一种改进的多普勒中心频率估计方法

在合成孔径雷达成像及其应用中,需要对多普勒中心频率进行估计。在分析目标回波多普勒历程的时频模型基础上,提出了一种时频滤波的方法,该方法通过滤除部分强散射点的时频分布来消除功率谱的扭曲,进而提高多普勒中心频率估计的精度。实验证明了该方法的有效性。     

Frequency increment optimization method for frequency diverse radar

The conventional Frequency diverse array (FDA) employs the fixed frequency increment,which restricts its applications in various environments. With the above findings,we propose an optimal frequency increment selection method based on oblique projection filtering for mainlobe interference suppression. We can obtain the optimal frequency increment by maximizing the output SINR of the oblique projection filter in each coherent processing interval (CPI). Inspired by the cognitive radar,the optimal frequency increment will be used in the next CPI. Simulation results demonstrate that jamming can be effectively suppressed with the radar configuration,and that better performance is achieved with an optimal frequency increment.     

低分辨雷达编队目标分辨新方法

对于编队飞行的目标,由于它们之间的间距较小,常规雷达无法直接在距离和方位上区别目标,如果利用逆合成孔径雷达成像技术对运动目标回波的多普勒频率的差别,获得了产高的横向分辨率目标是完全有可能分辨目标的,该文将图形化度准则估计目标的运动参数进行平动补偿的方法用到低分辨雷达一维横向成像,并采取超分辨方法提高分辨率,进行编队多目标的精确分辨,实测数据证明,该方法是一种有效的多分辨方法。     

Inshore ambiguity clutter suppression method aided by clutter classification

To address the problem that the clutter suppression performance is reduced for the multichannel synthetic aperture radar(SAR) because of the ambiguous component of the land clutter in the inshore area,we propose an inshore ambiguity clutter suppression method aided by on clutter classification.First,a multi-look interference feature covariance matrix(MIFCM) for each range-Doppler unit is constructed,which includes multi-look interference magnitude/phase and multi-look interference magnitude gradient information.Next,with the affine invariant riemannian(AIR) distance measure of MIFCMs,the clutter classification result can be acquired.Finally,with the clutter classification result,we select independent and identically distributed(IID) training samples to estimate the clutter covariance matrix in the ambiguous clutter region,with clutter suppression performed in the multichannel SAR image domain.Simulation result shows that the proposed method can accurately classify and suppress the azimuth ambiguous clutter in the inshore area.     

时频分析技术在抑制箔条干扰中的应用

研究了箔条干扰背景下利用时频投影理论解决离分辨雷达抑制杂波干扰的问题,文中模拟了在干扰背景中目标稳定的原始距离像,基于线性信号空间的Wigner-Ville分布,根据时频（TF）滤波和时频展开理论,即在特定时频通域里最优TF子空间就是该通域的特征信号子空间,设计目标距离像的通域及时频投影滤波器,对雷达回波进行脉冲周期内域通滤波,仿真表明该方法具有在箔条杂波背景下抑制干扰的良好能力。     

调频连续波(FMCW)聚束式SAR成像研究

针对调频连续波SAR与脉冲式SAR工作体制的不同,从而带来不同的回波表现形式,对基于调频连续波的聚束式SAR回波信号进行建模,分析信号的特征,揭示平台的连续运动在距离向产生一个多普勒频移的特性,从而影响方位聚焦．对于方位频谱混叠的问题,采用方位预滤波处理,通过插值实现采样率的提高,由于预滤波可以实现方位的块压缩,实际中的方位向点数并没有明显增加,最后基于FS算法完成残余聚焦,仿真数据处理结果验证了分析的正确性和算法的有效性．另外,对于平台连续运动引入的多普勒频移,分析了其对成像造成的影响,并给出了相应的补偿方法．     

基于多传感器信息融合的多目标跟踪与仿真研究

针对战场目标跟踪中雷达获得的目标角度精度低的问题,引入了高精度的红外方位探测信息进行关联,用以修正融合航迹点的方位角;建立了基于坐标变换和自适应α-β滤波的数据关联快速算法模型;进行了模拟战场实际目标的仿真试验。仿真结果显示：雷达与红外数据关联融合后,目标方位角和俯仰角的最大误差分别为6 mrad和5 mrad。表明该算法充分利用了红外与雷达的互补性,能很好地跟踪目标,达到了降低目标航迹的方位角和俯仰角跟踪误差的目的,使航迹状态估计更加精确。     

稳健波束形成在高频雷达干扰抑制中的应用

利用一种新的扩展Capon波束形成器对高频地波雷达非平稳射频干扰进行抑制,在指定误差范围内搜索得到最优干扰抑制情况下的波束导向矢量,并用牛顿迭代法快速求解方程.高频雷达仿真和实验数据处理结果表明,该法较大改善了高频雷达抑制射频干扰的性能.     

一种用于TOPS SAR-GMTI的空时自适应处理方法

针对在循序渐近对地扫描合成孔径雷达(TOPS SAR)模式下静止背景杂波的多普勒带宽很大,在有限的脉冲重复频率(PRF)条件下,会导致背景杂波出现严重的多普勒模糊问题,提出了一种基于谱压缩的空时自适应处理方法进行杂波抑制.经过谱压缩操作后,杂波的多普勒带宽减小到与其瞬时带宽相同,再利用空时自适应处理(STAP)方法进行杂波抑制,使得杂波抑制性能得到明显改善.同时,由于动目标径向速度的存在,会导致其多普勒频谱产生偏移,而直接采用匹配滤波方法对动目标进行聚焦,会造成虚假目标的出现.为了避免出现这一现象,可利用Deramp处理方法对动目标进行聚焦处理,能有效避免虚假目标的产生.同时利用TOPS SAR模式获得连续的重叠率很高的全孔径TOPS SAR图像,可以实现动目标的轨迹跟踪处理.最后,通过仿真实验验证了所提方法的有效性.     

基于子带SDL的宽带抗干扰恒定束宽波束形成

针对宽带恒定束宽波束形成通常需要大量阵元或延迟线所带来的硬件开销较大,并且抗干扰效果较差的问题,提出一种基于子带阵元延迟线(SDL)的宽带抗干扰恒定束宽波束形成算法。该算法通过建立子带SDL模型,利用子带滤波器组将阵元接收信号进行分解与重构,基于约束最小二乘算法进行子带抗干扰恒定束宽波束形成,并将滤波器组的冲击响应直接作为优化参量,可有效降低分解与重构产生的误差。为了衡量阵列响应的波动程度,提出归一化波动程度的概念。仿真结果表明,子带波束形成器具有比全带波束形成器更好的频率不变性和抗干扰能力,而且可以大大降低硬件开销。     

基于分数阶傅里叶变换的LFM干扰抑制算法

针对利用分数阶傅里叶变换(fractional Fourier transform,FrFT)进行干扰抑制时门限阈值设定的难题,为有效抑制DS/FH系统中的线性调频(linear frequency modulated,LFM)干扰,通过深入分析DS/FH和LFM信号的FrFT性质,提出了一种新的LFM干扰抑制算法,该算法充分利用FrFT时频面坐标轴旋转性质,通过计算信号的不同阶次FrFT并搜索其峰值,确定信号最优FrFT阶次,完成对LFM干扰信号的判别,最后采用频域陷波来抑制LFM干扰。理论分析和仿真实验表明,该算法能够有效的剔除DS/FH系统中的LFM干扰信号,不需要阈值门限设定,算法具有较好的稳健性和普适性。     

一种异构组网雷达系统抗欺骗式假目标方法

同构体系下组网雷达配置方式简单,抗欺骗式假目标算法单一。该文提出一种异构组网雷达系统抗欺骗式假目标方法,对于既包含两坐标雷达又包含三坐标雷达的异构组网雷达系统,首先利用三坐标雷达对目标进行定位,计算目标相对于两坐标雷达的距离、方位角信息。然后,将该计算值与两坐标雷达对目标的量测值进行比较,通过构造卡方检验对真假目标进行有效鉴别。仿真结果表明,该算法可以有效地鉴别欺骗式假目标,并分析了欺骗距离、目标量测个数和雷达测角精度对算法鉴别概率的影响。     

米波雷达方位角超分辨外场实验研究

介绍了一个由均匀线接收阵和米波雷达组成的外场实验系统,用于进行米波雷达的方位角超分辨实验。用采集的实验数据对几种常用的超分辨算法进行了实验,结果表明,FBLP算法和ESPAIT算法可清晰分辨出角间隔为0.2~0.3波束宽度的两架飞机。     

基于分维处理的单通道阵列频率与角度联合估计

针对现有无源单通道阵列频率与角度联合估计算法的信号采样时间较长以及运算复杂度较高等问题,提出了分维处理的频率与角度联合估计算法.其信号采样数据由时域采样数据与空域采样数据构成,前者来自于对参考阵元的多次采样,后者来自各阵元.仅对时域采样数据进行处理即可得到各信源的频率估计值;然后基于空域采样数据以各频率估计值为搜索频率,估计出各频率对应的空间谱,再利用频率误差与角度误差的关系以及方向矢量与噪声子空间的正交性从各空间谱中提取出与各频率估计值对应的角度估计值.与已有算法相比,该算法采样时间较短,复杂度较低,且直接对采样信号进行处理,避免了信号失真.理论推导与仿真分析证明了该算法的有效性.     

Range ambiguous clutter suppression for the SAR/GMTI system based on the frequency diverse array

A range ambiguous clutter suppression approach based on frequency diverse array configuration is proposed to handle the range ambiguity of the space borne wide-swath high-resolution synthetic aperture radar ground moving target indication (SAR/GMTI) system with a high pulse repetition frequency. Since echoes from different ambiguous range regions are separable in the transmit spatial frequency domain, a filter bank is employed to extract echoes from each region, and then the transmit beam forming is implemented to suppress the clutter in each range region. Simulation results demonstrate that, by making full use of the limited channels, the proposed method could weaken the influence of heterogeneous clutter in each region and reconstruct moving target signals without range ambiguity, so as to expand the detection region evidently.     

Effective Sea Clutter Spectrum Extraction Method for HFSWR in Adverse Conditions

An effective approach in solving the sea clutter spectrum extraction problem is studied in the paper. Different from the conventional signal to noise ratio (SNR) method based on Doppler frequency or range domain information, a method is developed to characterize the differences between the sea echo and those interferences are by signal to interference plus noise ratio (SINR) which jointly utilizing the range, Doppler frequency and azimuth domain information. Furthermore, these differences can be adaptable to adverse conditions by forming the necessary boundaries and constraints in searching of the maximum SINR, which greatly promotes the extraction of sea clutter spectrum. The real high frequency surface wave radar (HFSWR) data demonstrate that the proposed method is less influenced by those interferences and can effectively extract the sea clutter spectrum even under the adverse conditions. Furthermore, it has been shown as an effective method for ship detection and sea state remote sensing of HFSWR.     

Imaging algorithm for highly squinted SAR data processing based on phase disturbing

For quick look imaging, a phase disturbing algorithm (PDA) for focusing synthetic aperture radar (SAR)subaperture data acquired at a high squint angle is proposed. First, the signal model is addressed and then the range processing and azimuth processing are analyzed in detail. The PDA performs the linear range walk correction (LRWC) in the time domain and the range cell curvature correction (RCCC) in the frequency domain to mitigate the range-azimuth coupling. Additionally, a disturbing phase is introduced in the frequency domain to remove the variation of the Doppler chirp rate with the azimuth position caused by LRWC in the time domain,and so an identical reference function can be employed in azimuth processing. Simulated results and raw data processing validate the effectiveness of the proposed algorithm.     

基于小波变换和灰色关联度的航迹关联算法

超视距雷达和红外预警卫星能对弹道导弹助推段进行探测跟踪,因此两者的情报可以相互关联印证,从而提高情报质量。针对超视距雷达和红外预警卫星的航迹关联问题,提出了一种基于小波变换的灰色关联度的航迹关联方法。该算法将超视距雷达和红外预警卫星的方位角信息序列通过小波变换进行去噪,得到方位角航迹的整体走势,然后对走势相同的方位角航迹建立灰色关联矩阵,并根据该矩阵按照一定的规则进行航迹相关判定。仿真结果表明,相对灰色关联度的关联算法,该算法的正确关联率提高了约8%。     

机载雷达非正侧面阵近程杂波抑制新方法

根据机载雷达非正侧面阵的近程杂波随距离快变的特性,提出了俯仰向空域滤波子阵合成的算法．该算法利用平面阵列天线在俯仰向的自由度,先对近程杂波进行滤除,然后再在方位空域和时域做空时自适应处理．这样就增强了远程杂波的距离平稳性,很容易准确地估计协方差矩阵,从而提高了空时自适应处理抑制非正侧面阵杂波的性能．仿真结果证明了无误差时改善因子可以提高约30dB．     

一种多目标与多基地雷达之间的博弈策略

针对多基地多输入多输出雷达与多目标之间的对抗博弈,研究了一种多基地雷达系统的功率分配与波束成形联合技术.在一个确定的信干噪比约束下,多基地雷达系统的主要目的是极小化自身发射总功率,并期望通过波束成形算法来抑制互雷达通道干扰,提升目标检测的准确性.基于雷达之间的策略非合作博弈,证明了博弈的纳什均衡解的存在性和唯一性.然后...