OPTIMIZATION OF WEIGHTED HIGH-RESOLUTION RANGE PROFILE FOR RADAR TARGET RECOGNITION

For the recognition of high-resolution range profile （HRRP） in radar, the weighted HRRP can reduce the instability of range cells caused by the attitude change of targets. A novel approach is proposed to optimize the weighted HRRP. In the approach, the separability of weighted HRRPs in different targets is measured by de- signing an objective function, and the weighted coefficients are computed by using the gradient descent method, thus enhancing the influence of stable range cells. Simulation results based on five aircraft models show that the approach can effectively optimize the weighted HRRP and improve the recognition accuracy.

Radar high resolution range profile recognition via multi-SV method

For radar high resolution range profile (HRRP) recognition, three aspects are of great importance to improve the performance, i.e. discrimination for outlier, classification for inner and an accurate description for feature space. To tackle these issues, a novel target recognition method is designed, denoted by the multiple support vectors (multi-SV) method. With the proposed method, a special framework is constructed by a treble correlate support vector model to segment the feature space to two regions with the distribution of density, and then the description and classification hyperplane for each region are achieved. Based on the support vector framework, this method needs less memory and computation complexity to fit practical radar HRRP recognition. Finally, the experiment based on the measured data verifies the excellent performance of this method.

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 Target Recognition Approach to Projecting HRR Profiles onto Subspace

Abstract: A array of the azimuthally averaged range-profile vectors and the inter-class and intra-class divergence matrixesare constructed iwth many frames of the high resolution range profiles which result from radar echoes of airplanes. Takingthe methods of whitening transformation and SVD produces a system of subspace vectors for target recognition. Where-upon, a template library for target recognition is built by the projection of a class-mean vector made from the radar dataonto the subspace for recognition. By Euclidean distance, a comparison is made between the above projection and eachtemplate in the library, to decide which class the target belongs to. Finally, simulations with the experimental radar dataarte given to show that the proposed method is robust to variation in azimuth and immune to additive Gaussian noisewhen SNR≥5dB.

Radar group target recognition based on HRRPs and weighted mean shift clustering

When range high-resolution radar is applied to target recognition,it is quite possible for the high-resolution range profiles(HRRPs)of group targets in a beam to overlap,which reduces the target recognition performance of the radar.In this paper,we propose a group target recognition method based on a weighted mean shift(weighted-MS)clustering method.During the training phase,subtarget features are extracted based on the template database,which is established through simulation or data acquisition,and the features are fed to the support vector machine(SVM)classifier to obtain the classifier parameters.In the test phase,the weighted-MS algorithm is exploited to extract the HRRP of each subtarget.Then,the features of the subtarget HRRP are extracted and used as input in the SVM classifier to be recognized.Compared to the traditional group target recognition method,the proposed method has the advantages of requiring only a small amount of computation,setting parameters automatically,and having no requirement for target motion.The experimental results based on the measured data show that the method proposed in this paper has better recognition performance and is more robust against noise than other recognition methods.

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.

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.

HRRP target recognition based on kernel joint discriminant analysis

With the improvement of radar resolution,the dimension of the high resolution range profile(HRRP)has increased.In order to solve the small sample problem caused by the increase of HRRP dimension,an algorithm based on kernel joint discriminant analysis(KJDA)is proposed.Compared with the traditional feature extraction methods,KJDA possesses stronger discriminative ability in the kernel feature space.K-nearest neighbor(KNN)and kernel support vector machine(KSVM)are applied as feature classifiers to verify the classification effect.Experimental results on the measured aircraft datasets show that KJDA can reduce the dimensionality,and improve target recognition performance.

A New Radar Target Recognition Method Based on Polarimetric Processing and Neural Learning

The new millimeter-wave(MMW) radar target recognition method proposed uses polarmetric information to obtain stable amplitudes of range profiles and neural learning to extract angle-invariant features of range profiles and polarimetric processing reduces speckle to enhance ability to discriminate targets, and in comparison with conventional approaches, subclass features obtained by the neural learning carries more information and thus makes the correctness of target classification higher and simulation results vended the validity of this approach.

RADAR TARGET RECOGNITION BASED ON NEURAL NETWORK

The problem of radar target recognition using range profiles is investigated in this paper, based on a Radial Basis Function Network(RBFN). A preprocessing method is proposed, which performs amplitude average of the range profiles to obtain more stable patterns. After pointing out the limitedness of traditional empirical formula, this paper also gives a method of estimating the shape parameter a of a Gaussian kernel function according-to spatial distribution of the training samples. It is shown that the method proposed in this paper offers promise for target recognition, from both the theoretical analysis and the experimental results of rotating platform imaging based on data acquired in a microwave anechoic chamber.

High Range Resolution Profile Automatic Target Recognition Using Sparse Representation

Sparse representation is a new signal analysis method which is receiving increasing attention in recent years. In this article, a novel scheme solving high range resolution profile automatic target recognition for ground moving targets is proposed. The sparse representation theory is applied to analyzing the components of high range resolution profiles and sparse coefficients are used to describe their features. Numerous experiments with the target type number ranging from 2 to 6 have been implemented. Results show that the proposed scheme not only provides higher recognition preciseness in real time, but also achieves more robust performance as the target type number increases.

Ship recognition based on HRRP via multi-scale sparse preserving method

In order to extract the richer feature information of ship targets from sea clutter, and address the high dimensional data problem, a method termed as multi-scale fusion kernel sparse preserving projection(MSFKSPP) based on the maximum margin criterion(MMC) is proposed for recognizing the class of ship targets utilizing the high-resolution range profile(HRRP). Multi-scale fusion is introduced to capture the local and detailed information in small-scale features, and the global and contour information in large-scale features, offering help to extract the edge information from sea clutter and further improving the target recognition accuracy. The proposed method can maximally preserve the multi-scale fusion sparse of data and maximize the class separability in the reduced dimensionality by reproducing kernel Hilbert space. Experimental results on the measured radar data show that the proposed method can effectively extract the features of ship target from sea clutter, further reduce the feature dimensionality, and improve target recognition performance.

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.

Robust radar automatic target recognition algorithm based on HRRP signature

Automatic target recognition （ATR） is an important function for modern radar. High resolution range profile （HRRP） of target contains target struc- ture signatures, such as target size, scatterer distribu- tion, etc, which is a promising signature for ATR. Sta- tistical modeling of target HRRPs is the key stage for HRRP statistical recognition, including model selection and parameter estimation. For statistical recognition al- gorithms, it is generally assumed that the test samples follow the same distribution model as that of the train- ing data. Since the signal-to-noise ratio （SNR） of the received HRRP is a function of target distance, the as- sumption may be not met in practice. In this paper, we present a robust method for HRRP statistical recogni- tion when SNR of test HRRP is lower than that of train- ing samples. The noise is assumed independent Gaus- sian distributed, while HRRP is modeled by probabilistic principal component analysis （PPCA） model. Simulated experiments based on measured data show the effective- ness of the proposed method.

基于高分辨一维距离像及其特征的空间目标识别效果分析

目标高分辨一维距离像(High Resolution Range Profile,HRRP)中包含了丰富的目标尺寸、结构等目标特征,是进行空间目标身份识别的有效途径。但由于卫星宽带雷达实测数据获取难度大,前期相关研究多集中于基于HRRP的目标识别算法,结论也多是基于仿真数据和少量类别(几类)的前提下得到的,与工程应用实际情况有较大差距,工程指导意义有限。为解决这一问题,基于地基雷达获取的30类卫星目标的大量一维距离像实测数据,从识别正确率的角度对目标HRRP及其特征(组合)的可分性和在空间目标个体识别中的应用效果进行了量化分析,分析结果可为后续基于HRRP的空间目标个体识别技术研究和工程应用提供可靠依据。

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。

基于深度残差收缩网络的雷达空中目标识别

雷达空中目标高分辨距离像(high resolution range profile,HRRP)中往往包含一定的杂波噪声,利用HRRP开展空中目标识别需要重点考虑噪声的影响。针对上述问题,提出一种基于深度残差收缩网络(deep residual shrinkage network,DRSN)的雷达空中目标HRRP识别方法。该网络将深度残差网络、软阈值函数和注意力机制结合起来,采用跨层恒等连接方式,不仅可以避免网络层数过深造成梯度消失或梯度爆炸,从而导致网络学习能力下降的问题,还可以有效过滤掉识别过程中噪声特征的影响,使模型专注于目标区域的深度特征识别,提升强噪声背景下模型的识别能力。实验结果表明,相对于其他常用的深度学习模型,所提方法在各个信噪比条件下,识别效果均有一定的优势,该模型对噪声具有较强的鲁棒性。

类别数据流和特征空间双分离的类增量学习算法

针对类增量学习(CIL)中的灾难性遗忘问题,该文提出一种不同类的数据流和特征空间双分离的类增量学习算法。双分离(S2)算法在1次增量任务中包含2个阶段。第1个阶段通过分类损失、蒸馏损失和对比损失的综合约束训练网络。根据模块功能对各类的数据流进行分离,以增强新网络对新类别的识别能力。通过对比损失的约束,增大各类数据在特征空间中的距离,避免由于旧类样本的不完备性造成特征空间被新类侵蚀。第2个阶段对不均衡的数据集进行动态均衡采样,利用得到的均衡数据集对新网络进行动态微调。利用实测和仿真数据构建了一个飞机目标高分辨率距离像增量学习数据集,实验结果表明该算法相比其它几种对比算法在保持高可塑性的同时,具有更高的稳定性,综合性能更优。

基于自适应阈值卷积网络的抗干扰雷达目标识别

本文提出了一种自适应阈值卷积网络(ATCN),基于HRRP数据进行抗干扰雷达目标识别。ATCN中的核心模块是自适应阈值卷积单元(ATCU),该模块能准确高效地完成对HRRP数据的特征提取。在ATCU中,采用自适应阈值函数充当激活函数,自动调整阈值以面对不同信干比的数据;利用多个不同尺度的卷积核来捕获HRRP数据中的区域差异特征;引入通道注意力机制和残差连接优化网络结构。本文进行了大量的抗干扰目标识别实验,实验结果表明,相比于所选择的3种对比网络,本文的ATCN网络能在不同干扰类型和不同信干比下提供更优的平均识别率和更好的指标稳定性,且具有更少的网络模型参数量和浮点运算次数,具备轻量化和高效的特点。

基于Attention-Inception网络集成的雷达HRRP序列目标识别方法

传统的雷达高分辨距离像(High Resolution Range Profile,HRRP)序列识别方法依赖于人工提取特征,并且在使用现有的经典深度学习方法识别小数据集时存在梯度消失和过拟合问题,导致收敛速度慢,识别率低。针对上述问题,提出了一种基于注意力机制的集成Inception网络模型,通过集成Attention-Inception单分支网络,实现了HRRP序列更深层次特征的提取;通过对模型的损失函数加入L2正则化,缓解小数据集在集成网络中的过拟合问题;利用Inception Ⅰ和Inception Ⅱ结构提取HRRP序列多尺度特征,并引入注意力机制计算特征序列的分配权重;加入残差结构,减缓了集成网络梯度消失问题。在预处理后的HRRP序列上进行实验结果表明,所提方法的目标识别率达到93.3%,并且与未去除噪声的HRRP序列相比目标识别率提高了14.67%。