• Title/Summary/Keyword: SAR

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Extraction of Waterline from X-band Satellite SAR Images (X-밴드 위성 SAR 영상을 이용한 수위선 탐지)

  • Lee, Kyung-Yup;Kim, Youn-Soo
    • Aerospace Engineering and Technology
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    • v.10 no.2
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    • pp.163-169
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    • 2011
  • This paper introduces a method about water line detection using SAR image. The method includes pre-processing of the SAR image with the threshold of the histogram to recognize the boundary between the water and the landmass area. Finally we applied the image differentiation to detect the water line in the SAR image. The TerraSAR-X and the Cosmo-SkyMed images, which are the high spatial resolution X-band SAR data, are used for the evaluation of our algorithm. The accuracy is verified over the stream line in urban area with the result from the Cosmo-SkyMed.

A Study on the SAR Measurement System Validation at 150 MHz Band (150 MHz 대역에서의 SAR 측정시스템의 유효성 연구)

  • Choi, Donggeun;Kim, Kihwea;Choi, Jaehoon
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.24 no.10
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    • pp.1008-1016
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    • 2013
  • SAR measurement which was applied only to the mobile phone has been expanded in the Korean radio regulation law to the portable wireless communication equipments within 20 cm from the human body since Jan. 2012. The two-way radio operating at 150 MHz frequency band was newly included following the revised radio regulation in the target equipment of measurement. SAR measurement system at 150 MHz satisfying this regulation is necessary accordingly for SAR conformity assessment. The international SAR measurement standard(IEC 62209-2) includes the evaluation method on frequencies above 300 MHz, and the commercial SAR measurement system can measure SAR above 300 MHz only. The size of the reference dipole antenna(760 mm, return loss: -27.57 dB) and flat phantom ($1,300 mm(L){\times}900 mm(W){\times}200 mm(H)$), targeted SAR values for numerical analysis(1 g: 1.08 W/kg, 10 g: 0.77 W/kg) for SAR validation evaluation at 150 MHz frequency are proposed in this paper. The suggested dipole antenna and flat phantom are assembled and used to verify the conformity assessment of commercial SAR measurement system. The measured SAR values of 1 g and 10 g were obtained respectively to be 1.13 W/kg, 0.81 W/kg, and they satisfied the effective range(within ${\pm}10$ %) of IEC international standard. The standards based on this study are expected to be used for the domestic SAR measurement standard and IEC(International Electrotechnical Commission) international standard.

Investigation of SAR Systems, Technologies and Application Fields by a Statistical Analysis of SAR-related Journal Papers (SAR 관련 논문 통계 분석에 의한 SAR 시스템, 기술, 활용분야 고찰)

  • Lee Hoon-Yol
    • Korean Journal of Remote Sensing
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    • v.22 no.2
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    • pp.153-174
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    • 2006
  • The purpose of this paper is to establish the category of SAR(Synthetic Aperture Radar) systems, technologies and application fields, thus to provide the world-wide trend in SAR research and development activities by analysing SAR-related journal papers. This paper presents an analysis result of SAR-related journal papers published from the late 1960s to early 2005. Abstracts and indices of 2665 peer-reviewed, English journal papers published in 243 journals were collected from the Cambridge Scientific Abstracts and classified into the categories according to the system, technique, and application field. Statistics on each category were provided so that one can understand the historical and on-going development in SAR systems, techniques, and a variety of application fields such as land, ocean, cryosphere and atmosphere. This statistical analysis data would be a valuable guideline to establish a future SAR system application and satellite manoeuvering policy in Korea.

Technology Trend in Synthetic Aperture Radar (SAR) Imagery Analysis Tools (SAR(Synthetic Aperture Radar) 영상 분석도구 개발기술 동향)

  • Lee, Kangjin;Jeon, Seong-Gyeong;Seong, Seok-Yong;Kang, Ki-mook
    • Journal of Space Technology and Applications
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    • v.1 no.2
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    • pp.268-281
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    • 2021
  • Recently, the synthetic aperture radar (SAR) has been increasingly in demand due to its advantage of being able to observe desired points regardless of time and weather. To utilize SAR data, first of all, many pre-processing such as satellite orbit correction, radiometric calibration, multi-looking, and geocoding are required. For analysis of SAR imagery such as object detection, change detection, and DEM(Digital Elevation Model), additional processings are needed. These pre-processing and additional processes are very complex and require a lot of time and computational resources. In order to handle the SAR images easily, the institutions that use SAR images develop analysis tools and provide users. This paper introduces the function and characteristics of representative SAR imagery analysis tools.

A FREQUENCY DOMAIN RAW SIGNAL SIMULATOR FOR SAR

  • Kwak Sunghee;Kim Moon-Gyu;Shin Dongseok;Shin Jae-Min
    • Proceedings of the KSRS Conference
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    • 2005.10a
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    • pp.530-533
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    • 2005
  • A raw signal simulator for synthetic aperture radar (SAR) is a useful tool for the design and implementation of SAR system. Also, in order to analyze and verify the developed SAR processor, the raw signal simulator is required. Moreover, there is the need for a test system to help designing new SAR sensors and mission of SAR system. The derived parameters of the SAR simulator also help to generate accurate SAR processing algorithms. Although the ultimate purpose of this research is to presents a general purpose SAR simulator, this paper presents a SAR simulator in frequency domain at the first step. The proposed simulator generates the raw signal by changing various simulation parameters such as antenna parameters, modulation parameters, and sampling parameters. It also uses the statistics from an actual SAR image to imitate actual physical scattering. This paper introduces the procedures and parameters of the simulator, and presents the simulation results. Experiments have been conducted by comparing the simulated raw data with original raw SAR image. In addition, the simulated raw data have been verified through commercial SAR processing software.

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Refinement of Low Resolution DEM Using Differential Interferometry

  • Kim Chang-Oh;Lee Dong-Cheon;Kim Jeong-Woo;Kim Sang-Wan;Won Joong-Sun
    • Proceedings of the KSRS Conference
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    • 2004.10a
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    • pp.522-525
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    • 2004
  • Interferometry SAR (InSAR) is a technique to generate topographic map from complex data pairs observed by antennas at different locations. However, to obtain topographic information using InSAR is difficult task because it requires series of complicated process including phase unwrapping and precise recovery of the SAR geometry. Especially, accuracy of the DEM (Digital Elevation Model) produced by repeat pass single SAR pair could be influenced by atmospheric effect. Recently, a new InSAR technique to improve accuracy of DEM has been introduced that utilizes low resolution DEM with a number of SAR image pairs. The coarse DEM plays an important role in reducing phase unwrapping error caused by layover and satellite orbit error. In this study, we implemented DInSAR (Differential InSAR) method which combines low resolution DEMs and ERS tandem pair images. GTOPO30 DEM with 1km resolution, SRTM-3 DEM with 100m resolution, and DEM with 10m resolution derived from 1:25,000 digital vector map were used to investigate feasibility of DInSAR. The accuracy of the DEMs generated both by InSAR and DInSAR was evaluated.

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Evaluation of SAR Image Quality

  • Lee Young-ran;Kim Kwang Young;Kwak Sunghee;Shin Dongseok;Jeong Soo;Kim Kyung-Ok
    • Proceedings of the KSRS Conference
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    • 2004.10a
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    • pp.397-400
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    • 2004
  • Synthetic Aperture Radar(SAR) is an active micro­wave instrument that performs high-resolution observation under almost all weather conditions. Although there are many advantages of SAR instrument, many complicated steps are involved in order to generate SAR image products. Many research and algorithms have been proposed to process radar signal and to increase the quality of SAR products. However, it is hard to find research which compare the quality of SAR products generated with different algorithms and processing methods. In our previous research, a SAR processing s/w was developed for a ground station. In addition, quality assessment procedures and their test parameters inside a SAR processor was proposed. The purpose of this paper is to evaluate the quality of SAR images generated from the developed SAR processing s/w. However, If there are no direct measurements such as radar reflector or scattering field measurement values it is difficult to compare SAR images generated with different methods. An alternative procedures and parameters for SAR image quality evaluation are presented and the problems involved in the comparison methods are discussed. Experiments based on real data have been conducted to evaluate and analyze quality of SAR images.

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Spaceborne SAR System Design and Performance Analysis (위성 영상 레이다(SAR)시스템 설계와 성능분석)

  • Gwak, Yeong-Gil;Jeong, Cheol-Ho
    • Journal of Satellite, Information and Communications
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    • v.1 no.1
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    • pp.26-39
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    • 2006
  • A synthetic aperture radar (SAR) system can provide all-weather, day and night imaging capability, and thus, is very useful in surveillance for both civil and military applications. In this paper, the X-band spaceborne SAR system design procedure is introduced with the key design parameters for mission and system requirements characterized by the small satellite platform. The SAR imaging mode design technique is presented, and the design results are analyzed for standard mode performance evaluation. In line with the system requirements, the X-band SAR payload and ground reception/processing sub-systems are presented with the key design results and image applications examples. The designed small satellite SAR system shows the wide range of imaging capability, and proves to be an effective surveillance system in light-weight, high-performance and cost-effective points of view.

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SAR analysis with variety of the antenna structures on PCS handset (PCS 전화기의 안테나 구조에 따른 SAR 분석)

  • Kim, Hyoun-Kyoung;park, Ju-Derk;Kim, Jin-Suk;Kim, Nam
    • Proceedings of the Korea Electromagnetic Engineering Society Conference
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    • 2000.11a
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    • pp.306-310
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    • 2000
  • 본 논문에서는 안테나 구조해 따른 PCS 전화기에 의해 인체두부에 유기되는 SAR 값을 비교 분석하였고, SAR 값에 영향들 주는 요인을 분석하였다. 안테나의 종류, 안테나의 부착위치, 단말기의 구조에 따른 1 g 및 10 g 평균 첨두 SAR 값을 계산하였고, 인체 두부의 깊이에 따른 SAR 분포의 변화를 살펴보았다. 플립형 단말기에 부착된 안테나 중에서는 side mounted PIFA(Planar Inverted F Antenna)의 1 g 및 10 g 평균 첨두 SAR 값이 각각 0.686 W/kg과 0.353 W/kg으로 가장 낮았다. 폴더형 단말기에 부착된 모노폴 안테나에 의한 1 g 및 10 g 평균 첨두 SAR값은 플립형에 의한 SAR 값에 비해 약 30 % 가량 낮은 것으로 나타났다. 평균 첨두 SAR 값이 낮은 값을 보이는 두 구조인 side mounted PIFA와 폴더형 구조의 모노폴 안테나의 깊이에 따른 SAR 분포는 나머지 두 구조에 비해 비교적 완만한 경사를 보였다.

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Measurement Data Comparison of Fast SAR Measurement System by Probe Arrays with Robot Scanning SAR Measurement System

  • Kim, Jun Hee;Gimm, Yoon-Myoung
    • Journal of electromagnetic engineering and science
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    • v.14 no.4
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    • pp.336-341
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    • 2014
  • Dosimetry of radiating electromagnetic wave from mobile devices to human body has been evaluated by measuring Specific Absorption Rate (SAR). Usual SAR measurement system scans the volume by robot arm to evaluate RF power absorption to human body from wireless devices. It is possible to fast estimate the volume SAR by software deleting robot moving time with the 2D surface SAR data acquired by arrayed probes. This paper shows the principle of fast SAR measurement and the measured data comparison between the fast SAR system and the robot scanning system. Data of the fast SAR is well corresponding with data of robot scanning SAR within ${\pm}3$ dB, and its dynamic range covers from 10 mW/kg to 30 W/kg with 4.8 mm probe diameter.