共查询到19条相似文献,搜索用时 109 毫秒
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从扩频通信接收机等效基带信号的模型出发,分析了接收信号中扩频信号分量和窄带干扰分量的循环平稳性以及接收信号的波特率谱相关性与采样之间的关系,并给出基于频移滤波器窄带干扰抑制接收机的自适应实现结构,理论分析和仿真结果表明,使用频移滤波器的接收机抗窄带干扰性能优于基于线性时不变滤波器的接收机。 相似文献
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带内窄带脉冲干扰会对直接序列扩频信号估计性能产生较大的影响,针对此问题,提出了一种抑制窄带脉冲干扰并对扩频码序列及周期的盲估计算法。采用最大熵概率密度谱估计算法估计出接收信号的概率密度谱,进而用估计的概率密度谱设计滤波函数对信号滤波来抑制窄带脉冲干扰。利用二次谱算法对扩频码周期进行估计并通过 Viterbi 算法对扩频序列进行提取。仿真实验表明,该算法不仅能抑制较强的窄带脉冲干扰,而且能在无先验信息的条件下估计出扩频信号的扩频码周期及序列等信息,从而获知直扩通信中所传输的码元序列。 相似文献
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基于门限估计的直扩通信系统窄带干扰变换域抑制方法 总被引:13,自引:1,他引:13
该文提出一种基于门限估计的直接序列扩频(DS-SS)通信系统窄带干扰变换域抑制方法。该方法对直扩通信系统接收信号变换域数据的分布特点进行了分析,并采用高斯分布对其作了近似.由于高斯分布的方差即为直扩信号和高斯白噪声方差之和,因此估计出变换域数据的方差,将为频域抑制滤波器的门限设置提供参考。该文采用最大似然比(ML)准则对方差进行了估计,从而实现了频域抑制滤波器的自动门限设制。理论分析和计算机仿真结果均表明,该方法能够有效地抑制直扩通信系统中的窄带干扰。 相似文献
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窄带干扰(NarrowBand Interference,NBI)和宽带干扰(WideBand Interference,WBI)的存在将会大幅度地降低合成孔径雷达(Synthetic Aperture Radar,SAR)图像的质量.本文在对NBI和WBI的时频分析基础上,提出了一种基于Wigner分布(Wigner Distribution,WD)和时频面滑窗掩膜技术的干扰抑制算法.该算法首先利用瞬时时刻重构序列与原序列之间的联系,提出了一种基于WD的高效信号重构算法.然后采用平滑伪WD分布(Smoothed Pseudo Wigner Distribution,SPWD)作为时频掩膜抑制WD的交叉项,并结合WD信号重构算法和时频平面滑窗掩膜技术提取并重构干扰信号,最后将重构的干扰信号在原始回波中对消实现干扰抑制.该算法能有效抑制SAR图像中的时变NBI和WBI,同时能够尽可能保留有用信号.仿真数据和实测数据结果分析验证了本文方法的有效性. 相似文献
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K. P. Vijayakumar P. Ganeshkumar M. Anandaraj K. Selvaraj P. Sivakumar 《International Journal of Communication Systems》2018,31(10)
In this paper, a fuzzy logic–based jamming detection algorithm (FLJDA) is proposed to detect the presence of jamming in downstream data communication for cluster‐based wireless sensor networks. The proposed FLJDA keeps an eye on the existing nodes and new node to determine their behavior by applying fuzzy logic on measured jamming detection metrics. To monitor the behavior of the nodes, the FLJDA computes the jamming detection metrics, namely, packet delivery ratio and received signal strength indicator. The major features of this paper are the following: (1) The jamming detection algorithm is specifically implemented for downstream data communication, (2) cluster head estimates jamming detection metrics for detecting the jamming unlike the existing algorithms where individual nodes explicitly collect the jamming detection metrics, and (3) the proposed algorithm optimizes the jamming detection metrics on the basis of fuzzy logic unlike the existing approaches, which uses merely jamming detection threshold alone for jamming detection. The simulation results of the proposed system provide the true detection ratio as high as 99.89%. 相似文献
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为了有效抑制合成孔径雷达(SAR)系统中常见的窄带干扰(NBI),本文提出一种基于互补集合经验模态分解(CEEMD)和排列熵(PE)的NBI抑制方法。矩峰度系数法用于检测原始回波中是否存在NBI,对包含NBI的回波使用CEEMD将其分解为一系列本征模态函数(IMF)。计算所有IMF排列熵得到全局阈值以区分NBI和有用信号,并使用去除NBI后的IMF分量重建信号以获得良好聚焦的SAR图像。结果表明:所提方法能有效克服经验模态分解(EMD)带来的模态混叠问题,且干扰抑制性能优于传统频域陷波法及基于EMD的NBI抑制方法。 相似文献
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一种具有窄带干扰抑制能力的改进型LSL插值算法 总被引:1,自引:0,他引:1
本文提出了一种基于QR分解技术的最小二乘格形插值算法-QRD-LSL插值算法来抑制直扩系统中的窄带干扰.该算法利用直扩信号、噪声信号和窄带干扰信号数据样值间相关特性的差异,通过对直扩系统接收端数据样值序列进行插值运算来估计窄带干扰信号成分,从而达到抑制直扩系统中窄带干扰的目的.由于该算法引入了QR分解过程避免了对数据矩阵求逆运算,并引用动态范围较小的新变量参与阶递推运算,极大程度上提升了算法在稳态特征、收敛速度和计算复杂度等方面的性能.仿真结果表明:QRD-LSL插值算法较LSL插值算法和LSL预测算法至少可获得4dB的处理增益,且计算量与滤波阶数呈线性关系. 相似文献
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基于数字射频存储器(DRFM)的灵巧噪声干扰兼具压制式干扰效果和欺骗式干扰效果,难以被传统抗干扰方法有效抑制。针对这一问题,本文结合分数阶傅里叶变换(FrFT)与分数阶域滤波方法,提出了一种线性调频脉冲压缩雷达体制下的灵巧噪声干扰抑制方法。首先对接收信号进行分数阶傅里叶变换,随后根据发射信号在分数阶域的特征参数,设计分数阶域滤波器,对接收信号进行分数阶域滤波以滤除干扰,最后进行分数阶反变换还原目标信号。仿真结果表明,该方法能够对卷积噪声干扰与乘积噪声干扰两种典型的灵巧噪声干扰进行有效抑制,准确检测目标的位置。 相似文献
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Po-Rong Chang Jen-Tsung Hu 《Vehicular Technology, IEEE Transactions on》1999,48(2):467-477
This paper investigates the application of pipelined recurrent neural networks (PRNN's) to the narrow-band interference (NBI) suppression over spread-spectrum (SS) code-division multiple-access (CDMA) channels in the presence of additive white Gaussian noise (AWGN) plus non-Gaussian observation noise. Optimal detectors and receivers for such channels are no longer linear. A PRNN that consists of a number of simpler small-scale recurrent neural network (RNN) modules with less computational complexity is conducted to introduce best nonlinear approximation capability into the minimum mean-squared error nonlinear predictor model in order to accurately predict the NBI signal based on adaptive learning for each module from previous non-Gaussian observations. Once the prediction of the NBI signal is obtained, a resulting signal is computed by subtracting the estimate from the received signal. Thus, the effect of the NBI can be reduced. Moreover, since those modules of a PRNN can be performed simultaneously in a pipelined parallelism fashion, this would lead to a significant improvement in its total computational efficiency. Simulation results show that PRNN-based NBI rejection provides a superior signal-to-noise ratio (SNR) improvement relative to the conventional adaptive nonlinear approximate conditional mean (ACM) filters, especially when the channel statistics and exact number of CDMA users are not known to those receivers 相似文献
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YingXiaofan ChuZhenyong TianHongxin YiKechu 《电子科学学刊(英文版)》2004,21(4):322-327
The proposed scheme is based on Discrete Fourier Transform (DFT) domain processing. The key technology of this scheme is jamming parameters‘ accurate estimation and jamming reconstruction. Compared with the “threshold exciser”scheme.the proposed scheme can eliminate more jamming energy on the whole frequency band with the minimum loss of useful signal energy. As shown in the research and simulation, the proposed scheme is much better than the “threshold exciser” scheme, especially in the case of high power jamming whereas the “threshold exciser” scheme might be invalid. 相似文献
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该文提出了一种针对合成孔径雷达(SAR)的单比特多模态干扰方法,干扰机在截获SAR信号后,将其与单频阈值比较后量化为单比特数据。与传统高精度采样量化生成高逼真度假目标的欺骗干扰方法相比,单比特量化仅保留了数据的符号信息,降低了采样数据的位宽,达到简化系统、提升效率、降低成本的目的。同时,基于单频阈值的单比特量化在截获SAR信号中引入了丰富的谐波分量,通过合理设计阈值的幅度、频率与相位参数,可以将单频阈值泛化为多种阈值。不同阈值可以有效利用不同特性的谐波,进而达到单目标欺骗干扰、多目标欺骗干扰、射频干扰和类噪声干扰等多种干扰模态单一对抗或协同对抗、多模态间捷变的灵巧干扰效果。通过仿真实验定量分析了不同干扰模态下的干扰性能,验证了所提方法的有效性。 相似文献