• 제목/요약/키워드: multi-beam

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Seafloor terrain detection from acoustic images utilizing the fast two-dimensional CMLD-CFAR

  • Wang, Jiaqi;Li, Haisen;Du, Weidong;Xing, Tianyao;Zhou, Tian
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.13 no.1
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    • pp.187-193
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    • 2021
  • In order to solve the problem of false terrains caused by environmental interferences and tunneling effect in the conventional multi-beam seafloor terrain detection, this paper proposed a seafloor topography detection method based on fast two-dimensional (2D) Censored Mean Level Detector-statistics Constant False Alarm Rate (CMLD-CFAR) method. The proposed method uses s cross-sliding window. The target occlusion phenomenon that occurs in multi-target environments can be eliminated by censoring some of the large cells of the reference cells, while the remaining reference cells are used to calculate the local threshold. The conventional 2D CMLD-CFAR methods need to estimate the background clutter power level for every pixel, thus increasing the computational burden significantly. In order to overcome this limitation, the proposed method uses a fast algorithm to select the Regions of Interest (ROI) based on a global threshold, while the rest pixels are distinguished as clutter directly. The proposed method is verified by experiments with real multi-beam data. The results show that the proposed method can effectively solve the problem of false terrain in a multi-beam terrain survey and achieve a high detection accuracy.

Topology Optimization of Beam Splitter for Multi-Beam Forming Based on the Phase Field Design Method (페이즈 필드 설계법 기반의 다중 빔 형성을 위한 빔 분배기 위상최적설계)

  • Kim, Han-Min
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.32 no.3
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    • pp.141-147
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    • 2019
  • In this paper, a systematic beam splitter design for multi-beam forming is proposed. The objective of this research is to a design beam splitter that splits and focuses scattering microwaves into intense beams in multiple directions. It is difficult to split multi-beam to non-specific directions with theoretical approaches. Therefore, instead of using transformation optics(TO), which is a widely used process for controlling electromagnetic wave propagation, we used a systematic design process called the phase field design method to obtain an optimal topological structure of beam splitter. The objective function is to maximize the norm of electric field of the target areas of each direction. To avoid island structure and obtain the structure in one body, volume constraint is added to the optimization problem by using augmented Lagrangian. Target frequency is set to X-band 10GHz. The optimal beam splitter performed well in multi-beam forming and the transported electric energy of target areas improved. A frequency dependency test was conducted in the X-band to determine effective frequency range.

A SIW Fed Antipodal Linear Tapered Slot Planar Multi-Beam Antenna for Millimeter-Wave Application

  • Zhang, Yingsong;Hong, Wei;Kuai, Zhenqi
    • Journal of electromagnetic engineering and science
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    • v.10 no.3
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    • pp.175-178
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    • 2010
  • In this paper, a millimeter-wave multi-beam antenna is studied by rotating the antipodal linear tapered slot antenna(ALTSA) with respect to a center is successfully designed. In order to lowering the SLL and enhancing the isolation between the ALTSA elements, a row of metallic via is inserted between the ALTSAs. A 9 beams antenna is designed and experimented at Ka band. The measured and simulated results agree well with each other. The antenna can provide horizontal wide angle coverage up to ${\pm}62^{\circ}$. The gain of each beam can achieve about 12.5 dB. The mutual coupling between ports is all below 20 dB.

A Digital Bathymetric Model combining Multi Beam Echo Sounder and Sidescan Sonar

  • Park, Jo-Seph;Kim, Hik-Il
    • Proceedings of the KSRS Conference
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    • 2002.10a
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    • pp.330-330
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    • 2002
  • The combination of Multi-Beam Echo Sounder swath bathymetry and high-resolution towed Sidescan sonar provides a powerful method of examination about hydrographic survey results. In this paper, we investigate the fast method of 3D bathymetric reconstruction with the Digital Sidescan sonar(Benthos SIS 1500) and Shallow Multi-Beam Echo Sounder(Reson Seabat 8125). The Seabat 8125 is a 455KHz high resolution focused Multibeam echo sounder(MBES) system which measures the relative water depth across a wide swath perpendicular to a vessel's track. The Benthos SIS1500 is a chirp(nominal fq. 200KHz) sonar which map the topographical features & sediment texture of ocean bottom using backscattered amplitude. We generates the very large 3D bathymetric texture mapping model with the Helical System's HHViewer and describes additional benefits of combining MBES and Sidescan Sonar imagery, the removal of geometric distortions in the model and a deterministic sounding noise.

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Research on Development of Side Scan Sonar using multi-beam Sensors (멀티빔 센서를 이용한 사이드 스캔 소나 개발에 관한 연구)

  • 장유신;계중읍;구융서;박승수;김지한;이만형
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2004.10a
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    • pp.696-699
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    • 2004
  • A side scan sonar system uses the towfish installed sonars, It is an equipment that search images of the bottom surface of the sea in real time. It is a typical equipment that is related to a sea investigation such as a geological survey, seabed communication cable and power line cable placing repair investigation, fish breeding ground investigation, sea purification, relic and mineral investigation, and mine and submarine search. It used to fined objects and investigate on the seabed surface. But, recently, it is used to sea purification and geological survey that require information of the correct surface of the seabed. So, it needs various filtering technique and image processing techniques development to acquire high resolution image. therefore, this research develops a side scan sonar using multi-beam sensors that supply various information with the fast scan speed and correct high resolution that is not a simple underwater investigation equipment.

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Development of Target Signal Simulator for Multi-Beam Type FMCW Radar (다중빔 방식의 FMCW 레이더 표적신호 시뮬레이터 개발)

  • Lee, Seung-Youn;Choe, Tok-Son;Jung, Young-Hun;Lee, Seok-Jae;Yoon, Joo-Hong
    • Journal of the Korea Institute of Military Science and Technology
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    • v.15 no.3
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    • pp.343-349
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    • 2012
  • To detect targets for autonomous navigation of unmanned ground vehicle, mounted sensors are required to work all-weather condition. In this point of view, the FMCW radar is quietly appropriate. In this paper, we present development results of target signal simulator for multi-beam type FMCW radar. A target signal simulator make pseudo target signals which simulates multiple moving targets. And we describe how to make hit information for each target in multi-beam type radar. The developed methods are utilized for target tracking device. Moreover it can be applied to similar target signal simulator.

The Development and Performance Analysis of Beam Rotating Actuator for Multi-Beam Disk Drive (다중빔 광디스크용 빔 회전 구동기의 제작과 특성평가)

  • Kim, Byeong-Jun;Kim, Su-Hyeon;Gwak, Yun-Geun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.12
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    • pp.3026-3032
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    • 2000
  • To enhance the effective data transfer rate the multi-beam optical disk drive is presented. The Beam rotating actuator is necessary for putting multi-beam on more than one track. Ray tracing was also executed for real system set-up. The beam Rotating Actuator is made up of piezoelectric material, high stiffness wire hinge and dove prism. The actuator has about 1kHz natural frequency and suitable operational range. The dynamic equation for the actuator is derived for the control real system.

Study on Development of Side Scan Sonar Using Multi-beam Sensors (다중 빔 센서를 이용한 측면주사음탐기에 관한 연구)

  • Chang, Y.S.;Keh, J.E.;Park, S.S.;Lee, M.H.
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2006.06a
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    • pp.317-318
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    • 2006
  • The towfish oi a side scan sonar is an equipment that search images of the bottom surface of the sea in real time. It is a typical equipment that is related to a sea investigation such as a geological survey, seabed communication cable and power line cable placing repair investigation, fish breeding ground investigation, sea purification, relic and mineral investigation, and mine and submarine search. It used to find objects and Investigate on the seabed surface. But, recently, it is used to sea purification and geological survey that require information of the correct surface of the seabed. So, it needs various filtering technique and image processing techniques development to acquire high resolution image. Therefore, this research develops a side scan sonar using multi-beam sensors that supply various information with the fast scan speed and correct high resolution that is not a simple underwater investigation equipment.

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Piezoelectric Beam Rotating Actuator for Multiple Beam Disk Drives (압전소자률 이용한 다중빔 광디스크용 빔 회전 구동기)

  • 김병준;김수현;곽윤근
    • Journal of the Korean Society for Precision Engineering
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    • v.17 no.5
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    • pp.154-159
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    • 2000
  • A multi-beam optical disk drive is presented as a method for improving the effective data transfer rate by increasing the beam spot number formed on an optical disk. The beam rotating actuator is necessary for putting multi-beam on more than one track. The beam rotating actuator is made up of piezoelectric material, high stiffness wire hinge and dove prism. The actuator has good frequency response above 1KHz and suitable operational range. The dynamic equation for the actuator is derived.

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Dynamics Analysis of a Multi-beam System Undergoing Overall Rigid Body Motion Employing Finite Element Method (유한요소법을 사용한 강체운동을 하는 다중보계의 동적 해석)

  • Choe, Sin;Yu, Hong-Hui
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.9 s.180
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    • pp.2266-2273
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    • 2000
  • Equations of motion of a multi-beam system undergoing overall rigid body motion are derived by employing finite element method. An orientation angle is employed to allow the arbitrary orientation o f the beam element. Modal coordinate reduction technique, which has been successfully utilized in the conventional linear modeling method, is employed for the present modeling method to reduce the computational effort. Different from the conventional linear modeling method, the present modeling method captures the motion-induced stiffness variations which are important for the dynamic analysis of structures undergoing overall rigid body motion. The numerical results are compared to those of a commercial program to verify the reliability of the present method.