Abstract
Echosounders are ubiquitously used to measure bathymetry; they can also provide seabed reflectivity maps based on the measurement of the seafloor acoustic response and its variations. For each ping and beam, the backscattering strength BS is estimated and associated to the sounding. This single BS value is determined from the recorded time-series (pings) by using one or several time samples and transforming their magnitudes into a reflectivity level, according to the sonar equation. At the end, several BS values from consecutive pings or beams are generally averaged to minimise the variability of successive measurements. How they are calculated, and how (and why) they are averaged, is however open to interpretation.
Different methods are presented to reduce the time-series information to a single BS value in the context of Rayleigh scattering. To anchor these theoretical considerations to actual applications, the processes are applied to field data from a single beam echosounder designed at Sorbonne University and used on well-constrained seafloor patches in the Bay of Brest (France) in 2016. The echosounder was tilted mechanically from nadir to 60° and it transmitted a 100 kHz sine wave of 600 µs duration on the different terrains. The issue of the insonified area compensation of several time-samples is discussed, and inferred backscattering strengths are compared relatively and with ground-truth.
Different methods are presented to reduce the time-series information to a single BS value in the context of Rayleigh scattering. To anchor these theoretical considerations to actual applications, the processes are applied to field data from a single beam echosounder designed at Sorbonne University and used on well-constrained seafloor patches in the Bay of Brest (France) in 2016. The echosounder was tilted mechanically from nadir to 60° and it transmitted a 100 kHz sine wave of 600 µs duration on the different terrains. The issue of the insonified area compensation of several time-samples is discussed, and inferred backscattering strengths are compared relatively and with ground-truth.
Original language | English |
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Pages | 41 |
Publication status | Published - 19 Jun 2022 |
Event | International Conference on Underwater Acoustics ICUA-2022 - Southampton, UK United Kingdom Duration: 19 Jun 2022 → 23 Jun 2022 https://icua2022.org/ |
Conference
Conference | International Conference on Underwater Acoustics ICUA-2022 |
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Abbreviated title | ICUA-2022 |
Country/Territory | UK United Kingdom |
City | Southampton |
Period | 19/06/22 → 23/06/22 |
Internet address |
Keywords
- underwater acoustics
- sonar
- echosounder
- multi-frequency
- seabed mapping
ASJC Scopus subject areas
- Acoustics and Ultrasonics
- Ocean Engineering