The Cyclostationary Nature of Crosstalk Interference from Digital Signals in Multipair Cable--Part I: Fundamentals

This paper considers the cyclostationary nature of digital signals when determining crosstalk interference between such signals in multipair cable. This approach is necessary as the interference is only relevant at the decision instants in the receivers of the disturbed systems and any time variation of this interference with respect to the sampling instants changes the effect of this interference; previous studies in the area have ignored the cyclostationary nature of the digital signal. Expressions for the time-varying mean and variance of far-end and near-end crosstalk (FEXT and NEXT) have been derived. These expressions demonstrate the inherently smaller time variation of the NEXT interference when compared to the FEXT interference. An interesting result is that the calculation of the time-averaged value of the variance of FEXT and NEXT interference still requires the use of the cyclostationary properties of the digital signal. The results of this paper are extended and applied to various examples of the engineering of digital line systems in multipair cable in Part II of this paper.     

Design Criteria for Crosstalk Interference Between Digital Signals in Multipair Cable

This paper proposes design criteria for the crosstalk interference between digital line systems operating in multipair cable, with plesiochronous and synchronous network configurations. Existing solutions are shown to be appropriate in some cases, in some other cases to be based on imperfect design criteria, and in other cases, such as the plesiochronous case, to be absent. For engineering purposes, the application of a 3 dB additional margin to the design criterion based on the classical solution should be adequate for practical application in the network.     

Statistics of Impulsive Noise Crosstalk in Digital Line Systems on Multipair Cable

Crosstalk theory is applied to the prediction of error rates in digital line systems due to analog telephony signaling events on adjacent pairs in the same cable. Measurements of the margin against impulsive noise at a given probability of error have been performed, and these show reasonable agreement with predictions based on crosstalk theory. For a simple switching event, the regenerator NEXT impulsive noise figure for the near-end crosstalk path is defined. Measurements of the mean and variance of near-end crosstalk attenuation are then used to calculate the maximum exchange section loss (from central office to first line regenerator) which satisfies a suggested error performance criterion.     

Error Probability in the Presence of Intersymbol Interference and Additive Noise for Multilevel Digital Signals

A new method is presented to compute the average probability of error in the presence of intersymbol interference and additive noise for multilevel pulse-amplitude-modulation (PAM) and partial-response-coded (PRC) signaling schemes. The method is based upon nonclassical Gauss quadrature rules (GQR) and suffers no limitation on noise statistics, so that it applies also for non-Gaussian noise. Moreover it yields some remarkable advantages as compared with other methods, in particular, with the series expansion method that has recently received considerable attention. Expressions for the truncation error are also given and their derivation is reported in the Appendix. Finally, examples of applications are presented and comparisons with other methods are carried out.     

The Structure of General Interference Functions and Applications

This paper provides a theoretical framework for the analysis of interference-coupled multiuser systems. The fundamental behavior of such a system is modeled by interference functions, defined by axioms “nonnegativity, ”scale-invariance,” and “monotonicity.” It is shown that every interference function has an interpretation as the optimum of a min-max problem, where the optimization is over a closed comprehensive positive coefficient set. This provides new insight into the structure of general interference functions and its elementary building blocks. Conversely, it is shown that every closed comprehensive positive set can be expressed as a level set of an interference function. This shows a close connection between the analysis of interference functions and multiuser performance regions, which are typically closed comprehensive. The generality of this framework allows for a wide range of potential applications. As an example, we analyze the problem of interference balancing.      

高速数字通信中的远端串扰建模分析

当今电子产品不断更新换代,性能不断提升,需要处理的数据量不断增大,信号的速度也随之越来越快,印刷电路板（PCB）的面积反而越来越小。这就导致信号线的密度越来越大,不同信号线之间信号就会出现相互影响,也就是串扰。针对高速数字通信系统中传输链路之间的信号间串扰,建立等效电路模型,推导出远端串扰噪音的计算公式,提出改善措施,并最终使用HSPICE进行了仿真验证。     

Prediction of Crosstalk in Ribbon Cables: Comparison of Model Predictions and Experimental Results

The prediction of crosstalk in ribbon cables is investigated. Experimental results are obtained for a 20-wire ribbon cable and compared to the predictions of the multiconductor transmission line (MTL) model. Based on the experimental configuration tested, it would appear that accurate predictions of crosstalk can be achieved in these controlled-characteristic cables. The prediction accuracies are typically within ±1 dB for frequencies such that the line is electrically short and ±6 dB for frequencies such that the line is electrically long. It was found that the parasitic wires in the cable can have a significant effect (as much as 40 dB) on the coupling between a generator circuit and a receptor circuit in the cable. Therefore, to achieve accurate predictions in ribbon cables, one must consider the interactions between all wires in the cable. The wire insulation evidently cannot be ignored for frequencies such that the line is electrically long. The impedance of the reference wire cannot be ignored for low frequencies where the common-impedance coupling dominates the electromagnetic-field coupling.     

调频信号的数字合成方法

调频信号作为一种常见信号在电子技术的各个领域，特别是通信领域有着广泛的应用。因此调频信号的合成就成为了其中关键性的一项技术。传统的调频信号通常是通过模拟方法合成的。但是模拟合成有频率不稳定、参数设置不可量化等缺点，而用数字合成的方法就可以解决这些问题。数字频率合成通常采用DDS技术，调频信号的数字合成也基于这项技术。本文首先介绍了DDS的基本原理。然后提出用双DDS结构实现调频信号数字合成的方法。由于把调制波形的幅度量化成了频率字，构成了一个输出频率字的DDS。因此只要改变这个DDS波形RAM中的数据。就可以产生任意以周期信号为调制波形的调频信号，并且调制频率和深度都精确可调。     

数字波束形成天线旁瓣对消性能分析

本文分析了干扰信号带宽、通道幅相误差以及Ａ／Ｄ变换器的量化噪声等对数字波束形成的干扰对消效果的影响，给出了由于这些因素产生的剩余干扰功率的解析表达式及数值计算结果。     

BER Analysis of BPSK Signals in Ricean-Faded Cochannel Interference

The bit error rate of a binary phase shift keying (BPSK) signal in Ricean-faded cochannel interference is studied. A precise bit error rate expression is derived for a bandlimited BPSK signal corrupted by an arbitrary number of asynchronous Ricean-faded interfering signals. An error rate estimation based on a saddlepoint approximation is also provided. It is shown that this approximation is highly accurate. For the special case, when there is one synchronous Ricean-faded interfering signal in an interference-limited environment, an asymptotic error rate analysis based on the saddle point approximation reveals that fading in the cochannel interfering signal can have different impacts on the desired user's error rate performance. Our study shows that when the signal-to-interference ratio (SIR) is sufficiently large, the error floor of the desired user signal decreases with an increase of the Rice factor in the interfering user's fading channel. However, the opposite phenomenon can happen when the SIR is small.     

Closed-Form Analytical Results for the Rejection of Narrow-Band Interference in PN Spread-Spectrum Systems--Part II: Linear Interpolation Filters

The performance of PN spread-spectrum communication systems in the presence of narrow-band interference is studied when linear interpolation filters are employed for the estimation and subsequent suppression of the interference. Closed-form analytical expressions for the system's performance are established for a broad class of interference processes. The advantages of linear interpolation filters over predictive filters with identical number of taps are examined analytically and some unexpected results are obtained. The analytical results are illustrated by examples.     

数字家庭无线网络技术的干扰性研究

随着3C融合的不断深入,将会越来越容易地将家庭中的电子产品连接成网络。数字家庭的无线技术对家庭音响、游戏机、电视机、DVD等家用电器设备在处理声音、图像和视频等不同的领域各具优势。论文以数字家庭为背景,分析了无线网络技术之间的干扰问题,进行了系统化的定性分析,并对UWB对IEEE802.11a之间的干扰进行了定量的仿真,引出研究数字家庭无线网络技术之间干扰的重要性。     

An Analysis of a Real-Time Transform Domain Filtering Digital Communication System--Part II: Wide-Band Interference Rejection

Employing the technique of transform domain filtering described in Part I of this paper, a system is presented to detect a binary spread-spectrum signal embedded in a wide-band, stationary, colored Gaussian noise process. Using a specific example of a colored noise process, the performance of the system is analyzed. In addition, a specific technique using surface acoustic wave devices is presented which allows the estimation of the spectral density of the interference when such information is initially unknown.     

数字电视信号的发射与接收技术

系统地讨论了数字电视信号的发射及接收技术。稳定可靠的信号源与抗扰性能良好的传输方式是保证图像质量的前提,快速无失真的编解码是接收机的基本工作要求。只有从发射到传输再到接收均能保证高质量的工作,才能使数字电视信号真正地实现系统级的应用。文中分别对这3个环节进行了阐述,并展望了数字电视信号处理系统未来的发展方向     

滤波器在抗电磁干扰中的应用

扼要介绍各种滤波器在抗电磁干扰中的应用。     

单纤双向模数信号混传系统原理及应用

介绍了一种实用的单纤双向模数信号混传光纤传输系统的原理及特点,该系统采用不同波长的同种光源, 通过双向波分复用解复用器,可在一根单模光纤中同地同时单向传输模拟彩电信号和逆向传输数字信号。     

基于65nm工艺数字IC物理设计中信号串扰的预防

数字集成电路的不断发展和制造工艺的不断进步,使得物理设计面临着越来越多的挑战.特征尺寸的减小,使得后端设计过程中解决信号完整性问题是越来越重要.互连线间的串扰就是其中的一个,所以在后端设计的流程中,对串扰的预防作用也显得尤为重要.本文就TSMC 65nm工艺下,根据具体的设计模块,探索物理设计流程中如何才能更好的预防串扰对芯片时序的影响.