针对雷达LPI波形验证的目标RCS估算

根据某型雷达低截获概率波形设计的需要,分析了雷达探测目标的高频散射机理,并运用物理光学法、等效电磁流法计算了约定目标在不同姿态下和不同电磁波频率照射下的RCS值,从而为验证雷达波形在能探测到目标情况下的LPI性能提供了支撑。实验结果表明,基于电磁场理论的目标RCS估算方法是研究雷达LPI波形的一种有效工具,方法也适合于其他领域RCS估算的需要。     

一种基于稀疏分解的微多普勒频率估计算法

目标微动特性和微多普勒特征分析在真假目标识别方面发挥了重要作用。由于微动目标雷达同波具有非线性、多分量性等特征,需要相应的具有高分辨力、低交叉项、大的动态范围的分析工具,才能较好地揭示目标微多普勒特征。稀疏分解方法中的匹配追踪（MP）具有频域高分辨能力,对于信号细微特征提取具有很好的效果。研究了基于匹配追踪的微多普勒频率估计问题,该方法可以准确提取出目标微多普勒频率,为后续的目标识别提供了重要的依据。-     

ADS-B用于高精度雷达标定的方法

为了更好地解决高精度雷达标定的问题,提出了基于广播式自动相关监视系统(ADS-B)固定误差及目标回波中心动态修正的雷达标定新方法。首先分析了ADS-B位置数据误差的来源、类型及在雷达坐标系下的特征,同时对民航目标回波中心的变化作了分析建模,在此基础上进一步通过对雷达数据与ADS-B数据之差作动态联合修正,最终估算出雷达系统误差,提高了雷达系统误差标定的精度和稳定性。并利用多批次的实测数据对该标定新方法与其他方法进行了对比验证,结果表明,该方法有效提高了标定的精度和稳定性,并已成功应用于雷达标定设备中。     

雷达和红外成像双传感器信息融合目标识别研究

提出了一种利用目标的雷达和红外成像２种独立的传感器信息的互补性来构造特征向量的信息融合方法——联合向量空间法,并用对应的自适应信息融合系统进行目标识别。仿真证实比用单传感器的效果明显优越,从而说明了本文方法的有效性。     

基于多级模糊综合评判的雷达网目标识别技术

由于目前的战场环境非常复杂,目标识别具有重要意义。有关雷达的基于模糊综合评判的目标识别技术目前研究比较多,通过类似的方法可以进一步进行雷达网的目标识别,即采取两个单级模糊综合评判方法进行雷达网的目标识别,但这种方法具有一定的弱点,文中根据雷达网探测目标的特点,提出了一种基于多级模糊综合评判的雷达网目标识别方法。对这种方法与雷达网基于两个单级模糊综合评判进行目标识别的方法进行了仿真比较,结果表明前者较之后者具有计算量小、识别精确、便于工程应用的特点。     

基于S变换的时频特征提取与目标识别

目标的时间-频率联合分布能够很好地反映目标物理结构特征,可以作为雷达目标识别的一个有效手段。针对现有时频分析方法存在的识别率低和抗噪性能差等问题,提出一种基于S变换的空间目标回波信号电磁特征提取与识别方法。首先对目标的雷达回波进行时频分析,得出在较大方位角变化范围内和不同信噪比情况下,目标S变换的时频分布具有相对不变性的结论;然后基于这种稳定的时频分布特征,采用最小贴近度的方法进行分类识别。针对不同目标模型的仿真结果表明,该方法的识别率高于其他时频分析方法并且具有很好的鲁棒性。     

直觉模糊熵在雷达目标识别中的应用

直觉模糊熵是不确定性推理领域中一个重要概念.针对雷达目标识别系统的复杂性,介绍了直觉模糊集的基本概念,分析了满足直觉模糊集熵的性质,提出了一种基于直觉模糊熵的雷达目标识别结果的检验方法.实验结果表明了该方法具有灵活性、合理性和可信性.     

一种FMCW SAR地面运动目标谱图域参数估计方法

对调频连续波(FMCW)合成孔径雷达(SAR)地面运动目标的参数估计方法进行了研究,采用相位中心偏置天线(DPCA)技术对地杂波进行抑制,分析了载机及地面运动目标连续运动对回波信号的影响,推导了采用DPCA技术引入的回波慢时间包络(STE)项与地面运动目标参数之间的关系。在此基础上,提出了一种地面运动目标谱图域参数估计方法,该方法首先利用Radon变换在谱图域估计导致回波信号距离走动的目标等效径向速度,并对距离走动进行校正;其次,在谱图域中提取运动目标回波幅度,根据STE项引起的回波幅度变化与目标方位向速度之间的关系,估计目标的方位向速度,并进一步求解相应的目标径向速度。所提方法能够在谱图域完成地面运动目标二维速度估计,最后的仿真实验验证了所提方法的有效性和可行性。     

Target Detection and Parameter Estimation for MIMO Radar Systems

We investigate several target detection and parameter estimation techniques for a multiple-input multiple-output (MIMO) radar system. By transmitting independent waveforms via different antennas, the echoes due to targets at different locations are linearly independent of each other, which allows the direct application of many data-dependent beamforming techniques to achieve high resolution and excellent interference rejection capability. In the absence of array steering vector errors, we discuss the application of several existing data-dependent beamforming algorithms including Capon, APES (amplitude and phase estimation) and CAPES (combined Capon and APES), and then propose an alternative estimation procedure, referred to as the combined Capon and approximate maximum likelihood (CAML) method. Via several numerical examples, we show that the proposed CAML method can provide excellent estimation accuracy of both target locations and target amplitudes. In the presence of array steering vector errors, we apply the robust Capon beamformer (RCB) and doubly constrained robust Capon beamformer (DCRCB) approaches to the MIMO radar system to achieve accurate parameter estimation and superior interference and jamming suppression performance.     

Hardware-in-the-loop simulation technology of wide-band radar targets based on scattering center model

Hardware-in-the-loop(HWIL) simulation technology can verify and evaluate the radar by simulating the radio frequency environment in an anechoic chamber. The HWIL simulation technology of wide-band radar targets can accurately generate wide-band radar target echo which stands for the radar target scattering characteristics and pulse modulation of radar transmitting signal. This paper analyzes the wide-band radar target scattering properties first. Since the responses of target are composed of many separate scattering centers, the target scattering characteristic is restructured by scattering centers model. Based on the scattering centers model of wide-band radar target, the wide-band radar target echo modeling and the simulation method are discussed. The wide-band radar target echo is reconstructed in real-time by convoluting the transmitting signal to the target scattering parameters. Using the digital radio frequency memory(DRFM) system,the HWIL simulation of wide-band radar target echo with high accuracy can be actualized. A typical wide-band radar target simulation is taken to demonstrate the preferable simulation effect of the reconstruction method of wide-band radar target echo. Finally, the radar target time-domain echo and high-resolution range profile(HRRP) are given. The results show that the HWIL simulation gives a high-resolution range distribution of wide-band radar target scattering centers.     

弹道中段目标质心位置估计

 质心在目标上的位置是弹道中段目标的重要进动特征,也是目标的质量分布特征,可用于识别弹头和诱饵.针对旋转对称目标,提出了基于窄带雷达回波相位特性的质心位置估计方法.首先,选取目标对称轴上的任意点作为质心位置参考点,定义相应的质心位置参数,并构造以该点为相位参考中心的全姿态散射系数模板;然后,对窄带雷达回波采样序列进行相位匹配变换,搜索匹配函数的最大值,从而得到质心位置参数的估计值.仿真结果表明了该方法的有效性.     

Bayesian and Dempster-Shafer target identification for radarsurveillance

This paper considers the problem of target track identification in a radar surveillance system. To build a target identifier alongside a tracker, four features which are available for real-time processing in an air surveillance system are used here: target identity (TID) from a friend-and-foe identification (IFF) system, elevation measurement from the radar, target speed, and acceleration estimated by a tracker. These four features are combined to classify air targets into five different air target categories: friendly commercial, friendly military, hostile commercial (or unknown airline), hostile military, and false targets (clutter). Two popular statistic-based techniques, namely, the Bayesian and Dempster-Shafer methods, are applied to develop radar target identification algorithms for our application. Real-life as well as simulated air surveillance radar data are used to evaluate the practicality and effectiveness of this track identification approach in a radar surveillance system     

基于Keystone变换和MDCFT的高机动弱目标检测与参数估计

 常规雷达对隐身、超声速和高机动目标存在回波信噪比不足、距离徙动和多普勒谱扩展问题。将Keystone变换和修正离散Chirp-Fourier变换(MDCFT)相结合,提出了一种新的雷达信号处理算法。该算法通过Keystone变换补偿距离徙动问题,利用MDCFT对多普勒谱严重扩展的目标回波进行相参积累,提高目标检测性能的同时完成了对目标参数的估计,且该算法在方位向欠采样时仍可适用。最后对算法运算量及性能进行了分析,通过仿真验证了该算法的有效性。     

A New Method for Analyzing Integrated Stealth Ability of Penetration Aircraft

Taking into account the limitations of existing stealth performance analysis methods, a method termed as the integrated stealth performance analysis method is proposed for evaluating the stealth ability of the penetration aircraft. Based on various target radar cross section (RCS) scattering characters, this article integrates the relevant parameters needed for building up target circumferential RCS scattering model and proposes the RCS scattering controlling parameters to control the changing trends of the relevant model RCS scattering characters. According to the radar dynamic detecting characters during the whole penetration course, a dynamic stealth performance evaluating model is proposed accompanied by a series of stealth ability estimation rules. This new analysis method can enhance the integrality and dependability of the stealth analysis conclusions and summarize the relationship between the target RCS scattering characters and their effects on stealth performance. The rules indicated by this relationship can be used as the reference for designing new type of stealth aircraft and setting up specific penetration tactics.     

Angle/Doppler estimation in heavy-tailed clutter backgrounds

This work describes new methods on the modeling of the amplitude statistics of airborne radar clutter by means of alpha-stable distributions. We develop joint target angle and Doppler, maximum likelihood-based estimation techniques from radar measurements retrieved in the presence of impulsive uncorrelated noise modeled as an alpha-stable random process. We derive the Cramer-Rao bounds (CRBs) for the additive Cauchy interference scenario to assess the best case estimation accuracy which can be achieved. In addition, we introduce a new joint spatial- and Doppler-frequency high-resolution estimation technique based on the fractional lower order statistics of the measurements of a radar array. Simulation results demonstrate that the proposed methods can be of interest in the study of space-time adaptive processing (STAP) for airborne pulse Doppler radar arrays operating in impulsive interference environments     

High Range Resolution Profiles as Motion-Invariant Features for Moving Ground Targets Identification in SAR-Based Automatic Target Recognition

A quantitative model analysis is presented to justify the extraction of high range resolution (HRR) profiles from synthetic aperture radar (SAR) images as motion-invariant features for identifying moving ground targets. A comparative study is conducted to assess the effectiveness in the identification process between using HRR profiles and SAR images as target signatures. The results indicate that HRR profiles are just as viable as SAR image for identification. Furthermore, a score-level multi-look fusion identification method has been investigated. It is found that a correct accurate identification rate of greater than 99 percent, a low false alarm rate, and a high level of identification confidence can be achieved, providing very robust performance.     

Pulse Doppler signature of a rotary-wing aircraft

Field measurements of a modified Sikorsky S-55 helicopter target were carried out to investigate rotary-wing aircraft Doppler radar signature phenomenology. The results of the data analysis with regard to classification and identification of the aircraft based on its signature are presented. It was found that using the Doppler radar return and appropriate feature extraction techniques, the helicopter's design features can be estimated. Target backscatter from the main rotor blades, tail rotor blades, or hub can be used for target detection, acquisition, and classification as a rotary-wing aircraft. The extraction of configuration and blade count features can further define the helicopter for identification     

Maximum likelihood identification of glint noise

If the non-Gaussian distribution function of radar glint noise is known, the Masreliez filter can be applied to improve target tracking performance. We investigate the glint identification problem using the maximum likelihood (ML) method. Two models for the glint distribution are used, a mixture of two Gaussian distributions and a mixture of a Gaussian and a Laplacian distribution. An efficient initial estimate method based on the QQ-plot is also proposed. Simulations show that the ML estimates converge to truths     

FDEKF在反辐射无人机抗目标雷达关机中的应用

基于捷联惯导/反辐射导引头组合抗目标雷达关机制导方案,研究了有限差分卡尔曼滤波(FDEKF)方法在对目标雷达被动定位中的应用。考虑反辐射导引头测角存在非线性特性,提出了一种基于扩展状态变量维数的方法实现了目标状态估计和导引头非线性特性补偿。仿真结果表明,FDEKF是一种具有良好性能的非线性滤波方法,可以代替传统的EKF解决反辐射无人机对目标雷达的被动定位问题。     

联合截获威胁下的雷达射频隐身目标搜索算法

针对基于射频(RF)隐身需求的机载雷达目标搜索问题进行了研究。通过分析实际作战中射频辐射面临的截获威胁,提出了一种基于联合截获威胁的射频隐身性能表征方法,并给出了具体的值估算方法;对机载雷达搜索任务中辐射参数的优化问题进行了建模,并采用优化算法对目标函数进行求解。通过分析典型情景下解集的分布特点,给出了从最优解集中选取最终解的方法。结果表明,提出的射频隐身性能表征方法能更好地反映截获实现过程的多域需求,提出的雷达搜索方法能够在保证探测性能的同时,提高射频隐身性能和搜索速度,能够为相控阵雷达搜索任务中参数的优化控制提供方法和依据。