Propagation des signaux sonores en milieu marin aléatoire
Le probleme de l'evaluation de l'intensite et de la coherence du signal sonore recu par l... more Le probleme de l'evaluation de l'intensite et de la coherence du signal sonore recu par les systemes de detection sous-marine est resolu en milieu deterministe. Dans cette etude on introduit une composante aleatoire dans la celerite du milieu modelisant les fluctuations aleatoires du milieu marin. Pour caracteriser ces effets du milieu sur la propagation sonore, l'estimation des moments du champ sonore est necessaire. Une description des phenomenes d'environnement presents dans le milieu marin permet de determiner les types de perturbations pouvant etre prises en compte par les modeles deterministes, et ceux a considerer comme aleatoires. Les ondes internes sont toujours presentes et apparaissent comme l'effet perturbateur predominant. On generalise, dans le formalisme de ito, les equations de propagation paraboliques des moments du champ sonore obtenues par tatarskii: l'application du theoreme limite de papanicolaou-kohler permet d'affaiblir les hypotheses sur l'indice de refraction et d'estimer le domaine de validite des equations paraboliques des moments. Trois methodes de calculs des moments du champ sonore sont ensuite exposees: une etude statistique de type monte-carlo pour les moments d'ordres un et deux, une etude numerique basee sur les methodes paraboliques pour le moment d'ordre un et enfin, une methode modale resolvant les equations paraboliques stochastiques du moment d'ordre deux pour aboutir a l'intensite sonore moyenne et a l'autocorrelation verticale, ou encore a la densite angulaire d'energie. La comparaison des resultats et leur convergence permettent de valider ces methodes. Elle revelent que l'intensite sonore en milieu aleatoire admet des perturbations pouvant atteindre 8 db. Dans le cas de bathycelerimetries perturbees experimentalement, on retrouve des ecarts du meme ordre de grandeur qui pourraient donc s'expliquer par la presence d'ondes internes. Cette etude repond en partie aux besoins actuels quant a la determination stochastique des deux premiers moments du champ sonore en milieu aleatoire a basses frequences
Le problème de l'évaluation de l'intensité et de la cohérence du signal sonore reçu par les systè... more Le problème de l'évaluation de l'intensité et de la cohérence du signal sonore reçu par les systèmes de détection sous-marine est résolu en milieu déterministe. Dans cette étude on introduit une composante aléatoire dans la célérité du milieu modélisant les fluctuations aléatoires du milieu marin. Pour caractériser ces effets du milieu sur la propagation sonore, l'estimation des moments du champ sonore est nécessaire. On rappelle les équations de propagation des moments du champ sonore en milieu aléatoire en présence d'un bruit blanc gaussien (perturbations du milieu marin dues aux ondes internes): équations de propagation paraboliques des moments du champ sonore obtenues par Tatarskii. L'obtention de ces équations peut être généralisée dans le formalisme de Ito . De plus alors, l'application du théorème limite de Papanicolaou-Kohler permet d'affaiblir les hypothèses sur l'indice de réfraction et d'estimer le domaine de validité des équations paraboliques des moments.
2022 IEEE International Conference on Image Processing (ICIP), Oct 16, 2022
Many fields are interested in mapping and monitoring the sea floor natural structure and biology,... more Many fields are interested in mapping and monitoring the sea floor natural structure and biology, for environmental surveys, including identifying macro waste or detection of submerged artifacts such as cars, tires, wrecks, and even military applications, e.g., mine warfare whose detection depends heavily on the seabed structure. In this paper, we propose a new active learning method to improve seabed segmentation by deep learning. We perform segmentation of the sea floor using two data sources, sonar, and bathymetry. We train a network to fuse these two modalities and segment each sea floor pixel into nine fine ecological classes, then into three gross class sets, alive/not alive, and, in two different ways, whether mines can be hunted for or not. Once this training is done, a second stage involving a new active learning method based on network uncertainties greatly improves the performance.
This paper deals with underwater acoustic communication, and especially details an innovative app... more This paper deals with underwater acoustic communication, and especially details an innovative approach for off the shelves existing modems performances evaluation. The originality is to be able to predict the operational performances of existing acoustic modems in a real complex situation, without sea trials.
Three-dimensional mapping of the benthic invertebrates biophony with a compact four-hydrophones array
Applied Acoustics, 2019
Abstract Benthic invertebrates emit broadband transient sounds, that dominate coastal soundscapes... more Abstract Benthic invertebrates emit broadband transient sounds, that dominate coastal soundscapes and can inform on the environment and its ecological state. Numerous works have studied temporal patterns of Benthic Invertebrate Biophonies (BIB) and linked them to environmental parameters or ecological processes, but there is a lack of knowledge about the spatial variability of BIB. Here, we mapped Benthic Invertebrate Sounds (BIS) in three dimensions using a compact array (2 m × 2 m × 2 m) of four hydrophones within the scope of eco-acoustic s studies. Firstly, we developed tools to localize any individual sound emitted by benthic invertebrates. A theoretical calculation of the Cramer Rao Bounds (CRB) consolidated by in situ active emissions from known positions, demonstrated the accuracy of the localization. Secondly, by accumulating all the positions of the BIS recorded during a night, three methods are proposed to map the BIB at different spatial scales. An in situ measurement campaign carried out on a 300 m × 300 m artificial reef system revealed that the marine fauna was binary spatially distributed: rich and numerous on artificial reefs and poor and weak outside the reefs. At small ranges (10 m), the acoustic maps matched the geometric structures of the reefs with an accuracy of 0.5 m. At large scales (100 m and 300 m), the acoustic hot-spots on the maps corresponded to distant reefs, with an accuracy of 7 m and 10 m respectively. This study provides the first maps of the BIB at ecologically relevant scales and shows that they can be used to identify, quantify, follow and track benthic activity hot-spots. In combination with biological and ecological information, passive acoustic monitoring using such maps can be a powerful complementary tool for ecological studies, such as the quantification of grazing activity or the evaluation of the efficiency of marine ecologic restoration programs.
Ce cahier rappelle le besoin de connaissances nécessaires en termes de surveillance des herbiers ... more Ce cahier rappelle le besoin de connaissances nécessaires en termes de surveillance des herbiers de posidonies. Il présente les outils et les méthodes disponibles pour mettre en place une surveillance (ou un suivi) des herbiers adaptée aux champs de compétences des gestionnaires et aux problématiques de leur territoire. Les résultats de nos travaux d'analyse comparée des méthodes de surveillance de l'herbier de posidonies sont présentés dans un cahier technique, document de 96 pages, pédagogique et illustré qui s'adresse aux élus, gestionnaires et techniciens qui gèrent un espace maritime public ou privé, et/ou souhaitent l'aménager.
Propagation des signaux sonores en milieu marin aléatoire
Le probleme de l'evaluation de l'intensite et de la coherence du signal sonore recu par l... more Le probleme de l'evaluation de l'intensite et de la coherence du signal sonore recu par les systemes de detection sous-marine est resolu en milieu deterministe. Dans cette etude on introduit une composante aleatoire dans la celerite du milieu modelisant les fluctuations aleatoires du milieu marin. Pour caracteriser ces effets du milieu sur la propagation sonore, l'estimation des moments du champ sonore est necessaire. Une description des phenomenes d'environnement presents dans le milieu marin permet de determiner les types de perturbations pouvant etre prises en compte par les modeles deterministes, et ceux a considerer comme aleatoires. Les ondes internes sont toujours presentes et apparaissent comme l'effet perturbateur predominant. On generalise, dans le formalisme de ito, les equations de propagation paraboliques des moments du champ sonore obtenues par tatarskii: l'application du theoreme limite de papanicolaou-kohler permet d'affaiblir les hypothes...
2022 IEEE International Conference on Image Processing (ICIP)
Many fields are interested in mapping and monitoring the sea floor natural structure and biology,... more Many fields are interested in mapping and monitoring the sea floor natural structure and biology, for environmental surveys, including identifying macro waste or detection of submerged artifacts such as cars, tires, wrecks, and even military applications, e.g., mine warfare whose detection depends heavily on the seabed structure. In this paper, we propose a new active learning method to improve seabed segmentation by deep learning. We perform segmentation of the sea floor using two data sources, sonar, and bathymetry. We train a network to fuse these two modalities and segment each sea floor pixel into nine fine ecological classes, then into three gross class sets, alive/not alive, and, in two different ways, whether mines can be hunted for or not. Once this training is done, a second stage involving a new active learning method based on network uncertainties greatly improves the performance.
Monitoring fish species populations in very turbid environments is challenging. Acoustic cameras ... more Monitoring fish species populations in very turbid environments is challenging. Acoustic cameras allow work in very poor visibility but are often deployed as a fixed observation point, limiting the scope of the survey. A BlueView P900-130 acoustic camera was deployed in rocky marine habitats off the coast of French Guiana in order to assess the total abundance, size structure and spatial distribution of a demersal fish population. The relevancy of using an acoustic camera to achieve these three objectives was evaluated by comparing acoustic data to those obtained from fishing surveys. The detection and identification of large demersal fish species were possible with the shape and size of the acoustic signal and acoustic shadow silhouette as well as swimming behavior. Mobile surveys combined with stationary surveys increased the probability of distinguishing individuals from inanimate objects. Estimated total length based on the acoustic signal underestimated the actual length of fis...
Dans le cadre de la DCE, et plus particulierement de l’evaluation de l’etat ecologique des habita... more Dans le cadre de la DCE, et plus particulierement de l’evaluation de l’etat ecologique des habitats benthiques, le laboratoire IFREMER d'Arcachon a realise la cartographie des herbiers de zosteres du Bassin d’Arcachon en 2007-2008 et compare leur extension avec les donnees anterieures (1988 pour Zostera marina - 1989 et 2005 pour Zostera noltii).
Ocean acoustic tomography experiment using a vertical array
1995 International Conference on Acoustics, Speech, and Signal Processing
ABSTRACT Summary form only given. An acoustic tomography experiment, supported by European MAST c... more ABSTRACT Summary form only given. An acoustic tomography experiment, supported by European MAST contracts, has been carried out in the all occidental Mediterranean sea. During 10 months in 1994, acoustic phase shift keying signals have been emitted at a pulse rate of 1 per 4 hours and received by seven sources-receivers localized in the all basin and spaced by several hundred kilometers. In addition, signals from two of these sources localized near Corse and Sardinia were received on a vertical array moored at 800 m depth near Nice. So, it means a joint assessment of arrival angles and times of acoustic signals and a useful improvement in the general problem of identification of acoustic paths. Signals received on 16 hydrophones of this 40 meters long array were recorded and processed to extract the propagation time and arrival angle of each ray path. This paper reports the results of the analysis of these last data records and discusses the observation of wave fronts at each hydrophone depth, tractability, and study of arrival peaks as a function of time and angle
Real-time geoacoustic inversion of large band signals
Europe Oceans 2005, 2005
This paper describes the development of a real time geoacoustic inversion tool devoted to large b... more This paper describes the development of a real time geoacoustic inversion tool devoted to large band signals. The aim of this tool is to automatically infer geoacoustic bottom characteristics from transmission sound field pressure measurements in a deep ocean medium. The first part of the article is devoted to the direct problem. It describes the functionalities of the propagation simulation tool and its automatic connection with measurements parameters. Then the paper deals with an inversion method based on recent works on the subject in the scientific community. Finally real-time architecture and some concrete results obtained with in situ data in the Gulf of Oman are presented.
, développée par SEMANTIC TS, avec les méthodes optiques (systèmes vidéo remorqués MOBIDIC et MOO... more , développée par SEMANTIC TS, avec les méthodes optiques (systèmes vidéo remorqués MOBIDIC et MOOGLI) et acoustiques (système sonar latéral) mises en oeuvre par l'IFREMER dans trois sites distincts : (i) le site atelier des Embiez à l'Ouest de Toulon, (ii) le site atelier de Saint Raphaël (données obtenues dans le cadre du programme INTERREG IIIB / POSIDONIA, site web) et (iii) le bassin d'Arcachon pour la cartographie de l'herbier de zostères. La méthode DIVA est particulièrement performante lorsqu'elle intervient en complément des méthodes surfaciques habituellement mises en oeuvre par l'IFREMER.
The Journal of the Acoustical Society of America, 2008
aimed to develop a mapping method for underwater vegetation lying on seabed. First stage is to de... more aimed to develop a mapping method for underwater vegetation lying on seabed. First stage is to develop a method for detecting and characterizing vegetation on the seabed using the acoustic response from a conventional single beam echo sounder. This new method is then operated simultaneously with multibeam sonar producing micro-relief information and side scan sonar providing gray scale levels associated with bottom reflectivity. Then fusion of these three data is processed. We show efficiency of these multisensor data fusion concept to get very precise seabed vegetation mapping in a way reducing truth control (video and diving investigations). Sensors and method accuracy allow obtaining, like in biomedical field, real 3D scan pictures of seabed vegetation. This study is first applied to posidonia and cymodocea, which play a key role in Mediterranean's ecosystem. Then, extension of the method is investigated to address laminaria which may significantly affect the performance of acoustic and optical sensors used for sea-mines detection. This paper presents results of data fusion mapping on an Atlantic sea area covered by laminaria, studied and well known by the CEVA.
This paper presents the results of the analysis of long range propagation (-200 km) in a range-de... more This paper presents the results of the analysis of long range propagation (-200 km) in a range-dependent environment, The propagation medium is characterized by two deep sonnd channels. The range dependence enables energy transfer between the channels and leads to a mismatch between real data and ray predictions. To explain this mismatch, an analysis of hybrid ray propagation is presented. This analysis is completed by an interpretation in terms of chaos. This chaos is quantified in the particular ease of the Bay of Biscay environment. This paper puts forward that mesoscale pertnrbations, such as the Mediterranean outflow in the North Atlantic, can affect long-range propagation. However, it shows that the ray theory remains reliable for a propagation range of several hundred kilometers. Index Terms-Acoustic propagation, chaotic propagation, double SOFAR. M&e (SHOMj in the Ocean Acoustic Exploratory Devcloptkit (DE95901, Contract 97.87.026.00.470.29.45). C. Noel and C. Viala tire with Semantic TS, 83110 Sanery, France. Y. Stephnn is with the Centre Militairc d'Ocdanagraphie, Epsharn, 29200 Brest, France. Publisher Item Identifier S 0364-9059(99)08655-0.
Uploads
Papers by Claire Noel