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11th IEEE International Conference on Dependable, Autonomic and Secure Computing (DASC)

作者： Zou Linchen Zhang Jindong Zhu Daiyin Nanjing Univ Aeronaut & Astronaut Key Lab Radar Imaging & Microwave Photon Coll Elect & Informat Engn Nanjing Univ Aeronaut AstronautMinist Educ Nanjing 210016 Jiangsu Peoples R China

ISBN: (纸本)9781479933815

To satisfy the demand of real-time processing of airborne synthetic aperture radar (SAR), the polar format algorithm (PFA) is designed and implemented based on FPGA. In this design, the complicated two-dimensional interpolation of the canonic PFA is implemented using the principle of chirp-scaling (PCS) to improve the efficiency, the Floating-Point IP core and pipeline structure is applied to the realize high-speed floating-point-number computation, and an efficient scheme employed to control the read and write mode of DDR3 SDRAM is brought up to realize the transposition of matrix data demanded by the algorithm. The system is built on the KC705 evaluation board, and in a test with real SAR data, it takes approximately 1s to process 4096*4096 single-precision floating-point pixels with reasonable imaging result, when the system works at 200MHz.

关键词： Synthetic Aperture Radar Spotlight Imaging polar format algorithm FPGA

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An Electromagnetic Parameter Estimation Method for Microwave Photonic Signal Based on PSO

An Electromagnetic Parameter Estimation Method for Microwave...

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2021 CIE International Conference on Radar, Radar 2021

作者： Xie, Yiyuan Gao, Yuexin Xing, Mengdao Xidian University National Laboratory of Radar Signal Processing Xi'an China School of Aerospace Science and Technology Xidian University Xi'an China

ISBN: (纸本)9781665498142

Microwave photonics radar generates cross-band signals, which provides a basis for precise electromagnetic characteristics description and accurate identification of targets. As a result, a corresponding electromagnetic model parameter extraction method is urgently required under the cross-band and wide-angle condition. This paper proposes a parameter estimation method based on an improved Particle Swarm Optimization (PSO). The representation dictionary without range-azimuth coupling of scattering behavior for the data processed by PFA is firstly formed based on the attributed scattering center (ASC) model. Based on the proposed scattering behavior dictionary, the improved PSO algorithm and the CLEAN algorithm are implemented to estimate the electromagnetic parameters of each scattering center. Further, the simulated annealing (SA) algorithm is introduced to improve the method's capacity to find the global optimum. Finally, the structure of each scattering center can be identified according to the parameter estimation results. The processing results of simulation data verify the effectiveness of the algorithm. Compared with traditional algorithms, the proposed algorithm is insensitive to the initialization value and does not require image segmentation, which reduces the complexity of computation. © 2021 IEEE.

关键词： Attributed scattering center Cross-band radar imaging Parameter estimation Particle Swarm algorithm polar format algorithm

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A THz Video SAR Imaging algorithm Based on Chirp Scaling

A THz Video SAR Imaging Algorithm Based on Chirp Scaling

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2021 CIE International Conference on Radar, Radar 2021

作者： Jiang, Jiawei Li, Yinwei Zheng, Qibin School of Optoelectronic Information and Computer Engineering University of Shanghai for Science and Technology Shanghai China Terahertz Technology Innovation Research Institute University of Shanghai for Science and Technology Shanghai China

ISBN: (纸本)9781665498142

In video synthetic aperture radar (SAR) imaging mode, the polar format algorithm (PFA) is more computational effective than the backprojection algorithm (BPA). However, the two-dimensional (2-D) interpolation in PFA greatly affects its computational speed, which is detrimental to the real-time imaging of video SAR. In this paper, a terahertz (THz) video SAR imaging algorithm based on chirp scaling is proposed, which utilizes the small synthetic angular feature of THz SAR and the inherent property of linear frequency modulation. Then, two-step chirp scaling is used to replace the 2-D interpolation in the PFA to obtain a similar focusing effect, but with a faster operation. Point target simulation is used to verify the effectiveness of the proposed method. © 2021 IEEE.

关键词： Chirp Scaling polar format algorithm Terahertz Video SAR

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High sidelobe analysis and reduction in multistatic inverse synthetic aperture radar imaging fusion with gapped data

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IET RADAR SONAR AND NAVIGATION 2019年第7期13卷 1200-1206页

作者： Kang, Hailong Li, Jun Li, Han Zhang, Yuhong Xidian Univ Natl Lab Radar Signal Proc Xian 710071 Shaanxi Peoples R China Xidian Univ Sch Elect Engn Xian 710071 Shaanxi Peoples R China

Radar observations from different angles are often discontinuous in multistatic inverse synthetic aperture radar (ISAR) imaging. Based on Fourier transform, such as polar format algorithm and Range Doppler algorithm, the discontinuity of the angle will make the performance of traditional ISAR imaging algorithm worse. The sidelobe of the image will rise and the mainlobe may split. Generally, it is necessary to pre-process the gapped data and then the traditional ISAR imaging algorithm is used for imaging. The most commonly used pre-processing method is to interpolate the gap. However, the performance of this method is not satisfied, especially when the gap is large. The reason of sidelobe rising and mainlobe splitting is first analysed. Then, a sidelobe reduction method based on compressive sensing (CS) is proposed. This method establishes a relationship between the complete data and the gapped data, and the complete data can be solved from the gapped data by CS method. After that, the complete data will be used for imaging by utilising traditional ISAR imaging algorithm and the high sidelobe will be reduced effectively. The effectiveness of the proposed method is verified by the analysis and the simulation results.

关键词： synthetic aperture radar Fourier transforms radar imaging image fusion high sidelobe analysis multistatic inverse synthetic aperture radar imaging gapped data radar observations polar format algorithm Range Doppler algorithm traditional ISAR imaging algorithm pre-processing method sidelobe rising sidelobe reduction method complete data

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Wide-Angle ISAR Imaging Based on Joint ICPF and PFA Method 4

Wide-Angle ISAR Imaging Based on Joint ICPF and PFA Method

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4th IEEE International Conference on Signal and Image Processing (ICSIP)

作者： Kang, Hongyan Tian, Biao Liu, Yongxiang Natl Univ Def Technol Tech Serv Ctr Vocat Educ Changsha Peoples R China Natl Univ Def Technol Coll Elect Sci & Technol Changsha Peoples R China

ISBN: (纸本)9781728136608

In broadband inverse synthetic aperture radar (ISAR) imaging, in order to display the image with the same scale in the range direction and azimuth direction, it is necessary to improve the azimuth resolution by increasing the rotation angle of the target in the observation time because of the high range resolution. It will inevitably cause migration through range resolution cell (MTRRC) of scattering centers and induce time-varying Doppler. In this case, if the traditional Range-Doppler algorithm (RDA) is still applied, the image defocus in both range and azimuth directions will appear. In this paper, a method based on optimal sub-region selection (SRS) to estimate the rotation angle of the target by integrated cubic phase function (ICPF) and reconstructing the high-focus image by polar format algorithm (PFA) is proposed. The simulation results show the effectiveness of the method.

关键词： inverse synthetic aperture radar wide-angle migration through range resolution cell optimal sub-region selection integrated cubic phase function polar format algorithm

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A NEW TRAJECTORY-BASED polar format algorithm FOR BISTATIC SAR

A NEW TRAJECTORY-BASED POLAR FORMAT ALGORITHM FOR BISTATIC S...

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IEEE International Geoscience and Remote Sensing Symposium (IGARSS)

作者： Wang, Yan Li, Jingwen Chen, Jie Xu, Huaping Sun, Bing Beihang Univ Sch Elect & Informat Engn Beijing Peoples R China

ISBN: (纸本)9781467311595

The interpolation-based polar format algorithm (PFA) can be used in bistatic Synthetic Aperture Radar (SAR) image processing while suffering from heavy interpolation computation load and complicated space-dependent resolution. To decrease computation load, this paper presents a nonlinear trajectory-based PFA, in which sensors are designed to fly on conical surface to avoid range interpolation. Due to this conical bistatic geometry, two advantages can be achieved. First, part of computation load can be converted to navigation system and processing speed can be improved. Second, a space-independent range resolution can be approached. A following multi-scatter simulation validates the presented approach.

关键词： polar format algorithm nonlinear trajectory bistatic resolution

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Wavefront curvature compensation in PFA for spotlight bistatic SAR with arbitrary platforms paths

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JOURNAL OF ENGINEERING-JOE 2019年第19期2019卷 5819-5823页

作者： Miao, Yuxuan Chen, Tianfu Wu, Junjie Yang, Jianyu Univ Elect Sci & Technol China Sch Elect Engn Chengdu Sichuan Peoples R China

polar format algorithm (PFA) as is an efficient algorithm can be well applied to spotlight bistatic synthetic aperture radar (SAR). However, a planar wavefront assumption which leads to image distortion is made. In this study, a new method to compensate for the wavefront curvature of PFA image is presented and it can well correct the defocusing effect and geometry distortion even under arbitrary platforms paths. By projecting the coefficients of Taylor expansion from the azimuth-time domain to wavenumber domain, the new method does not need repeated interpolations to construct the compensation filters for all the errors, which can decrease computational expense in a way. Finally, the effectiveness of this method is verified by numerical simulation.

关键词： radar imaging geometry synthetic aperture radar wavefront curvature compensation spotlight bistatic SAR arbitrary platforms paths polar format algorithm bistatic synthetic aperture radar planar wavefront assumption image distortion PFA image defocusing effect geometry distortion azimuth-time domain compensation filters Taylor expansion

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SAR Moving Target Imaging Using Semi-blind Two-dimensional Autofocus algorithm

SAR Moving Target Imaging Using Semi-blind Two-dimensional A...

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International Symposium on Antennas and Propagation (ISAP)

作者： Wang, Chenqin He, Xueli Mao, Xinhua Nanjing Univ Aeronaut & Astronaut Coll Elect & Informat Engn Nanjing Jiangsu Peoples R China

ISBN: (纸本)9781538604656

Due to uncertainty on target's motion, synthetic aperture radar (SAR) processing can't compensate for the two-dimensional (2-D) phase error of moving targets completely. Therefore, moving targets SAR images often appear 2-D defocused. In this paper, we propose a 2-D autofocus method for refocusing the defocused moving targets SAR images. The new method only requires a direct APE estimation, while the residual 2-D phase error is computed directly from the estimated APE by exploiting the analytical relationship between the 2-D phase error and APE. The simulation experiment proves the proposed approach offers obvious advantages in both computational efficiency and estimation accuracy.

关键词： two-dimensional autofocus polar format algorithm moving target imaging

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Two-dimensional Autofocus for Spotlight SAR polar format Imagery

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IEEE TRANSACTIONS ON COMPUTATIONAL IMAGING 2016年第4期2卷 524-539页

作者： Mao, Xinhua Zhu, Daiyin Nanjing Univ Aeronaut & Astronaut Dept Elect Engn Nanjing 210016 Jiangsu Peoples R China

Conventional two-dimensional (2-D) autofocus algorithms blindly estimate the phase error in the sense that they do not exploit any a priori information on the structure of the 2-D phase error. As such, they often suffer from the low computational efficiency and the lack of data redundancy to accurately estimate the 2-D phase error. In this paper, an efficient semi-blind 2-D autofocus algorithm which is based on exploiting the a priori knowledge about the 2-D phase error structure, is presented. First, as a prerequisite of the proposed method, the analytical structure of the residual 2-D phase error in SAR imagery is investigated in the polar format algorithm framework. Then, by incorporating this a priori information, a novel 2-D autofocus approach is proposed. The new method only requires an estimate of the azimuth phase error and/or residual range cell migration, while the 2-D phase error can then be computed directly from the estimated azimuth phase error or residual range cell migration. Experimental results clearly demonstrate the effectiveness and the robustness of the proposed method.

关键词： Phase gradient autofocus polar format algorithm synthetic aperture radar two-dimensional autofocus

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polar format algorithm Wavefront Curvature Compensation under Arbitrary Radar Flight Path

Polar Format Algorithm Wavefront Curvature Compensation unde...

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2011 IEEE CIE International Conference on Radar(2011年IEEE国际雷达会议RADAR 2011)

作者： Xinhua Mao Daiyin Zhu Zhaoda Zhu College of Electronic and Information Engineering Nanjing University of Aeronautics and Astronautics China

ISBN: (纸本)9781424484447

An improved space-variant post-filtering approach to compensate the wavefront curvature effect in polar format imagery is presented in this paper, which is based on exploiting the endomorphism property of the polar format transformation. The main contribution of this paper is the construction of filter, which provides an accurate and general solution to wavefront curvature compensation. Point target simulation has validated the new approach.

关键词： synthetic aperture radar polar format algorithm wavefront curvature compensation

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