Research on PCA and KPCA Self-Fusion Based MSTAR SAR Automatic Target Recognition Algorithm

This paper proposes a PCA and KPCA self-fusion based MSTAR SAR automatic target recognition algorithm. This algorithm combines the linear feature extracted from principal component analysis （PCA） and nonlinear feature extracted from kernel principal component analysis （KPCA） respectively, and then utilizes the adaptive feature fusion algorithm which is based on the weighted maximum margin criterion （WMMC） to fuse the features in order to achieve better performance. The linear regression classifier is used in the experiments. The experimental results indicate that the proposed self-fusion algorithm achieves higher recognition rate compared with the traditional PCA and KPCA feature fusion algorithms.

New statistical model for radar HRRP target recognition

The mixture of factor analyzers （MFA） can accurately describe high resolution range profile （HRRP） statistical charac- teristics. But how to determine the proper number of the models is a problem. This paper develops a variational Bayesian mixture of factor analyzers （VBMFA） model. This procedure can obtain a lower bound on the Bayesian integral using the Jensen＇s inequality. An analytical solution of the Bayesian integral could be obtained by a hypothesis that latent variables in the model are indepen- dent. During computing the parameters of the model, birth-death moves are utilized to determine the optimal number of model au- tomatically. Experimental results for measured data show that the VBMFA method has better recognition performance than FA and MFA method.

Radar automatic target recognition based on feature extraction for complex HRRP

Radar high-resolution range profile （HRRP） has received intensive attention from the radar automatic target recognition （RATR） community. Usually, since the initial phase of a complex HRRP is strongly sensitive to target position variation, which is referred to as the initial phase sensitivity in this paper, only the amplitude information in the complex HRRP, called the real HRRP in this paper, is used for RATR, whereas the phase information is discarded. However, the remaining phase information except for initial phases in the complex HRRP also contains valuable target discriminant information. This paper proposes a novel feature extraction method for the complex HRRP. The extracted complex feature vector, referred to as the complex feature vector with difference phases, contains the difference phase information between range cells but no initial phase information in the complex HRRR According to the scattering center model, the physical mechanism of the proposed complex feature vector is similar to that of the real HRRP, except for reserving some phase information independent of the initial phase in the complex HRRP. The recognition algorithms, frame-template establishment methods and preprocessing methods used in the real HRRP-based RATR can also be applied to the proposed complex feature vector-based RATR. Moreover, the components in the complex feature vector with difference phases approximate to follow Gaussian distribution, which make it simple to perform the statistical recognition by such complex feature vector. The recognition experiments based on measured data show that the proposed complex feature vector can obtain better recognition performance than the real HRRP if only the cell interval parameters are properly selected.

A feature extraction method for synthetic aperture radar(SAR) automatic target recognition based on maximum interclass distance

Synthetic aperture radar(SAR) automatic target recognition is an important application in SAR.How to extract features has restricted the application of SAR technology seriously.In this paper,a new feature extraction method for SAR automatic target recognition based on maximum interclass distance is proposed,which integrates class and neighborhood information.This method can reinforce discriminative power using maximum interclass distance,so it can improve recognition rate effectively.

THE INFLUENCE OF SPECKLE ON HIGH RESOLUTION RANGE PROFILE RECOGNITION BASED ON THE MATCHING SCORE

Template database is the key to radar automation target recognition based on High Resolution Range Profile (HRRP). From the traditional perspective, average HRRP is a valid template for it can represent each HRRP without scatterer Moving Through Range Cell (MTRC). However, template database based on this assumption is always challenged by measured data. One reason is that speckle happens in the frame without scatterer MTRC. Speckle makes HRRP fluctuate sharply and not match well with the average HRRP. We precisely introduce the formation mechanism of speckle. Then, we make an insight into the principle of matching score. Based on the conclusion, we study the properties of matching score between speckled HRRP and the average HRRP. The theoretical analysis and Monte Carlo experimental results demonstrate that speckle makes HRRP not to match well with the average HRRP according to the energy ratio of speckled scatterers. On the assumption of ideal scattering centre model, speckled HRRP has a matching score less than 85% with the average HRRP if speckled scatterers occupy more than 50% energy of the target.

A new feature extraction method using the amplitude fluctuation property of target HRRP for radar automatic target recognition

Due to the aspect sensitivity of high-resolution range profile(HRRP),traditional radar HRRP target recognition methods usually use average profile within some target-aspect region as the target-aspect template.Actually,the amplitude fluctuation property of target HRRP also represents some feature information of the target.Based on the scattering center model,a new feature extraction method using the amplitude fluctuation property of target HRRP is proposed in this paper.The weighted HRRP feature extracted by the new method can represent the scatterer distribution in every range cell,thereby it can describe the scattering property of the target better.The experimental results based on measured data show that the new feature extraction method can greatly improve recognition performances.

基于语义引导层次化分类的雷达地面目标HRRP识别方法

高分辨距离像(HRRP)反映了目标空间散射结构在雷达视线方向的投影,近年来被认为是地面目标识别的重要途径。现有的HRRP识别方法采用手工特征加传统机器学习分类器,均属于平面分类方法,即采用统一标准不加区别的优选特征并单次决策最终类别。然而该方法在实际应用中面临种类繁杂、数据不平衡、HRRP姿态敏感性等诸多问题,难以获取最佳的应用效果。层次化方法采取分而治之思想,将一个复杂的细粒度识别任务拆解为多个简单的识别子任务。本文采用层次化识别的思路,提出了一种基于语义引导层次化分类的雷达地面目标识别方法。该方法以联合语义和数据构建的树形结构将一个复杂的细粒度识别任务拆解为多个简单的识别子任务,并针对每一个识别子任务匹配一套优选特征集和一个局部分类器。本方法在仿真数据和实测数据上完成了验证。实验结果表明了本文方法处理地面目标识别任务的有效性。

Radar HRRP statistical recognition with temporal factor analysis by automatic Bayesian Ying-Yang harmony learning

Radar high-resolution range profiles(HRRPs)are typical high-dimensional and interdimension dependently distributed data,the statistical modeling of which is a challenging task for HRRP-based target recognition.Supposing that HRRP samples are independent and jointly Gaussian distributed,a recent work[Du L,Liu H W,Bao Z.IEEE Transactions on Signal Processing,2008,56(5):1931–1944]applied factor analysis(FA)to model HRRP data with a two-phase approach for model selection,which achieved satisfactory recognition performance.The theoretical analysis and experimental results reveal that there exists high temporal correlation among adjacent HRRPs.This paper is thus motivated to model the spatial and temporal structure of HRRP data simultaneously by employing temporal factor analysis(TFA)model.For a limited size of high-dimensional HRRP data,the two-phase approach for parameter learning and model selection suffers from intensive computation burden and deteriorated evaluation.To tackle these problems,this work adopts the Bayesian Ying-Yang(BYY)harmony learning that has automatic model selection ability during parameter learning.Experimental results show stepwise improved recognition and rejection performances from the twophase learning based FA,to the two-phase learning based TFA and to the BYY harmony learning based TFA with automatic model selection.In addition,adding many extra free parameters to the classic FA model and thus becoming even worse in identifiability,the model of a general linear dynamical system is even inferior to the classic FA model.

空中目标动态电磁散射数据仿真系统设计与实现

电磁散射数据是目标识别研究的基础,但由于试验测量成本高、可重复性差等问题,空中目标电磁散射实测数据十分有限。基于去遮挡的N点模型和电磁计算数据插值研究了空中目标动态电磁散射数据仿真方法,设计了空中目标动态电磁数据仿真系统,该系统将电磁散射仿真与实际飞行场景相结合,支持场景自定义和空中目标三维模型库扩展。分析了飞机和巡航导弹2类目标仿真数据及成像结果,结果验证了仿真方法正确性和系统有效性,可为研究实际场景下的空中目标识别提供支撑。

一种联合EMD-RST的HRRP-RATR

针对高分辨雷达目标信号非平稳特性,提出了一种基于经验模态分解(Empirical mode decomposition,EMD)特征提取技术的雷达目标高分辨一维距离像自动目标识别(HRRP-ATR)方法。该方法首先利用EMD将雷达目标HRRP分解为多个平稳的内禀分量(Intrinsic mode function,IMF),分别采用AR模型、奇异值分解、能量分布进行特征提取。为缩减特征维数,引入粗糙集理论(RST)进行属性约简、规则提取以及分类,并同基于支持向量机(SVM)的分类方法进行比较,得到一些有价值的结论。

A WEIGHTED FEATURE REDUCTION METHOD FOR POWER SPECTRA OF RADAR HRRPS

Feature reduction is a key process in pattern recognition. This paper deals with the feature reduction methods for a time-shift invariant feature, power spectrum, in Radar Automatic Target Recognition (RATR) using High-Resolution Range Profiles (HRRPs). Several existing feature reduction methods in pattern recognition are analyzed, and a weighted feature reduction method based on Fisher's Discriminant Ratio (FDR) is proposed in this paper. According to the characteristics of radar HRRP target recognition, this proposed method searches the optimal weight vector for power spectra of HRRPs by means of an iterative algorithm, and thus reduces feature dimensionality. Compared with the method of using raw power spectra and some existing feature reduction methods, the weighted feature reduction method can not only reduce feature dimensionality, but also improve recognition performance with low computation complexity. In the recognition experiments based on measured data, the proposed method is robust to different test data and achieves good recognition results.

Feature Extraction of Radar Range Profiles Based on Normalized Central Moments

The normalized central moments are widely used in pattern recognition because of scale and translation invariance. The moduli of normalized central moments of the 1-dimensional complex range profiles are used here as feature vector for radar target recognition. The common feature extraction method for high resolution range profile obtained by using Fourier-modified direct Mellin transform is inefficient and unsatisfactory in recognition rate And. generally speaking, the automatic target recognition method based on inverse synthetic aperture radar 2-dimensional imaging is not competent for real time object identification task because it needs complicated motion compensation which is sometimes too difficult to carry out. While the method applied here is competent for real-time recognition because of its computational efficiency. The result of processing experimental data indicates that this method is good at recognition.

DE-JSMA:面向SAR-ATR模型的稀疏对抗攻击算法

DNN易受攻击的特点使得以智能算法为识别手段的SAR-ATR系统也存在一定脆弱性。为验证其脆弱性,结合SAR图像特征稀疏的特点,在显著图对抗攻击算法和差分进化算法基础上提出了DE-JSMA稀疏攻击算法,精确筛选出对模型推理结果影响较大的显著特征后,为显著特征优化出合适的特征值。为了更全面地验证攻击的有效性,构建了一种结合攻击成功率和对抗样本平均置信度的新指标Fc值。实验结果表明,在没有增加过多耗时,且保证高攻击成功率情况下,DE-JSMA将只能定向攻击的JSMA扩展到了非定向攻击场景,且在2种攻击场景下均实现了可靠性更高、稀疏性更优的稀疏对抗攻击,仅扰动0.31%与0.85%的像素即可达到100%与78.79%以上的非定向与定向攻击成功率。

基于注意力机制的SRU模型雷达HRRP目标识别

针对传统目标识别方法难以提取雷达高分辨距离像(HRRP)的深层特征问题,提出了一种基于注意力机制的简单循环单元(SRU)的模型进行HRRP目标识别。该模型通过SRU快速提取HRRP时序特性,引入自注意力机制自适应对重要特征进行加权,增强隐藏层状态特征的表达能力。同时通过堆叠由SRU,自注意力机制和前馈神经网络组成的模块构建深层网络,对HRRP深层特征自动提取。实验结果表明,对比其他模型,该模型可以有效识别目标。在二维可视化下,提取的深层特征可分性最好。

基于注意力胶囊网络的合成孔径雷达图像分类模型研究

特征提取是合成孔径雷达(synthetic aperture radar,SAR)图像自动识别与分类中的重要环节.由于SAR图像有相干斑噪声及几何畸变等特性,一般网络模型难以提取到有判别性的特征.为增强特征提取能力,提高分类准确率,提出将注意力机制与胶囊网络结合的一种注意力胶囊网络模型.注意力机制可聚焦寻找具有重要局部信息的特征,在图像识别过程中抑制干扰特征,定位重要特征.胶囊网络可捕捉图像中目标的位置与空间关系,使提取到的SAR图像特征含有更多便于分类的重要信息.结果表明:文中方法对SAR图像分类数据集中运动和静止目标的获取与识别(moving and stationary target acquisition and recognition,MSTAR)有显著效果.

基于微多普勒效应特征的空中目标识别

特征提取是基于微动特征雷达目标识别的关键一环。传统方法提取的特征为线性、浅层的,导致表征微多普勒效应的能力有限。针对这些问题,采用非线性网络进行特征学习,建立了基于微多普勒效应的飞机目标识别深度网络。通过构建处理微多普勒效应的卷积神经网络(CNN)模型,从微多普勒频域数据中自动提取非线性深层次属性特征,实现空中目标分类识别。在实际测量的微多普勒频域数据上的大量实验结果表明,所提方法具有良好的目标识别性能和泛化性能。

基于多分类器融合的雷达高分辨距离像目标识别与拒判新方法

由于雷达自动目标识别(Radar automatic target recognition,RATR)中库外目标的存在,评价系统性能时应综合考虑其识别性能和拒判性能.由此本文构造了一种将分类器的输出通过最近邻分类器(Nearest neighbor,NN)进行拒判和识别的"分类器–最近邻"系统,并在拒判和识别两个阶段分别采用多分类器融合技术以提高RATR系统的拒判和识别综合性能.此外,文中定义了一种代价函数以衡量系统综合性能并为系统拒判工作点的选取提供依据.进而,采用局部法和全局法两种算法确定拒判器的工作点.实测数据实验结果验证了本文方法的有效性,两种工作点选取算法均能够显著提高识别系统的综合性能.

基于注意循环神经网络模型的雷达高分辨率距离像目标识别

针对雷达高分辨率距离像(HRRP)数据的识别问题,该文利用HRRP生成的时序特性,提出一种基于循环神经网络的注意模型。该模型利用具有记忆功能的循环神经网络对时域数据进行编码,并根据HRRP中不同距离单元所映射的隐层对目标识别的重要性,自适应地赋予隐层不同的权值系数,并根据隐层特征编码特征进行HRRP目标识别。该模型利用了隐藏在HRRP数据内部的目标结构信息,提高了特征的区分度。实测数据的实验结果表明,该方法可以有效地进行识别,在样本存在一定余度数据和样本偏移的情况下,都能准确地找出目标支撑区域。

利用稳健字典学习的雷达高分辨距离像目标识别算法

基于字典学习算法的信号稀疏表示被广泛应用于信号处理领域。由于字典原子间存在冗余性,求解信号的稀疏表示会受到观测信号中扰动分量的影响,从而带来表示的不确定性,不利于雷达高分辨距离像(HRRP)目标识别任务。针对这一问题,该文提出一种稳健字典学习(SDL)算法,通过边缘化信号丢失,构建稳健损失函数用于学习自适应字典。该算法利用距离像在散射点不发生越距离单元走动的方位帧内具有结构相似性,约束临近训练样本间稀疏表示的非零元素位置相同,并通过结构化稀疏约束选择最优子字典用于测试样本的分类。基于实测HRRP数据的实验结果验证了所提算法的有效性。

一种利用目标雷达高分辨距离像幅度起伏特性的特征提取新方法

为了松弛高分辨距离像 (HRRP)的方位敏感性 ,传统的雷达HRRP目标识别方法大都采用目标在一定方位角域内的平均像作为方位模板 .实际上 ,距离像的幅度起伏特性也包含了一定的目标特征信息 .本文基于散射点模型理论 ,提出了一种利用距离像幅度起伏特性的特征提取新方法 .新方法提取的加权距离像特征反映了各个距离单元内目标散射点的分布情况 ,可以更好地描述目标散射特性 .基于外场实测数据的识别实验结果表明 ,新的特征提取方法可以大幅度地提高识别性能 .