Dissertations / Theses on the topic 'Underwater acoustic signals'
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Barsanti, Robert J. "Denoising of ocean acoustic signals using wavelet-based techniques." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1996. http://handle.dtic.mil/100.2/ADA329379.
Full textThesis advisor(s): Monique P. Fargues and Ralph Hippenstiel. "December 1996." Includes bibliographical references (p. 99-101). Also available online.
Yagci, Tayfun. "Target Classification And Recognition Using Underwater Acoustic Signals." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/3/12606373/index.pdf.
Full textvisual&rdquo
target detection methods left the stage to the computerized acoustic signature detection and evaluation methods. Despite this, the research projects have not sufficiently addressed in the field of acoustic signature evaluation. This thesis work mainly investigates classification and recognition techniques with TRN / LOFAR signals, which are emitted from surface and subsurface platforms and proposes possible adaptations of existing methods that may give better results if they are used with these signals. Also a detailed comparison has been made about the experimental results with underwater acoustic signals.
Eldred, Randy Michael. "Doppler processing of phase encoded underwater acoustic signals." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA241283.
Full textThesis Advisor(s): Miller, James H. Second Reader: Tummala, Murali. "September 1990." Description based on title screen as viewed on December 17, 2009. DTIC Identifier(s): Acoustic tomography, inverse problems, Fast Hadamard Transforms, theses. Author(s) subject terms: Acoustic tomography, Fast Hadamard Transform, maximal-length sequences, Doppler processing. Includes bibliographical references (p. 95-96). Also available in print.
Bissinger, Brett Bose N. K. Culver R. Lee. "Minimum hellinger distance classification of underwater acoustic signals." [University Park, Pa.] : Pennsylvania State University, 2009. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-4677/index.html.
Full textJack, Susan Heather. "The investigation of underwater acoustic signals using Laser Doppler Anemometry." Thesis, University of Edinburgh, 2000. http://hdl.handle.net/1842/15088.
Full textKendall, Elizabeth Ann Caughey Thomas Kirk. "Range dependent signals and maximum entropy methods for underwater acoustic tomography /." Diss., Pasadena, Calif. : California Institute of Technology, 1985. http://resolver.caltech.edu/CaltechETD:etd-04092008-080843.
Full textSanderson, Josh. "Hierarchical Modulation Detection of Underwater Acoustic Communication Signals Through Maximum Likelihood Combining." Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1410872323.
Full textHeaney, Kevin Donn. "Inverting for source location and internal wave strength using long range ocean acoustic signals /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1997. http://wwwlib.umi.com/cr/ucsd/fullcit?p9737384.
Full textEvans, Benjamin Kerbin. "The effect of coded signals on the precision of autonomous underwater vehicle acoustic navigation." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/29044.
Full textIncludes bibliographical references (p. 127-128).
Acoustic coded signaling offers potentially significant improvements over traditional "toneburst" methods in many underwater applications where error due to noise and multipath interference is a problem. In this thesis, the use of these spread spectrum techniques is analyzed for navigation of the REMUS autonomous underwater vehicle. The accuracy of the current system using Turyn and Barker sequences, as well as toneburst, is quantified, and the sources of the remaining error are examined.
by Benjamin Kerbin Evans.
Ocean E.
Blount, Richard J. Jr. "Underwater acoustic model-based signal processing applied to the detection of signals from a planar array of point source elements." Thesis, New York : Kluwer Academic/Plenum Publishers, 1985. http://hdl.handle.net/10945/21597.
Full textGalindo, Romero Marta. "Spatial Variations in the Acoustic Peak Pressure of Impulsive Low Frequency Anthropogenic Signals in Underwater Marine Environments." Thesis, Curtin University, 2017. http://hdl.handle.net/20.500.11937/59661.
Full textSobreira, Filipa Alexandra Veiga. "Effects of vessel noise on underwater vocalizations of bottlenose dolphins, Tursiops truncatus, in the Sado Estuary." Master's thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/21964.
Full textMaritime traffic is an important source of disturbance for coastal cetaceans, especially for local and resident populations, like the bottlenose dolphins (Tursiops truncatus) population in the Sado estuary. Vessel noise might mask important signals such as communication calls. To compensate masking effects, animals may change their vocal behavior by shifting vocal rate, call intensity, call type, call frequency and duration. To evaluate the potential impacts on the acoustic behavior of this population, abundance and acoustic characteristics of whistles, echolocation signals and burst-pulsed sounds were analyzed in relation to boat traffic. The samples used were obtained in field recordings of dolphin vocalizations made from March 2014 to April 2017. Boat traffic operating within a 1000 m radius was listed as absent or present. Vocal elements were classified according to visual graphical and aural characteristics in: whistles, slow-click trains, short-burst pulses, creaks, squawks, variable rate click trains, bangs, gulps, squeaks and grunts. Analysis of emission rates was based on the number of recognizable units per minute for all vocal elements. In the presence of vessels, differences in call rates were not significant for all types of vocal elements. For selected vocal elements, different acoustic parameters were examined, using a nonparametric MANOVA, and modifications between vessel presence and absence were found for the following vocal elements: whistles (X2 (7) = 56.42; N = 620; p < 0.001), creaks (X2 (8) = 19.53; N = 94; p = 0.012), grunts (X2 (8) = 80.968; N = 339; p < 0.001), gulps (X2 (7) = 58.76; N = 260; p < 0.001) and squeaks (X2 (10) = 25.894; N = 121; p = 0.004)). These results show modifications in acoustic behavior in the presence of vessels, suggesting that bottlenose dolphins in this population might adjust their vocal frequencies and produce shorter signals to maintain communication. This study shows that although resident bottlenose dolphins in Sado estuary seem to display some tolerance to the noise generated from boats in their habitat, it probably causes significant changes in their communication behaviors.
O tráfego marítimo é uma fonte de perturbação importante para os cetáceos costeiros, especialmente para populações locais e residentes, como a população de golfinhos-roazes (Tursiops truncatus) no estuário do Sado. O ruído provocado por embarcações pode mascarar sinais importantes, como os de comunicação. Para compensar os efeitos de mascaramento, os animais podem modificar o seu comportamento acústico alterando a taxa de emissão, a intensidade do sinal, o tipo de vocalização, a frequência e a duração dos sinais acústicos. Para avaliar os potenciais impactos no comportamento acústico desta população, foram analisados a abundância e as características acústicas dos assobios, dos sinais de ecolocalização e dos sons pulsados em relação ao tráfego de embarcações. As amostras utilizadas foram obtidas através de gravações subaquáticas realizadas na região do estuário do Sado, feitas de março de 2014 a abril de 2017. Os barcos foram considerados como presentes ou ausentes, tendo em conta um raio de 1000 m. Os elementos vocais foram classificados de acordo com as características visuais gráficas e auditivas em: assobios, trens de cliques, buzzes, rangidos, chorincos, trens de taxa variável, bangs, goles, guinchos e grunhidos. A análise das taxas de emissão baseou-se no número de unidades reconhecíveis por minuto para todos os elementos vocais. Na presença de embarcações, não existiram diferenças significativas para as taxas de emissão de todos os tipos de elementos vocais. Para elementos vocais selecionados, foram examinados diferentes parâmetros acústicos, utilizando uma MANOVA não paramétrica, e foram encontradas alterações entre presença e ausência de navios, para as seguintes vocalizações: assobios (X2 (7) = 56,42; N = 620; p <0,001), rangidos (X2 (8) = 19,53; N = 94; p = 0,012), grunhidos (X2 (8) = 80,968; N = 339; p <0,001), goles (X2 (7) = 58,76; N = 260; p < 0,001) e guinchos (X2 (10) = 25,894; N = 121; p = 0,004)). Estes resultados mostram modificações no comportamento acústico na presença de embarcações, revelando que os golfinhos-roazes desta população poderão ajustar as suas frequências vocais e produzir sinais mais curtos para manter a comunicação. Este estudo sugere que, embora os golfinhos-roazes residentes do estuário do Sado possam apresentar alguma tolerância ao ruído gerado por barcos no seu habitat, este provavelmente causa mudanças significativas nos seus comportamentos de comunicação.
Malfante, Marielle. "Automatic classification of natural signals for environmental monitoring." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAU025/document.
Full textThis manuscript summarizes a three years work addressing the use of machine learning for the automatic analysis of natural signals. The main goal of this PhD is to produce efficient and operative frameworks for the analysis of environmental signals, in order to gather knowledge and better understand the considered environment. Particularly, we focus on the automatic tasks of detection and classification of natural events.This thesis proposes two tools based on supervised machine learning (Support Vector Machine, Random Forest) for (i) the automatic classification of events and (ii) the automatic detection and classification of events. The success of the proposed approaches lies in the feature space used to represent the signals. This relies on a detailed description of the raw acquisitions in various domains: temporal, spectral and cepstral. A comparison with features extracted using convolutional neural networks (deep learning) is also made, and favours the physical features to the use of deep learning methods to represent transient signals.The proposed tools are tested and validated on real world acquisitions from different environments: (i) underwater and (ii) volcanic areas. The first application considered in this thesis is devoted to the monitoring of coastal underwater areas using acoustic signals: continuous recordings are analysed to automatically detect and classify fish sounds. A day to day pattern in the fish behaviour is revealed. The second application targets volcanoes monitoring: the proposed system classifies seismic events into categories, which can be associated to different phases of the internal activity of volcanoes. The study is conducted on six years of volcano-seismic data recorded on Ubinas volcano (Peru). In particular, the outcomes of the proposed automatic classification system helped in the discovery of misclassifications in the manual annotation of the recordings. In addition, the proposed automatic classification framework of volcano-seismic signals has been deployed and tested in Indonesia for the monitoring of Mount Merapi. The software implementation of the framework developed in this thesis has been collected in the Automatic Analysis Architecture (AAA) package and is freely available
Jung, Du San. "Detection of binary phase-shift keying signal in multioath propagation." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02Jun%5FJung.pdf.
Full textDessalermos, Spyridon. "Undersea acoustic propagation channel estimation." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Jun%5FDessalermos.pdf.
Full textThesis Advisor(s): Joseph Rice, Roberto Cristi. Includes bibliographical references (p. 117-119). Also available online.
Bienvenu, Kirk Jr. "Underwater Acoustic Signal Analysis Toolkit." ScholarWorks@UNO, 2017. https://scholarworks.uno.edu/td/2398.
Full textLindgren, Jakob. "Software defined acoustic underwater modem." Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-12170.
Full textAdams, Mark D. "Signal detection optimization for underwater acoustics." Master's thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-02022010-020009/.
Full textWeintroub, Jonathan. "Fish stock assessment by a statistical analysis of echo sounder signals." Master's thesis, University of Cape Town, 1986. http://hdl.handle.net/11427/19509.
Full textWalden, Alan Keith. "Signal processing techniques on an underwater acoustic projector." Thesis, Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/17336.
Full textChen, Teyan. "Novel adaptive signal processing techniques for underwater acoustic communications." Thesis, University of York, 2011. http://etheses.whiterose.ac.uk/1925/.
Full textLiu, Chunshan. "Advanced signal processing techniques for underwater acoustic communication networks." Thesis, University of York, 2011. http://etheses.whiterose.ac.uk/2102/.
Full textSarikaya, Tevfik Bahadir. "A Comparative Analysis Of Matched Field Processors For Underwater Acoustic Source Localization." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612578/index.pdf.
Full texts coherent matched field processor and broadband matched field processor with environmental perturbation constraints is given for certain environmental conditions. Finally, a new weighting approach to combine data for broadband matched field processing is introduced. The fact that information from different frequencies may have different reliability depending on the environmental conditions is considered to develop a weighting scheme. It is shown that a performance gain compared to existing processors can be achieved by using the weighting scheme introduced in this study.
Jai, Wun Hoa Arthur. "Underwater acoustic signal behavior prediction in the region of Kauai Island." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/33582.
Full textIncludes bibliographical references (p. 175-176).
Behavior of underwater sound propagation over long-ranges has been studied for several decades. The purpose of this is to describe sound propagation phenomena in various ocean environments. The key to understanding and visualizing is mathematical modeling. In the ocean acoustics community, four major mathematical techniques have been commonly used to model behavior of acoustic signal in the ocean environment. And they can be categorized into two different fields, range-independent and range-dependent. The accuracy of each method is depends on the environment characteristics. Since the propagating signal can be characterized through the mathematical modeling, it is then possible to use the propagating signal to perform beamforming and determine the characteristic of beam output.
by Wun Hoa Arthur Jai.
S.M.
Pistacchio, David J. "Source/receiver motion-induced Doppler influence on the bandwidth of sinusoidal signals." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Dec%5FPistacchio.pdf.
Full textThesis advisor(s): Kevin Smith, Roy Streit. Includes bibliographical references (p. 95-100). Also available online.
Ooppakaew, Wichian. "Advanced signal processing techniques for underwater acoustic transmission using steerable transducer arrays." Thesis, Northumbria University, 2012. http://nrl.northumbria.ac.uk/11371/.
Full textTrulsson, Felix. "A polynomial phase model for estimation of underwater acoustic channels using superimposed pilots." Thesis, Luleå tekniska universitet, Institutionen för system- och rymdteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-74460.
Full textPierce, Robert S. "Signal enhancement of laser generated ultrasound for non-destructive testing." Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/18395.
Full textNovaes, Marcos (Marcos Nogueira). "Multiresolution Signal Cross-correlation." Thesis, University of North Texas, 1994. https://digital.library.unt.edu/ark:/67531/metadc277645/.
Full textRiley, H. Bryan. "Matched-field source detection and localization in high noise environments a novel reduced-rank signal processing approach." Ohio : Ohio University, 1994. http://www.ohiolink.edu/etd/view.cgi?ohiou1173982711.
Full textRosario, Alexander Alvarez. "Sistema para monitoramento e análise de paisagens acústicas submarinas." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3151/tde-14062016-103939/.
Full textPassive Acoustic Monitoring (PAM) refers to the use of systems to listen and record underwater soundscape, in order to detect, track and identify sound sources through the pressure waves that they produce. It is said to be passive as these systems only hear, not put noise in the environment, such as sonars. Underwater PAM has various application areas, such as military surveillance systems, port security, environmental monitoring, development of population density rates of species, species identification, etc. National technology in the field is practically nonexistent despite its importance. In this context, this paper aims to contribute to the national technology development in the field by designing, building, and operating a self-contained PAM equipment, also developing signal-processing methods for automated detection of underwater acoustic events. A device, named \"OceanPod\"which has characteristics such as low manufacturing cost, flexibility and ease of setup and use, intended for scientific, industrial research and environmental control was developed. Several prototypes of the equipment were built and used in several missions at seawaters. These missions monitoring, enabled start creating an acoustic database, which provided the raw material for the automated acoustic events detectors and realtime test. Additionally, it is also proposed a new method of detecting, identifying sound events, based on statistical analysis of the time-frequency representation of the acoustic signals. This new method has been tested in the detection of cetaceans present in the database generated by missions monitoring.
Gieleghem, Ryan Thomas. "Robust acoustic signal detection and synchronization in a time varying ocean environment." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78186.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (p. 99-100).
Signal detection and synchronization in the time varying ocean environment is a difficult endeavor. The current common methods include using a linear frequency modulated chirped pulse or maximal length sequence as a detection pulse, then match filtering to that signal. In higher signal to noise ratio (SNR) environments (- 0 dB and higher) this has been a suitable solution. As the SNR drops lower however, this solution no longer provides an acceptable probability of detection for a given tolerable probability of false alarm. The issue derives from the inherent coherence issues in the ocean environment which limit the useful matched filter length. This thesis proposes an alternative method of detection based on a recursive least squares linearly adaptive equalizer which we term the Adaptive Linear Equalizer Detector (ALED). This detectors performance has demonstrated reliable probability of detection with minimal interfering false alarms with SNR as low as -20 dB. Additionally this thesis puts forth a computationally feasible method for implementing the detector.
by Ryan Thomas Gieleghem.
S.M.
Conn, Rebecca M. "Underwater source localization with a generalized likelihood ratio processor." Ohio : Ohio University, 1994. http://www.ohiolink.edu/etd/view.cgi?ohiou1176842869.
Full textCaley, Michael Stephen. "Development of a dynamic underwater acoustic communication channel simulator with configurable sea surface parameters to explore time-varying signal distortion." Thesis, Curtin University, 2016. http://hdl.handle.net/20.500.11937/1105.
Full textBoyle, John K. "Performance Metrics for Depth-based Signal Separation Using Deep Vertical Line Arrays." PDXScholar, 2015. https://pdxscholar.library.pdx.edu/open_access_etds/2198.
Full textMuzi, Lanfranco. "Advances in Autonomous-Underwater-Vehicle Based Passive Bottom-Loss Estimation by Processing of Marine Ambient Noise." PDXScholar, 2015. https://pdxscholar.library.pdx.edu/open_access_etds/2612.
Full textStylemans, Eric. "Etude d'un système de contre-mesure électroacoustique anti sous-marin destiné à la protection des navires." Valenciennes, 1997. http://www.theses.fr/1997VALE0007.
Full textYE, Zi. "Traitement statistique de l'information et du signal pour l'internet des objets sous-marins." Thesis, Institut polytechnique de Paris, 2021. https://tel.archives-ouvertes.fr/tel-03179373.
Full textThere has been recently a large development of human activities associated to the ocean world, where no standard has emerged for the Internet of Things (IoT) linked to marine autonomous objects. Though it has a limited bandwidth, the acoustic wave is the only way to communicate over average to large distances and it is thus used by many underwater systems to communicate, navigate, or infer information about the environment. This led to a high demand for wireless networks that require both spectral efficiency and energy efficiency with the associated low-complexity algorithms. Therefore, in this Ph.D. thesis, we proposed several original solutions to face this challenge.Indeed, due to the inherent Signal Space Diversity (SSD), rotated constellations allow better theoretical performance than conventional constellations with no spectral spoilage. We review the structural properties of uniformly projected rotated M-QAM constellations, so as to propose a low complexity soft demapping technique for fading channels. Then, we present an original blind technique for the reduction of the PAPR for OFDM systems using the rotated constellations with SSD. In order to reduce the complexity of blind decoding for this technique, we again rely on the properties of uniformly projected M-QAM rotated constellations to design a low-complexity estimator. Moreover, to face the selectivity of the acoustic channel, we suggest a sparse adaptive turbo detector with only a few taps to be updated in order to lower down the complexity burden. Finally, we have proposed an original self-optimized algorithm for which the step-sizes of both the equalizer and the phase estimator are updated adaptively and assisted by soft-information in an iterative manner, so as to meet the requirement of fast convergence and low MSE over time-varying channels
Han, Dong. "Caractérisation des objets enfouis par les méthodes de traitement d'antenne." Thesis, Aix-Marseille 3, 2011. http://www.theses.fr/2011AIX30003/document.
Full textThis thesis is devoted to the study of the localization of objects buried in underwater acoustic using array processing methods and acoustic waves. We have proposed a appropriate model, taking into account the water/sediment interface. The propagation modeling thus combines the reflected wave and the refracted wave to determine a new directional vector. The directional vector developed by acoustic scattering model is used in the MUSIC method instead of the classical plane wave model. This approach can estimate both of the object coordinates (angle and distance sensor-object) of known form, in near field or far field. We propose some fast algorithms without eigendecompostion. We combine DIRECT algorithm with spline interpolation to cope with the distorted antennas of many sensors, while maintaining a low computation time. To decorrelate the received signals, we firstly use a bilinear operator. We propose a method for the case of independent groups of correlated signals using the cumulants. Then we present a method using the cumulants matrix to eliminate Gaussian noise. But in practice, the noise is not always Gaussian or the characteristics are not always known. We develope two iterative methods to estimate the interspectral matrix of noise. The first algorithm is based on an optimization technique to extract iteratively the interspectral matrix of noise. The second algorithm uses the technique of maximum likelihood to estimate the signal parameters and the noise. Finally we test the proposed algorithms with experimental data. The results quality is very good
Xu, Kevin. "Maximum likelihood time-domain beamforming using simulated annealing." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80046.
Full textBibliography: p. 111-112.
by Kevin Xu.
S.M.
Duboisset-Chareyre, Laure. "Analyse bispectrale de signaux réels : application à la détection de transitoires." Grenoble INPG, 1997. http://www.theses.fr/1997INPG0168.
Full textCarmillet, Valerie. "Contribution à la détection en présence de réverbération : applications en acoustique sous-marine." Grenoble INPG, 1998. http://www.theses.fr/1998INPG0004.
Full textMauuary, Didier. "Détection, estimation et identification pour la tomographie acoustique océanique : étude théorique et expérimentale." Grenoble INPG, 1994. http://www.theses.fr/1994INPG0033.
Full textReal, Gaultier. "An ultrasonic testbench for reproducing the degradation of sonar performance in fluctuating ocean." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4753/document.
Full textThe ocean medium is subject to many sources of fluctuations. The most critical ones were found to be internal waves, occurring frequently and inducing fluctuations of the spatial distribution of the sound speed field. Because of the fairly long period of this phenomenon as compared to the propagation time of acoustic waves for sonar applications, the process can be considered frozen in time for each stochastic realization of the medium. The development of testbenches allowing to reproduce the effect of atmospheric turbulence on optic waves propagation under laboratory conditions lead to considerable advancements in the field of adaptive optics. We therefore see a vivid interest in being able to reproduce the effects of internal waves on sound propagation in controlled environments. An experimental protocol in a water tank is proposed: an ultrasonic wave is transmitted through a randomly rough acoustic lens, producing distortions of the received wavefront. The induced signal fluctuations are controlled by tuning the statistical parameters of the roughness of the lens. Especially, they are linked to dimensional parameters allowing to classify the configurations into regimes of fluctuations and to predict the statistical moment of the acoustic pressure up to the fourth order. A remarkable relevance of our experimental scheme is found when compared to theoretical and simulation results. The degradation of classical signal processing techniques when applied to our acquired data highlights the need for corrective detection techniques. A review of the existing techniques in other domains is proposed
Bouhier, Marie Edith. "Amélioration des performances en portée et en précision de localisation angulaire des systèmes de navigation sous-marine." Grenoble INPG, 1986. http://www.theses.fr/1986INPG0122.
Full textConan, Ewen. "Traitements adaptés aux antennes linéaires horizontales pour la discrimination en immersion de sources Ultra Basse Fréquence." Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2017. http://www.theses.fr/2017IMTA0016/document.
Full textThis work focuses on acoustic source depth discrimination in the ultra-low frequency range (ULF, 0-500 Hz), using a horizontal line array. Depth discrimination is a binary classification problem, aiming to evaluate whether a received signal has been emitted by a source near the surface or by a submerged one. This could serve applications such as anti-submarine warfare or marine biology.The acoustic field generated by a ULF source can be described as a sum of modes, which properties depend on environment and source location. This modal propagation leads to modal dispersion: the different modes propagate at different velocities. This forbid the use of classical beamforming schemes. However, the horizontal array can be used as a spatial filter to estimate the properties of the modes: this is modal filtering. With a sufficient array length, modes are resolved, and the filtered modes can be used to localise the source using matched-mode processing. If the array is too short, the poorly-filtered modes cannot be used for localisation. Therefore, we are looking for a less precise but more robust information on source location, which leads to source depth discrimination.In this work, the poorly-filtered modes are used to decide whether the source is near the surface or submerged. Because some of the modes (the "trapped modes") are weakly excited by a surface source, we propose this decision relies on the estimation of the trapped energy ratio, i.e. the ratio of acoustic energy borne by trapped modes to the total acoustic energy. The problem of depth discrimination is then formulated as a binary hypothesis test on source depth. This physical formulation allows using Monte-Carlo methods and simulations to predict performance in a given context. This enables comparison between several estimators of the trapped energy ratio and the choice of a relevant threshold which this ratio is compared to in order to decide between the two hypotheses. The approach developped in the manuscript is validated by its application to marine experimental data. The results are consistent with the conclusions drawn from simulations. The proposed method enables the succesfull identification of both a surface source (the noise of a travelling ship) and a submerged source (a ULF source towed 30 m below the surface), using a 360-m horizontal array
Courcoux-Caro, Milan. "Conception optimisée d’antenne pour de la localisation passive de sources acoustiques." Thesis, Brest, École nationale supérieure de techniques avancées Bretagne, 2022. http://www.theses.fr/2022ENTA0001.
Full textThe objective of this thesis work is to propose an approach of array design for the localization of aerial or underwater acoustic sources. First, we will see how to describe the propagation of waves emitted by the sources. Then we will draw up the different methods allowing to estimate the positions of the sources from the measurements acquired by the sensors and from the propagation model. The bibliographic work on the field of acoustic source localization will highlight the importance of the sensors’ positions in the performance of the source position estimators. This will lead to a second bibliographic work on antenna design, and more precisely on the selection of sensor positions. The state of the art on antenna design methods will allow us to propose the following method: a sequential Bayesian data-driven selection. This approach takes into account the information contained in the measurements previously acquired in the pre-designed antenna, in order to select the future sensors. The application of this approach is innovative in the context of acoustic source localization. In a second step, first results realized on synthetic data prove to be promising for the application of this approach in an underwater acoustic source localization context. The analyses provided in this manuscript will allow to judge the relevance of this approach in the tested context, as well as to evaluate and compare the performance of this antenna design with the literature. Finally, we will apply this approach on real data from an experiment set up during the thesis. The propagation environment will be aerial in a closed reverberant room with a large number of available sensors. Acquiring real data will allow, in addition to evaluating the performance of our approach, to provide a new antenna design. This is designed from synthetic data and then applied to real data
Simão, Daniel Hayashida. "Análise do consumo energético em redes subaquáticas utilizando códigos fontanais." Universidade Tecnológica Federal do Paraná, 2017. http://repositorio.utfpr.edu.br/jspui/handle/1/2774.
Full textThe present work employs fountain codes in an underwater network, in which data is transmitted using acoustic signals and has many applications. However, underwater networks are usually characterized by low propagation speed and smaller bandwidth than networks that use radio frequency signals, resulting in larger transmission delays. Then, aiming at minimizing the delays and increasing the energy efficiency of underwater networks, the present work employs fountain error-correcting codes at the transmitter. To that end, it was first necessary to model the energy consumption of a success data packet transmission in an underwater network using fountain codes. Our results show that the use of fountain codes is able to reduce up to 30% of energy consumption when the transmission distance is of 20 km for the case with a target frame error rate (FER) of Po = 10^−5 , and 25% for the same distance with a target FER of Po = 10^−3.
Tabella, Gianluca. "Subsea Oil Spill Risk Management based on Sensor Networks." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
Find full textSu, Shun-Chi, and 蘇順吉. "Studies on underwater acoustic stationary and transient signals spectrum features." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/20487262396994551309.
Full text中正理工學院
電機工程研究所
86
Underwater acoustic signals are non-linear, time-varying, and with low signal-to-noise ratio. These properties make the signal analysis difficulty and complex. For resolving targets through the underwater acoustic signals, effective methods are proposed in this thesis to process underwater acoustic signals, Base on these methods, an signal acoustic recognition system is also designed. Traditionally, the Fourier transform (FT) and Morlet wavelet transform (MWT) are the main tool for stationary and transient signals spectrum analysis, respectively. Here in, a modify power spectrum density (PSD) function is used to extract the critical features for stationary underwater acoustic signals, A multi-scaling MWT kernel is also proposed which can depict the underwater transient spectrum successfully. To illustrate the effectiveness of these two novel design methods, some experiments are taken to perform by using simulation and recorded real underwater acoustic signals. Experimented results show that the proposed methods can detect and analyze both stationary and transient underwater acoustic signals successfully. An underwater acoustic signals analysis is also implemented on Matlab base personal computer to detect, analyze, and recognize targets by stationary signal features. It is hoped that an automatic underwater targets recognition system can be realized by methods discussed in this thesis in the future.