scholarly journals Seabed Identification and Characterization Using Sonar

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Henry M. Manik
Keyword(s):  
Single Frequency ◽  
Single Beam ◽  
Sonar System ◽  
Mean Diameter ◽  
Backscattering Strength ◽  
Sonar Systems ◽  
Simple Analog ◽  
Identification And Characterization

Application of sonar technologies to bottom acoustics study has made significant advances over recent decades. The sonar systems evolved from the simple analog single-beam and single-frequency systems to more sophisticated digital ones. In this paper, a quantified sonar system was applied to detect and quantify the bottom echoes. The increasing of mean diameter is accompanied by a higher backscattering strength. From this study, identification and characterization using sonar is possible.

scholarly journals Measurement and Analysis of Acoustic Backscatter Value for Bottom Classification of waters Tidung Island

2021 ◽  
Vol 5 (2) ◽  
pp. 544-550
Author(s):  
M Hasbi Sidqi Alajuri ◽  
Henry M Manik ◽  
Sri Pujiyati
Keyword(s):  
Grain Size ◽  
Single Frequency ◽  
Acoustic Backscatter ◽  
Sediment Grain Size ◽  
Single Beam ◽  
Measurement And Analysis ◽  
Sediment Sampling ◽  
Backscattering Strength ◽  
Bottom Classification

Sediment in a water has an important role for organisms, namely as a habitat, a place for foraging for food, and a place for spawning. These sediment can affect the composition of organisms in the water. The purpose of this study is to calculate the value of acoustic backscatter for the classification of the bottom of the water and to see the effect of sediment grain size on the backscatter value obtained from a single beam acoustic instrument. Data collection was carried out from 10 to 12 June 2021 in the water of Tidung Island, Seribu Islands, using the SIMRAD EK-15 single beam, single frequency 200 kHz instrument. Sediment sampling was carried out at 13 stations. The results showed that the waters of Tidung Island were dominated by muddy substrate which was classified based on the Surface Backscattering Strength (SS) value. Meanwhile, the grain size of the sediment affects the SVb value, where the large the grain size of the bottom sediment, the SVb value will be higher. The higher SVb value the SS value will be higher. Keywords: Bottom Classification, Acoustic Backscatter, Tidung Island

scholarly journals Code Optimisation Framework for Multicode Sonar Systems

2021 ◽  
Author(s):  
◽  
Muhammad Rashed
Keyword(s):  
Transmission Loss ◽  
Matched Filter ◽  
Signal To Noise Ratio ◽  
Welch Bound ◽  
Optimisation Algorithm ◽  
Sonar System ◽  
Channel Effects ◽  
Sonar Systems ◽  
Mismatched Filters ◽  
Quadratically Constrained

<p>The ocean is a temporally and spatially varying environment, the characteristics of which pose significant challenges to the development of effective underwater wireless communications and sensing systems.  An underwater sensing system such as a sonar detects the presence of a known signal through correlation. It is advantageous to use multiple transducers to increase surveying area with reduced surveying costs and time. Each transducers is assigned a dedicated code. When using multiple codes, the sidelobes of auto- and crosscorrelations are restricted to theoretical limits known as bounds. Sets of codes must be optimised in order to achieve optimal correlation properties, and, achieve Sidelobe Level (SLL)s as low as possible.  In this thesis, we present a novel code-optimisation method to optimise code-sets with any number of codes and up to any length of each code. We optimise code-sets for a matched filter for application in a multi-code sonar system. We first present our gradient-descent based algorithm to optimise sets of codes for flat and low crosscorrelations and autocorrelation sidelobes, including conformance of the magnitude of the samples of the codes to a target power profile. We incorporate the transducer frequency response and the channel effects into the optimisation algorithm. We compare the correlations of our optimised codes with the well-known Welch bound. We then present a method to widen the autocorrelation mainlobe and impose monotonicity. In many cases, we are able to achieve SLLs beyond the Welch bound.  We study the Signal to Noise Ratio (SNR) improvement of the optimised codes for an Underwater Acoustic (UWA) channel. During its propagation, the acoustic wave suffers non-constant transmission loss which is compensated by the application of an appropriate Time Variable Gain (TVG). The effect of the TVG modifies the noise received with the signal. We show that in most cases, the matched filter is still the optimum filter. We also show that the accuracy in timing is very important in the application of the TVG to the received signal.  We then incorporate Doppler tolerance into the existing optimisation algorithm. Our proposed method is able to optimise sets of codes for multiple Doppler scaling factors and non-integer delays in the arrival of the reflection, while still conforming to other constraints.  We suggest designing mismatched filters to further reduce the SLLs, firstly using an existing Quadratically Constrained Qaudratic Program (QCQP) formulation and secondly, as a local optimisation problem, modifying our basic optimisation algorithm.</p>

Comparison of Single-beam and Multibeam Sonar Systems for Sediment Characterization: Results from Shallow Water Experiment

2019 ◽  
Author(s):  
Haiyan Ni ◽  
Wenbo Wang ◽  
Qunyan Ren ◽  
Licheng Lu ◽  
Jinrong Wu ◽  
...  
Keyword(s):  
Shallow Water ◽  
Multibeam Sonar ◽  
Single Beam ◽  
Sonar Systems

scholarly journals Measurement of bottom backscattering strength using single-beam echosounder

2018 ◽  
Vol 1075 ◽  
pp. 012036
Author(s):  
S Solikin ◽  
H M Manik ◽  
S Pujiyati ◽  
S Susilohadi
Keyword(s):  
Single Beam ◽  
Backscattering Strength

scholarly journals DISTRIBUTION AND DENSITY OF DEMERSAL FISHES IN YOUTEFA BAY, PAPUA, INDONESIA: A STUDY USING HYDROACOUSTIC TECHNOLOGY

2020 ◽  
Vol 67 (1) ◽  
Author(s):  
Baigo Hamuna ◽  
Sri Pujiyati ◽  
Lisiard Dimara ◽  
Nyoman Metta N. Natih ◽  
Alianto
Keyword(s):  
Vertical Distribution ◽  
Coastal Waters ◽  
Demersal Fish ◽  
Average Density ◽  
Average Volume ◽  
Single Beam ◽  
Schooling Fish ◽  
Backscattering Strength ◽  
Hydroacoustic Survey ◽  
Spatial And Vertical Distribution

A study was conducted to estimate the distribution and density of demersal fish in Youtefa Bay, Papua, Indonesia, using hydroacoustic technology. The hydroacoustic survey was carried out using a single beam echosounder SIMRAD EK-15 which operates at a frequency of 200 kHz. The hydroacoustic data was processed using Echoview software with a threshold between -70.00 to -34.00 dB. Schooling fish were detected at a maximum distance of 3 m from the seabed, with average volume backscattering strength ranging between -60.13 and -42.01 dB. The demersal fish density in the Youtefa Bay ranged from 0.09 to 42.19 fish m-3 with an average density of 12.62 fish m-3. The schools of demersal fish were dominantly detected in the coastal waters of Enggros Village to Abe Pantai Village. The condition of substrate and water depth seems to influence the spatial and vertical distribution of demersal fish in the Youtefa Bay.

scholarly journals Estimating Sand Bedload in Rivers by Tracking Dunes: a comparison of methods based on bed elevation time-series

2019 ◽  
Author(s):  
Kate C. P. Leary ◽  
Daniel Buscombe
Keyword(s):  
Time Series ◽  
Sampling Rate ◽  
Bedload Transport ◽  
Single Beam ◽  
Bed Elevation ◽  
Sonar Systems ◽  
Optimal Beam ◽  
Field Methodology ◽  
Spatio Temporal ◽  
Bed Material

Abstract. Quantifying bedload transport is paramount to the effective management of rivers with sand or gravel-dominated bed material. However, a practical and scalable field methodology for reliably estimating bedload remains elusive. A popular approach involves calculating transport from the geometry and celerity of migrating bedforms, extracted from time-series of bed elevation profiles acquired using echosounders. Various echosounder sampling methodologies of how to extract bed elevations profiles exist. Using two sets of repeat multibeam sonar surveys with large spatio-temporal resolution and coverage, we compute bedload using three field techniques (one actual and two simulated) for acquiring bed elevation profiles: repeat multi-, single-, and multiple single-beam sonar. Significant differences in flux arise between repeat multibeam and single beam sonar. Mulitbeam and multiple single beam sonar systems can potentially yield comparable results, but the latter relies on knowledge of bedform geometries and flow that collectively inform optimal beam spacing and sampling rate. These results serve to guide design of optimal sampling, and for comparing transport estimates from different sonar configurations.

scholarly journals Estimating sand bed load in rivers by tracking dunes: a comparison of methods based on bed elevation time series

2020 ◽  
Vol 8 (1) ◽  
pp. 161-172 ◽  
Author(s):  
Kate C. P. Leary ◽  
Daniel Buscombe
Keyword(s):  
Time Series ◽  
Sampling Rate ◽  
Bed Load ◽  
Spatiotemporal Resolution ◽  
Single Beam ◽  
Bed Elevation ◽  
Sonar Systems ◽  
Load Transport ◽  
Optimal Beam ◽  
Field Methodology

Abstract. Quantifying bed-load transport is paramount to the effective management of rivers with sand or gravel-dominated bed material. However, a practical and scalable field methodology for reliably estimating bed load remains elusive. A popular approach involves calculating transport from the geometry and celerity of migrating bedforms, extracted from time series of bed elevation profiles (BEPs) acquired using echo sounders. There are various echo sounder sampling methodologies to extract bed elevation profiles. Using two sets of repeat multibeam sonar surveys with high spatiotemporal resolution and coverage, we compute bed load using three field techniques (one actual and two simulated) for acquiring BEPs: repeat multibeam, single-beam, and multiple single-beam sonar. Significant differences in flux arise between repeat multibeam and single-beam sonar. Multibeam and multiple single-beam sonar systems can potentially yield comparable results, but the latter relies on knowledge of bedform geometries and flow that collectively inform optimal beam spacing and sampling rate. These results serve as a guide for design of optimal sampling and for comparing transport estimates from different sonar configurations.

Evaluation of a Single-Beam Sonar System to Map Seagrass at Two Sites in Northern Puget Sound, Washington

2008 ◽  
Author(s):  
Andrew W. Stevens ◽  
Jessica R. Lacy ◽  
David P. Finlayson ◽  
Guy Gelfenbaum
Keyword(s):  
Puget Sound ◽  
Single Beam ◽  
Sonar System

Acoustic Visualization of Nonlinear Internal Gravity Waves Using an Improved High Frequency Sonar System

2006 ◽  
Vol 40 (1) ◽  
pp. 97-102
Author(s):  
Michael T. McCord ◽  
Earl W. Carey
Keyword(s):  
Fine Structure ◽  
Gravity Waves ◽  
High Frequency ◽  
High Sensitivity ◽  
Internal Gravity Waves ◽  
Horizontal Resolution ◽  
Naval Research ◽  
Sonar System ◽  
Industry Applications ◽  
Sonar Systems

High frequency sonar systems have been used by the Naval Research Laboratory to study nonlinear internal gravity waves and define the fine structure of ocean temperature and salinity layers that are found in coastal waters, usually within 130 meters of the surface. Of particular interest is the fine structure of these waves, which are being investigated using high sensitivity sonar systems that provide 1 m horizontal resolution and less than 8 cm vertical resolution. This article describes the integration of commercial and custom-designed components, including a recently patented transmitter-receiver switch. The significance of this T-R switch is that it improves the sensitivity of short-range sonar systems, enables a more refined measurement of nonlinear internal gravity waves, and could have broad industry applications.

Single-Beam Z-Scan: Measurement Techniques and Analysis

1997 ◽  
Vol 06 (03) ◽  
pp. 251-293 ◽  
Author(s):  
P. B. Chapple ◽  
J. Staromlynska ◽  
J. A. Hermann ◽  
T. J. Mckay ◽  
R. G. Mcduff
Keyword(s):  
Beam Quality ◽  
Measurement Techniques ◽  
Optical Power ◽  
Single Frequency ◽  
Optical Nonlinearities ◽  
Single Beam ◽  
Optical Propagation ◽  
Experimental Parameters ◽  
And Control ◽  
Optical Power Limiting

The Z-scan technique is a popular method for measuring degenerate (single frequency) optical nonlinearities using a single laser beam. In order to perform reliable measurements, it is necessary to carefully characterize and control a number of experimental parameters, such as the beam quality, the power and temporal characteristics of the laser, the collection aperture size and position, the sample reflectivity, sample thickness and imperfections in the sample. Failure to control these parameters leads to inaccurate determinations of the nonlinearities. In this paper, we review the theory of Z-scan and examine each of these issues from experimental and theoretical viewpoints. This work will be of interest to anyone who performs Z-scan experiments and to those interested in optical power limiting and nonlinear optical propagation.

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