Browsing Reprints by Title
Now showing items 516-535 of 548
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Through-the-sensor geoacoustic inversion along a towed horizontal line array: results from real data set in the Mediterranean sea
(NURC, 2007/12)The assessment of active sonar performances in shallow water strongly depends on the environmental conditions. Of most importance, bottom properties are known to strongly affect the forward acoustic propagation and ... -
Time dependence of infrasonic ambient seafloor noise on a continental shelf
(NATO. SACLANTCEN, 1986/06)SACLANTCEN is conducting a long term programme of ambient noise measurements that cover the frequency band from 1 to 100 Hz. A sea-bed sensor consisting of three seismometers and a hydrophone has been deployed close to the ... -
Time domain finite difference methods for range dependent Biot media
(NATO. SACLANTCEN, 1997)The physics of sound propagation in saturated, porous (Biot) media differs from propagation in fluids and elastic/anelastic solids because of the existence of a second compressional wave, the "slow" wave. Many environments ... -
Time-frequency representation of model based high frequency broad band scattering from a rough interface
(NATO. SACLANTCEN, 1997)A formulism for scattering a broad band high frequency pulse from a randomly rough surface of n penetrable oceanic sediment is developed and used to investiyate the ability of local cosine transform (LCT) rime-frequency ... -
Toward the development of secure underwater acoustic networks
(CMRE, 2019/05)Underwater acoustic networks (UANs) have been recognized as an enabling technology for various applications in the maritime domain. The wireless nature of the acoustic medium makes UANs vulnerable to various malicious ... -
Towards fully autonomous underwater vehicles in ASW scenarios: an adaptive data driven AUV mission management layer
(CMRE, 2019/06)We present an adaptive, data driven Mission Management Layer (MML) to manage the phases (surveillance, track prosecution and target reacquisition) of the mission of AUVs operating as receiver nodes in a multistatic network ... -
Tracking an unknown number of targets using multiple sensors: a belief propagation method
(CMRE, 2019/06)We propose a multisensor method for tracking an unknown number of targets. Low computational complexity and very good scalability in the number of targets, number of sensors, and number of measurements per sensor are ... -
Two dimensional internal-wave spectra
(NATO. SACLANTCEN, 1975/10)Although spatial fluctuations of the sound speed in the ocean have a variety of causes, internal waves are thought to produce most of the fluctuations over horizontal scales ranging from several tens of metres to several ... -
Two-dimensional space-series analysis for sea-floor roughness
(NATO. SACLANTCEN, 1979/10)For a quantitative description of the sea-floor roughness, a numerical method has been developed to obtain the two-dimensional power spectrum and the autocorrelation function. The determination of these parameters gives ... -
Underwater acoustics - modelling: keynote address
(NATO. SACLANTCEN, 1975/10) -
Underwater communications research and development at CMRE
(CMRE, 2019/06)A key to developing autonomous maritime systems for NATO is communication among data gathering platforms below and above the water. However, unlike the mature technologies that are used for terrestrial networks, underwater ... -
Underwater intruder detection sonar for harbour protection: state of the art review and implications
(NURC, 2006/08)Sonar is the sensor of choice for wide-area underwater surveillance because sonar (based on sound waves) typically provides a much larger area of coverage than radar (electromagnetic waves) or video (visible light) can ... -
Underwater optical and acoustic imaging: a time for fusion? a brief overview of the state-of-the-art
(CMRE, 2019/06)Underwater optical imaging has several drawbacks inherent to the physical medium such as light attenuation and turbidity. Sonars try to obviate those issues although, typically, they have lower resolutions. Combining visual ... -
Underwater photography for quantitative description of bottom roughness
(NATO. SACLANTCEN, 1985/04)Knowledge of the roughness of the sea floor is obviously of great importance in marine geology for understanding the processes of the ocean bottom, and in underwater acoustics for understanding the scattering process. The ... -
Underwater source localization using a hydrophone-equipped glider
(CMRE, 2014/01)Buoyancy-driven underwater gliders are autonomous underwater vehicles that were originally developed to collect oceanographic data. CMRE is studying the use of this technology for the characterization of denied areas, ... -
Underwater target classification in synthetic aperture sonar imagery using deep convolutional neural networks
(CMRE, 2019/06)Deep convolutional neural networks are used to perform underwater target classification in synthetic aperture sonar (SAS) imagery. The deep networks are learned using a massive database of real, measured sonar data collected ... -
Uniqueness problems in extracting environmental parameters from high-frequency shallow-water reverberation measurements
(NATO. SACLANTCEN, 1997)Inversion techniques that extract environmental parameters from measured reverberation often lead to mathematical problems that are not well-posed. Two examples illustrate this possibility. The first hows how a model can ... -
Unmanned surface vessels for surface and subsurface threats in harbours: background and practical lessons
(NURC, 2009/12)The use of Unmanned Surface Vehicles (USVs) in harbour protection missions has been studied through technology surveys and experimentation within the programme of work at NURC. The crucial subsystems and vehicle payloads ... -
Use of the towship for assessing towed-array performance and analyzing data quality
(NATO. SACLANTCEN, 1982/11)A series of relatively simple tests are presented and discussed, which used in conjunction with the noise received from the towship, can be used in real time to assess the performance of a towed array and the quality of ... -
User-orientated software for signal analysis
(NATO. SACLANTCEN, 1979/12)A conflict exists between dedicated analysis instruments which are easy to use but inflexible and general purpose computers which are adaptable but require program development. A software package has been. developed which ...