共查询到19条相似文献，搜索用时 187 毫秒
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分析了基于二阶统计的CSPRIT算法在空间相关高斯噪声环境中存在的问题，提出将四阶累积量与CSPRIT算法相结合，处理一维二元相移键控信号（BPSK）和多元幅移键控信号（MASK），实现信号到达角（DOA）的估计和波束形成器的构造。与基于二阶统计的CSPRIT算法相比，基于四阶累积量的改进算法能够有效抑制空间相关的高斯噪声，提高信号估计精度。计算机仿真验证了该算法的有效性。 相似文献
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提出基于空间平滑技术的高阶累积量空间谱估计。在经典的空间谱估计中,均利用信号的二阶统计量,并且假设噪声是白噪声。在实际应用场合,噪声通常是色噪声,这时采用高阶统计量可以获得比二阶矩更理想的性能。本文利用空间平滑技术对单一的高阶累积量算法进行改进。新算法具有同时测向能力、测向精度高、超分辨能力,能在低信噪比环境中取得好的性能。计算机仿真证明了该方法的有效性。 相似文献
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基于高阶累积量和循环谱的调制方式识别研究 总被引：1，自引：0，他引：1
接收机采用高阶累积量和循环谱这两种低信噪比的算法,对检测到的各种信号进行调制方式识别,其中包括BPSK、QPSK、2FSK、4FSK、MSK等5种已调信号,然后,通过MATLAB编程,进行系统仿真,仿真结果表明,循环谱对高斯噪声有更强抑制作用。 相似文献
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利用高阶累积量切片对调频信号能量聚集和噪声抑制的特性,引入高阶累积量后置处理算子,提出一种新型的微弱性网络攻击信号高敏锐度检测算法。算法有效分离攻击信号的时频耦合,首先把信号采用离散分数阶傅立叶变换实现离散化处理,然后利用高阶累积量切片算子对攻击信号在分数阶傅立叶域上进行后置能量聚集,增大信号累积量,有效抑制了合法网络信号的背景干扰。仿真实验表明,新算法能在-15 dB低信噪比背景下,有效检测出隐蔽性很强的弱性网络攻击信号。能有效应用到计算机网络安全防御和对抗中。 相似文献
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本文分析了以往利用图像块能量、高阶累积量建立背景约束的准则。考虑到能量块门限为定值的不足，对能量块门限进行自适应估计，实验结果表明这种算法兼顾了实时性和精确性，能有效地对固定背景的进行提取。 相似文献
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《科技通报》2015,(12)
在网络持续波动攻击中出现一种小扰动信号,由于该类攻击信号的振幅不大,常规的检测算法难以有效定位检测,无法保证网络安全。提出一种基于小扰动多普勒扩散参量估计的网络波动入侵源定位检测算法。首先进行网络攻击模型构建,分析网络攻击信号的小扰动振幅特性,由于高阶累积量对噪声有盲分离作用,利用高阶累积量切片对小扰动入侵信号的能量聚集和噪声抑制特性,引入高阶累积量后置处理算子,进行小扰动入侵源定位聚焦,采用DOA参量估计算法进行网络攻击信号的多普勒扩散参量估计,实现对小扰动入侵源定位和检测。仿真结果表明,采用该算法能有效实现了对网络波动攻击的小扰动入侵信号的准确定位和检测,分离出振幅较小入侵信号,检测准确率较传统方法高。 相似文献
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调制识别是非协作通信系统接收机设计中的重要研究课题。针对高阶累积量可以剔除噪声的干扰,本文研究了基于高阶累积量的MPSK信号调制方式识别技术。在SNR≥5dB时,正确识别率达到了99%以上。经理论推导和仿真实验,证实了该方法的有效性。 相似文献
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为消除语音识别系统中的噪声干扰,研究了传统谱减法和改进的谱减法,描述了两种算法的原理和特点,并对两种算法进行了编程实现。matlab仿真结果表明,改进的谱减法不仅可以消除噪声,还可以抑制＂音乐噪声＂的产生,比传统谱减法更具优势。 相似文献
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本文分别介绍了一种基于指纹人脸识别的多生物特征身份认证方法,并针对传统的指纹人脸方法提出相应的改进算法。对指纹识别,本文提出采用局部归一化方法结合Gaussian滤波器来计算指纹方向,再对局部脊线补偿法(Loca lRidge Compensation)进行快速运算,能够更加快速准确地进行指纹识别。人脸识别通过定位人脸位置并且进一步提取人脸特征来进行匹配,使用LBP(Local binary patterns)算子对人脸样本进行局部特征提取,对LBP处理后的人脸图像使用主成分分析(PCA)进行降维,并采取了极限学习机(Extreme learning machine,ELM)分类器进行匹配,将指纹、人脸的识别结果在决策层进行融合,最后做出判断,从而得到准确稳定的身份认证系统。 相似文献
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Ayd?n K?z?lkaya 《Journal of The Franklin Institute》2005,342(1):39-67
In this paper, the problem of estimating the parameters of a two-dimensional autoregressive moving-average (2-D ARMA) model driven by an unobservable input noise is addressed. In order to solve this problem, the relation between the parameters of a 2-D ARMA model and their 2-D equivalent autoregressive (EAR) model parameters is investigated. Based on this relation, a new algorithm is proposed for determining the 2-D ARMA model parameters from the coefficients of the 2-D EAR model. This algorithm is a three-step approach. In the first step, the parameters of the 2-D EAR model that is approximately equivalent to the 2-D ARMA model are estimated by applying 2-D modified Yule-Walker (MYW) equation to the process under consideration. Then, the moving-average parameters of the 2-D ARMA model are obtained solving the linear equation set constituted by using the EAR coefficients acquired in the first step. Finally, the autoregressive parameters of the 2-D ARMA model are found by exploiting the values obtained in first and second steps. The performance of the proposed algorithm is compared with other 2-D ARMA parameter and spectral estimation algorithms available in the technical literature by means of three different criteria. As a result of this comparison, it is shown that the parameters and the corresponding power spectrums estimated by using the proposed algorithm are converged to the original parameters and the original power spectrums, respectively. 相似文献
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提出了一种基于小波阈值去噪的语音增强算法。根据含噪语音中噪声、清音和浊音的不同特点,首先对它们进行检测区分,然后采用改进的Garrote阈值函数分别对噪声、清音和浊音运用不同的阈值方案进行处理。该方法在很大程度上抑制了噪声,又减少了语音段清音的损失,提高了信噪比,在MATLAB7.1中的仿真实验结果表明,该方法具有较好的增强效果。 相似文献
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扩展频谱技术有多种实现方式,本文主要介绍的是直接序列扩频技术及仿真直接序列扩频信号的产生与调制经过高斯白噪后的解调、判决、捕获过程。 相似文献
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《Information processing & management》2023,60(1):103122
Aiming at the problem that watermark information is easy to be lost in two-dimensional text image watermarking, a three-dimensional text image watermarking model is proposed based on multilayer overlapping of extracted two-dimensional information, and a specific method is accordingly realized by means of embedding, extracting and overlapping of multiple watermarks in sequence. We discuss the influence of the sequence order, positional distancing and color difference of the extracted multiple two-dimensional information on displaying a three-dimensional text watermark image. In addition, considering the crucial evaluation indices of the invisibility and robustness for the watermarking algorithm, the selection method for superior embedding regions of multiple watermarks is also constructed to enhance the robust performance of watermarks under the premise of effective invisibility. Moreover, we embed the multiple two-dimensional information into the host image by using the undecimated dual-tree complex wavelet transforms - bidiagonal singular value decomposition algorithm. In this way, the extracted multiple two-dimensional information is automatically overlapped to generate the three-dimensional text watermarking according to the optimal matching parameters. We use standard image processing data set to carry out experiments, the results show that the peak signal to noise ratio before and after embedded watermarks is higher than 39 dB, and the peak signal to noise ratio between the original watermarks and the extracted watermarks is more than 37 dB, which is superior to the current reported watermark model. Therefore, it is suggested that the proposed model shows good invisibility and robustness and can reduce the loss of watermark during transmission and attack as much as possible. 相似文献