Browsing CMRE Publications by Type "Papers and Articles"
Now showing items 201-220 of 562
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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 ... -
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 ... -
Experimental evaluation of Net-LBL: an acoustic network-based navigation system
(CMRE, 2019/06)This paper describes the use and in-field evaluation of a Networked-Long Base Line system (Net-LBL) where a network of underwater nodes cooperate to support the localisation and navigation of mobile vehicles. To avoid the ... -
Experimental results of 300 kHz shallow water synthetic aperture sonar
(NURC, 2007/11)The design of a shallow water synthetic aperture sonar (SAS) requires an understanding of key system and environmental issues. The main factors which limit SAS performance are micronavigation accuracy, where micronavigation ... -
Experiments with multi-vehicle operations: the Rapid Environmental Picture Atlantic exercise 2014
(CMRE, 2019/06)The paper describes the Rapid Environmental Picture Atlantic exercise 2014 (REP14-Atlantic), with special focus on the experiments with autonomous underwater, surface and air vehicles, and discusses how large scale ... -
Exploiting phase information in synthetic aperture sonar images for target classification
(CMRE, 2019/05)It is demonstrated that the phase information present in complex high-frequency synthetic aperture sonar (SAS) imagery can be exploited for successful object classification. That is, without using the amplitude content of ... -
Extended target tracking applied to X-band radar data
(CMRE, 2019/06)X-band marine radar systems are flexible and low-cost tools for monitoring multiple targets in a surveillance area. They are able to provide high resolution measurements in both space and time. Such features offer the ... -
Extended target tracking using joint probabilistic data association filter on X-band radar data
(CMRE, 2019/06)X-band Marine radar systems are low-cost tools for monitoring multiple targets in a surveillance area. Although they may suffer from several sources of interference, high resolution measurements in both space and time can ... -
Extracting acoustic source information of shipping noise for dynamic ambient noise modelling
(CMRE, 2019/05)Shipping traffic is one of the largest contributors to anthropogenic noise in the ocean. Noise generated by merchant ships elevates natural occurring ambient noise level by 20-30 dB in many areas of the world?s ocean. In ... -
Fast unsupervised seafloor characterization in sonar imagery using lacunarity
(CMRE, 2019/06)A new unsupervised approach for characterizing seafloor in side-looking sonar imagery is proposed. The approach is based on lacunarity, which measures the pixel-intensity variation, of through-the-sensor data. No training ... -
Flow noise interference in measurements of infrasonic ambient noise
(NATO. SACLANTCEN, 1982/06)Estimates are presented of the local noise generated at infrasonic frequencies by turbulent water flowing in the vicinity of hydrophones used for measurements of ambient noise in the sea. Three situations are discussed: a ...