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256 |
Yu Wei-dong, Yang Ru-liang, Deng Yun-kai, Zhao Feng-jun, Lei Hong |
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The Load Design and Implementation of HJ-1-C Space-borne SAR Hot! |
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HJ-1-C is a Synthetic Aperture Radar (SAR) satellite in the Constellation of “2+1” for China environment and disaster monitoring. It works at S-band with a resolution of 5 m. SAR payload uses a reflector antenna and a high-power concentrated transmitter. Its light weight and high efficiency is very suitable for a small satellite platform. Now HJ-1-C satellite has been launched into orbit and has acquired Chinese first S-band SAR images from space, which demonstrate excellent quality and rich information about scenes imaged. This success verifies our design, testing and experiment work on the payload. With its following operation, HJ-1-C satellite is expected to make a great contribution to the applications of environment protection and disaster monitoring in China. This paper introduces the design and development of HJ-1-C SAR payload, present its main parameters and performance, describes its device details and its manufacture, testing and experiment process. Some images acquired in the orbit are showed.
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2014 Vol. 3 (3): 256-265
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1211
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[PDF 6251KB]
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2921
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266 |
Zheng Shi-kun, Ji You-zhi, Cui Zhao-yun, Fang Yong-gang, Zhou Li-ping |
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Design and Analysis of HJ-1-C Satellite SAR Antenna |
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With truss deployable mesh parabolic reflector, the HJ-1-C SAR antenna has complex structure and multiple steps during the deployed processing. The design of the antenna is difficult in terms of deployed reliability and electrical performance. This paper makes intensive research on system, structure and electrical design, and the analysis of mechanical and thermal performance in the actual space conditions is also presented. The successful deploying in orbit and high image quality of the HJ-1-C satellite indicate that the mechanical, electronic, thermal and reliability design of the antenna satisfy the project requirement, and these research provides valuable experience for the design of the centralized mesh parabolic SAR antenna.
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2014 Vol. 3 (3): 266-273
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1040
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[PDF 5148KB]
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2986
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274 |
Zhao Hai-yang, Wang Xiao, Wang Wei-hua, Zheng Xin |
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System Design of a S-band Solid-state Transmitter in Satellite-borne SAR |
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The system design of a S-band solid-state transmitter in satellite-borne SAR is introduced. A series of critical technologies, such as high reliability, environmental adaptability, and structure miniaturization, which are necessary in satellite applications, are analyzed and discussed. The technologies are experimentally verified at different periods. Multichannel combined technology is used for the transmitter, and the output peak power is more than 3 kW. Because of the high efficiency, small size, lightweight, and high power, it is especially applicable in small satellite platforms.
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2014 Vol. 3 (3): 274-281
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1640
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[PDF 2933KB]
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2247
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282 |
Huang Zhi-rong, Zheng Shi-kun, Zhu Jia-long, Chen Guo-ding |
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Design Optimization of Expansion Driven Components for the HJ-1-C Satellite |
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Expansion-driven HJ-1-C satellite components are prone to fatigue and fracture; thus, a reliability study on the optimal design is performed. According to the Failure Mode and Effects Analysis (FMEA) of the components, the main failure modes are stress relaxation and impact breakage of the torsion and scroll springs. On the basis of the failure modes, a prototype spring is tested, and the relative reliabilities are calculated. Then, reliability measures are proposed, and the design optimization of the springs is carried out. The improvements introduced by the prototype spring are indicative of the effectiveness and reliability of the design optimization process, which can help design and analyze similar antenna reflectors in the future.
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2014 Vol. 3 (3): 282-287
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844
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[PDF 1571KB]
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1808
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339 |
Tian Wei, Xu Xu, Bian Xiao-Lin, Chai Xun, Wang Shi-ang, Gong Hua-ze, Xiong Wen-cheng, SHAO Yun |
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Applications of Environmental Remote Sensing by HJ-1C SAR Imageries Hot! |
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The HJ-1C satellite was successfully launched in November 19, 2012. The HJ-1C and HJ-1A/1B satellites, which were launched in September 06, 2008, constitute the “2+1” small satellite constellation for environmental and disaster monitoring. This study focuses on the analysis and evaluation of the satellite
performance with respect to environmental remote sensing, including land use interpretation, land cover classification, oil spill identification, retrieval of sea waves, and monitoring of coastal mariculture. The data used in this study cover the city of Beijing and the sea of the Fujian Province. Nine HJ-1C satellite images (level-2, S band, VV Pol, strip mode, 5 m resolution) from December 2012 to January 2013 are used. The conclusions are as follows: (1) the HJ-1C SAR images can be used to manually identify farmland, woodland, roads, rivers, urban construction, and rural residential areas; (2) the accuracy of the automatic land cover classification increased significantly when the HJ-1C SAR and HJ-1B CCD fusion images are used; (3) the HJ-1C satellite can be used to identify oil spills, to invert wave parameters, and to extract information regarding inshore aquaculture.
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2014 Vol. 3 (3): 339-351
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1593
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[PDF 12699KB]
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4453
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352 |
Lu Ping-ping, Du Kang-ning, Yu Wei-dong, Wang Yu, Deng Yun-Kai |
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Feature Fusion Based Road Extraction for HJ-1-C SAR Image |
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Road network extraction in SAR images is one of the key tasks of military and civilian technologies. To solve the issues of road extraction of HJ-1-C SAR images, a road extraction algorithm is proposed based on the integration of ratio and directional information. Due to the characteristic narrow dynamic range and low signal to noise ratio of HJ-1-C SAR images, a nonlinear quantization and an image filtering method based on a multi-scale autoregressive model are proposed here. A road extraction algorithm based on information fusion, which considers ratio and direction information, is also proposed. By processing Radon transformation, main road directions can be extracted. Cross interferences can be suppressed, and the road continuity can then be improved by the main direction alignment and secondary road extraction. The HJ-1-C SAR image acquired in Wuhan, China was used to evaluate the proposed method. The experimental results show good performance with correctness (80.5%) and quality (70.1%) when applied to a SAR image with complex content.
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2014 Vol. 3 (3): 352-360
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1512
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[PDF 7631KB]
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2010
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368 |
Zhang Wei, Wang Lei |
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Application Capacity Evaluation of HJ-1-C towards Ice Disaster during On-orbit Test Period |
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On November 19, 2012, HJ-1-C was launched successfully, which is the first civil Synthetic Aperture Radar (SAR) satellite in China and is also the only S-band SAR on-orbit satellite in the world. During the on-orbit period, National Disaster Reduction Center of China (NDRCC) preliminarily evaluated the application capacity towards the ice disaster, and also evaluated the relative precision by using multispectral images of ZY-3 satellite. The result shows that, the S-band SAR satellite has super response towards ice. Entirely freeze-up area, non entirely freeze-up area and drift ice area can be effectively identified, and the S-band SAR satellite has better disaster reduction application capacity. The S-band SAR satellite data will fill up the band’s blank of SAR satellite in China and even the world, and its disaster reduction potentiality remains to be excavated further more.
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2014 Vol. 3 (3): 368-374
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976
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[PDF 7135KB]
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1729
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