共查询到19条相似文献,搜索用时 125 毫秒
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在单用户直接序列超宽带(DS-UWB)信号的伪码(PN)周期估计的基础上,采用信号功率谱二次处理的方法,实现了多用户DS-UWB信号的PN码周期盲估计。该方法对接收信号的功率谱进行二次谱处理,最后得到的二次谱就会在接收的多用户DS-UWB 信号的PN码周期整数倍处出现一系列的尖峰脉冲,通过检测这些脉冲的间距就可以得到PN码周期的估计。通过理论推导表明了该方法的可行性,利用计算机仿真,验证了多用户DS-UWB信号在PN码周期的整数倍确实存在二次功率谱的脉冲串,这些脉冲串还具有类似高斯脉冲二次功率谱的形状。同 相似文献
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随机共振滤波器能够在强噪声背景中跟踪微弱信号(非周期或周期信号)波形,并将幅度放大,这正好弥补了匹配滤波器在强噪声背景下检测性能的严重不足。本文给出了FHN随机共振的简化模型及计算方法,在深入分析FHN随机共振模型参数对其滤波性能影响的基础上,结合随机共振滤波器和匹配滤波器,提出了一种基于FHN随机共振模型检测确知信号的方法。首先将接收信号经FHN随机共振滤波器进行滤波,再进行匹配滤波,最后将滤波结果和门限进行比较判断信号是否存在。经过实验验证,该方法具有较好的效果。 相似文献
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在现代谱估计中,由于Yule-Walker沃克谱估计算法中平稳随机序列的长度n在某些情况下偏小,使计算出的ARMA随机过程的功率谱密度不能精确逼近真实值,所以我们在用自相关法估计AR模型参数时加入了kalman滤波器。将估计的AR模型系数及高斯白噪声作为滤波器的输入及部分参数,对最终估计的功率谱进行修正。实验结果表明,... 相似文献
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为了在低信噪比的情况下,能够用很少的采样样本得到很高的检测概率,考虑到现实生活中噪声和信号在传输过程中的衰落,所以在非白高斯信道中采用线性模型对信号进行估计,在此基础上对导频运用匹配滤波检测,讨论了决定检测概率的重要因素——偏移系数的最大值的选取。仿真结果表明,选取非白高斯噪声信道是必要的;偏移系数选取最优值将会得到很好的检测性能;对导频进行检测可以减少采样数。 相似文献
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从一个新的角度结合具体的算法讲述了Kalman滤波器的原理,并对噪声为非高斯情况下结合熵的理论提出了假设,解决了噪声为非高斯情形下的滤波器设计的瓶颈。传统的Kalman滤波器是在噪声为高斯的情形下得出的最优滤波估计,但是现实生活中大多数噪声却是未知的、不确定性并且非高斯的。为了清楚说明熵原理应用于非高斯滤波器的设计结果,运用了数学统计的方法,对比滤波效果,说明了其可行性,证明了这种方法更适应于对噪声情况未知、参数不明确的情况,为研究广义噪声的随机系统提出了一种新的通用的解决途径。 相似文献
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从一个新的角度结合具体的算法讲述了Kalman滤波器的原理,并对噪声为非高斯情况下结合熵的理论提出了假设,解决了噪声为非高斯情形下的滤波器设计的瓶颈.传统的Kalman滤波器是在噪声为高斯的情形下得出的最优滤波估计,但是现实生活中大多数噪声却是未知的、不确定性并且非高斯的.为了清楚说明熵原理应用于非高斯滤波器的设计结果,运用了数学统计的方法,对比滤波效果,说明了其可行性,证明了这种方法更适应于对噪声情况未知、参数不明确的情况,为研究广义噪声的随机系统提出了一种新的通用的解决途径. 相似文献
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相位匹配噪声估计的高阶谱去噪方法 总被引:1,自引:0,他引:1
大多数去噪方法只能对高斯噪声或某一类有色噪声进行去噪处理.提出一种新的相位匹配噪声估计的高阶谱去噪方法.利用该方法既可以去除高斯噪声又可以去除非高斯噪声,通过高阶谱和相位匹配实时的逼近当前噪声,建立二次去除噪声方法,通过实验证明该方法能够非常明显的去除高斯与非高斯噪声,在无法分出噪声的种类情况下进行信号的去噪,取得非常好的去噪效果. 相似文献
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This paper proposes a new non-parametric method to estimate the power spectral density of atmospheric radar signals using uniform filter banks through polyphase approach. The performance of proposed method is investigated for a simulated broadband and narrowband signals. This method reduces the variance without affecting the resolution and improves the signal to noise ratio significantly when compared to the existing method (periodogram/modified periodogram). The variance reduction is observed to be more in case of narrowband signals. The method has the computational cost similar to modified periodogram approach. This method is tested for practical atmospheric data collected at NARL, Gadanki, India, through the mesosphere–stratosphere–troposphere (MST) radar, back scattered echoes, in particular from high altitudes, which has low signal to noise ratio. Results have been validated using simultaneous Global Positioning System (GPS) Sonde data. 相似文献
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Representing the reception condition directly, signal-to-noise ratio (SNR) is an important parameter in mobile propagation channels, and therefore is widely used in system performance evaluations and adaptive applications. Hence, this paper puts forward a frequency domain SNR estimator in mobile communications, where we exploit the signal model with the band-limited fading channel and the additive white Gaussian noise. With the above model, the noise power spectrum density can be estimated from the periodogram of channel-plus-noise signals, subsequently leading to our SNR estimation. Moreover, in order to degrade the intrinsic spectrum leakage of fast Fourier transform in periodogram calculation, the leakage expression is derived analytically and then an adaptive process is proposed to make a tradeoff between leakage reduction and noise smoothing. We verify our algorithm by simulations and observe high accuracy in a wide range of velocities and SNRs. Additionally, unlike the conventional work, the proposed estimator is not strictly based on the assumption of specific Doppler spectral shapes except for the requirement of the band-limited channel, hence it is robust to general mobile channels. 相似文献
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针对随机振动中谱估计算法,分析了周期图估计算法对噪声系列的功率谱相关系数及加窗造成的信息损失,在此基础上分析了由直接谱估计算法构建的多窗口谱分析法,建立了其噪声模型,推导了估计方差减小与参与运算的窗口数的关系。针对白噪声序列,得到MTSA估计器避免加窗而造成信息损失时窗口数与信号序列的关系,最后推出了MTSA估计器的统计特征。 相似文献
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针对传统微弱信号检测方法存在检测准确性较低、检测时间较长等缺点,提出混沌背景中微弱网络传输信号有效检测方法。根据Wiener-Khinchine定理对信号函数计算,并经过傅里叶变换获得信号的自相关函数与其相对应的功率谱,利用周期图法分析获得微弱信号的检测原理,运用Briot-Bouquet引理进行计算,根据计算结果证明瞬态信号以及周期信号的存在,并以此为基础构建混沌背景下噪声的检测模型,从预测误差中检测出在噪声层下的微弱网络传输信号。仿真结果表明,所提方法能够快速检测出在混沌背景下的微弱信号,且检测时间较短、检测误差较低,可广泛引用在现实生活中。 相似文献
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Traditional and fuzzy cluster analyses are applicable to variables whose values are uncorrelated. Hence, in order to cluster time series data which are usually serially correlated, one needs to extract features from the time series, the values of which are uncorrelated. The periodogram which is an estimator of the spectral density function of a time series is a feature that can be used in the cluster analysis of time series because its ordinates are uncorrelated. Additionally, the normalized periodogram and the logarithm of the normalized periodogram are also features that can be used. In this paper, we consider a fuzzy clustering approach for time series based on the estimated cepstrum. The cepstrum is the spectrum of the logarithm of the spectral density function. We show in our simulation studies for the typical generating processes that have been considered, fuzzy clustering based on the cepstral coefficients performs very well compared to when it is based on other features. 相似文献
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Generalized adaptive subspace detector for range-Doppler spread target with high resolution radar 总被引:3,自引:0,他引:3
DAI FengZhou LIU HongWei & WU ShunJun National Lab of Radar Signal Processing Xidian University Xi’an China 《中国科学:信息科学(英文版)》2011,(1):172-181
A generalized adaptive subspace detector for range-Doppler spread target(RDST-GASD)in the non-Gaussian clutter is derived in this paper.The subspace model of multi-pulse wideband radar target returns is established in the frequency-slow time domain.The clutters are modeled as nonhomogeneous spherically invariant random vectors(SIRVs);that is,the power of the clutter is different from one range cell to another.The clutter covariance matrix is estimated with the secondary data.The constant false alarm rate(CF... 相似文献
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The Burg reflection-coefficient method for maximum entropy (antoregressive) spectral estimation is generalized to apply to multichannel complex signal. It is shown that all resulting power matrices are positive definite. Preliminary numerical results obtained for a monochromatic signal with noise indicate that the determinants of the power matrices are rapidly reduced as the number of filter coefficients is increased, and that superior spectral resolution can be expected. 相似文献