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Zhu Daiyin,Zhu Zhaoda,

电子与信息学报 , 2003,
Abstract: In this paper, ground slow-moving target imaging via airborne interferometric SAR/ISAR technique is investigated. Land clutter suppression and SCR improvement are achieved by range and cross-range two-dimensional high resolution of SAR imaging and spatial domain cancellation of interferometer. True azimuth of moving target is determined using phase-comparison interferometer. Furthermore, high resolution image of the slow-moving target is obtained by IS AR processing. The block diagram and the operational principle of the airborne interferometric SAR/ISAR system are discussed in detail. Quantitative relations for SAR, interferometer spatial domain cancellation, direction finding and ISAR processing are derived. Theoretical analysis and preliminary computer simulation reveal the validity of this technique.
A Modified Method of SAR Moving Target Detection and Imaging Based on Fractional Fourier Transform

Deng Bin,Qin Yu-liang,Wang Hong-qiang,Li Xiang,

电子与信息学报 , 2008,
Abstract: To overcome the shortcomings of the conventional method of SAR moving target detection and imaging based on the Fractional Fourier Transform(FrFT), a modified method, which combines filtering in fractional Fourier domain, reassigned spectrogram and CLEAN, is presented for the detection, parameter estimation and imaging of moving targets. This method is able to estimate precisely the initial Doppler frequency and the Doppler centroid, and to distinguish between multiple targets lying in the same line in the time-frequency plane. The transform formulas between FrFT numeral results and Doppler parameters are also given in the paper. Simulated results prove the validity of the approach.
SAR Imaging of Moving Target based on Knowledge-aided Two-dimensional Autofocus  [PDF]
Xinhua Mao
Computer Science , 2015,
Abstract: Due to uncertainty on target's motion, the range cell migration (RCM) and azimuth phase error (APE) of moving targets can't be completely compensated in synthetic aperture radar (SAR) processing. Therefore, moving targets often appear two-dimensional (2-D) defocused in SAR images. In this paper, a 2-D autofocus method for refocusing defocused moving targets in SAR images is presented. The new method only requires a direct estimate of APE, while the residual 2-D phase error ( or RCM) is computed from the estimated APE by exploiting the analytical relationship between the 2-D phase error ( or RCM) and APE. Because the parameter estimation is performed in the reduced-dimension space by exploiting prior knowledge on phase error structure, the proposed approach offers clear advantages in both computational efficiency and estimation accuracy.
An Effective Method for Ground Moving Target Imaging and Location in SAR System

Sheng Wei,Mao Shi-yi,

电子与信息学报 , 2004,
Abstract: This paper addresses the research of ground moving target imaging and positioning in Synthetic Aperture Radar (SAR) system. First it analyzes the difference between ground moving target imaging process and that for stationary ones. The method brought forward in this paper uses the direction of road and bridge of the gazing ground as prior known knowledge, and it can accurately estimate the coordinates and velocities of the moving targets while t = 0. It means that the method can get the position of the moving targets and image them with the same precision as stationary targets imaging in SAR system. There is no special postulation in the proposed algorithm contrast to the conventional method which always assumes that the targets located on the vertical side of SAR at the point of t = 0. Finally two different forms of matched filters are given out for moving targets imaging and the different results are analyzed. The smearing and position shifting effect when using stationary target matched filter to process the moving target echo is also analyzed at the last part.
Signatures of Moving Target in Polar Format Spotlight SAR Image
Xinhua Mao;Dai-Yin Zhu;Zhao-Da Zhu
PIER , 2009, DOI: 10.2528/PIER09030908
Abstract: The synthetic aperture radar (SAR) signatures of moving target are the basis of ground moving target detection and imaging (GMTI&Im). However, previous studies are mainly based on the 2-D separable SAR processing, and little work has been done to investigate the signatures of moving target after the application of a particular fine resolution SAR image formation algorithm. In this paper, the spectrum of moving target after polar format algorithm (PFA) processing is derived. Based on this spectrum, detailed analysis on the SAR signatures of moving target, including the geometric displacement, residual range migration, and the defocusing effect in both range and azimuth dimensions are performed. Simulation results validate the theoretical analysis.
SAR Imaging of Moving Targets via Compressive Sensing  [PDF]
Jun Wang,Gang Li,Hao Zhang,Xiqin Wang
Mathematics , 2011,
Abstract: An algorithm based on compressive sensing (CS) is proposed for synthetic aperture radar (SAR) imaging of moving targets. The received SAR echo is decomposed into the sum of basis sub-signals, which are generated by discretizing the target spatial domain and velocity domain and synthesizing the SAR received data for every discretized spatial position and velocity candidate. In this way, the SAR imaging problem is converted into sub-signal selection problem. In the case that moving targets are sparsely distributed in the observed scene, their reflectivities, positions and velocities can be obtained by using the CS technique. It is shown that, compared with traditional algorithms, the target image obtained by the proposed algorithm has higher resolution and lower side-lobe while the required number of measurements can be an order of magnitude less than that by sampling at Nyquist sampling rate. Moreover, multiple targets with different speeds can be imaged simultaneously, so the proposed algorithm has higher efficiency.
Imaging of moving targets with multi-static SAR using an overcomplete dictionary  [PDF]
Ivana Stojanovic,William C. Karl
Mathematics , 2009, DOI: 10.1109/JSTSP.2009.2038982
Abstract: This paper presents a method for imaging of moving targets using multi-static SAR by treating the problem as one of spatial reflectivity signal inversion over an overcomplete dictionary of target velocities. Since SAR sensor returns can be related to the spatial frequency domain projections of the scattering field, we exploit insights from compressed sensing theory to show that moving targets can be effectively imaged with transmitters and receivers randomly dispersed in a multi-static geometry within a narrow forward cone around the scene of interest. Existing approaches to dealing with moving targets in SAR solve a coupled non-linear problem of target scattering and motion estimation typically through matched filtering. In contrast, by using an overcomplete dictionary approach we effectively linearize the forward model and solve the moving target problem as a larger, unified regularized inversion problem subject to sparsity constraints.

He Junxiang,Li Jingwen,Zhou Yinqing,

电子与信息学报 , 1996,
Abstract: Based on the analysis of SAR radar return model, an approach using Doppler-rate matching filter is proposed. It can solve the problem of azimuth defocus because of the quadratic phase mismatch. Then a fast algorithm structure given by matching matrix is presented. The computer simulation results illustrate its availability.
Moving target simulation with real data and its application to SAR

Wang Qi,Wang Yanfei,

电子与信息学报 , 2003,
Abstract: This paper presents a new SAR raw data simulation method that is used to test and analyze the algorithm of moving target detection. The simulated SAR raw data are generated by superimposing the simulation moving target echo to a real background reflection data. The compound data are tested with the R-D imaging algorithm and MTI algorithm .The result validates the simulation method.
Suppress the Fixed Background Clutter for Detecting Moving Target in a SAR Image

Chen GuangDong,Zhu ZhaoDa,Zhu DaiYin,

电子与信息学报 , 2005,
Abstract: A new and powerful method for detecting moving targets in a synthetic aperture radar(SAR) image is presented. Phase errors induced by many moving targets are largely quadratic, which provides a basis, by way of a change in the Doppler rate, for estimating the combined effects of azimuth constant velocity and radial acceleration. In this paper, the data in the SAR image is corrected by subtracting the quadratic phase error, and inverse changed by adding the same quadratic phase for comparing, both results are transformed to time domain, where the fixed background clutter have same image intensity. The absolute value of subtracting the two signal expected to have superior moving target detection performance. The experiment result prove this method is valid.

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