Jitter in synchronous residual time stamp

This paper presents jitter characteristics of synchronous residual time stamp (SRTS) used in ATM adaptation layer (AAL) type 1. It is pointed out that low frequency jitter appears at the receiver output of SRTS, similar to pulse stuffing synchronization. The jitter waveform in the SRTS is presented together with its Fourier series representation, and the low frequency jitter amplitude is determined. There is a parameter called the residue that plays the same role as the stuffing ratio in pulse stuffing synchronization, where the low frequency jitter amplitude exhibits a peak when the residue is a rational number. It is shown that the jitter waveform and the low frequency jitter amplitude are somewhat different from those obtained by the analog with pulse stuffing synchronization. The dependencies of the low frequency jitter amplitude to some parameters are also considered. It appears that the higher the reference frequency, the smaller the resulting low frequency jitter amplitude. Some numerical examples are given to demonstrate the validity of the analysis     

Modeling of the synchronization process jitter spectrum with inputjitter

The synchronous residual time stamp (SRTS) is one approach approved for the encoding and transporting of the continuous bit rate (CBR) service clock in ATM Adaptation Layer 1 (AAL1) allowing CBR services to be transported in ATM cells over the B ISDN. It has been shown by the authors and others that the SRTS method generates waiting time jitter analogous to that produced by other synchronization processes such as pulse stuffing synchronization. Modeling of the synchronization process as it applies to the SRTS method requires a time domain approach to produce an exact expression of the jitter. In this paper, we apply a new time domain analysis technique previously developed by the authors to derive the expressions for the jitter spectrum of the synchronization process in the presence of input jitter on the service clock. Furthermore, the particular form taken by the jitter spectrum when the input jitter is sinusoidal is also found. Experiments verifying the synchronization process jitter spectrum, both with and without sinusoidal input jitter, are reported. Confirmation is also provided that it is possible to approximate timing jitter by phase jitter as long as certain frequency-amplitude limits are observed     

Non-Compressed Video Signal Optical Transmission Equipment and Its Applications for Studio to Transmitter Link (STL)

This paper describes the newly developed video signal transmission equipment for Synchronous Optical Network (SONET) and the Synchronous Residual Time Stamp (SRTS) method for video signals. It explains why a low jitter signal transmission is possible by optimizing the SRTS parameters and reducing high frequency jitters by PLL circuit. Moreover, the broadcasting Transport Stream (TS) signal transmission methods for Studio to Transmitter Link (STL) are reviewed and the proposed reference clock transmission method is discussed. The TS signal transmission experiments are carried out using two route trunks between Sapporo and Asahikawa, for evaluating the characteristics of the reference clock, the modulator output signal, and the quality of the received video. The low jitter and error-free video signals transmission is realized in these trunks     

Analysis and Simulation of Jitter Sequences for Testing Serial Data Channels

This paper presents a novel modeling analysis of jitter as applicable to testing of serial data channels. Jitter is analyzed by considering separate and combined components. The primary goal is the generation of a signal containing a known amount of each jitter component. This signal can then be used for testing high speed serial data channels. Initially, jitter components are analyzed and modeled individually. Next, sequences for combining them are modeled, simulated and evaluated. Model simulation using Matlab is utilized to show the unique features of the components when they are combined into different injection sequences for producing the total jitter. Sequence dependency is investigated in depth and the validity of superposition of jitter components for typical values is confirmed. A good agreement between theory and simulation is verified; these results allow test engineers to have an insight into the interactions among jitter components in serial data channels.     

System reduction by continued-fraction expansion about s=j?i

A method of system reduction using the continued fraction expansion about arbitrary points on the real frequency axis is proposed. It gives a good approximation and the procedure is suitable for digital computation.     

ATM网络中电路仿真业务定时恢复的改进方法

ＡＴＭ技术很好地解决了数据的透明传送问题，但定量信息在ＡＴＭ网中的传递透明性由于统计复用而受到损害，目前用于电路仿真精力的定量恢复方法根据是否使用公共时钟大致分为同步和异步两种模式，由于ＳＤＨ网的推广，同步方式已ＩＴＵ－Ｔ采用，主要有ＳＦＥＴ、ＴＳ和ＳＲＴＳ三种，由于ＡＴＭ业务的多样性，它们最大都有可能引入ＩＵＩ的低频抖动，本文提出了一种改进方法，首次将２级∑－△量化应用于定量恢复，可使任何业务的     

A matrix method for continued fraction inversion

Previously used methods for converting a continued fraction function into a rational transfer function have been restricted to a special kind of continued fraction. This letter presents a method for inverting a general fraction; each partial quotient including the remainder could be a polynomial of s or s^-1or both.     

Clock jitter error in multi-bit continuous-time sigma-delta modulators with non-return-to-zero feedback waveform

This paper presents a detailed study of the clock jitter error in multi-bit continuous-time ΣΔ modulators with non-return-to-zero feedback waveform. It is demonstrated that jitter-induced noise power can be separated into two main components: one that depends on the modulator loop-filter transfer function and the other dependent on input signal parameters, i.e. amplitude and frequency. The latter component, not considered in previous approaches, allows us accurately to predict the resolution loss caused by jitter, showing effects not taken into account previously in literature despite the fact that they are especially critical in broadband telecom applications. Moreover, the use of state-space formulation makes the analysis quite general and applicable to either cascade or single-loop architectures. Closed-form expressions are derived for in-band error power and signal-to-noise ratio that can be used to optimize modulator performance in terms of jitter insensitivity. Time-domain simulations of several modulator topologies (both single-loop and cascade) intended for VDSL application demonstrate the validity of the presented approach.     

I and Q decomposition of self-noise in square-lawclock regenerators

A method for obtaining power spectra for the self-noise components in phase and in quadrature to the desired generated clock signal for PAM systems is described. A previously recognized cross spectrum is also discussed. Results can be expressed either in a closed form or as the sum of rapidly convergent series, depending on the signalling waveform used. A computation of the in-phase and quadrature spectra for Nyquist pulses for excess bandwidth factors ranging from 0.1-0.9 is included, along with demonstration showing that for signalling waveforms with even or odd symmetry, cross power spectrum is zero at all frequencies. It is also shown that if the cross power spectrum is not zero due to asymmetry in the signalling waveform, sampling keyed to other than zero-crossing of the timing wave can give a lower timing jitter     

Timing Extraction in Baseband Pulse Transmission

Timing extraction through nonlinearity in the presence of pulse overlaps is studied for baseband PCM or PAM systems. It is shown that the systematic jitter can be reduced by proper choices of nonlinearity, coding scheme, and pulse waveform. Discussions on choice of nonlinearity indicate that square-law rectification is desirable for elimination of jitter sources. This nonlinearity derives a frequency-domain expression for amplitude and phase of the timing wave that separates the effects of pulse pattern and pulse shapes and provides insight to their contributions to timing jitter. Proper choices of coding scheme and pulse waveform reduce amplitude and phase variation in the timing wave. For example, an optimum prefiltering (or correlative coding) reduces amplitude variation to one eighth for bipolar sequence. In the case of symmetrical reshaping by a Bessel (flat delay) filter, the maximum jitter exceeds 20 degrees if the order of a filter is less than ten. An asymmetrical reshaping makes the maximum jitter less than four degrees for the same order of filter. Some features of nonlinearities that approximate square-law rectification are discussed.     

A General Spectral Analysis of Time Jitter Produced in a Regenerative Repeater

A general theory is presented for evaluating the spectral density of time jitter produced in a self-timed regenerative repeater. The timing circuit consists of a general memoryless nonlinear device followed by a narrow-band tank circuit tuned as close as possible to the symbol rate; the signal (timing wave) at the output of the circuit has both amplitude and phase modulations that cause the timing error (jitter). The theory includes the cases of arbitrary pattern statistics, pulse waveform, and nonlinear processing, in contrast to previous work which is strongly limited to the assumptions of pattern symbol independence and particular nonlinearities. The time jitter is treated as a discrete-parameter random process and its spectral density is finally related to the input message statistics, pulse waveform, and timing circuit parameters. In most cases the spectral density turns out to be a rational function of exp (j2pifT),fbeing the frequency andTthe symbol period. Hence, a spectral factorization can be obtained that leads to a useful linear equivalent circuit of the timing (nonlinear) circuit (NLC). This last feature is illustrated by three examples.     

Arithmetic coding in lossless waveform compression

A method for applying arithmetic coding to lossless waveform compression is discussed. Arithmetic coding has been used widely in lossless text compression and is known to produce compression ratios that are nearly optimal when the symbol table consists of an ordinary alphabet. In lossless compression of digitized waveform data, however, if each possible sample value is viewed as a “symbol” the symbol table would be typically very large and impractical. the authors therefore define a symbol to be a certain range of possible waveform values, rather than a single value, and develop a coding scheme on this basis. The coding scheme consists of two compression stages. The first stage is lossless linear prediction, which removes coherent components from a digitized waveform and produces a residue sequence that is assumed to have a white spectrum and a Gaussian amplitude distribution. The prediction is lossless in the sense that the original digitized waveform can be recovered by processing the residue sequence. The second stage, which is the subject of the present paper, is arithmetic coding used as just described. A formula for selecting ranges of waveform values is provided. Experiments with seismic and speech waveforms that produce near-optimal results are included     

一种快速计算雷达散射截面空域特性的方法

将最佳一致有理逼近理论和矩量法（MoM）相结合,提出了一种新的二维外推技术并对任意形状复杂目标雷达散射截面的空域二维特性进行了快速计算。与渐进波形估计（AWE）技术相比,Maehly逼近的优势在于不需要计算阻抗矩阵元素的高阶导数,能在更宽的范围内精确逼近MoM计算结果,并且很容易和MoM计算机代码相结合。与MoM逐点计算相比,Maehly逼近结合MoM能有效地提高计算效率。数值结果表明Maehly逼近结合MoM与MoM逐点计算的结果吻合良好,证明了该方法的有效性。     

任意波形发生器ROM查找表的设计

基于直接数字合成器(DDS)技术设计的任意波形发生器中,ROM查找表是DDS模块的一个重要环节,主要用于存储系统的波形数据。介绍使用C语言、Matlab和DSP Builder三种方法生成正弦波、三角波、锯齿波和方波的查找表初始化波形数据,并对每一种方法的程序设计、参数设置以及波形仿真都作了详细说明,所有波形数据均在GW48 SOPC开发系统中测试通过。     

Reconstruction method for jitter tolerant data acquisition system

A waveform digitizing system tolerant to deterministic jitter can be obtained by isolating the deterministic part of the jitter and calibrating the system to eliminate its effects. Calibration of the system can be made from measured nonuniform sampling times. It will be shown that this information allows reconstructing the signal at uniformly spaced sampling times. To reconstruct a signal from its nonuniform samples, we use the Shannon expansion combined with a time stretching/compressing method. Moreover, the reconstruction of a signal from a finite number of samples introduces a truncation error. We propose, using a windowing technique, to reduce the truncation error, which improves considerably the resolution, or the number of effective bits of an analog to digital conversion system.     

基于微波光子学的倍频三角波生成方法

为了克服传统任意波形生成方法中电子瓶颈问题，分析了基于微波光子学的射频任意波形的技术类型、特点和应用背景，采用一种基于并联马赫-曾德尔调制器的倍频三角波生成方法，引入均方根误差对输出信号和理想波形来评价，并进行了理论分析和仿真验证。结果表明，通过10GHz驱动信号生成了20GHz的三角波信号，均方根误差为0.038，即输出信号与理想信号吻合度较高; 与其它方法相比，该方法可生成倍频三角波，信号波形与理论波形吻合度良好。该研究对未来基于微波光子学的射频任意波生成有指导意义。     

渐近波形估计技术用于介质柱宽角度RCS的计算

基于渐近波开估计（AWE）技术和矩量法（MOM）快速预测任意形状非均匀介质柱体的单站雷达散射截面RCS方向图,采用矩量法求解介质柱的电场积分方程,得到介质柱在某一给定方向入射波照射下的极化电流,然后利用AWE技术将任一角度入射波照射下的极化给定角度附近展开成Taylor级数,通过Pade逼近将Taylor级数转化为有理函数,由此可获得介质柱在任一角度入射波照射下的极化电流,进而计算出RCS方向图。计算结果表明AWE完全能逼近MOM精确计算的曲线,同时可加快计算速度。     

斜程大气传输光束孔径平滑到达角与像点起伏

像面到达角起伏、波面抖动和像点抖动通常是研究大气干扰情况下高分辨成像系统波前特性的重要方法之一。采用Rytov近似、包含湍流内外尺度影响的修正von Karmam近似谱和接收光学系统孔径滤波函数和传输权重函数中的Airy函数的高斯函数近似,研究了斜程湍流大气中传输束状波的波面抖动、像面到达角起伏和像点抖动规律,导出了圆孔接收系统测量到的包含湍流内外尺度影响的束状波孔径平滑波面抖动、像点抖动和像面到达角方差理论模型。     

Minimisation of timing jitter in CDMA code tracking

A method for chip waveform design that minimises the tracking jitter in code division multiple access (CDMA) synchronisation is presented. The method is based on the use of prolate spheroidal wave functions. Examples of optimised waveforms are given and their performance compared to other conventional pulse shapes in terms of timing error variance and bandwidth occupancy.