共查询到20条相似文献,搜索用时 781 毫秒
1.
Time-frequency approaches to ISAR imaging of maneuvering targetsand their limitations 总被引:2,自引:0,他引:2
Zheng Bao Changyin Sun Mengdao Xing 《IEEE transactions on aerospace and electronic systems》2001,37(3):1091-1099
Inverse synthetic aperture radar (ISAR) imaging of the noncooperative maneuvering target is a challenging task because of its time variant orientation and rotation velocity which cannot be measured accurately. This correspondence investigates the principles of ISAR imaging of maneuvering targets, and proposes an algorithm for application in situations where the maneuverability is not too severe and the Doppler variation of subechoes from scatterers can be approximated as a first-order polynomial. The imaging results obtained by using real data show the effectiveness of the new method 相似文献
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The simultaneous imaging and tracking of a moving target is one of the most difficult problems in inverse synthetic aperture radar (ISAR) signal processing. The problem is addressed here using a two-antenna imaging radar. The target range shift is sensed with an exponentially averaged envelope correlation algorithm while the angle change is measured with a differential phase shift algorithm. The three state Kalman filters are used in range and azimuth dimensions to provide both a filtered estimate and a one-sample-ahead prediction for the purpose of target tracking. The filtered range shift provides an accurate information for range bin alignment, and the target angle change provides the angular positions of the synthetic array elements. Therefore, the ISAR imaging simply becomes processing of a circular-arc aperture. The algorithms are verified both by computer simulations and also with experimental data processing 相似文献
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The inverse synthetic aperture radar (ISAR) algorithm for imaging objects moving in a straight line requires range alignment as a preprocessing step since scatterers migrate through the various range bins. The conventional correlation alignment method fails when applied in ground scenarios like an airport due to the clutter environment. A procedure using Hough Transform (HT) alignment is presented which overcomes this disadvantage and provides information for clutter elimination 相似文献
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High resolution 3D “snapshot” ISAR imaging and featureextraction 总被引:1,自引:0,他引:1
Mayhan J.T. Burrows M.L. Cuomo K.M. Piou J.E. 《IEEE transactions on aerospace and electronic systems》2001,37(2):630-642
We have developed a new formulation for three dimensional (3D) radar imaging of inverse synthetic aperture radar (ISAR) data based on recent developments in high resolution spectral estimation theory. Typically for non real-time applications, image formation is a two step process consisting of motion determination and image generation. The technique presented focuses on this latter process, and assumes the motion of the target is known. The new technique offers several advantages over conventional techniques which are based on the correlation imaging function. In particular, the technique provides for a direct 3D estimate (versus back projection to a 3D target grid matrix) of the locations of the dominant scattering centers using only a minimum set of independent 2D range-Doppler ISAR “snapshots” of the target. Because of the snapshot nature of the technique, it is particularly applicable to 3D imaging of sectors of sparse-angle data, for which the sidelobes of the correlation imaging integral become high. Furthermore, the technique provides for an estimate of amplitude and phase of each scattering center as a function of aspect angle to the target, for those aspect angles which encompass the set of 2D range-Doppler snapshots. Results illustrating the technique developed are presented for both simulated and static range data 相似文献
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双基地角时变下的ISAR稀疏孔径自聚焦成像 总被引:1,自引:1,他引:0
针对双基地角时变下的逆合成孔径雷达(ISAR)成像分辨率低以及稀疏孔径存在相位误差引起图像散焦等问题,提出了一种基于贝叶斯压缩感知(BCS)的双基地ISAR稀疏孔径自聚焦高分辨成像算法。在平动补偿后回波数据的基础上,首先构造补偿相位将由双基地角时变引起的多普勒偏移补偿掉,然后构造随双基地角变化的稀疏基矩阵,建立基于压缩感知的双基地ISAR稀疏孔径观测模型,并将相位误差作为ISAR成像的模型误差,接着假设目标图像各像元服从Laplace先验、噪声统计特性服从Gaussian分布,利用贝叶斯推理进行"分布式"迭代求解,在高分辨成像的同时实现了相位自聚焦,仿真结果验证了算法的有效性和优越性。 相似文献
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A 2-D high-resolution spectral analysis algorithm with application to an inverse synthetic aperture radar (ISAR) imaging, is presented. This algorithm is based on two-dimensional linear prediction using autoregressive (AR) coefficients. Stability is guaranteed by AR process pole adjustment. An ISAR target is modeled for a complex scatterer geometry. Computer simulation results are provided for the high-resolution reconstruction of ISAR images 相似文献
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Junfei Li Hao Ling 《IEEE transactions on aerospace and electronic systems》2003,39(1):343-351
Genetic algorithms (GA) are proposed for inverse synthetic aperture radar (ISAR) imaging. GA is used for motion parameters search in place of exhaustive search in the adaptive joint time-frequency (AJTF) algorithm. While maintaining the same accuracy, GA has lower computational complexity, especially for targets with higher order motions. 相似文献
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以空间目标为研究对象,针对双基地逆合成孔径雷达(BISAR)成像中双基角变化及同步误差导致的二维ISAR像散焦问题,提出了基于粒子群优化(PSO)的非参数自聚焦算法。算法首先将回波中平动和转动及同步误差等因素导致的相位变化项统一建模,其次将二维图像对比度最大作为优化目标,利用PSO算法对所有高次项相位进行整体优化估计,然后对高阶相位项进行补偿,最后基于补偿后剩余的一阶线性相位项进行方位压缩得到目标的二维ISAR像。算法可解决参数相位误差估计法中因模型误差导致的聚焦精度下降问题,同时也降低了BISAR自聚焦算法的复杂度。通过与参数法自聚焦算法的性能进行对比仿真实验,验证了算法的有效性。 相似文献
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This work presents a novel approximate iterative and recurrent approach for image reconstruction from inverse synthetic aperture radar (ISAR) data. Mathematical models of the quadrature components of the ISAR signal, reflected by an object with a complex geometry, are devised. Approximation matrix functions are used to describe deterministic signals reflected by point scatterers located at nodes of the uniform grid (model) during inverse aperture synthesis. Minimum mean square error (MMSE) equations and Kalman equations are derived. To prove the validity and correctness of the developed iterative MMSE method and recurrent Kalman procedure, numerical experiments were performed. The computational results demonstrate high resolution images, unambiguous and convergent estimates of the point scatterers' intensities of a target from simulated ISAR data 相似文献
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This paper presents a new three-dimensional (3-D) near-field inverse synthetic aperture radar (ISAR) imaging technique. A 3-D ISAR image can be obtained by processing coherently the backscattered fields as a function of the frequency and two rotation angles about axes which are mutually orthogonal. Most of the existing ISAR algorithms are based on the Fourier transform and as such can tolerate only small amounts of wavefront curvature. Wavefront curvature must be taken into account when imaging an object in the near-field. Near-field ISAR imaging of large objects using a direct Fourier inversion may result in images which are increasingly unfocused at points which are more distant from the center of rotation. An algorithm based on an azimuth convolution between a near-field focusing function and the frequency domain backscattered fields is discussed. This convolution is efficiently implemented by using fast Fourier transform (FFT) techniques. Furthermore, in order to further alleviate the computational load of the algorithm, the discrete Fourier transform (DFT) of the focusing function is evaluated by means of the stationary phase method. Experimental results show that this technique is precise and virtually impulse invariant 相似文献
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《中国航空学报》2021,34(2):252-264
The technique of imaging a target with a complicated motion using an Inverse Synthetic Aperture Radar (ISAR) system is an effective tool in the field of radar signal processing. After the translational compensation, the received signal reflected from the target can take the form of a multi-component Polynomial Phase Signal (m-PPS), and the high quality ISAR image can be provided via the combination between the estimated parameters of the m-PPS and the Range Instantaneous-Doppler technique (RID). For a target with a high maneuvrability, the occurrence of scatterers Migration Through Resolution Cell (MTRC), caused by the rotational movement could be appearing. That is why the variation in the amplitude of the echo during the time of observation cannot be neglected. The purpose of this study is the parameters estimation of the m-PPS signal with order three in the case of the Time Varying Amplitude (TVA). The Improved-version of the Product High-order Ambiguity Function (IPHAF) with TVA is proposed to improve the quality of the ISAR image compared with traditional techniques based on a constant amplitude; the experimental outcomes confirm that the new IPHAF-TVA method presented in this study is an effective technique to make the ISAR image very clear. 相似文献
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在聚束合成孔径雷达(SAR)自聚焦处理时,残留距离徙动(RRCM)必须在自聚焦处理之前完全去除,否则 将会严重降低自聚焦的性能。本文提出了一种基于二维逆滤波的自聚焦算法,该算法在补偿相位误差的同时也补 偿掉距离和方位的二维耦合相位,消除了RRCM对自聚焦的影响,提高了逆滤波自聚焦算法的性能。最后通过实 测数据处理验证了本文提出的二维逆滤波自聚焦算法的有效性。 相似文献
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Werness S.A.S. Carrara W.G. Joyce L.S. Franczak D.B. 《IEEE transactions on aerospace and electronic systems》1990,26(1):57-67
A digital processing algorithm for fine-resolution imaging of synthetic aperture radar (SAR) moving targets is described. The targets may have any translational and rotational motion components relative to the data collection platform. The algorithm requires the presence of up to three prominent points in the image of the target; the signals from these points provide estimates of the unknown target motion parameters. Phase compensation and data formatting based on these estimates eliminate motion-induced phase errors. This algorithm has been implemented on a VAX computer and used to process both simulated and real SAR data of moving targets. Results obtained using the simulated data are presented 相似文献
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在方位维逆合成孔径雷达(ISAR)运动补偿成象中,为了获得方位维的高分辨力,需要处理的数据量很大。预加处理首先对原始数据进行频移和滤波,然后由滤波后的数据进行抽取,从而大大压缩了所需处理的数据,减小了运动补偿和成象的计算量,提高了成象处理速度。电磁仿真数据和外场实测数据的处理结果验证了预加处理的有效性。 相似文献
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The problem of inverse synthetic aperture radar (ISAR) image reconstruction of targets at low elevation angle is considered. In this geometric condition the main causes affecting the reconstructed ISAR image are the multipath effect due to the reflection of the Earth's surface and the angular motions of the target produced by external action like wind, fast maneuvering, and sea waves as in the case of ships. The aim of this work is to analyze the effects that the multipath and the target angular motions jointly produce on the ISAR image. The results show that multipath generates some artifacts in the image whereas the target oscillations undergo a spatial-dependent blurring of the point spread function of the ISAR system. These theoretical results are validated by presenting some numerical examples relevant to aircrafts and ships in rectilinear or circular motion. A wide discussion on possible solutions of this problem is made in the conclusion 相似文献
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一种超高分辨率机载聚束SAR两维自聚焦算法 总被引:1,自引:1,他引:0
受运动参数测量误差和大气扰动等因素影响,合成孔径雷达(SAR)图像通常会发生散焦,利用自聚焦对散焦的SAR图像进行后处理是一种有效的重聚焦手段。传统的自聚焦算法都只是针对方位一维相位误差的估计和补偿。随着成像分辨率的提高,自聚焦时残留距离徙动的校正成为SAR成像面临的一个新挑战。本文推导得到了极坐标格式算法处理后残留距离徙动和方位相位误差的解析表达式,分析了两者之间的内在关系,并利用该关系,提出了一种能够同时进行残留距离徙动和方位相位误差补偿的两维自聚焦算法。实测数据处理结果表明,在残留距离徙动效应不可忽略的条件下,该方法能够极大地改善原有自聚焦算法的聚焦性能。 相似文献
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Developmentofinversesyntheticapertureradar(ISAR),whichpossesseshighcross-rangeresolutioncapabilities,madeitpossibletoresolvet... 相似文献