共查询到18条相似文献,搜索用时 109 毫秒
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相干干扰环境下,自适应阵列性能会急剧下降,常用的处理方法是空间平滑。然而,采用常规均匀空间平滑的自适应阵列对相干干扰的抑制能力较差,而且会损失阵列孔径。该文提出一种改进的相干干扰抑制方案:首先,提出了一种自适应的加权空间平滑(Weighted Spatial Smoothing, WSS)算法,它将各子阵的相关矩阵进行加权平均,可以最大程度地解相干;然后,在WSS基础上,利用线性约束最小方差(LCMV)准则得到子阵波束形成器最佳权矢量;最后,提出了一种利用子阵间的相位关系对全阵做波束形成的方法。该方案大大提高了阵列对抗相干干扰的能力,同时避免了一般空间平滑后阵列的孔径损失。理论分析和仿真结果说明了方法的有效性和稳健性。 相似文献
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自适应波束形成可以实现空间信号分离。在基于子阵平滑技术的同频信号测向的前提之下,给出了在主瓣和零点约束及阵列静态噪声功率输出最小条件下的波束形成方法,并给出了求解加权矢量的算法。仿真结果表明:本文提出的空间信号分离的方法是有效的。 相似文献
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针对标准Capon波束形成器中真实导向矢量与期望导向矢量存在误差时,其性能会急剧下降的问题,提出了基于加权空间平滑与导向矢量估计相结合的鲁棒波束形成算法。该算法利用加权空间平滑方法,对子阵进行特殊的划分,根据子阵间自相关矩阵与互相关矩阵权重差异,采用嵌套的方式获得加权矩阵,继而得到更加精确的协方差矩阵,接着,使用不确定范围约束期望导向矢量来获得真实导向矢量。仿真结果表明,和传统的自适应波束形成算法相比较,本文算法在面对协方差矩阵中含有期望信号以及角度失配问题时,鲁棒性得到明显提升。 相似文献
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子空间重构的一类自适应波束形成算法 总被引:2,自引:0,他引:2
针对多维阵列的全维自适应波束形成算法运算量大和小样本条件下性能下降问题,该文提出采用子空间重构技术的自适应波束形成算法(SRC-BF)。该方法利用多维域的全维阵列数据可分维构造的特点,首先在训练样本集上估计分维阵列数据的信号子空间;然后基于张量积性质重构全维信号子空间并自适应剔除交叉项;最后采用子空间投影算法计算自适应加权矢量。理论分析和仿真结果表明该方法具有较低的运算复杂度,能有效提高自适应波束形成算法在小样本条件下的输出信干噪比。 相似文献
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任意形状旁瓣波束形成技术研究 总被引:2,自引:0,他引:2
在自适应零陷形成的基础上,提出了一种自适应加权算法,用于任意阵型阵列构成具有任意形状旁瓣的波束图,并考虑基元方向性对波束图的影响.给出了实现自适应加权算法的三个步骤,预先设定所需旁瓣形状及旁瓣级,采用循环,最终使旁瓣与预设形状吻合.将该算法用于均匀线阵和抛物线阵,均得到期望的结果,并与道夫-切比雪夫加权作了相应比较.研究表明,基元的方向性对该算法波束形成的影响很小,新算法可以消除基元宽带方向性对波束的影响. 相似文献
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一种均匀圆阵子阵干扰抑制DOA估计算法 总被引:1,自引:0,他引:1
常规空间谱估计算法在强干扰背景下往往无法正确估计弱信号的来波方向。针对此问题,本文提出了一种均匀圆阵子阵干扰抑制波达方向估计算法。将整个阵列划分为若干个子阵,利用提出的最小二乘波束形成算法分别对子阵波束加权以抗干扰,加权后的子阵可以看作是一个‘有向阵元’,将它们组成一个新的虚拟阵列,再进行超分辨谱估计。该方法通过子阵波束形成抑制强干扰,子阵输出中消除了强干扰分量,因此能够实现弱信号波达方向的正确估计,同时弱信号到达角估计的成功概率也得到了提高。最后计算机仿真实验验证了本文算法的有效性和正确性。 相似文献
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利用遗传算法(GA)将大型阵列划分为非均匀邻接子阵,以主旁瓣比作为适应度函数,并对遗传操作增加约束条件,得到具有栅瓣抑制能力的子阵结构。为进一步抑制平面阵俯仰和方位上的高旁瓣,对平面阵进行两级子阵划分,使平面阵方向图在俯仰和方位上均具有良好的主旁瓣电平比;为消除非均匀子阵结构各子阵通道噪声功率不同对子阵级自适应波束形成算法的影响,通过对阵列协方差矩阵进行奇异值分解、重构特征子空间,提出了基于特征空间重构的子阵级自适应波束形成方法。仿真结果表明了该方法的可行性与有效性。 相似文献
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Many practical signal environments involve correlation between desired and undesired signals, causing narrowband adaptive array beamformers to exhibit signal cancellation. Spatial smoothing is a technique that can perform beamforming in such environments. This method can be incorporated into an adaptive algorithm, such as least mean squares (LMS), possibly altering the well-known performance characteristics of the algorithm. We discuss methods for combining spatial smoothing with the LMS algorithm in an array with a generalized side-lobe canceler (GSC) structure. The first of these methods is an electronic version of mechanically dithering the array. We show that this well-known method obeys a set of nonhomogeneous dynamical equations, resulting in a limit cycle that increases the misadjustment of the algorithm. The previously reported parallel spatial processing algorithm is also shown to have this increased misadjustment. We then introduce two methods that do not suffer from this misadjustment increase. We compare the methods' computational complexity and performance, in terms of stability and steady-state behavior, including weight misadjustment, GSC output power, and signal-to-noise ratio (SNR). In conclusion, we find that the limit cycle of the first method can be avoided without any increase in complexity by using one of the new methods 相似文献
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相干信号源自适应波束形成 总被引:1,自引:0,他引:1
介绍了常规自适应波束形成的一般理论,并在此基础上分析了期望信号与干扰信号相干时常规自适应波束形成失效原理,引入了空间平滑技术,给出了空间平滑技术去相干的原理和在自适应波束形成上的应用,同时给出了计算机仿真结果。 相似文献
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讨论了如何将CSMG自适应波束形成算法与空间平滑法相结合,应用到同时存在相干干扰和非相干干扰的环境中。该算法具有空间平滑法和CSMG波束形成算法的优点,能对相干干扰抑制,并且在非相干干扰方向也能形成很好的零陷,大大提高了系统的抗干扰性能。对该算法、普通CSMG算法和与空间平滑算法相结合的MVDR算法进行了计算机仿真,并对仿真结果进行了比较,证明了该算法结构的可靠性和优越性。 相似文献
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Anisotropic diffusion can provide better compromise between noise reduction and edge preservation. In multispectral images, there exist different spatial local structures in the same band. Therefore, the levels of smoothing of anisotropic diffusion process should conform to both of image spectral and spatial features. In this paper, we present an effective denoising algorithm by integrating the spectral-spatial adaptive mechanism into a well-balanced flow (WBF) based anisotropic diffusion model, in which an adjustable weighted function is introduced to perform the appropriate levels of smoothing and enhancing according to different feature scales. Moreover, we make the fidelity term in the model to be adaptive by replacing the original noisy signal with the last evolution of the smoothed image. Consequently, the proposed algorithm can better control the diffusion behavior than traditional multispectral diffusion-based algorithms. The experimental results verify that our algorithm can improve visual quality of the image and obtain better quality indices. 相似文献
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Two-Dimensional Adaptive Array Beamforming With Multiple Beam Constraints Using a Generalized Sidelobe Canceller 总被引:1,自引:0,他引:1
《Signal Processing, IEEE Transactions on》2005,53(9):3517-3529
This paper deals with the problem of two-dimensional (2-D) adaptive array beamforming with multiple beam constraints (MBC) using a generalized sidelobe canceller (GSC). We present a method for the construction of signal blocking matrix required by the 2-D GSC. The resulting 2-D adaptive beamformer can provide almost the same performance as conventional 2-D adaptive beamformers based on a linearly constrained minimum variance (LCMV) criterion. The effectiveness of the proposed GSC is that the construction of the required signal blocking matrix requires only the computation of a few entries from analytical formulas. In comparison with conventional methods, the proposed technique gets rid of the computational complexity due to the eigendecomposition required for finding the 2-D signal blocking matrix. For dealing with the performance degradation due to coherent interference, we present a 2-D weighted spatial smoothing scheme to effectively alleviate the coherent jamming effect. Several simulation examples are provided for illustration and comparison. 相似文献