共查询到18条相似文献,搜索用时 187 毫秒
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合成孔径激光雷达(SAL)能实现远距离目标的高分辨率成像.然而,由于所用激光波长很短,SAL系统中微小机械振动都可能在目标回波信号中引入巨大相位误差,所以,SAL很难实现稳定的相位史数据,高分辨率SAL图像的形成往往要应用额外的相位误差消除技术,特别是相位梯度自聚焦(PGA)技术.演示了一个运转良好的条带模式SAL实验室成像装置.采用一台1 550 nm波段的线性调波长激光器作为探测光源,该装置能够形成聚焦良好的高分辨率图像.通过细致的系统设计,基本抑制了在回波信号中产生相位误差的各种振动.该装置产生的相位史数据非常稳定,高分辨率图像的形成仅需简单遵照标准的SAL成像理论,无需额外借助PGA.采用点目标定标,测量得到该成像装置的方位和距离分辨率接近其理论估计.详细给出了2.4 m距离上多种目标的良好聚焦图像及相应的稳定相位史数据. 相似文献
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针对目前双通道SAR地面运动目标检测(GMTI)方法采样数据量过大的问题,该文提出一种基于压缩感知的双通道SAR运动目标检测方法。该方法首先沿方位向进行随机稀疏采样得到双通道原始回波数据,然后通过匹配滤波方法实现距离向聚焦,并利用压缩感知技术实现方位聚焦,最后运用传统相位中心偏置天线(DPCA)技术进行杂波抑制。通过公式推导从理论上分析了该算法利用双通道方位稀疏采样数据实现杂波抑制的可行性,同时详细分析了运动参数对目标成像的影响。仿真与实测数据实验表明该算法在方位向欠采样情况下仍具有良好的杂波抑制性能。 相似文献
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基于Fourier基的压缩感知(Compressed Sensing,CS)算法已被成功应用于平稳运动目标的逆合成孔径雷达(Inversed Synthetic Aperture Radar,ISAR)成像。但由于建模时对ISAR回波方位相位高次项的忽略,Fourier基矩阵对机动目标回波数据方位信息的稀疏表示失效,导致对机动目标的成像在方位向模糊。鉴于时频分析技术良好的时频局部化特性,将其引入到雷达回波方位向分析中,以改进用于表示雷达回波数据的稀疏基,实现对选定时间切片内回波数据多普勒频率的稀疏表示。改进后的基矩阵在通过CS技术解析回波在时间切片内方位信息的同时,又保证了利用有限数据成像的分辨率。与基于Fourier基CS成像等现有方法相比较,新方法在方位向的成像质量上有较大改进。仿真实验验证了算法的有效性。 相似文献
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本文提出了一种基于UWB SAR图像ROI(Region of Interest)切片的运动目标成像和参数估计方法。该方法作为图像域GMTD算法的后续步骤,可在检测出运动目标并提取其多通道图像域ROI切片之后,对运动目标进行聚焦成像并估计目标相对载机的运动速度,然后基于运动目标的多通道聚焦像估计其距离向速度,在此基础上,估计运动目标的方位向速度、方位向位置、距离向位置等参数,从而获得运动目标的二维速度和位置参数。基于半实测数据的实验证明了本文所提方法的有效性。 相似文献
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为了实现星载合成孔径雷达(SAR)的高分辨率宽测绘带成像,该文提出一种基于柱形抛物面天线的多发多收合成孔径雷达系统(MIMO SAR)。根据对系统结构和短偏移正交(STSO)发射波形的分析,该文给出该系统的具体处理方法。基于柱形抛物面天线易于在俯仰向形成高增益窄波束的优势,该系统能够利用数字波束形成技术对不同波形回波数据进行有效分离,从而获取更多的方位向等效相位中心。通过方位向多通道数据重构处理,成像场景回波数据可利用传统成像算法进行成像。仿真结果表明,该系统能够确保MIMO SAR的成像质量,并具有良好的成像性能。 相似文献
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给出了一种基于优化技术的运动补偿方法,通过对运动目标的径向非匀速运动引起的时变的非线性相位主非然速转动引起的转角不均匀进行补偿,从而获得了理想的同分辨目标二维像,本文用这种优化补偿方法对外场实验的飞机回波数据进行了成像实验,成像结果表明,目标二维聚焦聚良好,与传统的运动补偿方法相比,成像质量明显得到改善。 相似文献
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对于合成孔径雷达(SAR)图像,地面静止场景中同时存在运动目标;由于其运动参数未知,动目标在SAR图像上呈现方位向偏移和散焦;而在高分辨条件下,运动目标更可能会存在跨距离单元徙动现象,从而影响运动目标的聚焦成像。文中结合多通道合成孔径雷达-地面动目标显示技术,提出了基于杂波抑制干涉(CSI)和子视图相关法(MD)的动目标聚焦成像技术。该方法结合多通道SAR图像信息,在CSI抑制杂波后进行动目标检测,根据动目标散焦范围挑出包含动目标的区域;然后,用MD算法估计动目标所在距离单元的方位调频率,重新设计方位匹配滤波函数,对该区域内散焦的运动目标聚焦成像。仿真数据和实测数据的处理结果均证明了该方法能较好地实现动目标的聚焦成像。 相似文献
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A synthetic aperture radio/inverse synthetic aperture radar (SAR/ISAR) coherent system model and inversion to image a target moving with an unknown constant velocity in a stationary background are presented. The approach is based on a recently developed system modelling and inversion principle for SAR/ISAR imaging that utilizes the spatial Fourier decomposition of SAR data in the synthetic aperture domain to convert the SAR system model's nonlinear phase functions into linear phase functions suitable for a computationally manageable inversion. It is shown that SAR/ISAR imaging of a moving target can be converted into imaging the target in a stationary squint-mode SAR problem where the parameters of the squint-mode geometry depend on the target's velocity. A method for estimating the moving target's velocity that utilizes a spatial Doppler analysis of the SAR data within overlapping subapertures is presented. The spatial Doppler technique does not require the radar signal to be narrowband, so the reconstructed image's resolution is not sacrificed to improve the target's velocity estimator. 相似文献
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Karakasiliotis A.V. Lazarov A.D. Frangos P.V. Boultadakis G. Kalognomos G. 《Signal Processing, IET》2008,2(3):277-290
A two-dimensional (2-D) inverse synthetic aperture radar (ISAR) return signal model that employs stepped frequency (SF) modulation is developed. The geometry of the examined ISAR scenario is described by analytical geometrical equations. The target to be imaged is represented by a rectangular grid of point scatterers, moving along a rectilinear trajectory at constant speed, without any rotational motion. Thus, the inverse synthetic aperture results from the translational motion of the target for a short period of time. The process of ISAR signal modelling through coherent summation of the SF-modulated signals reflected from different point scatterers of the target is thoroughly described. Moreover, an efficient ISAR image reconstruction approach, including cross-correlation-based range compression and fast-Fourier-transform-based azimuth compression, is presented through analytical mathematical expressions. Numerical simulations are carried out for various SF ISAR scenarios and high-resolution ISAR images are obtained by applying the proposed ISAR image reconstruction approach. Simulation results (ISAR images and corresponding entropy values) indicate the validity of the proposed 2-D SF ISAR return signal model and the efficiency of the proposed imaging algorithms. Finally, a numerical simulation result is illustrated, which shows the comparison of the performance of the proposed ISAR image reconstruction algorithms based on SF and linear frequency modulation waveforms. It is shown that the two waveforms attain almost the same ISAR image resolution. 相似文献
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《Signal Processing, IET》2008,2(3):189-191
Inverse synthetic aperture radar (ISAR) is a non-cooperative target recognition technique that has been investigated for target identification by the combat identification (ID) community for the past decade. Recently, ISAR imaging of moving targets has been an area of vigorous research. ISAR imaging is an effective way to acquire high resolution images of targets of interest at long range and as such is an irreplaceable tool in the task of non-cooperative target recognition. Its applications include detection, imaging, and classification of ships and aircraft with airborne, maritime, and land-based radar systems. Being radar-based, this imaging technique can be employed in all weather and day/night conditions. 相似文献
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High resolution ultrasonic imaging may be achieved via the synthetic aperture focusing technique, provided that the synthetic antenna is correctly spatially sampled. We show that spatial undersampling is possible, using a digital spotlighting technique that permits to recover the correct reconstructed images from aliased data. The proposed method is applied to experimental ultrasonic data. 相似文献
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高分辨宽测绘带静态场景成像与运动目标检测与成像是星载合成孔径雷达(SAR)两个重要功能需求,也是新体制SAR的前沿和重点.现有的基于阵列接收多相位中心技术可解决方位分辨率与测绘带宽的矛盾,但其空时等效单通道数据难以实现运动目标的有效检测.现有的多通道SAR能改善杂波抑制和运动目标检测性能,但其对静态场景成像时仍存在方位分辨率与测绘带宽的矛盾.本文提出一种基于空时等效采样复用的信号处理新方法,同时改善了星载SAR在高分辨率宽测绘带静态场景成像与运动目标检测与成像两方面的性能.进而,本文深入研究目标径向速度在等效回波信号中引入的周期调制产生的目标方位像的"假峰"效应,并提出了有效的抑制"假峰"的补偿方法.最后,数值仿真试验验证了新方法的有效性. 相似文献