Simple method for multiple soundings extraction for wide beamwidth echosounders
| Type | Proceedings paper | ||||||||
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| Date | 2013 | ||||||||
| Language | English | ||||||||
| Author(s) | Le Bouffant Naig1, Berger Laurent 1, Lurton Xavier1 |
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| Affiliation(s) | 1 : Ifremer, Unité Navires et Systèmes Embarqués, Centre de Brest, BP 70, 29280 Plouzané, France | ||||||||
| Meeting | UAM 2013 - 1st international conference and exhibition on Underwater Acoustics (UA2013), 23-26 June 2013, Corfu island, Greece | ||||||||
| Source | 1st Underwater Acoustics Conference and Exhibition, 23rd to 28th June 2013 Corfu island, Greece, Proceedings. Edited by John S. Papadakis & Leif Bjørnø ISBN: 978-. ISBN: 978-618-80725-0-3. Session 33: Improvements in bathymetry mapping and sediment characterization, pp.1397-1406 | ||||||||
| Keyword(s) | multibeam, bathymetry, interferometry, beamwidth | ||||||||
| Abstract | 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 detections from wide beamwidth systems, which does not involve direct phase-ramp processing such as truncating, cleaning, smoothing and angle-crossing determination. Upon amplitude criteria all samples from a phase ramp are selected, and geographically positioned through their slant range and antenna relative angle, deduced from the raw phase values. Detections corresponding to seabed echoes are then selected through geometrical contiguity criteria and allocated to geographical grid nodes. Depth of each grid node is then taken as median depth of related detections. Results of such processing are presented upon characteristic seabeds, and compared to MBES-embedded high-density extraction. Resolution and accuracy issues of different strategies are discussed. |
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