scholarly journals Using Orthogonal Combined Signals in Broadband ADCP for Improving Velocity Measurement

2020 ◽  
Vol 8 (6) ◽  
pp. 450
Author(s):  
Yujing Lin ◽  
Fei Yuan ◽  
En Cheng
Keyword(s):  
Current Velocity ◽  
Velocity Measurement ◽  
Water Environment ◽  
Acoustic Doppler Current Profiler ◽  
Processing Method ◽  
Velocity Measurements ◽  
Signal Parameters ◽  
Current Profiler ◽  
Signal Combination ◽  
Conventional Signal

Broadband Acoustic Doppler Current Profiler (BBADCP) is a widely used technology in velocity measurements. To adapt to the varied water environment and different measurement requirements, flexible tuning of transmitted signal parameters will improve the feasibility and accuracy of velocity measurement. Compared with the conventional signal, the orthogonal combined signal designed in this paper can generate a wealth of signal combination examples and improve the accuracy of the velocity measurement under the same conditions. The proposed orthogonal combined signal consists of two orthogonal sub-signals with a symmetrical spectrum. Each is designed based on time delay to eliminate or weaken the current velocity ambiguity. Then, the processing method of the received signal when the pulse signals are the same or different coded signal is discussed. The numerical simulation results show that, when using the proposed method, the standard deviation of the estimated current velocity has different degrees of reduction at different current velocities. Our simulation also shows that, compared to the convention method, the proposed method can improve the SNR by 10 dB. This can help significantly increase the scope of the configuration.

scholarly journals The Finescale Response of Lowered ADCP Velocity Measurements Processed with Different Methods

2012 ◽  
Vol 29 (4) ◽  
pp. 597-600 ◽  
Author(s):  
A. M. Thurnherr
Keyword(s):  
Acoustic Doppler Current Profiler ◽  
Processing Method ◽  
Vertical Shear ◽  
Inversion Method ◽  
Velocity Data ◽  
Velocity Measurements ◽  
Processing Methods ◽  
Velocity Inversion ◽  
Current Profiler ◽  
Specific Implementation

Abstract In a paper published in 2002 in this journal, K. Polzin et al. derive corrections for spectra of vertical shear calculated from lowered acoustic Doppler current profiler (LADCP) velocity data. To illustrate and validate the corrections, they use velocities derived with a specific implementation of the shear method for LADCP processing that is no longer supported or widely used. In several recent publications, spectral corrections specific to this old processing method have been applied without modification to LADCP data processed with the more modern and much more widely used velocity-inversion method, which is associated with significantly less damping at high vertical wavenumbers than the older method. The purpose of this work is to derive and validate spectral corrections appropriate for different LADCP processing methods.

scholarly journals Kajian Pola Arus Laut dan Distribusi Sedimen Di Perairan Pantai Muara Kamal Jakarta Utara

2018 ◽  
Vol 1 (1) ◽  
Author(s):  
Permana Ari Soerjawo ◽  
Thonas Indra Maryanto
Keyword(s):  
Current Velocity ◽  
High Tide ◽  
Clay Fraction ◽  
Secondary Data ◽  
Acoustic Doppler Current Profiler ◽  
Google Earth ◽  
Ocean Current ◽  
Primary Data ◽  
Sediment Distribution ◽  
Current Profiler

ABSTRAKPola arus laut dan distribusi sedimen merupakan proses dinamika di suatu perairan yang mempunyai karakteristik berbeda-beda, sehingga berpengaruh terhadap pembentukan geomorfologi pantai di seluruh dunia. Penelitian ini bertujuan untuk mengetahui pola arus dan sedimen di perairan Pantai Muara Kamal Jakarta Utara di tahun 2012. Data yang digunakan merupakan data primer dan data sekunder, data primer meliputi data arus yang didapat dari pemasangan ADCP(Acoustic Doppler Current Profiler), data pasang surut dan sedimen perairan yang diambil dengan sedimen grab. Data sekunder berupa peta LPI (Lingkungan Pantai Indonesia) tahun 2000 skala 1:50.000 dari BIG (Badan Informasi Geospasial) dan citra satelit Google Earth tahun 2009. Hasil penelitian menunjukan bahwa kecepatan arus yang paling besar terdapat pada lapisan permukaan dengan kecepatan 0,242 m/s kearah barat daya (207,8o), kecepatan arus terkecil terdapat pada lapisan dasar yaitu 0,141 m/s kearah barat daya (207o). Hasil simulasi model hidrodinamika 2D, menunjukkan bahwa pada saat pasang arus laut mengarah ke daratan (selatan) dan pada saat surut arus laut mengarah ke laut lepas (barat laut). Berdasarkan kandungan ukuran butir sedimen di perairan Pantai Muara Kamal Jakarta Utara adalah pasir (64.98 - 72.15%) fraksi pasir tertinggi distasiun B(belakang geotekstil), lanau (24.56 - 29.36%) fraksi lanau tertinggi di stasiun C (depan geotekstil) dan Lempung (1.64 – 5.64%) fraksi lempung tertinggi di stasiun C (depan geotekstil). Kata kunci: Arus, Pantai Muara Kamal, Sedimen, model hidrodinamika 2D   ABSTRACTOcean current and sediment distribution are the dynamic process that have different charactheristic and therefore influenced beach geomorfophology around the world. This research aims to understand both ocean current and sediment pattern in Muara Kamal North Jakarta in 2012. This research used primary and secondary data, primary data were consisted of current data from ADCP (Acoustic Doppler Current Profiler), tidal data and bottom sediment samples. Secondary data involved of Indonesia Coastline Environmental map of year 2000 with scale 1:50.000 from Geospatial information Agency and a satellite data from Google earth of year 2009. The results showed that greatest ocean current velocity contained in the surface layer at a speed of 0,242 m/s with to southwest direction (207.8o), the smallest current velocity was in bottom layer is 0.141 m/s with southwest directiont (207o). Based on 2D hydrodynamic model simulation indicated that when high tide ocean current was flowed to the mainland (south) when low tide the current was flowed to the open sea direction. Based on the content grain size of the sediment, the studi area consisted of sand (64.98 - 72.15%) the highest sand fraction at station B(rare of geotextile) , silt (24.56 - 29.36%) the highest silt fraction at station C (front of geotextile) andclay (1.64 – 5.64%) the highest clay fraction at station C(front of geotextile) Key Words: Current, Muara Kamal Shoreline, Sediment, 2D hydrodynamics model

scholarly journals Analysis of in situ water velocity distributions in the lowland river floodplain covered by grassland and reed marsh habitats - a case study of the bypass channel of Warta River (Western Poland)

2017 ◽  
Vol 65 (4) ◽  
pp. 325-332 ◽  
Author(s):  
Ireneusz Laks ◽  
Krzysztof Szoszkiewicz ◽  
Tomasz Kałuża
Keyword(s):  
Acoustic Doppler Current Profiler ◽  
Water Velocity ◽  
Concrete Slabs ◽  
Lowland River ◽  
Vegetation Types ◽  
Velocity Measurements ◽  
Flow Energy ◽  
Current Profiler

AbstractThe analysis of in situ measurements of velocity distribution in the floodplain of the lowland river has been carried out. The survey area was located on a bypass channel of the Warta River (West of Poland) which is filled with water only in case of flood waves. The floodplain is covered by grassland and reed marsh habitats. The velocity measurements were performed with an acoustic Doppler current profiler (ADCP) in a cross-section with a bed reinforced with concrete slabs. The measured velocities have reflected the differentiated impact of various vegetation types on the loss of water flow energy. The statistical analyses have proven a relationship between the local velocities and the type of plant communities.

scholarly journals 3D reconstruction of ocean velocity from high-frequency radar and acoustic Doppler current profiler: a model-based assessment study

Ocean Science ◽  
2020 ◽  
Vol 16 (3) ◽  
pp. 575-591
Author(s):  
Ivan Manso-Narvarte ◽  
Erick Fredj ◽  
Gabriel Jordà ◽  
Maristella Berta ◽  
Annalisa Griffa ◽  
...  
Keyword(s):  
3D Reconstruction ◽  
Current Velocity ◽  
High Frequency ◽  
Acoustic Doppler Current Profiler ◽  
Marine Ecology ◽  
Optimal Interpolation ◽  
Data Reconstruction ◽  
Reconstruction Methods ◽  
Current Profiler

Abstract. The effective monitoring and understanding of the dynamics of coastal currents is crucial for the development of environmentally sustainable coastal activities in order to preserve marine ecosystems as well as to support marine and navigation safety. This need is driving the set-up of a growing number of multiplatform operational observing systems, aiming for the continuous monitoring of the coastal ocean. A significant percentage of the existing observatories is equipped with land-based high-frequency radars (HFRs), which provide real-time currents with high spatio-temporal coverage and resolutions. Several approaches have been used in the past to expand the surface current velocity measurements provided by HFR to subsurface levels, since this can expand the application of the technology to other fields, like marine ecology or fisheries. The possibility of obtaining 3D velocity current fields from the combination of data from HFRs with complementary data, such as the velocity current profiles provided by in situ acoustic Doppler current profiler (ADCP) moorings is explored here. To that end, two different methods to reconstruct the 3D current velocity fields are assessed by a standard approach conceptually similar to OSSEs (observing system simulation experiments), where 3D numerical simulations are used as true ocean in order to evaluate the performance of the data-reconstruction methods. The observations of currents from a HFR and ADCP moorings are emulated by extracting the corresponding data from the 3D true ocean, and used as input for the methods. Then, the 3D reconstructed fields (outputs of the methods) are compared to the true ocean to assess the skills of the data-reconstruction methods. These methods are based on different approaches: on the one hand, the reduced order optimal interpolation uses an approximation to the velocity covariances (which can be obtained from historical data or a realistic numerical simulation) and on the other hand, the discrete cosine transform penalized least square is based on penalized least squares regression that balances fidelity to the data and smoothness of the solution. This study, which is based on the configuration of a real observatory located in the south-eastern Bay of Biscay (SE-BoB), is a first step towards the application of the data-reconstruction methods to real data, since it explores their skills and limitations. In the SE-BoB, where the coastal observatory includes a long-range HFR and two ADCP moorings inside the HFR footprint area, the results show satisfactory 3D reconstructions with mean spatial (for each depth level) errors between 0.55 and 7 cm s−1 for the first 150 m depth and mean relative errors of 0.07–1.2 times the rms value for most of the cases. The data-reconstruction methods perform better in well-sampled areas, and both show promising skills for the 3D reconstruction of currents as well as for the computation of new operational products integrating complementary observations, broadening the applications of the in situ observational data in the study area.

A Comparison of an Unmanned Survey Vessel to Manned Vessels for Nearshore Tidal Current and Transport Measurements

2011 ◽  
Vol 45 (5) ◽  
pp. 71-77 ◽  
Author(s):  
Eddie Weeks ◽  
Chunyan Li ◽  
Harry Roberts ◽  
Richard F. Shaw ◽  
Nan Walker
Keyword(s):  
Energy Efficiency ◽  
Water Use ◽  
Current Velocity ◽  
Autonomous Vehicles ◽  
Tidal Current ◽  
Acoustic Doppler Current Profiler ◽  
Side Scan Sonar ◽  
Coastal Embayments ◽  
Current Profiler ◽  
Chirp Sonar

AbstractThe focus of marine autonomous vehicles has largely been for offshore applications. The use of such observational platforms in estuaries and coastal embayments has been limited by the designs of the widely used AUVs, which are mostly for open ocean studies. Here we discuss the development and testing of an automated unmanned boat for shallow water use for (1) current velocities using an acoustic Doppler current profiler, (2) bathymetry using an echo sounder, (3) seabed configuration using a side-scan sonar, or (4) shallow, sub-bottom stratigraphy using a chirp sonar. After 91 h and 453 km of total distance surveyed, results demonstrate the numerous advantages this automated boat (Auto-boat) possesses over manned survey vessels. For example, the Auto-boat had the advantage in the accuracy of repeating a planned route continuously over at least a tidal cycle to resolve tidal and subtidal current velocity profiles. It provides endurance, energy efficiency, ease of operation, and capability of coverage of shallow areas close to shore.

scholarly journals Method for processing XCP data with improved accuracy

2017 ◽  
Vol 6 (1) ◽  
pp. 209-215
Author(s):  
Xinyue Zhang ◽  
Qisheng Zhang ◽  
Xiao Zhao ◽  
Qimao Zhang ◽  
Shenghui Liu ◽  
...  
Keyword(s):  
Electric Field ◽  
Data Processing ◽  
Acoustic Doppler Current Profiler ◽  
Accurate Method ◽  
Current Data ◽  
Processing Method ◽  
Ocean Current ◽  
Data Processing Method ◽  
Current Profiler ◽  
Improved Accuracy

Abstract. An expendable current profiler (XCP) is a device used for monitoring ocean currents. In this study, we focus on the technology available for processing XCP data and propose a more accurate method for calculating the current velocity from the nanovolt-scale current-induced electric field measured using an XCP. In order to confirm the accuracy of the proposed data processing method, a sea test was performed in the South China Sea region, wherein, for the first time in China, ocean current and electric-field data were collected from the sea surface to a depth of 1000 m using an XCP. The current-data processing method described herein was used to determine the eastward and northward relative velocity components of the current from the measured data, which were then compared with the current data obtained using an acoustic Doppler current profiler, in order verify the accuracy of the measurements as well as that of the data processing method.

scholarly journals Analysis of acoustic Doppler current profiler mean velocity measurements in shallow flows

2020 ◽  
Vol 74 ◽  
pp. 101755
Author(s):  
Matthew R. Klema ◽  
Abdul G. Pirzado ◽  
S. Karan Venayagamoorthy ◽  
Timothy K. Gates
Keyword(s):  
Acoustic Doppler Current Profiler ◽  
Velocity Measurements ◽  
Mean Velocity ◽  
Shallow Flows ◽  
Current Profiler

scholarly journals Method for processing XCP data with improved accuracy

2017 ◽  
Author(s):  
Xinyue Zhang ◽  
Qisheng Zhang ◽  
Xiao Zhao ◽  
Qimao Zhang ◽  
Shenghui Liu ◽  
...  
Keyword(s):  
Electric Field ◽  
Data Processing ◽  
Acoustic Doppler Current Profiler ◽  
Accurate Method ◽  
Current Data ◽  
Processing Method ◽  
Ocean Current ◽  
Data Processing Method ◽  
Current Profiler ◽  
Improved Accuracy

Abstract. An expendable current profiler (XCP) is a device used for monitoring ocean currents. In this study, we focus on the technology available for processing XCP data and propose a more accurate method for calculating the current velocity from the nanovolt-scale current-induced electric field measured using an XCP. In order to confirm the accuracy of the proposed data processing method, a sea test was performed in the South China Sea region, wherein, for the first time in China, ocean current/electric field data were collected from the sea surface to a depth of 1000 m using an XCP. The current-data processing method described herein was used to determine the eastward and northward relative velocity components of the current from the measured data, which were then compared with the current data obtained using an acoustic Doppler current profiler, in order to verify the accuracy of the measurements as well as that of the data processing method.

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