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Search Results: 1 - 10 of 82507 matches for " Yang Ru-liang "
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A Spaceborne SAR Simulator

YUE Hai-xia,YANG Ru-liang,

遥感技术与应用 , 2004,
Abstract: This paper introduces a real-time spaceborne SAR simulator and the hardware design based onthe PCI bus and CPLD chip. This simulator is mainly based on the parameters of the SAR and the satelliteorbit. The foundations of the simulation method are the point target model, the ellipse orbit model, andthe ellipse earth model. First, the simulation software can calculate both the phase-shifted data and theweighted data of the azimuth direction of antenna. These data can be synthesized and stored in one file.Second, these data are transferred to the time-controlled unit through PCI bus. Then, the LFM generatesthe linear frequency modulated signal, which is phase-shifted and weighted in the simulator, by means ofthe delay signal generated by CPLD timer. Finally, the system echo signal is formed. This signal can beused to verify the system characteristics, such as resolution, bandwidth, and the spectrum features etc..After digitalization, the data are stored in the storage device in the PC. Based on the classical R-Dalgorithm, the compressed data can be achieved. The compression results in this paper show that thismethod is feasible, and that the flexibility of the software and the hardware of the simulator hasadvantages in the system update and the distributed target simulator design.
Research on spatial matching of spaceborne precipitation radar and ground radar data

SHANG Jian,YANG Ru-Liang,

中国科学院研究生院学报 , 2009,
Abstract: Research on spatial matching of spaceborne radar data and ground radar data is important both in theory and application. The data matching method adopted by NASA Goddard Space Flight Center (GSFC) is introduced, and a refined 3-D grid is put forward. Three groups of spaceborne and ground radar data are matched using the two means. Qualitative comparisons and point-to-point quantitative comparisons are made, so as to analyze and test the effectiveness of the proposed method.
A Squint Mode Bistatic Synthetic Aperture Radar Image Formation Algorithm Based on Second Range Compression

Zhang Sheng-kang Yang Ru-liang,

电子与信息学报 , 2008,
Abstract: An squint mode image formation algorithm for “Tandem” Bistatic Synthetic Aperture Radar(BSAR) is addressed in terms of its geometry and echo models, which is relative to second range compression in monostatic SAR. Aspects of second range compression, range migration and azimuth focusing, which are different with those in monostatic SAR due to the separation of receive-transmit platforms, are resolved successfully. The algorithm is validated for bistatic SAR with arbitrary bistatic angle geometry.
An Inverse Problem Based Approach for Differential SAR Tomography Imaging

Ren Xiao-zhen,Yang Ru-liang,

电子与信息学报 , 2010,
Abstract: When reconstructing elevation-velocity image, the observation data obtained from differential SAR tomography in baseline-time plane does not follow uniform distribution. If the elevation-velocity image of multiple scatterers is obtained using two-dimensional FFT method, the imaging result is not very good because of high sidelobes. In this paper, a new differential SAR tomography imaging algorithm is proposed based on Backus- Gilbert technique. In this algorithm, the elevation-velocity imaging is converted into an inverse problem of two- dimensional integral function, and Tikhonov regularization is used to get the regularized solution of the inverse problem. Simulation results show that the proposed algorithm can overcome the influence caused by non-uniform samples, and acquire better imaging result.
The Calibration Technique of Polarimetric SAR Using Distributed Targets

Xi Yu-xiao,Yang Ru-liang,

电子与信息学报 , 2003,
Abstract: The Sarabandi's Calibration Algorithm(SCA) using distributed targets is modified in the paper. Then the calibration experiment with the Modified Sarabandi's Calibration Algorithm(MSCA) is carried out, using the uncalibrated image data and calibrated image data from the same scene obtained by SIR-C system L band SAR. Finally, the calibration result of MSCA is compared with that obtained by SIR-C calibration group and the performance of MSCA is verified.
Study on Azimuth Ambiguity Analysis of Single Phase Center Multiple Beams Synthetic Aperture Radar

Li Shi-qiang,Yang Ru-liang,

电子与信息学报 , 2005,
Abstract: A fundamental constraint in Synthetic Aperture Radar(SAR) designing is the contradiction between swath width and azimuth resolution. Single phase center multiple beams technique can alleviate the contradiction in some extent and is one of solutions to implement high resolution wide swath spaceborne synthetic aperture radar systems. In this paper, based on the introduction to the principle of single phase center multiple beams technique, the origin of azimuth ambiguities of single phase center multi-beam synthetic aperture radar is analyzed and the formula to compute azimuth ambiguities is presented. Then a simulation example of computing azimuth ambiguities of single phase center multi-beam synthetic aperture radar is given. The results of the paper can be reference for designing single phase center multi-beam synthetic aperture radar systems.
An Improved Secondary Range Compression Imaging Algorithm for Air-borne Squint SAR

Chen Qi,Yang Ru-liang,

电子与信息学报 , 2007,
Abstract: In this paper, a refined Secondary Range Compression (SRC) imaging algorithm for large squint air-borne Synthetic Aperture Radar (SAR) is presented. Based on the squint range mode, refined SRC algorithm for squint mode SAR is deduced directly. By compensating the cubic phase term of range frequency, the problem of range compressing unsymmetrical sidelobe is improved effectively, By compensating the parallel phase term introduced by forward looking beam, the shift of image location in azimuth is solved. Implemented steps and algorithm flow are given, imaging effects are compared in different squint angle as well. The simulation demonstrates that imaging quality is improved obviously and this algorithm is suitable for large squint air-borne SAR imaging.
Two-Dimensional Automatic Gain Control in Synthetic Aperture Radar

Wang Rui,Yang Ru-liang,

电子与信息学报 , 2004,
Abstract: In this paper, a method of automatic gain control for synthetic aperture radar is given. In this way, radar signal is processed in two dimensions. Comparison to the traditional AGC, this method keeps the properties of signal and widens the dynamic range of the receiver. Then the operation mode and coefficient of 2-Dimensional AGC are described, and the computer simulation results and the real radar image are given.
Dual Channels Along -Track Interferometry SAR Ground Moving Target Detection

Zheng Ming-jie,Yang Ru-liang,

电子与信息学报 , 2005,
Abstract: This paper provides a ground moving target detection algorithm in Range-Doppler domain with Along-Track Interferometry(ATI) for dual channels SAR after studying ATI theory deeply. It describes the procedure of detection in detail and analyzes the effect of Signal-Noise-Ratio(SNR), Signal-Clutter-Ratio(SCR) and moving target's velocity. Finally, some typical computer simulation results are presented. Comparing with routine method, the method in the paper requires lower SCR of moving target, and can detects targets both in and out of the clutter main lobe frequency. In addition, it needn't compress echoes in azimuth, so the computation decreases.
Distributed Micro-satellites SAR Orbit Design and Ambiguity Function Analysis

Zuo Yan-jun,Yang Ru-liang,

电子与信息学报 , 2007,
Abstract: sing on satellite trajectories, the formula of formation flying orbit elements is derived. The imaging geometric model of distributed satellites SAR is presented and the ambiguity function of distributed satellites SAR is analyzed. Moreover, a design example of the space circular formation flying is given. According to the design result, the ambiguity function simulations of distributed satellites SAR with different formation configurations and different satellites are developed. The relation between satellites formation configurations, number and ambiguity function is studied, and it is theory basis of following imaging algorithm research.
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