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15 pages, 3842 KiB

Open AccessArticle

Assessing the Performance of the Phase Difference Bathymetric Sonar Depth Uncertainty Prediction Model

by Tannaz H. Mohammadloo, Matt Geen, Jitendra S. Sewada, Mirjam Snellen and Dick G. Simons

Remote Sens. 2022, 14(9), 2011; https://doi.org/10.3390/rs14092011 - 22 Apr 2022

Cited by 4 | Viewed by 2483

Realistic predictions of the contribution of the uncertainty sources affecting the quality of the bathymetric measurements prior to a survey is of importance. To this end, models predicting these contributions have been developed. The objective of the present paper is to assess the performance of the bathymetric uncertainty prediction model for Phase Difference Bathymetric Sonars (PDBS) which is an interferometric sonar. Two data sets were acquired with the Bathyswath-2 system with a frequency of 234

k

Hz

at average water depths of around 26

m

and 8

m

with pulse lengths equal to

0.0555

m

s

and

0.1581

m

s

, respectively. The comparison between the bathymetric uncertainties derived from the measurements and those predicted using the current model indicates a relatively good agreement except for the across-track distances close to the nadir. The performance of the prediction model can be improved by modifying the term addressing the effect of footprint shift, i.e., spatial decorrelation, on the bottom due to fact that at a given time the footprints seen by different receiving arrays are slightly different. Full article

(This article belongs to the Special Issue Multibeam Echosounder Measurements – Addressing Variability and Expanding the Horizon)

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17 pages, 4043 KiB

Open AccessReview

Direction-of-Arrival Estimation Methods in Interferometric Echo Sounding

by Piotr Grall, Iwona Kochanska and Jacek Marszal

Sensors 2020, 20(12), 3556; https://doi.org/10.3390/s20123556 - 23 Jun 2020

Cited by 13 | Viewed by 7136

Abstract

Nowadays, there are two leading sea sounding technologies: the multibeam echo sounder and the multiphase echo sounder (also known as phase-difference side scan sonar or bathymetric side scan sonar). Both solutions have their advantages and disadvantages, and they can be perceived as complementary to each other. The article reviews the development of interferometric echo sounding array configurations and the various methods applied to determine the direction-of-arrival. “Interferometric echo sounder” is a broad term, applied to various devices that primarily utilize phase difference measurements to estimate the direction-of-arrival. The article focuses on modifications to the interferometric sonar array that have led to the state-of-the-art multiphase echo sounder. The main algorithms for classical and modern interferometric echo sounder direction-of-arrival estimation are also outlined. The accuracy of direction-of-arrival estimation methods is dependent on the configuration of the array and external and internal noise sources. The main sources of errors, which influence the accuracy of the phase difference measurements, are also briefly characterized. The article ends with a review of the current research into improvements in the accuracy of interferometric echo sounding and the application of the principle of interferometric in other devices. Full article

(This article belongs to the Special Issue Sensor Applications on Marine Recognition)

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17 pages, 10938 KiB

Open AccessArticle

Fine-Scale Sea Ice Structure Characterized Using Underwater Acoustic Methods

by Vanessa Lucieer, Amy W. Nau, Alexander L. Forrest and Ian Hawes

Remote Sens. 2016, 8(10), 821; https://doi.org/10.3390/rs8100821 - 5 Oct 2016

Cited by 11 | Viewed by 8764

Abstract

Antarctic sea ice is known to provide unique ecosystem habitat at the ice–ocean interface. Mapping sea ice characteristics—such as thickness and roughness—at high resolution from beneath the ice is difficult due to access. A Geoswath Plus phase-measuring bathymetric sonar mounted on an autonomous underwater vehicle (AUV) was employed in this study to collect data underneath the sea ice at Cape Evans in Antarctica in November 2014. This study demonstrates how acoustic data can be collected and processed to resolutions of 1 m for acoustic bathymetry and 5 cm for acoustic backscatter in this challenging environment. Different ice textures such as platelet ice, smooth ice, and sea ice morphologies, ranging in size from 1 to 50 m were characterized. The acoustic techniques developed in this work could provide a key to understanding the distribution of sea ice communities, as they are nondisruptive to the fragile ice environments and provide geolocated data over large spatial extents. These results improve our understanding of sea ice properties and the complex, highly variable ecosystem that exists at this boundary. Full article

(This article belongs to the Special Issue Underwater Acoustic Remote Sensing)

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