基于自适应脉冲压缩-Capon滤波器的MIMO阵列雷达CFAR检测器

针对强杂波背景和有限训练样本数量条件下采用脉内编码压缩波形的MIMO阵列雷达目标检测问题,借鉴自适应波束形成技术中Capon最小功率估计器的相干源信号对消思想,提出了自适应脉冲压缩—Capon滤波器(简记为APC-Capon滤波器),并基于此滤波器的输出设计了一种CFAR检测器.理论分析和数值仿真均表明,该滤波器能够在执行非迭代自适应脉冲压缩并抑制各发射波形自相关距离旁瓣和互相关干扰的同时,实现杂波信号对消,即杂波抑制功能.检测性能仿真表明,尽管相同尺寸参数(包括发射阵元数、接收阵元数、脉冲编码位数、相参脉冲个数)条件下,所设计的基于APC-Capon滤波技术的CFAR检测器的性能不如训练样本数量充足时基于匹配滤波+样本矩阵求逆(SMI)技术的AMF检测器,但是随着尺寸参数的适当增大,前者的检测性能将逐渐超过后者在较小尺寸参数时的检测性能,且不显著增加计算复杂度和训练样本数量,而后者则因大尺寸参数时对计算复杂度和训练样本数量的需求过高而在实际中难以实现.仿真还表明,APC-Capon滤波器及其相应的CFAR检测器对发射波形的相关性(包括自相关性能和互相关性能)有一定的依赖性,但随着发射波形数量的增加,这种依赖...     

A CFAR detector for MIMO array radar based on adaptive pulse compression-Capon filter

Under the condition of strong clutter and finite training samples,a novel CFAR detector based on the proposed adaptive pulse compression-Capon filter (APC-Capon filter) is presented for MIMO array radar which transmits intrapulse coded waveforms.Both theoretical analysis and numerical simulations show that the proposed APC-Capon filter can utilize the non-reiterative adaptive pulse compression technique to alleviate both range sidelobes and mutual interference;at the same time it also can borrows ideas from the coherent signals cancellation of adaptive beamforming to perform clutter suppression.The detection performance simulations show that,with the same size parameters (including code length and the numbers of transmitter elements,receiver elements as well as pulses),the proposed CFAR detector is inferior to the adaptive matched filter (AMF) detector.But as the size parameters increase,the proposed CFAR detector will gradually outperform the AMF detector with smaller size parameters,and more importantly,unlike the AMF detector which has a lot of difficulties in performing due to the inordinate demands for the computational complexity and training sample size,this demands of the proposed CFAR detector will not significantly increase.The simulations also show that,the correlation properties of these intrapulse coded waveforms have certain effect on the APC-Capon filter and its corresponding CFAR detector.But fortunately,the effect will decrease as the number of intrapulse coded waveforms increases.     

基于CFAR和摆角自修正多目标交通雷达算法优化

基于FSK体制多目标交通雷达进行了多目标检测算法的相关研究与优化。多目标检测时,采用恒虚警检测方法设置自适应检测门限进行处理。同时,对于由雷达安装摆角引起的系统抓拍性能下降问题,采用基于样本统计特性的雷达摆角自修正算法,提高了目标检测率以及场景适应性。实际道路测试表明,多车道、多目标的有效抓拍率达到95%,具有很好的多目标监测效果。对于多目标交通雷达推广应用具有很大的现实意义。     

A real-time CFAR thresholding method for target detection in hyperspectral images

In order to support immediate decision-making in critical circumstances such as military reconnaissance and disaster rescue, real-time onboard implementation of target detection is greatly desired. In this paper, a real-time thresholding method (RT-THRES) is proposed to obtain the constant false alarm rate (CFAR) thresholds for target detection in real-time circumstances. RT-THRES utilizes Gaussian mixture model (GMM) to track and fit the distribution of the target detector’s outputs. GMM is an extension to Gaussian probability density function, which could approximate any distribution smoothly. In this method, GMM is utilized to model the detector’s output, and then the detection threshold is calculated to achieve a CFAR detection. The conventional GMM’s parameter estimation by Expectation-Maximization (EM) requires all data samples in the dataset to be involved during the procedure and the the parameters would be re-estimated when new data samples available. Thus, GMM is difficult to be applied in real-time processing when newly observed data samples coming progressively. To improve GMM’s application availability in time-critical circumstance, an optimization strategy is proposed by introducing the Incremental GMM (IGMM) which allows GMM’s parameter to be estimated online incrementally. Experiments on real hyperspectral image and synthetic dataset suggest that RT-THRES can track and model the detection outputs’ distribution accurately which ensures the accuracy of the calculation of CFAR thresholds. Moreover, by applying the optimization strategy the computational consumption of RT-THRES maintains relatively low.

     

基于FPGA的雷达恒虚警模块的设计

恒虚警处理技术可以使雷达在保持较高发现概率的同时,降低虚警概率。为了提高机载雷达在杂波与噪声背景条件下发现目标的能力,针对复杂统计模型应用的局限性,提出了一种基于FPGA的恒虚警模块的设计思想,并在软件平台环境下,对设计方法的可行性进行了仿真验证。     

雷达故障测试路径动态优化方法研究与实现

为了优化自动测试流程以及将故障诊断算法动态插入到雷达故障诊断循环中,提出了一种新的测试软件框架.该软件框架将雷达故障状态测试流程与故障诊断算法流程分离,使得测试流程与算法流程可以成为计算机中不同的线程或进程.基于该软件框架,定义了一种测试流程优化目标函数.利用此函数,讨论了一种基于预定义测试流程的动态优化方法.实现了在测试人员自主修改测试路径后,默认测试流程自动优化.     

一种新型雷达探测器在远程无线监控系统中的应用

以TWH9250A微波雷达探测模块为核心器件,作物体移动探测传感头,采用TWH9236/TWH9638系列无线电发射与接收模块遥控操作,选取普通手机作为远程无线通讯工具,配以外围电路实现了现场监控区域全方位、无死角远程无线监控,同时具有现场防盗报警、现场人员求救、解警等功能。设计采用的器件,性价比高,功能完善。经测试,该系统探测灵敏度高,工作稳定性好,可应用于厂矿、银行、商店、仓库、实验室、家庭等局部重地的防盗报警、远程无线监控领域。     

A new matrix test for randomness

Let ${{\mathcal S}}$ be one of the two multiplicative semigroups: M × M Boolean matrices, or the semigroup of M × M matrices over the field GF(2). Then for any matrix ${A\in {\mathcal S}}$ there exist two unique smallest numbers, namely the index and period k, d, such that A ^k  = A ^k+d . This fact allows us to form a new statistical test for randomness which we call the Semigroup Matrix Test. In this paper, we present details and results of our experiments for this test. We use Boolean matrices for M = 2, . . . , 5, and matrices over GF(2) of the size M = 2, . . . , 6. We also compare the results with the results obtained by the well-known Binary Matrix Rank Test.     

A new maximum likelihood polarimetric interferometric synthetic aperture radar coherence change detection (ML-PolInSAR-CCD)

Coherent change detection (CCD) use the sample degree of coherence as a measure of the temporal change collected between two complex-valued SAR images observed in the same area and using also the same geometry and polarization. The problem of classical CCD approaches shows a temporal change only when there are in areas of the image that have high clutter-to-noise power ratio. All experiments regarding the maximum-likelihood (ML) CCD, found to estimate useful information also in lower clutter-to-noise power ratio. Experiments used only electromagnetic transmissions in the same polarization. This work extends the formulation of the probability distribution function of the CCD in a multi-dimensional version useful for multi-polarization SAR data. Results of this ML-polarimetric interferometric SAR-CCD (ML-PolInSAR-CCD) show surprising recovery of both amplitude and phase CCD information. This information recovery is useful for improved interferometric SAR (InSAR), permanent scatterers interferometry (PS-InSAR) and SAR tomography applications.     

雷达模拟器中海杂波模拟的一种新方法

海杂波的建模方法已趋于成熟,而如何在光栅显示器上快速逼真地模拟海杂波是当前模拟器面临的一个重要问题。在成熟的海杂波模型基础上,用ZMNL快速模拟杂波序列,并通过距离和近程增益调制可快速逼真地模拟海杂波。     

Reduced-rank space-time adaptive detection for airborne radar

For airborne radar,there are usually insufficient independent and identically distributed(IID)training data because of geometric considerations and terrain variations.The rank reduction technique is one of the most effective approaches to circumvent this problem.In this study,we investigate four reduced-rank spacetime adaptive detectors for airborne radar,namely,the reduced-rank sample-matrix-inversion(RR-SMI),the reduced-rank adaptive matched filter(RR-AMF),the reduced-rank adaptive coherence estimator(RR-ACE),and the reduced-rank generalized likelihood ratio test(RR-GLRT).Their asymptotic analytical probabilities of detection(PD’s)and false alarm(PFA’s)are all derived.These detectors all asymptotically attain a constant false alarm rate(CFAR).It is shown that these four reduced-rank detectors exhibit detection performance which is better than or comparable to that of two existing reduced-rank detectors,proposed by Reed and Gau(RG1and RG2).Moreover,these four reduced-rank detectors are more robust to change in power of clutter and noise than RG1 and RG2.     

一种新的雷达辐射源信号识别方法

为了提高神经网络对分布复杂的雷达信号类型的识别率,提出一种结合小波变换、互信息特征选择及神经网络的分类新方法。首先利用小波变换对信号进行特征提取,然后通过基于互信息的特征选择来对特征进行选择,最后把选择出的特征作为神经网络的训练样本对其进行辐射源类型的识别。仿真结果显示,该方法能够利用较少的特征值得到较高的识别正确率。     

A new proximity test for polynomial zeros

We combine some known techniques and results of Turan and Schönhage to improve substantially numerical performance of the computation of the minimum and the maximum distances from a fixed complex point to roots (zeros) of a fixed univariate polynomial.     

一种提高脉冲雷达接收机干扰抑制力的新方法

针对短波脉冲雷达接收机高灵敏度和高信噪比的性能要求,在射频前端设计了一个提高接收机干扰抑制力的预选滤波器,给出了基于电调谐变容二极管的二级LC串联谐振实现滤波的设计方案,详细阐述了设计原理及方法,讨论了变容二极管温漂对滤波器特性的影响,提出一种滤波器自校解决温漂的新方法.测试结果表明,该滤波器系统实现了频率跟踪,可工作在1 MHz～30 MHz,插入损耗小于2.3 dB,对带外干扰抑制能力可达29 dB,提高了接收机灵敏度及信噪比,在电离层扰动探测中得到了很好的应用.     

雷达微弱目标检测的有效方法

针对低信噪比条件下微弱运动目标检测问题,提出了一种基于检测前跟踪的动态规划改进算法,根据雷达图像中包含的来袭目标运动参数信息,预测来袭目标的运动轨迹,并沿着预测运动轨迹积累能量.仿真结果表明,该算法能够较准确地估计目标航迹,计算量较小,在强杂波背景下能较好地检测出低信噪比运动目标,对于威胁预警区域较大的来袭目标能更好进行实时探测.     

一种新的跳频信号检测算法

本文提出了一种基于功率谱估计的跳频信号检测的新方法,该方法主要是利用定频信号、跳频信号的功率谱随时间变化的差异性,通过对定频信号功率谱进行对消以实现跳频信号的检测,分析了影响定频信号功率谱对消的因素,计算机仿真结果证实了该方法的有效性。     

A new method for fetal ECG detection

Presented in this work is the theoretical basis of a new method we propose for the analysis of fetal ECG (FECG). This method is intended to detect the fetal HR from a weak FECG signal, and to supply us with an average FECG complex. The FECG signals studied in this work were recorded from the maternal abdominal wall. The core of our method is the computation of a triple parametric transform, using analyzing functions which have a greater correlation with the ECG signal than the correlation of the standard sine and cosine functions used in a Fourier transform. The functions used are trains of square waves characterized by the width of the square wave, their periodicity, and some initial phase value. This method, applied here to a medical problem, can be more generally applied to handle weak quasiperiodic sharp signals of any origin.     

A new stability test for nonlinear nonautonomous systems

We consider a class of nonlinear nonautonomous systems, whose linear parts are slowly varying matrices. Stability conditions and estimates for the region of attraction of the zero solution are derived. These conditions are formulated in terms of the determinants of the variable matrices.