MIMO雷达波达方向估计的性能分析

针对单基地多输入多输出雷达波达方向估计精度问题,推导了单目标情况下波达方向估计的克拉美罗界．结果表明波达方向估计精度取决于收发阵列的导向矢量以及发射信号的相关矩阵,当发射阵元间距为半波长时,多输入多输出雷达波达方向估计的克拉美罗界在大部分角度范围内优于相控阵雷达．多输入多输出雷达还能够通过增大发射阵元间距来得到更小的克拉美罗界,从而获得远优于相控阵雷达的波达方向估计性能．     

混合双基地雷达系统结构对方位估计性能的影响

建立了兼具传统相控阵雷达和多输入多输出(MIMO)雷达特点的混合双基地雷达系统结构,综合考虑传统相控阵的相干处理增益和MIMO雷达的空间分集增益对目标方位估计性能的影响．给出接收角(AOA)和发射角(AOD)估计的CRB,通过对不同结构下系统CRB的分析来判断估计性能的优劣．分析表明: 估计AOA时,接收端采用相控阵结构,发射端采用混合结构,可以提高估计性能;发射端采用相控阵结构而接收端采用尽可能多的接收阵列,可以获得较好的估计性能．在实际应用中,需要折中考虑不同结构中相干处理增益和空间分集增益对系统估计性能的影响．     

MIMO双基地雷达多目标角度-多普勒频率联合估计

为了实现无同步双基地雷达多目标参数估计,建立了多输入多输出(MIMO)双基地雷达多目标信号处理模型,提出了一种多目标角度-多普勒频率联合估计算法.该算法首先对MIMO接收机输出的虚拟阵列多目标回波数据进行解相干处理,然后基于传播算子,构造特殊矩阵.通过特征参数与待测参数之间的对应关系,实现了多目标发射角、接收角和双基多普勒频率的联合估计.该算法不涉及多维非线性谱峰搜索,只需一次特征值分解,且估计出的参数可自动配对.仿真结果证明了所提算法的正确性和有效性.     

低快拍下MIMO雷达收发角度联合估计方法

在多输入多输出(MIMO)雷达中,基于二阶统计特性的子空间角度算法在低快拍条件下的估计性能急骤下降,甚至在单快拍时失效。针对该问题,提出一种扩展阵列孔径的二维联合空间平滑多目标波离方向(DOD)和波达方向(DOA)估计方法。该算法对MIMO雷达的发射端和接收端进行二维联合空间平滑,并利用MIMO雷达虚拟阵列的旋转不变特性对阵列孔径进行扩展,然后根据ESPRIT算法获得目标的DOD和DOA,且DOD和DOA自动配对。与基于二阶统计特性的子空间算法相比,且所提算法在低快拍条件下具有更加优越的角度估计性能,因所提算法能够适用于单快拍条件。仿真结果表明了所提方法的有效性和优越性。     

非平稳噪声下相干信源MIMO雷达角度估计

为解决非平稳噪声、多径效应和相干电子干扰下多输入多输出雷达角度估计问题,提出了一种基于斜投影算子和Teoplitz矩阵重构的角度估计方法．通过Toeplitz重构把非平稳噪声转化为高斯白噪声,再用斜投影算子排除非相干信源,实现对相干信源的角度估计．该方法没有阵列孔径损失,可适用于任意阵列结构,且信源过载能力和阵元节省能力较强．最后通过仿真验证了该算法比多级维纳滤波器算法更适合于低信噪比的情况．     

一种MIMO雷达低角跟踪环境下的波达方向估计新方法

针对多径效应,提出了一种相干源条件下MIMO雷达低仰角跟踪时波达方向估计的新方法．结合MIMO雷达的特点,考虑接收多径回波信号和发射多径信号,利用改进的只需一维搜索的最大似然算法对阵列接收数据进行了双端处理,即接收阵列处理和发射阵列处理．这相当于扩大了单端处理时的阵列孔径,不但提高了低信噪比下仰角分辨力和估计精度,还降低了计算量．     

阵元利用率最高的MIMO雷达阵列结构优化算法

提出了一种多输入多输出雷达阵列结构优化新算法．首先要求在实际物理阵元数最少的条件下能够在接收端获得尽可能多的有效虚拟阵元数,即系统总的物理阵元利用率最高; 然后约束多输入多输出雷达的虚拟阵列满足最小冗余阵的要求,从而提高系统的分辨率并克服栅瓣和高旁瓣的影响．理论分析和算法求解结果都表明,该算法优化出的多输入多输出雷达阵列是收发为同一阵列的非均匀线阵,在物理阵元总数相同的条件下,较其他阵列结构具有更好的波束性能．     

基于Unitary ESPRIT的双基地MIMO雷达目标定位算法

针对双基地MIMO雷达目标定位问题,提出一种基于Unitary ESPRIT的双基地MIMO雷达目标定位算法.该算法利用MIMO雷达发射阵列和接收阵列的相位延迟特性对接收数据矩阵进行重构,使协方差矩阵为Centro-Hermitian矩阵,然后通过酉变换将协方差矩阵从复数域变换为实数域,最后利用Unitary ESPRIT算法实现目标的DOD和DOA估计,且DOD和DOA自动配对.与传统的ESPRIT算法相比,该方法有效地增加接收数据信息,提高了目标角度估计性能,且所有的特征值分解及矩阵计算均在实数域进行,大大降低了运算复杂度.仿真结果验证了该算法的有效性.     

基于互信息理论的MIMO天波超视距雷达波形优化方法

多输入多输出（MIMO）天波超视距雷达（OTHR）技术在雷达发射端发射低增益宽波束,在接收端进行波束形成得到高增益的窄波束,可以满足多层电离层探测和杂波抑制的需求。该文将两层电离层结构应用到MIMO-OTHR中,并针对OTHR杂噪比（CNR）比较高的特点,提出一种互信息理论方法对发射波形进行自适应优化。仿真结果表明该方法明显提升了目标距离分辨率和检测概率,说明在MIMO-OTHR中,经过合理的波形优化,可以利用多径回波改善雷达系统性能。     

小斜视角的MIMO雷达波数域成像方法

针对传统逆合成孔径雷达（ISAR）成像技术存在的运动补偿难题，通过使用确定性阵列与单次快拍并行空间采样取代传统IsAR中的非确知性合成阵列与长时间多脉冲采样，给出了一种MIMO雷达波数成像方法．该成像方法利用发射／接收阵元的角度分集和信号分集，在单次快拍观测期间即可实现目标散射函数波数域二维支撑域上的有效观测，避免了ISAR成像中对目标运动的补偿难题．仿真验证了该方法的可行性．     

双基地制导雷达反隐身性能建模与仿真

为满足防空系统抗击隐身目标的需求,提出了一种计算双基地制导雷达RCS和导弹发射距离的方法.基于单双基地雷达的RCS特性,建立了双基地制导雷达探测距离随站间距离变化的数学模型.最后以正面抗击F-117A为例进行单双基地对比仿真,证明了双基地制导雷达反隐身的可行性.     

FMCW-InISAR imaging for high-speed target based on bistatic configuration

Interferometric inverse synthetic aperture radar(InISAR) imaging has been proved to be a powerful means for obtaining threedimensional(3-D) space shape of noncooperative targets. Frequency modulated continuous wave(FMCW) InISAR(FMCWInISAR) has unique advantages of low power, low cost, and small volume compared with traditional coherent pulsed InISAR.However, FMCW-InISAR imaging has two additional issues to consider, the one is the invalidation of the assumption of stopgo, which is caused by the relatively long sweep interval of FMCW; the other is the isolation of the transmitting and receiving antennas, which is the inherent issue of the transmitter-receiver community radar systems. To solve these two problems, a bistatic FMCW-InISAR imaging algorithm for high-speed targets is proposed in this paper. For improving the isolation of the transmitting and receiving antennas, a bistatic configuration based FMCW-InISAR system is designed. According to the characteristics of bistatic, a bistatic equivalent motion model and corresponding signal model are established.Since the assumption of stopgo is invalid in the case of FMCW, indicating that the target cannot be viewed as motionless during a sweep repetition interval(SRI), a parametric estimation based quadratic phase factor(QPF) compensation method is investigated to eliminate the range walk caused by the radial motion of the target during the SRI. In addition, considering the farfield trait of the target and combining the traditional InISAR imaging process, a combined QPF compensation technique is proposed to reduce the computational burden of the algorithm. Finally, the effectiveness and the robustness of the proposed algorithm are evaluated by some simulations.     

MSPDAF算法在低空监视信息融合中的应用

为了实现对低空空域运行航空器的有效跟踪,进而保障低空空域运行安全,将一次雷达与无源雷达进行组合,运用MSPDAF算法进行两种雷达协同监视的信息融合,并将回波源于目标的概率应用于目标状态估计中.仿真结果表明,该算法相比单独一种雷达的跟踪算法具有更好的融合精度,能够在电磁环境复杂的低空空域中有效地进行目标跟踪,从而可以应用到低空空域航空器的监视,为低空运行提供更高的安全保障.     

双基地MIMO雷达目标定位及互耦自校正算法

利用均匀线阵互耦矩阵的带状和对称Toeplitz特性,提出了一种基于旋转不变技术估计目标参数(ESPRIT)的双基地多输入多输出(MIMO)雷达目标定位及互耦自校正算法.该算法通过ESPRIT算法中子阵的选取,将目标二维方位角估计与互耦参数估计相"去耦",角度估计过程不需任何互耦矩阵信息,且估计精度高、分辨力强;基于对目标二维方位角的估计,算法还可以精确地估计出互耦矩阵,从而实现双基地MIMO雷达的互耦自校正.该算法对目标二维方位角与互耦矩阵的估计不涉及任何角度搜索和迭代过程,具有较小的运算量.计算机仿真结果证明了该算法的正确性和可行性。     

无源雷达时差定位方法研究

用民用蜂窝基站发出的信号作为信源,对目标所反射的蜂窝信号进行接收处理,利用到达时间差定位方法,可以实现对目标的定位.基于蜂窝通信系统的无源雷达尤其适合探测超低空飞行目标,克服了传统雷达存在超低空探测"盲区"的缺陷,具有优良的远程预警能力.     

New Precision Guidance Method Based on Bistatic Synthetic Apterture Radar

A new method is presented to improve guidance precision. This method is based on bistatic synthetic aperture radar. The illuminator works in side looking mode, providing the synthetic aperture and the receiver is disposed on the seeker which operates in the forward looking mode. The receiving antenna is composed of four sub-antennas and so four synthetic aperture radar (SAR) images are to be generated. Target is positioned in SAR images by image matching. The bearing and elevation of image element of target are measured by the principle of monopulse angular measurement. Theory of the proposed method is derived and simulation on bearing measurement is done. Simulation shows that the method is valid and if SNR of target's image is above 30 dB, the angular measuring difference is within the confines of 0.04 degree.     

Length estimation of extended targets based on bistatic high resolution range profile

The approach to estimate the length of extended targets by using the bistatic high resolution range profile (HRRP) is analyzed in this paper. The relationship between the bistatic HRRP and the monostatic HRRP of extended targets are investigated. It is demonstrated by simulations that the target length measured by the bistatic HRRP is more meaningful and accurate than that by the monostatic HRRP, though the monostatic HRRP has been well developed and widely used in target recognizing and classification. The estimation results of a cone shaped target are present and compared at the end of the paper. To assure the reliability of the simulation, the bistatic HRRP is obtained through the scattering field data calculated by a full-wave numerical method, FE-BI-MLFMA.     

脉冲式与连续波式导航雷达反截获能力分析

为了分析脉冲雷达与连续波雷达的探测效能,重点研究了在不同蒸发波导高度条件下两种体制导航雷达的反截获能力.首先给出了脉冲式和连续波式导航雷达截获因子的度量方法,然后对这两种体制的雷达在标准大气和蒸发波导条件下的截获因子进行了仿真.仿真结果表明,在反截获方面,连续波式导航雷达明显优于脉冲式导航雷达.     

双基地MIMO雷达波形解相关算法

The auto-correlation and cross-correlation properties of transmit waveforms have great effects on the performance of MIMO radar systems. However, it is difficult to design waveforms that have ideal auto-correlation properties as well as cross-correlation ones. In this paper, an MMSE based waveform de-correlation algorithm is proposed to cancel the effects of the auto-correlation and cross-correlation of transmit waveforms in the receiver. The received signal model of bistatic MIMO radars is first derived. Then, the de-correlation filters are derived by using the MMSE method to reduce the influences of colored noise enhancement. Finally, the polynomial expansion method is used to simplify the computational complexity of the proposed de-correlation filters. The performance of the proposed method is verified by applying it to bistatic MIMO radar multi-target localization. Simulation results demonstrate the effectiveness of the proposed algorithm.     

脉冲制无源雷达动目标时延快速估计方法

根据脉冲制非合作双基地雷达系统的特点,讨论了固定目标的互相关检测与时延估计原理,针对运动目标多普勒频移对互相关检测造成的失配损失很大而无法继续使用的问题,提出了一种“分段相关-视频积累”快速时延估计算法,并对线性调频脉冲串信号在互相关和“分段相关-视频积累”两种方法下的处理性能进行了理论分析和仿真比较。实验表明“分段相关-视频积累”方法能够在参考通道与目标通道的信噪比相差十分悬殊的情况下,有效地完成微弱动目标的检测与快速时延估计。