零均值独立复杂噪声背景下二维谐波估计的时间平均矩方法

对于零均值独立乘性噪声背景下二维谐波的三次非线性耦合估计问题,由于缺乏理论支持及有效的计算方法,至今尚无有效的解决办法.本文首先分析了不同的噪声模型对谐波耦合分析所产生的影响,通过对原始采样数据进行平方预处理,改变了采样信号的信噪模型,利用新模型下噪声的统计特性及噪声间的相关特性,通过定义一种特殊四阶时间平均矩,首次解决了零均值独立噪声背景下谐波频率的二维三次非线性耦合问题.数学推导了该特殊四阶时间平均矩的矩多谱,理论证明了相应估计子渐进无偏性和一致性.理论分析和试验结果表明,该方法用于二维谐波的三次耦合分析时,不再需要对噪声的统计特性及噪声间的相关特性作任何限制.     

乘性和加性噪声相关背景下的二维谐波频率估计

本文利用二维循环统计量方法对乘性噪声之间相关、乘性噪声和加性噪声之间也相关这种复杂噪声背景下的谐波恢复问题进行了研究.首先,提出了二维噪声互可混的概念,用它来体现多个二维噪声之间的关系;然后,在乘性噪声为非零均值时,定义了二维循环均值来估计信号频率.在乘性噪声和加性噪声为零均值时,定义特殊的二维六阶时间平均多矩谱切片来估计信号频率.仿真实验证明了算法的有效性.     

基于遗传算法的复杂背景噪声中二维谐波的二次耦合分析

本文利用二维循环统计量方法对乘性噪声之间相关,乘性噪声和加性噪声之间也相关这种复杂噪声背景中二维谐波的二次非线性耦合问题做了分析。利用当且仅当二维谐波中存在二次非线性耦合谐波时,所定义的二维三阶时间平均矩谱仅在参与二次耦合谐波频率处取得极值的性质,提出了采用遗传算法来分析二维谐波的：二次非线性耦合问题的算法。仿真实验证明了算法的有效性。     

乘法噪声中非线性耦合谐波分析

针对信号的非平稳性质,引入傅里叶级数多谱和比例多周期图的概念,分别提出了零均值乘法噪声二次耦合及非零均值乘法噪声三次耦合谐波频率估计方法,仅使用单个数据记录即可得到耦合频率估计,并且可以抑制加性平稳噪声而无须假定其颜色和分布.最后给出了仿真实验结果.     

零均值复杂噪声背景下二维谐波的三次非线性耦合分析

该文利用一种四阶时间平均矩谱,通过对原始数据取平方的办法,改变了原始信号中噪声的统计特性,首次对零均值独立噪声背景下的二维谐波的三次耦合问题给出了解决方法,文中给出了详细的理论分析和证明。由于该方法也适合于非零均值噪声下的谐波耦合问题,因此这种方法不再需要对噪声的均值、颜色和分布作任何限制。仿真结果表明了该方法的有效性。     

四元数和超复数在二维二次非线性相位耦合分析中的应用

针对二维二次非线性相位耦合分析中的分维配对问题,本文首先对一般二维谐波信号模型进行变换,构造了符合四元数结构的新的信号模型.接着讨论了Hamilton四元数、三维超复数及"新四元数"在估计二维谐波频率中的可能性.最后根据上述模型利用特殊的三阶累积量切片分析了加性高斯有色噪声中二维二次非线性相位耦合及联合Hamilton四元数和超复数在二维二次非线性相位耦合中的应用前景.此方法避免了在复数模型的二维二次非线性相位耦合分析中构造复杂的增广矩阵,并从根本上解决了通过分维求取频率之后,频率配对中所有可能产生的错误频率对,以及有可能产生的两维频率估计精度的不平衡性.仿真实验验证了本文的理论.     

乘性和加性噪声中二维谐波频率估计

噪声中的谐波恢复问题是信号处理领域的一个典型问题,在众多领域中有着广泛的应用。本文主要研究零均值乘性和加性噪声并存下的二维谐波信号频率估计问题,提出了一种基于数据矩阵的奇异值分解和子空间的旋转不变性的零均值乘性和加性噪声中的谐波频率的估计方法。乘性噪声为零均值情形下传统的估计方法往往难以直接应用或估计失效。本文利用谐波模型信号特征,通过对观测信号进行平方运算构造了一个数据矩阵。通过对数据矩阵的特征值进行理论分析,结合子空间旋转不变性,得到了零均值乘性和加性噪声中的谐波频率和数据矩阵之间的一种内在关系。这个性质可以用于零均值乘性和加性噪声并存下的二维谐波信号频率估计,并且所得的二维频率能自动配对。仿真实验验证了本文所提算法的有效性。      

复杂噪声背景下的谐波恢复及非线性耦合谐波分析

本文主要在乘性噪声之间相关、乘性和加性噪声之间也相关的复杂噪声背景下,研究谐波恢复及非线性耦合谐波分析,提出噪声互可混的概念,推广了有关非线性耦合谐波分析的结论,用特殊定义的六阶时间平均矩谱切片成功地解决了复杂噪声背景下的谐波恢复问题.仿真实验证明了算法的有效性.     

乘性和加性噪声中谐波恢复的循环统计量方法

本文从循环平衡的观点出发来研究乘性和加性噪声中的谐波恢复问题.首先，在一定条件下建立了一般复过程的有限长付里叶变换的大样本性质．然后，得到了任意阶循环矩的样本估计关于循环频率的一致收敛速度．对于乘性和加性噪声中的谐波信号，建立了一、二、三阶循环矩样本估计的统计性质．在此基础上，分别提出了基于不同阶循环矩的谐波分最个数和频率的估计方法，并得到了估计的强相容性质和强收敛速度，最后给出了模拟实验结果．     

乘性和加性噪声中谐波恢复和循环统计量方法

本文从循环平衡的观点出发来研究乘性和加性噪声的谐波恢复问题。首先，在一定条件下建立了一般复过程的有限长付里叶变换的大样本性质。然后，得到了任意阶循环矩的样本估计关于循环频率的一致收敛速度。对于乘性和加性噪声中的谐波信号，建立了一、二、三阶循环矩样本估计的统计性质。在此基础上，分别提出了基于不同阶循环矩的谐波分量个数和频率的估计方法，并得到了估计的强相容性质和强收敛速度，最后给出了模拟实验结果。     

Direction of Arrival Estimation in the Presence of Noise Coupling in Antenna Arrays

The direction of arrival (DOA) estimation problem in the presence of signal and noise coupling in antenna arrays is addressed. In many applications, such as smart antenna, radar and navigation systems, the noise coupling between different antenna array elements is often neglected in the antenna modeling and thus, may significantly degrade the system performance. Utilizing the exact noise covariance matrix enables to achieve high-performance source localization by taking into account the colored properties of the array noise. The noise covariance matrix of the antenna array consists of both the external noise sources from sky, ground and interference, and the internal noise sources from amplifiers and loads. Computation of the internal noise covariance matrix is implemented using the theory of noisy linear networks combined with the method of moments (MoM). Based on this noise statistical analysis, a new four-port antenna element consisting of two orthogonal loops is proposed with enhanced source localization performance. The maximum likelihood (ML) estimator and the Cramer-Rao lower bound (CRLB) for DOA estimation in the presence of noise coupling is derived. Simulation results show that the noise coupling in antenna arrays may substantially alter the source localization performance. The performance of a mismatched ML estimator based on a model which ignores the noise coupling shows significant performance degradation due to noise coupling. These results demonstrate the importance of the noise coupling modeling in the DOA estimation algorithms.     

基于伪逆算子的超分辨率信号处理方法研究

为了解决信号压缩过程中旁瓣串扰问题并提高参数估计时频率的估计精度,在研究超分辨信号处理理论的基础上,从框架理论入手,提出了可改善系统性能的恒噪声灵敏度分解算法。首先在基于矩阵表示的超分辨信号处理模型的基础上,采用矩阵伪逆算子,进行基于信号压缩的微波成像处理,讨论了伪逆算子应用于信号分解过程中的噪声性能;然后针对伪逆算子导致系统噪声增益增加的问题,通过根据信号处理的噪声指标要求设定处理门限,实现对信号的超分辨处理。仿真实验结果表明,该方法可消除匹配滤波类算法不可避免的旁瓣串扰问题,并可在一定程度上改善系统分辨率性能。     

Hybrid analytical modeling of noise coupling to signal traces in a power bus with embedded film capacitor

An accurate hybrid analytical method is proposed to determine the coupling of switching noise to signal traces in a multilayer power bus with embedded film capacitor. We used the induction equivalent theorem to derive the solution of noise coupling and the segmentation method to calculate the electric field of the noise in a power bus. The proposed method was verified by measurements of impedance parameters in the frequency domain.     

Multi-aggressor capacitive and inductive coupling noise modeling and mitigation

Crosstalk noise in on-chip interconnect plays a major role in the performance of modern integrated circuits. Multi-aggressor capacitive and inductive coupling complicates both the modeling and mitigation of the noise. A novel method to model and analyze noise in RLC multi-line structures is proposed in this paper, exhibiting an error of up to 9% as compared to SPICE. This method is physically intuitive since it decomposes the noise produced by each of the aggressors into individual capacitive and inductive noise sources. The proposed model and related layout noise mitigation guidelines are applied to crosstalk noise reduction in multi-line structures.     

Statistical approach to quantify the presence of phase coupling using the bispectrum

The bispectrum is a method to detect the presence of phase coupling between different components in a signal. The traditional way to quantify phase coupling is by means of the bicoherence index, which is essentially a normalized bispectrum. The major drawback of the bicoherence index (BCI) is that determination of significant phase coupling becomes compromised with noise and low coupling strength. To overcome this limitation, a statistical approach that combines the bispectrum with a surrogate data method to determine the statistical significance of the phase coupling is introduced. Our method does not rely on the use of the BCI, where the normalization procedure of the BCI is the major culprit in its poor specificity. We demonstrate the accuracy of the proposed approach using simulation examples that are designed to test its robustness against noise contamination as well as varying levels of phase coupling. Our results show that the proposed approach outperforms the bicoherence index in both sensitivity and specificity and provides an unbiased and statistical approach to determining the presence of quadratic phase coupling. Application of this new method to renal hemodynamic data was applied to renal stop flow pressure data obtained from normotensive (N = 7) and hypertensive (N = 7) rats. We found significant nonlinear interactions in both strains of rats with a greater magnitude of coupling and smaller number of interaction peaks in normotensive rats than hypertensive rats.     

利用希尔伯特变换进行谐波恢复

非高斯有色噪声中具有相位耦合的谐波恢复问题是迄今为止没有得到很好解决的问题，本文基于希尔伯特变换和高阶累积量提出一种新方法：ＨＢＳＴＣＨ－ＳＶＤ－ＴＬＳ。仿真实验表明，该方法不仅次好地解决了非高斯有色噪声中的具有二次相位耦合的谐波恢复问题，而且具有广泛的适用性。     

非高斯有色噪声中基于四阶累积量噪声建模的谐波恢复方法

本文提出一种在非高斯ＡＲＭＡ噪声中谐波恢复的高阶累积量方法，该方法首先通过Ｈｉｂｌｅｒｔ变换构造复数观测值，然后使用它的一种特殊的四阶累积量建立噪声过程ＡＲ参数，由此对观测值滤波，最后通过ＳＶＤ－ＴＬＳ方法估计谐波信号参数，本文方法克服了以往对非高斯噪声分布的非对称性假设，成功地解决了对称分布非高斯有色噪声中的谐波恢复问题，并且适用于于谐波信号存在二次相应耦合情形，仿真实验验证了文中结论。     

Mechanism of the noise reduction method by superposition ofhigh-frequency current for semiconductor injection lasers

Semiconductor injection lasers sometimes reveal excess noise called the mode hopping noise, which is associated with the mode hopping phenomena among longitudinal modes. The mode hopping phenomena are caused by coupling effects among lasing modes. To reduce this kind of noise superposition of high-frequency (HF) current on the injection current is frequently used. This reduction method is theoretically analyzed based on the mode competition theory and is compared with experimental measurements. It is confirmed that the coupling effect among the longitudinal modes is released with the HF superposition because of enhanced vibration of the injected electron, resulting in reduction of the mode hopping noise     

混合信号集成电路的衬底耦合噪声分析

本文系统分析了混合信号集成电路的衬底噪声耦合的研究进展.简要分析了衬底噪声的基本机理,及其对混合信号电路的影响,在此基础上分析比较了目前已提出的几种主要的衬底耦合噪声模型.通过分析不同类型衬底内的噪声耦合,介绍了一些电路设计中的去耦方法.最后讨论了衬底耦合噪声研究的发展方向.     

一种互耦和相干源条件下的DOA估计方法

空间平滑算法是一种常用的解相干处理方法,而阵元间互耦的存在会导致空间平滑算法失效,从而无法准确估计相干源DOA。针对这个问题,文中提出了一种新的DOA估计方法。该方法基于信号子空间和噪声子空间的正交性原理,利用入射信号源中的独立信号源可以有效估计出互耦矩阵,再通过估计的互耦矩阵对接收数据协方差矩阵进行互耦补偿,克服了互耦对空间平滑算法的影响,从而保证了相干源DOA能准确估计。计算机仿真实验表明了该方法的有效性。