scholarly journals Smart Ocean: A New Fast Deconvolved Beamforming Algorithm for Multibeam Sonar

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 4013 ◽  
Author(s):  
Jie Huang ◽  
Tian Zhou ◽  
Weidong Du ◽  
Jiajun Shen ◽  
Wanyuan Zhang
Keyword(s):  
High Frequency ◽  
Real Data ◽  
Side Lobe ◽  
Tunnel Effect ◽  
Computation Complexity ◽  
Acoustic Image ◽  
Multibeam Sonar ◽  
Sonar System ◽  
Topographic Survey ◽  
Beamforming Algorithm

A new fast deconvolved beamforming algorithm is proposed in this paper, and it can greatly reduce the computation complexity of the original Richardson–Lucy (R–L algorithm) deconvolution algorithm by utilizing the convolution theorem and the fast Fourier transform technique. This algorithm makes it possible for real-time high-resolution beamforming in a multibeam sonar system. This paper applies the new fast deconvolved beamforming algorithm to a high-frequency multibeam sonar system to obtain a high bearing resolution and low side lobe. In the sounding mode, it restrains the tunnel effect and makes the topographic survey more accurate. In the 2D acoustic image mode, it can obtain clear images, more details, and can better distinguish two close targets. Detailed implementation methods of the fast deconvolved beamforming are given, its computational complexity is analyzed, and its performance is evaluated with simulated and real data.

Wave-selective beamforming with Distributed Acoustic Sensing

2021 ◽  
Author(s):  
Daniel C. Bowden ◽  
Sara Klaasen ◽  
Eileen Martin ◽  
Patrick Paitz ◽  
Andreas Fichtner
Keyword(s):  
Real Data ◽  
Primary Sources ◽  
Seismic Sources ◽  
Fibre Optic ◽  
Wave Type ◽  
Matched Field Processing ◽  
Fibre Optic Cable ◽  
Secondary Scattering ◽  
Distributed Acoustic Sensing ◽  
Beamforming Algorithm

<p>As fibre-optic DAS deployments become more common, researchers are turning to tried-and-true methods of locating or characterizing seismic sources such as beamforming. However, the strain measurement from DAS intrinsically carries its own sensitivities to both wave type and polarization (Martin et al. 2018, Paitz 2020 doctoral thesis). Additionally, a measurement along a conventional fibre-optic cable only provides one component of motion, and so certain azimuths may be blind to certain types of seismic sources, unless the cable layout can be designed to be oriented in multiple directions.</p><p>In this work, we explore the development and application of a beamforming algorithm that explicitly searches for multiple wavetypes. This builds on 3-component beamforming or Matched Field Processing (MFP) algorithms by Riahi et al. (2013), and Gal et al. (2018), where in addition to gridsearching over possible source azimuths, a distinct gridsearch is performed for each possible wavetype of interest. This does not solve the problem that a given cable orientation might be less sensitive to certain directions, but at least an array-response function can be robustly defined for each type of seismic excitation. This might help further distinguish whether beamforming observations are dominated by primary sources or by secondary scattering (van der Ende and Ampuero, 2020 preprint).</p><p>Much of this work uses analytic theory and synthetic examples. Time permitting, the enhanced algorithm will also be applied to data from the Mt. Meager experiment to explore its feasibility and efficacy with real data (EGU contribution from Klaasen et. al, 2021).</p>

scholarly journals Stationary Time Statistical Property of Ionospheric Clutter in High-Frequency Surface-Wave Radar

2019 ◽  
Vol 2019 ◽  
pp. 1-6
Author(s):  
Shang Shang ◽  
Kangning He ◽  
Zhaobin Wang ◽  
Xuguang Yang
Keyword(s):  
Surface Wave ◽  
High Frequency ◽  
Real Data ◽  
Radar System ◽  
Detection Performance ◽  
Frequency Selection ◽  
Statistical Property ◽  
Stationary Time ◽  
Wave Radar

In HFSWR (high-frequency surface-wave radar) system, the detection performance is impacted seriously by ionospheric clutter. Frequency selection is an effective method to avoid the effect of ionospheric clutter. The key to the method is the stationarity of ionospheric clutter over a period of time. This paper mainly researches the stationary time statistical property of the ionospheric clutter. A large number of real data including ionospheric clutter in HFSWR are processed and analyzed. It shows that ionospheric clutter in HFSWR has the characteristics of approximate stationarity within a period of time.

scholarly journals A Novel Sub-Bottom Profiler and Signal Processor

Sensors ◽  
2019 ◽  
Vol 19 (22) ◽  
pp. 5052
Author(s):  
Tan ◽  
Zhang ◽  
Yang ◽  
Sun
Keyword(s):  
Real Data ◽  
Synthetic Aperture ◽  
Motion Error ◽  
Buried Objects ◽  
Synthetic Aperture Sonar ◽  
Receiver Array ◽  
Sonar System ◽  
Data Processing Method ◽  
Imaging Performance ◽  
Along Track

In this paper, we introduce a novel sub-bottom profiler, making good use of the Mills cross configuration of multibeam sonar and synthetic aperture techniques of the synthetic aperture sonar system. The receiver array is mounted along the ship keel, while the transmitter array is mounted perpendicular to the receiver array. With the synthetic aperture technique, the along-track resolution can be greatly improved. The system often suffers from motion error, which severely degrades the imaging performance. To solve this problem, the imaging algorithm with motion compensation (MC) is proposed. With the presented method, the motion error is first estimated based on overlapped elements between successive pulses. Then, the echo data is processed by using the range migration algorithm based on the phase center approximation (PCA) method, which simultaneously performs the MC with the estimated motion error. In order to validate the proposed sub-bottom profiler and data processing method, some simulations and lake trial results are discussed. The processing results of the real data further indicate that the presented configuration has great potential to find buried objects in seabed sediments.

Wave tracing: Ray tracing for the propagation of band-limited signals: Part 1 — Theory

Geophysics ◽  
2008 ◽  
Vol 73 (5) ◽  
pp. VE377-VE384 ◽  
Author(s):  
Kenneth P. Bube ◽  
John K. Washbourne
Keyword(s):  
Ray Tracing ◽  
High Frequency ◽  
Characteristic Frequency ◽  
Fresnel Zone ◽  
Imaging Techniques ◽  
Real Data ◽  
New Approach ◽  
Head Waves ◽  
Band Limited ◽  
Ray Bending

Many seismic imaging techniques require computing traveltimes and travel paths. Methods to compute raypaths are usually based on high-frequency approximations. In situations such as head waves, these raypaths minimize traveltime but are not paths along which most of the energy travels. We have developed a new approach to computing raypaths, using a modification of ray bending that we call wave tracing; it computes raypaths and traveltimes that are more consistent with the paths and times for the band-limited signals in real data than the paths and times obtained using high-frequency approximations. Wave tracing shortens the raypath while keeping the raypath within the Fresnel zone for a characteristic frequency of the signal.

Robust Adaptive Beamforming Applied to Planar Array

2013 ◽  
Vol 347-350 ◽  
pp. 3930-3933
Author(s):  
Hai Yan Song ◽  
Jie Shi ◽  
Bo Sheng Liu ◽  
Ye Tian ◽  
Jun Ye
Keyword(s):  
Natural Extension ◽  
Side Lobe ◽  
Adaptive Beamforming ◽  
Interference Rejection ◽  
Vector Error ◽  
Second Order Cone ◽  
Planar Array ◽  
Robust Adaptive ◽  
Steering Vector Error ◽  
Beamforming Algorithm

Capon beamforming has better resolution and interference rejection capability. However, its performance will seriously degrade due to noise, array steering vector error, and other factors. In this paper, a robust Capon beamforming applied to a planar array is described. It is shown that the proposed method is the natural extension of the original Vector Optimization Robust Beamforming algorithm to the case of a planar array, and can be reformulated as a convex second-order cone program and solved by SEDUMI. Computer simulation has shown that the proposed method has better performance than other conventional methods, such as narrower main lobe and lower side lobe.

High‐frequency laser sonar system

2002 ◽  
Vol 112 (5) ◽  
pp. 2408-2408
Author(s):  
Benjamin A. Cray ◽  
Ashwin Sarma ◽  
Ivars P. Kirsteins
Keyword(s):  
High Frequency ◽  
Sonar System ◽  
Frequency Laser

Physics-based inversion of high-frequency multibeam sonar data

2011 ◽  
Vol 130 (4) ◽  
pp. 2339-2339
Author(s):  
Darrell Jackson ◽  
Brian T. Hefner
Keyword(s):  
High Frequency ◽  
Multibeam Sonar

scholarly journals Quantitative and Comparative Analyses of Limit Order Books with General Compound Hawkes Processes

Risks ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 110
Author(s):  
Qiyue He ◽  
Anatoliy Swishchuk
Keyword(s):  
High Frequency ◽  
Likelihood Estimation ◽  
Real Data ◽  
Error Rates ◽  
Algorithmic Trading ◽  
Swarm Optimization ◽  
Hawkes Processes ◽  
Price Movements ◽  
Order Books ◽  
Limit Order Books

In this paper, we solve the problem of mid price movements arising in high-frequency and algorithmic trading using real data. Namely, we introduce different new types of General Compound Hawkes Processes (GCHPDO, GCHP2SDO, GCHPnSDO) and find their diffusive limits to model the mid price movements of 6 stocks-EBAY, FB, MU, PCAR, SMH, CSCO. We also define error rates to estimate the models fitting accuracy. Maximum Likelihood Estimation (MLE) and Particle Swarm Optimization (PSO) are used for Hawkes processes and models parameters’ calibration.

scholarly journals A Single-Dataset-Based Pre-Processing Joint Domain Localized Algorithm for Clutter-Suppression in Shipborne High-Frequency Surface-Wave Radar

Sensors ◽  
2020 ◽  
Vol 20 (13) ◽  
pp. 3773
Author(s):  
Liang Guo ◽  
Xin Zhang ◽  
Di Yao ◽  
Qiang Yang ◽  
Yang Bai ◽  
...  
Keyword(s):  
Surface Wave ◽  
High Frequency ◽  
Secondary Data ◽  
Real Data ◽  
Training Sample ◽  
Clutter Suppression ◽  
Low Velocity ◽  
Unscented Transformation ◽  
Wave Radar ◽  
Suppression Method

Due to the motion of the platform, the spectrum of first-order sea clutter will widen and mask low-velocity targets such as ships in shipborne high-frequency surface-wave radar (HFSWR). Limited by the quantity of qualified training samples, the performance of the generally used clutter-suppression method, space–time adaptive processing (STAP) degrades in shipborne HFSWR. To deal with this problem, an innovative training sample acquisition method is proposed, in the area of joint domain localized (JDL) reduced-rank STAP. In this clutter-suppression method, based on a single range of cell data, the unscented transformation is introduced as a preprocessing step to obtain adequate homogeneous secondary data and roughly estimated clutter covariance matrix (CCM). The accurate CCM is calculated by integrating the approximate CCM of different range of cells. Compared with existing clutter-suppression algorithms for shipborne HFSWR, the proposed approach has a better signal-to-clutter-plus-noise ratio (SCNR) improvement tested by real data.

The Influence of High-Frequency Phase of Laser Wavefront on the Distribution of Focal Spot

2014 ◽  
Vol 644-650 ◽  
pp. 1433-1437
Author(s):  
Fu Xing Fu
Keyword(s):  
Laser Beam ◽  
Surface Properties ◽  
High Frequency ◽  
Focal Spot ◽  
Laser Intensity ◽  
Side Lobe ◽  
Laser Beams ◽  
Damage Effect ◽  
Frequency Phase ◽  
Peak Value

When laser beam is effected on the material, the surface properties of material can be damaged, and the damage effect is different for the different laser beams. Nevertheless, the distribution of laser intensity is influenced by the proportion of high-frequency phase in wavefront. By researching the propagation character of wavefront phase, the relation of high-frequency phase and laser intensity is given in this paper. The results show that the focal spot increases gradually with the increase of the proportion of high-frequency phase, the peak value of intensity decreases obviously, and the number of side lobe increases observably.

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