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| Registros recuperados: 32 | |
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| Hellequin, Laurent; Boucher, Jean; Lurton, Xavier. |
| Processing simultaneous bathymetry and backscatter data, multibeam echosounders (MBESs) show promising abilities for remote seafloor characterization. High-frequency MBESs provide a good horizontal resolution, making it possible to distinguish fine details at. the water-seafloor interface. However, in order to accurately measure the seafloor influence on the backscattered energy,the recorded sonar data must first be processed and cleared of various artifacts. generated by the sonar system itself. Such a preprocessing correction procedure along with the assessment of its validity limits is presented here and applied to a 95-kHz MBES (Simrad EM1000) data set. Beam pattern effects, uneven array sensitivities, and inaccurate normalization of the ensonified... |
| Tipo: Text |
Palavras-chave: Seafloor classification; Multibeam echo sounder MBES; K distribution; Backscatter model. |
| Ano: 2003 |
URL: http://archimer.ifremer.fr/doc/2003/publication-708.pdf |
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| Ladroit, Yoann; Lurton, Xavier; Sintes, Christophe; Augustin, Jean-marie; Garello, Rene. |
| For modern multibeam echosounders, the use of a robust and reliable quality estimator associated with each sounding is an absolute necessity. Indeed, due to the large volume of data acquired, a lot of time is lost, both during the survey and the post-processing. This is a costly problem for hydrographers. The definition of a quality estimator based on the characteristics of the beamformed signal gives an answer to this problem. It has been successfully implemented by several sonar manufacturers and its relevance in measuring the quality of each sounding has been demonstrated. The defined Quality Factor can also be used directly in the sonar measurement process, such as in detection algorithm, in order to improve the performance of the systems. This makes... |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00106/21728/20275.pdf |
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| Lurton, Xavier. |
| Multi-Beam Echo-Sounders (MBES) designed for seafloor-mapping applications are today a major tool for ocean exploration and monitoring. Concerns have been raised about their impact towards marine life and especially marine mammals, although their inherent characteristics (high frequencies, short signals and narrow transmitting lobes) actually minimize this possibility. The present paper proposes an analysis of MBES radiation characteristics (pulse design, source level and radiation directivity pattern) accounting for the various geometries met today and expressed according to the metrics used for acoustical impact assessment (maximum Sound Pressure Level, and cumulative Sound Exposure Level). A detailed radiation model is proposed, including the... |
| Tipo: Text |
Palavras-chave: Multibeam echosounders; Marine mammals; Sonar impact assessment; Sound Pressure Level; Sound Exposure Level; Directivity pattern. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00278/38957/37497.pdf |
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| Le Chenadec, Gilles; Boucher, Jean-marc; Lurton, Xavier. |
| Backscattered signal statistics are widely used for target detection and seafloor characterization. The K-distribution shows interesting properties for describing experimental backscattered intensity statistics. In addition to the fact that its probability distribution function accurately fits actual sonar data, it advantageously provides a physical interpretation linked to the backscattering phenomenon. Sonar systems usually record backscattered signals from a wide angular range across the ship's track. In this context, previous studies have shown that backscatter statistics strongly depend on the incidence angle. In this paper, we propose an extension of previous works to model the angular evolution of the K-distribution shape parameter. This evolution... |
| Tipo: Text |
Palavras-chave: K distribution; Sonar statistical analysis; Seafloor classification. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2599.pdf |
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| Fettweis, M; Toorman, E; Verney, Romaric; Chapalain, Marion; Legrand, S; Lurton, Xavier; Montereale-gavazzi, G; Roche, M; Shen, X; Van Den Eynde, Dries; Van Lancker, Vera. |
| Context To protect the marine environment more effectively, the European Union adopted the Marine Strategy Framework Directive (MSFD) in 2008, aiming to achieve the Good Environmental Status (GES) of the EU's marine waters by 2020 and to protect the resource base upon which marine-related economic and social activities depend. A major challenge in the implementation of the MSFD is to achieve the necessary scientific knowledge on the marine environment, its processes and the methods to monitor them. The focus of INDI67 is on the evaluation and development of indicators to monitor GES of descriptor 6 and 7. Seafloor integrity (descriptor 6) refers to the structure and functions of the benthic ecosystems. It relates to the comprises physical, chemical and... |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00634/74632/74526.pdf |
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| Beaudoin, Jonathan; Smyth, Steve; Furlong, Arnold; Floc'H, Henri; Lurton, Xavier. |
| High rate sound speed profiling systems have the potential to maximize the efficiency of multibeam echosounder systems (MBES) by increasing the accuracy at the outer edges of the swath where refraction effects are at their worst. In some cases, high rate sampling on the order of tens of casts per hour is required to capture the spatio-temporal oceanographic variability and this increased sampling rate can challenge the data acquisition workflow if refraction corrections are to be applied in real-time. Common bottlenecks result from sound speed profile (SSP) preprocessing requirements, e.g. file format conversion, cast extension, reduction of the number of points in the cast, filtering, etc. Without the ability to quickly pre-process SSP data, the MBES... |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00115/22615/20329.pdf |
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| Lurton, Xavier; Eleftherakis, Dimitrios; Augustin, Jean-marie. |
| The sediment backscatter strength measured by multibeam echosounders is a key feature for seafloor mapping either qualitative (image mosaics) or quantitative (extraction of classifying features). An important phenomenon, often underestimated, is the dependence of the backscatter level on the azimuth angle imposed by the survey line directions: strong level differences at varying azimuth can be observed in case of organized roughness of the seabed, usually caused by tide currents over sandy sediments. This paper presents a number of experimental results obtained from shallow-water cruises using a 300-kHz multibeam echosounder and specially dedicated to the study of this azimuthal effect, with a specific configuration of the survey strategy involving a... |
| Tipo: Text |
Palavras-chave: Azimuth dependence; Seafloor backscatter; Multibeam echosounder; Sand ripples. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00386/49782/50326.pdf |
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| Sinquin, Jean-marc; Lurton, Xavier; Vignaud, Christophe; Mathieu, Gregory; Bisquay, Herve. |
| Hydrographic and geosciences surveys, using acoustic devices, need to use accurate water sound velocity profiles. Because the acoustic path depends on the sound velocity profile (SVP), the use of the most accurate SVP is one of the keys to conducting effective surveys (with multibeams, for instance). To date, the existing software available does not answer to both the needs of efficiency and simplicity (sometimes not so easy to operate, sometimes not so accurate). DORIS provides a handy freeware to post-process SVP for the hydrographic communities. |
| Tipo: Text |
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| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00339/45065/44473.pdf |
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| Fabri, Marie-claire; Loubrieu, Benoit; Dupre, Stephanie; Opderbecke, Jan; Lurton, Xavier. |
| Ce document a pour objectif de préparer une réunion sur le choix du type de charge utile "Acoustique" pour le H-ROV. Ce document s'intéresse à la charge utile "cartographie acoustique". Il est réalisé avec l'objectif de préparer une réunion du groupe de travail scientifique du H-ROV. Il propose un bilan des différentes charges utiles acoustiques embarquables sur un engin sous-marin, ainsi que leur avantages et leurs inconvénients au regard des caractéristiques techniques du H-ROV. Au final un SONDEUR MULTIFAISCEAUX a été le choix considéré comme étant le plus adapté à l'environnement probable d'exploration du HROV (milieu à fort relief) ainsi qu'à ses caractéristiques techniques (autonomie réduite). Lors de l'intégration sur le SKID "Acoustique", il faudra... |
| Tipo: Text |
Palavras-chave: H-ROV; Cartographie acoustique. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00233/34382/32753.pdf |
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| Lamarche, Geoffroy; Lurton, Xavier. |
| Multibeam echosounders are becoming widespread for the purposes of seafloor bathymetry mapping, but the acquisition and the use of seafloor backscatter measurements, acquired simultaneously with the bathymetric data, are still insufficiently understood, controlled and standardized. This presents an obstacle to well-accepted, standardized analysis and application by end users. The Marine Geological and Biological Habitat Mapping group (Geohab.org) has long recognized the need for better coherence and common agreement on acquisition, processing and interpretation of seafloor backscatter data, and established the Backscatter Working Group (BSWG) in May 2013. This paper presents an overview of this initiative, the mandate, structure and program of the working... |
| Tipo: Text |
Palavras-chave: Multibeam echosounders; Calibration; Reflectivity; Mapping; Seafloor. |
| Ano: 2018 |
URL: http://archimer.ifremer.fr/doc/00385/49655/50179.pdf |
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| Ladroit, Yoann; Sintes, Christophe; Lurton, Xavier; Garello, Rene. |
| Sonar signal simulation is an important area of research for industrials and scientific of the domain. Indeed, it can be used in many ways by sonar manufacturers, both for designing a system or in order to explain physical phenomenon on data. Therefore, by minimizing the expensive testing time at sea, a well designed simulator can be a very interesting financial asset. Traditional sonar signal simulation also contains problems to be dealt with. It is often necessary to find a balance between the computational power consumption, the needed accuracy of the physical phenomenon description and the scale at which simulated signals are relevant. In our simulation model we propose a solution based on a very dense grid (resolution of about the concerned... |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00106/21727/20274.pdf |
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| Demer, Da; Berger, Laurent; Bernasconi, M; Bethke, E; Boswell, K; Chu, D; Domokos, R; Dunford, A; Fassler, S; Gauthier, S; Hufnagle, Lt; Jech, Jm; Le Bouffant, Naig; Lebourges-dhaussy, Anne; Lurton, Xavier; Macaulay, Gj; Perrot, Yannick; Ryan, T; Parker-stetter, S; Stienessen, S; Weber, T; Williamson, N. |
| Acoustic instrument calibration is fundamental to the quantitative use of its data for estimating aquatic resource abundance. Regular calibrations also allow instrument performance to be monitored to detect changes due to the environment or component dynamics, degradation, or failure. This is the second ICES Cooperative Research Report (CRR) focussed on calibrations of acoustic instruments. The first, CRR No. 144 (Foote et al., 1987), was published during the era of analogue electronics more than a quarter of a century ago. Since then, not only has the acoustic equipment improved vastly with digital electronics and signal processing, but the techniques for applying them to studies of marine organisms have both advanced and diversified. Motivating,... |
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| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00586/69821/67711.pdf |
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| Lurton, Xavier. |
| Les phénomènes de propagation liés à l'utilisation de sonars actifs par petits fonds sont décrits de façon adéquate par un modèle géométrique de l'énergie moyenne. Cette approche, classique pour l'évaluation des pertes de propagation, est étendue ici aux aspects temporels du signal transmis, en particulier les niveaux de réverbération: le calcul ainsi défini permet une amélioration très significative par rapport aux méthodes usuelles par rayons propres, tant en charge de calcul qu'en fiabilité des résultats. Une autre extension est proposée pour l'évaluation de l'influence du relief de surface, dont l'effet est de diffuser l'énergie incidente vers des directions angulaires voisines: ce phénomène est traité sous forme d'un couplage entre les différentes... |
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| Ano: 1989 |
URL: http://archimer.ifremer.fr/doc/00281/39250/37823.pdf |
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| Guillon, Laurent; Lurton, Xavier. |
| Signals received by low-frequency multibeam echosounders are strongly affected by sound penetration inside the upper sediment layers and by backscattering from buried layers down to depths of a few meters; this may lead to serious ambiguities and misinterpretations of experimental data. These phenomena are modeled here using a concept of equivalent input backscattering strength (EIBS), based on a combination of classical models of local backscattering strength and propagation inside fluid layered media. The local backscattering strength at a buried interface is expressed first to account for the impedance adaptation due to the overlying layers, for the angular refraction effects due to the velocity profile, and for the layered structure of the underlying... |
| Tipo: Text |
Palavras-chave: Sound propagation; Sediment structure; Multibeam sonar; Echosounding; Backscatter; Acoustic properties; Sediment properties. |
| Ano: 2001 |
URL: http://archimer.ifremer.fr/doc/2001/publication-729.pdf |
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| Registros recuperados: 32 | |
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