Adaptive Detection and Interference Rejection of Multiple Point-Like Radar Targets

We present an adaptive algorithm aimed at detecting multiple point-like radar targets embedded in correlated Gaussian noise. The proposed detector modifies and improves the adaptive beamformer orthogonal rejection test (ABORT) idea to address detection of multiple targets. More precisely, it relies on the so-called two-step generalized likelihood ratio test (GLRT) design procedure implemented without assignment of a distinct set of secondary data. The newly proposed detector can guarantee the constant false alarm rate (CFAR) property and the performance assessment, conducted resorting to simulated data, has shown that it exhibits better rejection capabilities of mismatched signals than previously proposed detectors, at the price of an acceptable performance loss for matched signals     

基于ANSG的雷达信号DOA估计算法

针对阵列信号处理中雷达信号的波达方向(DOA)估计,提出自适应噪声子空间生成(ANSG)算法。通过数值方法,得到阵列接收信号的协方差矩阵,以迭代方式处理约束最小化问题,实现ANSG。根据噪声子空间的表达式获得DOA估计,并且先验信息可以很好地融入算法的流程中,能够有效地解决复杂环境下的多信号源DOA估计问题。仿真结果表明,该算法适用于单频、线性频率调制以及二进制相移键控雷达信号,DOA估计精度和运算速度优于MUSIC。     

子空间约束的一阶秩1干扰下的自适应检测

在复杂电磁环境中,雷达获取的回波数据若受到干扰,会影响到雷达的探测性能.该文针对雷达目标自适应检测问题,假定待检测单元和部分参考数据受到1阶秩1干扰,且干扰约束在某个已知的子空间内.首先基于双步广义似然比(2SGRLT)准则,提出子空间约束(SC)的2SGLRT检测器(SC-2SGLRT).进一步采用修正的双步广义似然比(M2SGLRT)准则,提出子空间约束的M2SGLRT检测器(SC-M2SGLRT),该检测器的性能明显优于SC-2SGLRT.最后基于3步(3S)广义似然比检验准则,提出子空间约束的3步广义似然比检测器(SC-3SGLRT),该检测器性能与SC-2SGLRT相当,且计算量最小.计算机仿真分析表明,充分利用参考数据和干扰先验信息,有助于提升检测性能.     

色噪声下认知雷达自适应检测波形设计

研究了存在色噪声时认知雷达的自适应检测波形设计问题.推导了检测率、虚警率与发射波形关系的表达式.介于此表达式的复杂性,引入两个渐近准则,即相对熵和散度准则,并在这两个准则下推导了最优检测波形的闭式解.经理论分析和实验仿真得出如下结论:1)两种信息论准则对应的最优波形是一致的;2)最优检测波形与目标、噪声匹配;3)最优检测波形的信噪比同时也达到最优.     

Adaptive Detection of a Signal Known Only to Lie on a Line in a Known Subspace, When Primary and Secondary Data are Partially Homogeneous

This paper deals with the problem of detecting a signal, known only to lie on a line in a subspace, in the presence of unknown noise, using multiple snapshots in the primary data. To account for uncertainties about a signal's signature, we assume that the steering vector belongs to a known linear subspace. Furthermore, we consider the partially homogeneous case, for which the covariance matrix of the primary and the secondary data have the same structure but possibly different levels. This provides an extension to the framework considered by Bose and Steinhardt. The natural invariances of the detection problem are studied, which leads to the derivation of the maximal invariant. Then, a detector is proposed that proceeds in two steps. First, assuming that the noise covariance matrix is known, the generalized-likelihood ratio test (GLRT) is formulated. Then, the noise covariance matrix is replaced by its sample estimate based on the secondary data to yield the final detector. The latter is compared with a similar detector that assumes the steering vector to be known     

MIMO雷达对分布式目标测向研究

现有的陈列测向算法对分布式目标性能较差,该文研究基于Capon算法的MIMO雷达测向问题,并在相同条件下对不同发射信号和不同阵元配置的阵列测向性能进行仿真比较,结果表明MIMO雷达的测向性能要明显优于阵列雷达.最后给出了结论.     

海面RCS与雷达海上目标检测

该文结合海面雷达有效反射面积(RCS)的分析,根据某雷达的技术特点,再结合该雷达对海面目标探测工作的实践,探讨一些海面目标的检测方法.     

干扰检测技术在某雷达接收机中的应用

介绍某雷达接收系统中一种干扰检测设计方案。对此方案的特点及运用范围均进行明确阐述,对接收系统中干扰检测信息进行分类,并介绍不同处理方法,具有较强实用性。     

有源噪声对雷达对抗侦察系统的干扰分析

以雷达对抗侦察系统的工作流程为基本出发点,从理论上分析了雷达对抗侦察系统在各个阶段受有源噪声干扰的可能性以及可能受到有源噪声干扰的性能指标,在此基础之上,给出了有源噪声对雷达对抗侦察系统性能指标影响的模型,并进行了相应的仿真分析。     

Signal Detection in the Presence of Cochannel Interference and Noise

The problem of detection of a sinusoidal signal in the presence of white Gaussian noise and an interfering sinusoid at a nearby frequency is discussed. In the case of coherent detection, several possible receivers are analyzed and probability of error curves are calculated. In some cases it is possible to reduce the effect of cochannel interference significantly by proper choice of a receiver. In the case of incoherent detection, error probability curves have been calculated for the standard envelope detector for several values of frequency separation. The performance of the envelope detector can be degraded substantially by the presence of an interfering sinusoid.     

Adaptive Detection of Signals in Impulsive Noise Environments

A detector structure and an adaptive algorithm are proposed for the reception of signals in noise backgrounds possessing broad-tailed probability distributions typical of impulsive noise. The adaptive detector combines the best features of linear matched filtering and hard-limiting receiver structures resulting in a small-signal SNR performance which is an improvement over either of these detectors alone. Furthermore, the adaptive detector is relatively easy to implement and is shown to provide efficient and robust performance for a wide range of underlying noise distributions.     

分布式干扰下雷达探测区计算与仿真

针对导弹在飞行中段实现突防的电子干扰要求,提出了采用分布式星载有源干扰的方法来实现。为了有效计算各干扰机对目标雷达的干扰功率,巧妙利用空间两条直线的夹角公式,求得干扰机主瓣方向与该干扰机到雷达连线方向的夹角和雷达主瓣方向与雷达到各干扰机连线方向的夹角,从而将该方法从二维推广到三维。提出了有干扰和无干扰情况下,雷达探测区的通用公式。所提方法不仅适用于单干扰机对单雷达,也可用于多干扰机对多雷达场景。最后进行了详细的仿真分析,验证了理论分析的正确性和有效性。     

基于自适应DPCA的机载雷达杂波和干扰抑制的研究

分析了机载雷达相位中心偏置天线(DPCA)和自适应相位中心偏置天线(ADPCA)处理算法,对机载雷达DPCA的杂波和干扰抑制等进行了数值仿真。仿真结果表明,通过DPCA可以将淹没在强杂波背景中-47dB信噪比的目标提高到6.3dB;但当存在干扰或者机载雷达不满足DPCA的理想条件时,信噪比恶化非常严重;当干扰有效辐射功率(ERP)增大到1 W时,信噪比变为-15dB;当采用ADPCA处理后,即使在干扰ERP为400 W时,处理后的信噪比仍超过6dB。     

空域自适应处理技术在外辐射源雷达探测中的应用

外辐射源雷达系统具有隐蔽性好、反隐身能力及简单可靠等优点,近年来受到更多的重视。但在实际应用中直达波、多径信号及同频等杂波信号严重削弱了该体制雷达的探测性能,限制了其应用。该文分析了基于数字阵列体制下以调频广播信号为照射源的无源雷达,提出了空域自适应处理方法来抑制杂波信号,检测到杂波抑制前系统无法检测到的目标。从处理结果来看空域自适应处理方法有效抑制了杂波信号,大大改善了外辐射源雷达的探测性能。     

地基相控阵雷达对弹道目标的探测性能评估

为解决地基相控阵雷达对弹道目标探测的最优部署问题,建立弹道中段目标轨道运动和进动模型,提出弹道中段多部地基相控阵雷达的弹道目标探测概率模型,以及平均检测概率、稳定跟踪时间和资源冗余时间3种组合的雷达探测性能评估指标。依据弹道目标RCS及探测距离随观测时间的变化情况,通过仿真实验对多种部署方式下地基雷达对弹道目标探测性能评估指标的分析,得出的结论为弹道导弹防御系统中地基雷达的部署方式提供了有效的参考依据。     

Eigentargets Versus Kernel Eigentargets: Detection of Infrared Point Targets Using Linear and Nonlinear Subspace Algorithms

The Eigentargets method, based on the linear principal component analysis (LPCA), has been used successfully to detect infrared point targets. LPCA is based only on the second-order correlations without taking higher-order statistics into account. That results in the limitation of Eigentargets in target detection. This paper extends Eigentargets, a linear subspace method, to kernel Eigentargets, a detection method based on a nonlinear subspace algorithm. Because the kernel Eigentargets is capable of capturing the part of higher-order statistics, the better detection performance can be achieved. Moreover, the Gaussian intensity model is modified to generate training samples of infrared point targets.     

The Rao and Wald Tests Designed for Distributed Targets with Polarization MIMO Radar in Compound-Gaussian Clutter

In high resolution radars, the distributed target is usually modeled as a few isolated points referred to multiple dominant scattering centers, while the clutter is a compound-Gaussian model. Additionally, the polarimetric diversity can be exploited to enhance detection performance. Motivated by extending the detection problem of multiple-input multiple-output (MIMO) radar to such cases, this paper mainly addresses distributed targets detection problem with polarization MIMO radar against a compound-Gaussian clutter dominated scenario with unknown covariance matrix. The adaptive detectors based on Rao and Wald criteria are studied, and a two-step design procedure is adopted. Specifically, the Rao and Wald tests are derived by assuming a known covariance matrix, and then a suitable estimation of the covariance matrix based on the secondary data is inserted into the derived detectors to make them fully adaptive. Some numerical results are presented together with a polarization generalized likelihood ratio test (GLRT), showing that the derived detectors provide excellent detection performance in spiky clutter for distributed targets, and that the polarimetric diversity can be exploited to improve detection performance. Overall, the Wald test performs the best.