AMTI与SAR兼容系统的研究

本文通过对AMTI和SAR信号处理算法的分析,提出了一个完整的AMTI与SAR兼容的雷达体制处理模型,并对该体制的可行性进行了深入的理论论证。计算机模拟结果表明,该系统不仅具有对静止目标的良好成像能力,而且能成功地检测出强地杂波背景下的运动目标。     

The strip imaging of airborne squint sidelooking mode SAR

Airborne squint side-looking strip imaging mode SAR has the advantages of better flexibility and larger field in applications than the classic side-looking mode SAR. Because of the large range migration and serious range-azimuth coupling terms, the imaging processing of squint mode SAR is a full two-dimensional (2-D) phenomenon. In this paper, different algorithms, which can be used for the imaging processing of squint mode SAR, are compared with each other in terms of their focusing quality and their ability to handle the large range migration of the squint side-looking mode SAR. And their abilities of real-time imaging are also discussed. The algorithms contained here are 2-D FFT method, fast polynomial transform(FPT) method, and the direct correcting method based on range-Doppler focusing algorithms. Other new methods are also discussed here briefly.     

合成孔径雷达运动目标的检测和成像研究

运动目标的检测和成像是合成孔径雷达的难题之一，但又具有很强的实际意义，本文将ADPCA技术同MP法结合起来用于运动目标的检测和成像，其中将ADPCA技术用于运动目标的检测．MP法则解决了运动目标参数提取这一难点．计算机模拟的结果验证了该两算法的可行性，本文最后给出了可行的运动目标成像框图．     

车载X波段合成孔径雷达的数据采集及成像处理

叙述了车载X波段合成孔径雷达的试验情况,并对所采集的数据进行了成像处理。处理结果表明,其分辨率优于3m×2m。     

基于波束形成的分布式卫星SAR成像

针对分布式卫星SAR系统的正侧视工作模式，建立了雷达信号的回波模型，提出了利用修改的距离－多普勒（RD）算法进行单个星载SAR成像的算法及波束形成合成分布工卫星SAR图像的算法。理论分析和仿真结果表明：利用该算法能提高图像的信噪比，使图像质量得到提高。     

发射机固定的双站SAR对运动目标的成像

该文研究发射机固定的双站合成孔径雷达(双站SAR)的运动目标成像问题,应用WVD Radon变换来估计运动目标回波的多普勒参数,以此来调节成像和运动补偿处理参数,得到较好的运动目标成像效果。计箅机仿真结果证明该文推导的正确性。     

分布式卫星SAR的慢速目标检测与成像

基于分布式卫星SAR的正侧视工作模式,该文建立了分布式卫星SAR的回波模型,提出了通过杂波抑制进行慢速目标检测和成像的算法。理论分析和仿真结果表明;该方法能有效地抑制杂波,提高运动目标的动态检测范围。     

Statistical analysis of multi-look polarimetric SAR imagery

With a multiplicative speckle model, this paper shows the multi-look polarimetric synthetic aperture radar (SAR) data obeys a generalized K-distribution. To validate this distribution model, the multi-look intensity K-distribution is particularly tested. The relationship between the heterogeneity coefficient of the scene and the proper statistical model is experimentally established. In addition, based on the results of the statistical analysis, an adaptive classification scheme is presented, and the improved classification shows the importance of the statistical analysis.     

同步轨道星机双基地三通道SAR地面运动目标指示算法

基于分数阶傅里叶变换(FrFT)和多通道杂波抑制干涉技术,提出一种同步轨道星机双基地SAR地面慢速运动目标检测和参数估计方法。首先根据同步轨道星机双基地SAR的特点,给出该模式下杂波对消的DPCA条件;然后从系统空间几何模型和回波信号入手,详细推导了动目标聚焦成像、杂波抑制、动目标检测和参数估计的原理,最后通过计算机仿真,验证了该文算法的有效性。     

机载SAR有源干扰分析与比较

机载合成孔径雷达的干扰是当前电子对抗领域关注的焦点问题.在首先介绍了几种常用的SAR有源干扰方法的基础上,重点阐述了相干干扰的工作原理.然后,从压制系数出发,推算出了达到SAR压制系数条件下,不同干扰方式的功率表达式.结合仿真结果,对不同干扰方法的干扰性能进行了评估和比较.最后,针对各种干扰方法的性能优缺点,提出了综合运用多种方法对机载SAR进行有源干扰的作战策略.对机载SAR有源压制干扰的作战应用具备一定的指导意义.     

星载SAR系统设计与仿真

以星载SAR为应用背景,研制了星载SAR系统设计与仿真软件SARSIMS。SARSIMS可以完成不同波段SAR系统的总体参数设计、总体参数分析、回波仿真,条带、聚束和扫描成像模式的成像以及SAR系统的仿真。SAR系统设计的可视化是SARSIMS的主要特点,斑马图交互设计减少了设计难度和设计工作量,提高了设计效率,保证了SAR系统设计可以满足不同的要求。     

分布式卫星SAR的波束形成和多视处理成像

针对分布式卫星SAR的正侧视工作模式,该文建立了雷达信号的回波模型,提出了分布式卫星SAR中单个星载SAR的成像算法和利用波束形成和多视处理合成分布式卫星SAR图像的算法。理论分析和仿真结果表明:该算法能在不改变图像分辨力的情况下提高图像的信噪比和抑制相干斑,改善图像质量。     

SAR复图像域上的噪声抑制和目标特征提取

基于SAR图像的稀疏先验,提出了一种基于l_k范数的复图像域正则化方法,用于SAR复图像的噪声抑制和目标特征提取.文中通过算法设计及其收敛性的研究,保证了该方法的可行性和稳健性.同时,基于正则化方法与广义岭估计的契合之处,提出了一种新的正则化参数的选取方法.理论分析和实验结果均表明,本文方法可操作性强,具有有效的噪声抑制和目标特征稀疏表示寻优功能.     

Simulation of ship generated turbulent and vortical wake imaging by SAR

Synthetic Aperture Radar (SAR) imaging of ocean surface features is studied.The simulation of the turbulent and vortical features generated by a moving ship and SAR imaging of these wakes is carried out.The turbulent wake damping the ocean surface capillary waves may be partially responsible for the suppression of surface waves near the ship track.The vortex pair generating a change in the lateral flow field behind the ship may be partially responsible for an enhancement of the waves near the edges of the smooth area.These hydrodynamic phenomena as well as the changes of radar backscatter generated by turbulence and vortex are simulated.An SAR imaging model is then used on such ocean surface features to provide SAR images.Comparison of two ships‘simulated SAR images shows that the wake features are different for various ship parameters.     

SAR并行成像处理的研究

该文对SAR并行成像处理进行了深入研究,在串行成像算法的基础上,提出了SAR并行成像处理的一种粗粒度并行算法和一种混合FFT算法,并在国产曙光系列并行机上进行了实现,实验结果证实了该算法是有效的.     

基于因子分析法和图像对比度的穿墙雷达杂波抑制

在穿墙成像中,墙体反射波、天线耦合波等杂波常常将目标信号淹没,严重影响了目标的探测、定位等后续处理。为解决这一问题,该文采用因子分析法抑制杂波,并提出一种新的准则图像对比度,作为因子选择的衡量标准。为验证了这一方法的有效性,该文设计了暗室穿墙实验,分别对木板墙和混凝土墙后目标进行探测,并采用所提出的方法对得到的回波数据进行处理,实验结果表明,该方法能够在目标信息未知的条件下,得到最优的杂波抑制结果。     

Design and analysis of multi-mode cluster SAR

Cluster Synthetic Aperture Radar (SAR) system is composed of a group of spaceborne SAR systems. With its agility of combination, this system can work in several different modes. In this letter, the basic configuration and the working mode of the system are presented. The special performance of the system compared with the conventional SAR system is indicated.     

Impact of wide-band I/Q modulation errors in SAR imaging analysis and compensation method resaerch

Direct quadrature modulation technology is suitable for wide-band radar signal generation. However, this method has rigorous requirements on amplitude and phase balance of the orthogonal input signals. If the requirements are not satisfied, there would be modulation errors such as image frequency and oscillator leakage that cannot be filtered. The modulation errors will therefore raise the noise floor of the range profile and reduce the dynamic range of the Synthetic Aperture Radar (SAR) image as a whole. In this paper, the wide-band In-phase/Quadrature-phase (I/Q) modulation errors are modeling analyzed, and the influence of wide-band I/Q modulation errors on SAR imaging is discussed. Furthermore, a compensation method of modulation errors is proposed, and the circuit implementation of the radar signal generation and pre-distortion is presented. The experimental results illustrate that the curves of the I/Q amplitude and phase imbalance errors are successfully extracted and the rejection of image frequency improved significantly, thus meets the requirements of the SAR imaging.     

极化干涉SAR的研究现状与启示

阐述极化与干涉结合的基本考虑,介绍极化干涉SAR相干最优和相干目标分解的基本思想,总结分析极化干涉SAR技术、典型星载极化SAR系统研制和极化干涉SAR应用的研究现状,以得到开展极化干涉SAR技术研究的启示。     

高分辨率PLL频率合成器的关键指标分析

为了解决设计锁相环(PLL)频率合成器时关键指标相互矛盾的问题,以后置分频PLL频率合成器和前置倍频PLL频率合成器为例推导其频率分辨率、自然谐振频率、阻尼系数、环路捕捉时间、杂波抑制度等指标的数学表达式,研究了自然谐振频率和其他指标之间的联系,分析了频率分辨率与环路捕捉时间、杂波抑制度之间的矛盾.理论分析和仿真结果表明:相对于基本形式的PLL频率合成器,后置分频PLL频率合成器和前置倍频PLL频率合成器的频率分辨率得到同倍的提高,但后者的环路杂波抑制度和捕捉时间指标均随频率分辨率的提高而恶化,从而证明后置分频PLL频率合成器设计的有效性.这些结论可以作为设计PLL频率合成嚣的参考准则.