefficient at the sea floor
(NATO. SACLANTCEN, 1986/06)One of the most commonly used techniques for determinati on of the geoacoustical properties of the sea bed is the measurement of plane wave reflection coefficients at the ocean bottom. An incident field is pr oduced by ... -
Evaluation of low-frequency bottom backscattering strength vs grazing angle by means of multiple beamforming
(NATO. SACLANTCEN, 1986/06)Bottom backscattering strength was measured in deep water as a function of grazing angle in the Balearic Abyssal Plain of the Mediterranean. The measurements were made with a towed, narrowband low-frequency omnidirectional ... -
Experience with a MAP 300 array processor
(NATO. SACLANTCEN, 1979/12)The paper is a summary of the experience collected during almost two years of programming a CSPI MAP 300 array ' processor in signal processing applications. After a short overview of the most interesting features of SNAP ... -
Experimental data on the refraction of underwater explosion pulses
(NATO. SACLANTCEN, 1971/12)There are several reasons why a researcher in underwater acoustics might be interested in the use of explosion pulses as sources. The most generally recognized reason is that explosions are convenient and powerful sources ...
