共查询到20条相似文献,搜索用时 62 毫秒
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Sarkar等人提出的直接数据域算法中,利用时域两脉冲(或空域两阵元等)加权对消实现对感兴趣信号(SOI)的去除,得到不合感兴趣信号(SOI)只含有干扰信号的样本,进而估计滤波权.但由于预处理使用的是一维滤波,在SOI去除的同时,也对消了一部分杂波,使得估计的杂波能量不足,引起改善因子损失,因此对消滤波器阻带带宽应尽量小.而由于实际应用中一般不可能精确已知SOI方向,过窄的滤波带宽往往又不能完全对消SOI.为了提高SOI的误差鲁棒性,同时改善杂波抑制性能,提出了一种改进的算法,先用MTI(三脉冲对消)抑制主瓣杂波,再用一种改进的直接数据域方法抑制其它杂波.仿真结果验证了该算法的有效性. 相似文献
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提出一种基于混合遗传算法的唯相位直接数据域最小二乘算法.通过采用标准遗传算法与Neider-Mead单纯形法相结合的混合遗传算法,提高了优化效率和运算速度.首先根据标准直接数据域算法推导得出目标函数,继而将目标函数作为适应度函数,将所有自适应权值的未知相位作为决策变量,通过混合遗传算法进行非线性优化,从而求得各个自适应权值的优化解.作为一种唯相位自适应算法,它在硬件实现上比传统算法更具简单性.同时,它只对单快拍数据进行处理,避免了样本协方差矩阵的构造以及矩阵求逆运算,更适合于实时处理.仿真结果表明,算法具有良好的信号恢复和干扰置零性能,比基于非线性其轭梯度法的唯相位直接数据域算法性能更优. 相似文献
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提出一种基于直接数据域最小二乘方法的自适应多波束形成算法,包括前向计算、后向计算和前一后向计算.利用天线阵元输出复电压的单快拍数据构建矩阵方程,采用共轭梯度法求解得到阵列的自适应权值向量,从而在所有期望信号方向形成接收波束,同时在各干扰方向形成深零陷,使信干噪比显著提高.由于只需对单快拍数据进行处理,并且避免了样本协方差矩阵的构造及矩阵求逆运算,故计算复杂度较传统算法低.仿真结果表明,算法具有良好的期望信号恢复和干扰置零性能.因此,可适用于卫星通信和移动通信等领域的实时性处理. 相似文献
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在机载雷达抑制地杂波的应用中,降阶空时自适应处理是目前研究的重点,而在各种降阶算法中以Goldstein和Reed等人提出的多级维纳滤波器(MWF)算法最具代表性。本文首先将MWF算法由广义旁瓣对消结构推广到直接处理结构,在此基础之上引入预条件处理以改善杂波和噪声协方差矩阵的条件数,提出了预条件多级维纳滤波器(PMWF)算法,并给出了算法的预条件共轭梯度法实现。利用杂波和噪声协方差矩阵的分块Toeplitz结构,可使PMWF算法的计算量降低为O(NKlog_2NK)。仿真实验表明,PMWF算法与经典的MWF算法相比,当处理阶数相同时,其信杂噪比改善有明显的提高,且以主杂波附近的改善尤为显著。 相似文献
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在对音频信号进行去噪处理时,要应用具有时频转换分析能力的小波变换。在Donoho提出的小波域阈值算法的基础上,针对选取阈值时并未考虑分解尺度造成滤波效果差这一缺点,提出了一种基于分解尺度来确定阈值并根据相邻高频系数图的比较来确定最优分解尺度的改进算法。经过实际信号的仿真表明,改进后的算法可以有效地去除噪声干扰,在信噪比上也明显优于原算法。 相似文献
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In the field of space-time adaptive processing (STAP), direct data domain (D3) methods avoid non-stationary training data and can effectively suppress the clutter within the test cell. However, this benefit comes at the cost of a reduced system degree of freedom (DOF), which results in performance loss. In this paper, by exploiting the intrinsic sparsity of the spectral distribution, a new direct data domain approach using sparse representation (D3SR) is proposed, which seeks to estimate the high-resolution space-time spectrum only with the test cell. The simulation of both side-looking and non-side-looking cases has illustrated the effectiveness of the D3SR spectrum estimation using focal underdetermined system solution (FOCUSS) and L1 norm minimization. Then the clutter covariance matrix (CCM) and the corresponding adaptive filter can be effectively obtained. D3SR maintains the full system DOF so that it can achieve better performance of output signal-clutter-ratio (SCR) and minimum detectable velocity (MDV) than current D3 methods, e.g., direct data domain least squares (D3LS). Therefore D3SR can deal with the non-stationary clutter scenario more effectively, where both the discrete interference and range-dependent clutter exists. 相似文献
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时变加权的机载双基雷达降维空时自适应处理 总被引:1,自引:0,他引:1
针对机载双基雷达传统降维空时自适应处理方法杂波抑制性能较差的问题,提出了一种新的降维方法.该方法对杂波协方差估计矩阵进行降维处理,利用时变加权技术对降维后的权值矢量进行更新,以补偿杂波的距离相关性,提高杂波协方差估计准确度.理论分析和仿真结果表明:在不同的双基雷达配置情况下,该方法均可以对非均匀杂波进行有效抑制;且相对时变加权技术最优空时自适应处理,运算量和所需训练样本数大幅减少.此外,与多普勒补偿或角度多普勒补偿方法相比,该方法无需了解有关雷达平台和配置场景的先验知识,适于工程实现. 相似文献
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机载火控雷达慢速目标检测 总被引:1,自引:0,他引:1
该文研究机载火控雷达对慢速目标的检测方法以及发射信号带宽对慢速目标的检测性能的影响。通常情况下,机载火控雷达地杂波多普勒频率多重模糊,主瓣杂波带宽大,常规处理性能很差。该文结合实际情况。重点分析了机载火控雷达检测地面慢速目标的特点,分析了主瓣杂波这一制约系统检测性能的主要因素,比较了两类空时二维处理方案对慢速目标的检测性能。采用较大的发射带宽是火控雷达的发展方向,雷达发射信号的带宽是影响系统对慢速目标检测性能的重要因素,该文通过理论分析和仿真试验比较了不同带宽情况下系统对慢速目标的检测能力。 相似文献
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Wang Yongliang Peng Yingning 《电子科学学刊(英文版)》1996,13(4):310-318
A convenient implementation approach to space-time adaptive processing for airborne radar has been proposed, which is added by some auxiliary array elements in the area of main-lobe clutter on the basis of 2-D Capon approach . It is of practical use for its small computational load. This approach possesses the ideal performance in the area of main-lobe clutter . In addition, the approach which is added by some auxiliary beams in the area of main-lobe clutter has also been discussed. 相似文献
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用来处理机载天线阵列所获数据的自适应技术被称作空时自适应处理技术。为了准确估计出检测距离单元杂波干扰的统计特性,传统的STAP算法要求训练样本和待检测样本中的杂波干扰应该是独立同分布(IID)的。但对于MIMO雷达体制和在雷达实际工作的非均匀杂波环境下很难做到这一点。本文将适用于均匀杂波环境的子空间算法推广到了非均匀环境下,仿真结果表明推广后的子空间算法在非均匀杂波环境下有着优秀的性能。 相似文献
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For the realistic case where there is no secondary snapshot that does not contain the desired signal and exhibits the statistical characteristics similar to the snapshot under test, direct data domain (D3) beamforming approaches have been proposed to estimate a desired signal in the presence of interference. However, the basic idea of the D3 methods is realized by making significant sacrifices with respect to the number of degrees of freedom (DoFs). In this paper, we present a multi-snapshot approach for D3 beamforming. Using the least-squares method with multiple snapshots, we can eliminate the interference without causing a severe reduction in the number of DoFs. In addition, to consider a mismatch between nominal and actual target steering vectors, we propose a D3 approach combined with a probability constraint to prevent the self-nulling effect, and the relationship between the probability constraint and norm constraint is discovered. The simulations verify that the proposed method provides better performance and robustness than the conventional D3 approaches. 相似文献
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When the Airborne Early Warning (AEW) radar transmits medial or high Pulse Repetitive Frequency (PRF) signal, the range ambiguity occurs. The clutter of short-range clutter has serious range dependence problem for non-Side Looking Airborne Radar (non-SLAR). As a result, the clutter plus noise covariance matrix can not be estimated correctly, and the performance of clutter suppression obtained by Space-Time Adaptive Processing (STAP) degrades greatly. The uniform linear array has not elevation degrees; therefore, the short-range clutter can not be suppressed directly. A short-range clutter suppression method is proposed. The method first estimate the elevation angles of the am-biguous short-range gate, then eliminates short-range clutter by space time interpolation and adds moving target protection in the procedure. This method can suppress the short-range clutter well. Simulation results show the validity of the method. 相似文献