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传统的相位梯度自聚焦(PGA,phase gradient autofocus)算法仅适用于窄带聚束式合成孔径成像。提出了一种适用于宽带条带式合成孔径声纳的相位梯度自聚焦(SPGA,stripmap phase gradient autofocus)算法。SPGA算法通过多普勒频移估计线性侧摆;SPGA算法消除了侧摆对回波信号包络的影响,使成像模糊仅仅是由方位向相位误差引起的,这样才可以由Dechirp后的距离压缩域数据的相位误差梯度得到侧摆的估计;SPGA算法利用估计得到的侧摆对距离徙动校正前的回波数据进行包络和相位补偿。仿真表明该算法有效地估计出了侧摆,提高了成像质量,且成像没有发生方位向偏移,明确地确定出了目标的位置。 相似文献
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多径环境中宽带信号的时延-尺度性能分析 总被引:3,自引:0,他引:3
该文根据宽带目标回波模型,建立了多径宽带回波模型,分别推导出了多径环境下矩形、高斯包络线性调频信号和双曲调频信号宽带模糊度函数。分析比较了不同的发射波形在多径环境中的时间分辨率。并通过对多径矩形包络线性调频信号和高斯包络双曲调频信号回波的仿真,分别给出了两条和三条路径时,两种不同发射信号的多径回波信号的宽带模糊度函数图。仿真结果表明在多径环境中高斯包络的双曲调频信号多普勒容限优于矩形包络线性调频信号,这样我们就可以忽略尺度对模糊度函数的幅值的影响。 相似文献
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介绍了准两点注入式调频技术,以及相关电路设计和实验结果。理论分析和实践表明,准两点注入式锁相调频源具有平坦的宽带调制特性,能满足高码速率测控通信发射设备的实际要求。 相似文献
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利用声表面波(SAW)技术设计实现了一种用于裁判之间的无线无源联络系统.其基本原理是主裁判携带的收发器发射射频查询脉冲信号,边裁携带的用SAW器件实现的无源信号发生器接收到查询信号后,利用阻抗变化所引起的不同反射性,把由边裁控制的按钮开关的状态调制到对查询信号的反射回波上,收发器通过对接收信号的处理获得边裁的信息.这种方法与通常的无线收发机相比,信号发生器工作在无源状态,无需电池供电,同时利用声波的延迟特性,提高了抗干扰性.实验结果表明:本方法能够有效实现无源信息传输. 相似文献
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实现单站无源测距是新型单站无源定位系统的关键,由于定位要求距离远,隐蔽性强,并保证生存能力,通常采用质点运动学原理的测距方法。针对脉冲多普勒雷达的回波特性,为提高目标定位跟踪的精度,提出一种多普勒频率变化率的改进测距方法,用多脉冲相干积累算法提取多普勒频率变化率,辅以角度进行测距定位,并引入修正的协方差扩展卡尔曼滤波进行定位跟踪,从而减小多普勒频率变化率的估计误差。在Monte-Carlo上仿真结果表明,方法是有效和可行的,不仅能提高信噪比和跟踪收敛速度,而且在多普勒频率变化率的估计和定位跟踪上都能达到较高的精度,优于原有单站无源测距方法,有一定的工程应用前景。 相似文献
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逆合成孔径雷达成像是宽带雷达实现目标信
息获取和精细描述的重要途径,但在成像过程中存在复杂运动导致散焦和成像分辨率不高两
个难题。针对目标复杂运动导致成像散焦问题,本文总结了微动对雷达波调制、进动目标成
像、
三维运动成像、分离部件成像等技术现状;针对成像分辨率不高问题,分析了多频段宽带回
波相参配准、融合成像等技术进展。本文介绍了雷达成像新技术,为解决上述两个难题带来
新的思路和途径,其中,雷达关联成像不依赖于雷达与目标的相对运动,可避免成像的复杂
运动补偿;太赫兹雷达成像容易实现大带宽和窄波束,获得目标精细雷达像。最后对新兴技
术的难点和发展趋势进行了展望。 相似文献
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《中国科学:信息科学(英文版)》2012,(8):1898-1909
To implement target detection,tracking and imaging in a multifunctional radar system,the wideband measurements for inverse synthetic aperture radar(ISAR)imaging are usually sparsely recorded.Considering the incoherence problem in such sparse-aperture ISAR(SA-ISAR)systems,we concentrate on the study of a coherent processing method in this work.Based on an all-pole model,the incoherence parameters between abutting sub-apertures can be effectively estimated.After coherence compensation,an optimization-based SAISAR imaging approach is provided from the view of statistics.Simulation and real data experiments validate the feasibility and effectiveness of the proposals. 相似文献
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In compressive sensing (CS) based inverse synthetic aperture radar (ISAR) imaging approaches, the quality of final image significantly depends on the number of measurements and the noise level. In this paper, we propose an improved version of CSbased method for inverse synthetic aperture radar (ISAR) imaging. Different from the traditional l 1 norm based CS ISAR imaging method, our method explores the use of Gini index to measure the sparsity of ISAR images to improve the imaging quality. Instead of simultaneous perturbation stochastic approximation (SPSA), we use weighted l 1 norm as the surrogate functional and successfully develop an iteratively re-weighted algorithm to reconstruct ISAR images from compressed echo samples. Experimental results show that our approach significantly reduces the number of measurements needed for exact reconstruction and effectively suppresses the noise. Both the peak sidelobe ratio (PSLR) and the reconstruction relative error (RE) indicate that the proposed method outperforms the l 1 norm based method. 相似文献
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随着天线制造技术、超宽带技术、合成孔径技术和信息处理技术的发展,雷达的体积不断减小,探测精度和成像分辨率大大提升,雷达开始在民用领域中活跃起来,尤其是应用于穿透成像、微波遥感成像、滑坡监测和机场异物检测等领域的民用雷达发展十分迅速。为了让民用雷达在复杂的自然环境中具有更高、更稳定的性能,雷达信息处理技术一直在不断创新。本文介绍了民用雷达的新趋势和新技术,以及探墙雷达、微型SAR、边坡雷达和异物检测(Foreign object debris,FOD)雷达实时信息处理的关键问题和解决方案。 相似文献
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进行合成孔径雷达(SAR)成像仿真是研究成像雷达的一个重要手段。该文在分析SAR成像仿真机理的基础亡,提出了一种利用视景仿真软件Vega进行SAR实时成像的仿真方法。该方法在建立场景模型的基础卜,利fEH场景纹理材料的物理属性数据及雷达参数计算雷达散射截面(RCS),再把RCS值输入一个能模拟雷达真实设备的传感器模型,就得到SAR实时仿真图像。为了满足SAR成像仿真的需求,对Vega软件中的纹理材料数据库文件进行了修改,建立了新的纹理材料数据库文件。仿真结果表明新方法能较好地满足SAR实时成像仿真需求,有助于促进SAR成像实时仿真技术的发展。 相似文献
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Jue Wang Jun Wang Yong Wu Yun Zhu Zhen Luo Yaqi Deng 《International journal of remote sensing》2016,37(18):4460-4485
Multistatic passive radar imaging system (MPRIS) does not behave as well as traditional inverse synthetic aperture radar (ISAR) imaging system does on account of the limited illuminators of opportunity and relatively narrow bandwidth of the signals. Furthermore, in the MPRIS, limited by the unavoidable measurement errors of the positions of the illuminators or receivers, or the manoeuvrability of the moving target, the translation motion of the target cannot be compensated accurately, in which the echo will be contaminated by an error phase, resulting in the occurrence of serious image defocus and the degeneracy of the image quality. In this article, two nonparametric autofocusing techniques based on the principles of minimum entropy and maximum contrast, respectively, are proposed to deal with the undesired problems under the multistate geographical configuration consisting of one illuminator and several receivers distributed around a target. The error phase is corrected by introducing an adjustment phase in the frequency domain and the adjustment phase can be searched by iteratively solving an equation that is derived by optimizing the quality measure of the image. Since no assumption is made during the derivation, the proposed techniques could be used to compensate any form of the phase error. In addition, the influence of the multistatic configuration on the image resolution is analysed and an optimized configuration is obtained. The effectiveness of the proposed algorithms is verified via the theoretical derivations and simulations. 相似文献
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Stefan Hinz Franz Meyer Michael Eineder Richard Bamler 《Computer Vision and Image Understanding》2007,106(2-3):231
This paper reviews the theoretical background for upcoming dual-channel radar satellite missions to monitor traffic from space and exemplifies the potentials and limitations by real data. In general, objects that move during the illumination time of the radar will be imaged differently than stationary objects. If the assumptions incorporated in the focusing process of the synthetic aperture radar (SAR) principle are not met, a moving object will appear both displaced and blurred. To study the impact of these (and related) distortions in focused SAR images, the analytic relations between an arbitrarily moving point scatterer and its conjugate in the SAR image have been reviewed and adapted to dual-channel satellite specifications. Furthermore, a specific detection scheme is proposed that integrates complementary detection and velocity estimation algorithms with knowledge derived from external sources as, e.g., road databases. Results using real SAR data are presented to validate the theory. 相似文献
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弹载合成孔径雷达(SAR)的方位成像能力受飞行导弹的观测角影响,其末制导段采用前侧视工作方式。因此,必需合理设计制导律使前侧视条件成立。为了保证末制导段弹目间具有合适的夹角,采用变结构控制方法设计了一种固定前置角制导律,该制导律能够解决合成孔径雷达导引头对于前置角约束的问题。在制导律设计过程中,首先建立了弹目相对运动关系模型和具有终端角度约束时的视线角变化模型;在此基础上采用变结构控制的方法设计了固定前置角制导律;进而,对该固定前置角导引律进行了性能分析,得出了其一般攻击特性;最后,通过弹道仿真论证了其正确性与有效性。 相似文献