Consulta: creatorFacets:"Lurton, Xavier"
Registros recuperados: 32
Data/hora: 13/06/2024 06:17:25

Introduction to the Special Issue “Seafloor backscatter data from swath mapping echosounders: from technological development to novel applications”
Provedor de dados: 5
Autores: Lamarche, Geoffroy; Lurton, Xavier.
Tipo: Text
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00435/54621/56084.pdf

Processing of high-frequency multibeam echo sounder data for seafloor characterization
Provedor de dados: 5
Autores: 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

Control of the repeatability of high frequency multibeam echosounder backscatter by using natural reference areas
Provedor de dados: 5
Autores: Roche, Marc; Degrendele, Koen; Vrignaud, Christophe; Loyer, Sophie; Le Bas, Tim; Augustin, Jean-marie; Lurton, Xavier.
The increased use of backscatter measurements in time series for environmental monitoring necessitates the comparability of individual results. With the current lack of pre-calibrated multibeam echosounder systems for absolute backscatter measurement, a pragmatic solution is the use of natural reference areas for ensuring regular assessment of the backscatter measurement repeatability. This method mainly relies on the assumption of a sufficiently stable reference area regarding its backscatter signature. The aptitude of a natural area to provide a stable and uniform backscatter response must be carefully considered and demonstrated by a sufficiently long time-series of measurements. Furthermore, this approach requires a strict control of the acquisition...
Tipo: Text
Palavras-chave: Multibeam echosounder; Seafloor backscatter; Repeatability; Calibration; Reference area; Monitoring.
Ano: 2018
URL: http://archimer.ifremer.fr/doc/00422/53384/54234.pdf

Definition and Application of a Quality Estimator for Multibeam Echosounders
Provedor de dados: 5
Autores: 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...
Tipo: Text
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00106/21728/20275.pdf

Modelling of the sound field radiated by multibeam echosounders for acoustical impact assessment
Provedor de dados: 5
Autores: 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

Protocole de protection de la faune marine et campagnes sismiques
Provedor de dados: 5
Autores: Ducatel, Cecile; Le Gall, Yves; Lurton, Xavier.
Ce document précise les mesures prises par l’Ifremer pour la protection de la faune marine lors de l’utilisation des sources sismiques appartenant à la classe 1 (&gt; 500 in 3). Avant de présenter le protocole à appliquer lors des campagnes de géosciences marines, les principes de l’évaluation des risques sonores sont rappelés.
Tipo: Text
Palavras-chave: Sismique; Mammifères marins; Tortues; Seuils; PTS; TTS; Zone d’exclusion; MMOs; PAM; Recherche pré-tir; Démarrage progressif; Arrêt des tirs.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00623/73516/72827.pdf

Angular dependence of K-distributed sonar data
Provedor de dados: 5
Autores: 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

Protection protocol for marine fauna and seismic campaigns
Provedor de dados: 5
Autores: Ducatel, Cecile; Le Gall, Yves; Lurton, Xavier.
This document explains measures taken by Ifremer to protect marine fauna when using class 1 seismic sources (&gt; 500 in3). Before presenting the protocol to be applied during marine geoscience campaigns, the acoustic risk assessment principles are recapped.
Tipo: Text
Palavras-chave: Seismic; Marine mammals; Turtles; Thresholds; PTS; TTS; Exclusion zone; MMOs; PAM; Pre-shot research; Ramp-up; Stopping shots.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00623/73519/73003.pdf

INDI 67. Developments of Indicators to improve monitoring of MSFD descriptors 6 and 7 (INDI67) : final report
Provedor de dados: 5
Autores: 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...
Tipo: Text
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00634/74632/74526.pdf

Streamlining Sound Speed Profile Pre-Processing: Case Studies and Field Trials
Provedor de dados: 5
Autores: 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...
Tipo: Text
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00115/22615/20329.pdf

Analysis of seafloor backscatter strength dependence on the survey azimuth using multibeam echosounder data
Provedor de dados: 5
Autores: 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

DORIS Software. New Tool to Process Sound Velocity Profiles
Provedor de dados: 5
Autores: 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
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00339/45065/44473.pdf

Choix du type de charge acoustique potentielle pour le H-ROV
Provedor de dados: 5
Autores: 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

Recommendations for improved and coherent acquisition and processing of backscatter data from seafloor-mapping sonars
Provedor de dados: 5
Autores: 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

DORIS: Processing and management of Sound Velocity Profiles for echosounding applications
Provedor de dados: 5
Autores: Sinquin, Jean-marc; Vrignaud, Christophe; Mathieu, Gregory; Lurton, Xavier.
If a bathymetric echosounder is the essential device to carry on hydrographic surveys, other external sensors are absolutely also necessary (positioning system, motion unit or sound velocity profiler). And because sound doesn‛t go straight away into the whole bathymetric swath its measurement and processing are very sensitive for all the water column. DORIS is the very answer for an operational sound velocity profile processing.
Tipo: Text
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00353/46466/46239.pdf

Extended Scatterers Model for Fast Sonar Signal Simulation
Provedor de dados: 5
Autores: 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...
Tipo: Text
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00106/21727/20274.pdf

Calibration of acoustic instruments
Provedor de dados: 5
Autores: 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,...
Tipo: Text
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00586/69821/67711.pdf

Backscatter calibration of high-frequency multibeam echosounder using a reference single-beam system, on natural seafloor
Provedor de dados: 5
Autores: Eleftherakis, Dimitrios; Berger, Laurent; Le Bouffant, Naig; Pacault, Anne; Augustin, Jean-marie; Lurton, Xavier.
The calibration of multibeam echosounders for backscatter measurements can be conducted efficiently and accurately using data from surveys over a reference natural area, implying appropriate measurements of the local absolute values of backscatter. Such a shallow area (20-m mean depth) has been defined and qualified in the Bay of Brest (France), and chosen as a reference area for multibeam systems operating at 200 and 300 kHz. The absolute reflectivity over the area was measured using a calibrated single-beam fishery echosounder (Simrad EK60) tilted at incidence angles varying between 0° and 60° with a step of 3°. This reference backscatter level is then compared to the average backscatter values obtained by a multibeam echosounder (here a Kongsberg EM...
Tipo: Text
Palavras-chave: Calibration; Seafloor backscatter; Multibeam echosounder; Single-beam echosounder.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00429/54016/57434.pdf

Application de la modélisation géométrique de la propagation acoustique sous-marine en petits fonds et hautes fréquences
Provedor de dados: 5
Autores: 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...
Tipo: Text
Ano: 1989
URL: http://archimer.ifremer.fr/doc/00281/39250/37823.pdf

Backscattering from buried sediment layers: The equivalent input backscattering strength model
Provedor de dados: 5
Autores: 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

Acoustique sous-marine. Présentation et applications
Provedor de dados: 5
Autores: Lurton, Xavier.
Sound waves are the only practical means of remote investigation and transmission in seawater. All along the XXth century, underwater acoustics became one of the major technologies used for exploration and exploitation of the oceans for scientific, industrial, or military purposes. It is nowadays able to play, inside the oceans, the roles devoted to radio and radar in atmosphere and space, and is widely employed in the fields of navigation, fisheries, defence, oceanography and ocean engineering. This book presents, in a clear and concise way, the basic physical phenomena governing underwater acoustical waves, the general features of sonar systems, and an overview of their applications.
Tipo: Text
Palavras-chave: Acoustique sous-marine; Propagation; Traitement du signal; Sonar; Sondeur; Underwater acoustics; Propagation; Signal processing; Sonar; Echosounder.
Ano: 2001
URL: http://archimer.ifremer.fr/doc/00017/12790/9731.pdf

A Measurement Quality Factor for Swath Bathymetry Sounders
Provedor de dados: 5
Autores: Lurton, Xavier; Augustin, Jean-marie.
The quality estimation associated with individual soundings measured and computed by swath bathymetry sonars is a paramount issue which is most often imperfectly addressed today by sonar manufacturers. In this paper, a unified definition is proposed for a quality factor usable for all swath bathymetry sonars; the depth-relative error is directly estimated from the signal characteristics used in the sounding computation. The basic algorithms are presented for both phase-difference (oblique incidence) and amplitude (normal incidence) detection, and can be readily implemented in any swath bathymetry system using these detection principles. This approach gives a direct access to the objective bathymetric performance of individual soundings, and hence avoids...
Tipo: Text
Palavras-chave: Bathymetry; Interferometry; Multibeam echosounder (MBES); Sonar.
Ano: 2010

Quantitative characterisation of seafloor substrate and bedforms using advanced processing of multibeam backscatter-Application to Cook Strait, New Zealand
Provedor de dados: 5
Autores: Lamarche, Geoffroy; Lurton, Xavier; Verdier, Anne-laure; Augustin, Jean-marie.
A comprehensive EM300 multibeam echo-sounder dataset acquired from Cook Strait, New Zealand, is used to develop a regional-scale objective characterisation of the seafloor. Sediment samples and high-resolution seismic data are used for ground-truthing. SonarScope (R) software is used to process the data, including signal corrections from sensor bias, specular reflection compensation and speckle noise filtering aiming at attenuating the effects of recording equipment, seafloor topography, and water column. The processing is completed by correlating a quantitative description (the Generic Seafloor Acoustic Backscatter-GSAB model) with the backscatter data. The calibrated Backscattering Strength (BS) is used to provide information on the physical...
Tipo: Text
Palavras-chave: Backscatter; Multibeam echo-sounder; Sediment waves; Habitat mapping.
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00031/14260/11552.pdf

Seafloor change detection using multibeam echosounder backscatter: case study on the Belgian part of the North Sea
Provedor de dados: 5
Autores: Montereale-gavazzi, Giacomo; Roche, Marc; Lurton, Xavier; Degrendele, Koen; Terseleer, Nathan; Van Lancker, Vera.
To characterize seafloor substrate type, seabed mapping and particularly multibeam echosounding are increasingly used. Yet, the utilisation of repetitive MBES-borne backscatter surveys to monitor the environmental status of the seafloor remains limited. Often methodological frameworks are missing, and should comprise of a suite of change detection procedures, similarly to those developed in the terrestrial sciences. In this study, pre-, ensemble and post-classification approaches were tested on an eight km2 study site within a Habitat Directive Area in the Belgian part of the North Sea. In this area, gravel beds with epifaunal assemblages were observed. Flourishing of the fauna is constrained by overtopping with sand or increased turbidity levels, which...
Tipo: Text
Palavras-chave: Multibeam; Seafloor backscatter; Change detection; Seafloor integrity; Marine Strategy Framework Directive; Reference calibration area.
Ano: 2018
URL: http://archimer.ifremer.fr/doc/00387/49807/50379.pdf

Analyse des risques pour les mammifères marins liés à l'emploi des méthodes acoustiques en océanographie
Provedor de dados: 5
Autores: Lurton, Xavier; Antoine, Loic.
The use of acoustical systems in various human activities in the ocean (industry, defence, science) raises the issue of their impact upon marine mammals populations. Several serious accidents linked to the use of naval sonars led the military, industrial and scientific communities to investigate the potential dangers of their own activity.    This report aims at identifying the risks for the cetaceans linked to the use of acoustic and seismic systems currently used for oceanographic science. The analysis proposed here stays within the frame of bibliography synthesis and elementary modelling, and brings no new scientific elements on the topic. An overview of the status of cetacean populations is given first, with a summary of the possible acoustical...
Tipo: Text
Palavras-chave: Seismics; Sonar; Acoustics; Oceanography; Acoustical methods; Auditory threshold; Stranding; Acoustical risks; Marine mammals.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/rapport-2390.pdf

Acoustic impact assessment of boomers on marine mammals
Provedor de dados: 5
Autores: Lurton, Xavier.
Scientific surveys for geoscience use a medium - power type of acoustic sources called Boomers. Their acoustic signal characteristics are shown not to impact the physiology of marine mammals. Therefore scientific surveys collecting data using boomers do not require specific mitigation plans .
Tipo: Text
Palavras-chave: Boomer; Marine Mammals; Acoustic Impact.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00369/47970/47994.pdf

Insights into the Short-Term Tidal Variability of Multibeam Backscatter from Field Experiments on Different Seafloor Types
Provedor de dados: 5
Autores: Montereale-gavazzi, Giacomo; Roche, Marc; Degrendele, Koen; Lurton, Xavier; Terseleer, Nathan; Baeye, Matthias; Francken, Frederic; Van Lancker, Vera.
Three experiments were conducted in the Belgian part of the North Sea to investigate short-term variation in seafloor backscatter strength (BS) obtained with multibeam echosounders (MBES). Measurements were acquired on predominantly gravelly (offshore) and sandy and muddy (nearshore) areas. Kongsberg EM3002 and EM2040 dual MBES were used to carry out repeated 300-kHz backscatter measurements over tidal cycles (similar to 13 h). Measurements were analysed in complement to an array of ground-truth variables on sediment and current nature and dynamics. Seafloor and water-column sampling was used, as well as benthic landers equipped with different oceanographic sensors. Both angular response (AR) and mosaicked BS were derived. Results point at the high...
Tipo: Text
Palavras-chave: Multibeam echosounder; Seafloor; Backscatter; Monitoring; Short-term variability; Sensitivity; High-frequency.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00485/59637/62660.pdf

A quality estimator of acoustic sounding detection
Provedor de dados: 5
Autores: Lurton, Xavier; Ladroit, Yoann; Augustin, Jean-marie.
Swath sonar bathymetry accuracy depends on the intrinsic performance of acoustic signal processing. We propose here a quality factor, quantifying the accuracy associated with every sounding computation. This descriptor is derived from simple models either for amplitude (variance of the centre-of-gravity instant of a fluctuating bell-shaped envelope) or for interferometric phase (local variance for a number of processed samples). The purpose is to attach to each individual sounding an objective quality level that is sonar independent, and directly applicable in bathymetry processing, either in data editing, or as an input parameter to statistical post-processing. This concept is illustrated by examples from experimental data.
Tipo: Text
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00115/22601/20308.pdf

Sound radiation of seafloor-mapping echosounders in the water column, in relation to the risks posed to marine mammals
Provedor de dados: 5
Autores: Lurton, Xavier; Deruiter, Stacy.
Currently, more and more attention is focusing on the impact of anthropogenic sound sources on marine life, particularly marine mammals. Indeed, several unusual cetacean strandings linked to the use of high-power sonar have been observed over the past years. Hydrography and seafloor-mapping make extensive use of acoustic sources; this paper aims to present the order of magnitude of sound radiated by such echosounders, and hence estimate their potential impact on marine mammals. The paper begins with a presentation of the main issues related to sound-mediated risks to marine life and a reminder of echosounder characteristics and geometry. Next, the numerical results from several case studies are compared with currently accepted threshold values for marine...
Tipo: Text
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00115/22607/20313.pdf

A framework to quantify uncertainties of seafloor backscatter from swath mapping echosounders
Provedor de dados: 5
Autores: Malik, Mashkoor; Lurton, Xavier; Mayer, Larry.
Multibeam echosounders (MBES) have become a widely used acoustic remote sensing tool to map and study the seafloor, providing co-located bathymetry and seafloor backscatter. Although the uncertainty associated with MBES-derived bathymetric data has been studied extensively, the question of backscatter uncertainty has been addressed only minimally and hinders the quantitative use of MBES seafloor backscatter. This paper explores approaches to identifying uncertainty sources associated with MBES-derived backscatter measurements. The major sources of uncertainty are catalogued and the magnitudes of their relative contributions to the backscatter uncertainty budget are evaluated. These major uncertainty sources include seafloor insonified area (1–3 dB),...
Tipo: Text
Palavras-chave: Multibeam echosounder; Calibration; Incidence angle.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00429/54018/57435.pdf

Swath bathymetry using phase difference: Theoretical analysis of acoustical measurement precision
Provedor de dados: 5
Autores: Lurton, Xavier.
The phase difference principle is widely applied nowadays to sonar systems used for sea floor bathymetry, The apparent angle of a target point is obtained from the phase difference measured between two close receiving arrays. Here we study the influence of the phase difference estimation errors caused by the physical structure of the backscattered signals. It is shown that, under certain current conditions, beyond the commonly considered effects of additive external noise and baseline decorrelation, the processing may be affected by the shifting footprint effect: this is due to the fact that the two interferometer receivers get simultaneous echo contributions coming from slightly shifted seabed parts, which results in a degradation of the signal coherence...
Tipo: Text
Palavras-chave: Sonar signal processing; Sidescan sonar; Sea floor bathymetry; Multibeam echosounder; Interferometry; Bathymetry precision; Acoustic scattering.
Ano: 2000
URL: http://archimer.ifremer.fr/doc/2000/publication-710.pdf

Simple method for multiple soundings extraction for wide beamwidth echosounders
Provedor de dados: 5
Autores: Le Bouffant, Naig; Berger, Laurent; Lurton, Xavier.
Bathymetric multibeam echosounders (MBES) classically improve their bottom detection resolution by increasing the number of beams with narrower beamwidths. Many independent detections are thus obtained when extracting one sounding in each beam. However when the pulse footprint on the bottom gets narrower than the beamwidth, which often happens at high incidence angles, it is possible to extract several independent bottom detections within the same beam. These high-density soundings extraction methods present a still higher interest for MBES designed with rather “wide” beams (say 3° or more), so as to offer other benefits, such as compacity, low-cost, or low sidelobe levels as for fishery applications. This paper presents a simple way to derive multiple...
Tipo: Text
Palavras-chave: Multibeam; Bathymetry; Interferometry; Beamwidth.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00146/25719/23801.pdf