基于EEMD算法的高速取样示波器时基抖动的去除

高速取样示波器对信号取样时会产生明显的时基抖动，造成信号失真，可以将其看成是一种随机噪声，因此去除时基抖动是测量数据分析时的难题。本文在传统中值法、中值改进法、PDF反卷积法和综合法去除时基抖动的基础上，提出了利用EEMD算法解决时基抖动的思路。本文详细地介绍了EEMD基本原理，通过标准正弦信号仿真验证了该方法的可行性，并对实际测量数据进行了处理，这些结果均表明EEMD算法去除时基抖动的有效性。     

基于光脉冲源的脉冲标准法中的时基漂移去除

时基漂移是影响取样示波器在时域精密测量高速脉冲信号的关键因素,所以要尽可能设法去除。本文研究以示波器86100C取样模块86118为设备背景,首次利用互相关算法对实时采集的数据,进行了去除时基漂移的研究,并用反卷积技术实现了示波器的校准。研究结果表明,互相关算法去除时基漂移效果明显、优于其他算法,并在一定程度上提高了光脉冲法校准示波器的校准准确度。     

高速采样示波器中的时基失真及其估计

介绍了时基失真的概念及产生原理。改进了美国NIST提出的时基失真的数学模型，据此模型仿真出时基失真的数据，进而仿真出测量数据。给出了为估计采样示波器的时基失真所采取的方法——最小二乘法。这种方法需要在多相位、多频率上测量信号，可以精确地估计谐波模型的阶数。最后介绍了如何根据已经得到的估计值来修正时基失真。     

数字存储示波器时基失真与采样抖动的评价研究

提出了数字存储示波器采样间隔抖动和采样时基失真的一种时域评价方法.通过两段正弦波形段的滑动拟合结果,使用两者间对应点相位上的差异,实现了采样间隔的测量,获得其抖动波形和时基失真的测量结果.在一组仿真数据上进行了实验验证,并揭示了量化误差对抖动评价影响的规律,以及抖动测量结果的周期性变化规律.在数字存储示波器的实测数据上进行了实验验证,获得了有效的抖动波形结果.该方法可以用来观察和比较采样间隔的抖动以及采样时基失真特性.     

一种基于LMS的振动信号相位差自适应无偏估计方法及应用

针对振动信号相位差估计问题,提出了一种基于LMS的自适应无偏估计方法。该方法通过一路信号与其正交的三角运算来配准另一路信号,相位差的正切值等于两个配准系数之比;根据均方误差最小原则对配准系数进行迭代更新,从而实现相位差自适应估计;理论推导出噪声引起的估计偏差,并据此对估计结果进行偏差补偿,实现相位差无偏估计,给出了补偿公式和方法流程。实验结果表明:该方法能准确估计出两路同频振动信号相位差,经偏差补偿后估计精度显著提高;在相位差发生突变时,能进行快速跟踪测量,具有较好动态测量特性;该方法在变化流量下科氏流量计振动信号相位差估计中的应用,验证了方法的工程实用性。     

基于NTN技术的宽带取样示波器带宽不确定度的研究

NTN技术是一种校准宽带取样示波器的新方法,其提供的测量量是kick-out脉冲响应(显示)波形数据,而宽带取样示波器的带宽是对kick-out脉冲响应波形数据进行反卷积分离等处理获得的导出量.提出了一种基于NTN技术的宽带取样示波器带宽不确定度的评定方法.首先分析了NTN技术引入不确定度的主要因素;然后提出了由测量量导出带宽的不确定度的传递算法流程,并推导了线性内插的不确定度传递算法;最后给出了宽带取样示波器带宽不确定度的评定结果.     

基于NTN技术的宽带取样示波器过渡时间不确定度的研究

NTN技术是一种校准宽带取样示波器的新方法,NTN技术提供的测量量是kick—out脉冲响应（显示）波形数据,而宽带取样示波器的过渡时间是对kick—out脉冲响应波形数据进行反卷积分离等处理才能获得的导出量。提出了一种基于NTN技术的宽带取样示波器过渡时间的不确定度的全面评定方法。首先分析了NTN技术引入不确定度的主要因素,给出了不确定度计算公式;然后结合数据处理过程推导出不确定度的传递算法;最后给出了宽带取样示波器过渡时间不确定度的评定结果。     

模拟示波器扫描线性误差的不确定度评定

主要对模拟示波器扫描线性误差指标测量不确定度进行分析和评价,讨论了影响示波器扫描线性误差测量不确定度的主要来源,包括示波器校准仪时标信号误差、示波器读值误差和读值重复性的影响等,并通过一个模拟示波器的评价实例,给出了扫描线性误差测量不确定度分析和评价结果。     

一种用于宽带取样示波器的幅值校准方法

取样示波器采用顺序等效采样原理,可以实现对高速稳定信号进行采样、波形恢复、信号质量分析等,在高速通信、信息对抗等领域有广泛应用。但作为取样示波器核心器件的取样器,采用双肖特基二极管对称结构,因器件、布局布线等非对称性,导致差分输出的两路信号存在偏差等,造成测量波形的不准确。为更加准确地重建被测信号的真实值,提出一种基于最小二乘法的二进制幅值校准方法。通过实验验证,此方法能够准确计算校准系数,实现对幅值的校准,相对误差在1%以内,并且在采样点数较少的情况下仍然适用。结果表明,此方法可以用于宽带取样示波器的幅值校准。     

基于NTN技术的宽带取样示波器自动校准系统

与其它宽带取样示波器校准技术相比,NTN校准技术能够精确地获得取样示波器的冲激响应和复传递函数。但是,由于NTN校准技术要求两台取样示波器的输入端直接对接,这样就很难通过前面板对取样示波器进行操作。为此,介绍了一种基于NTN校准技术的宽带取样示波器自动校准系统,并详细介绍了系统的组成、功能及校准结果。该系统的整个校准工作是在PC机控制下完成的。     

Time-base nonlinearity determination using iterated sine-fitanalysis

A new method is presented to determine the time-base errors of sampling instruments. The method does not require a time-base error model and thus provides accurate estimates where model-based methods fail. Measurements of sinewaves at multiple phases and frequencies are used as test signals. A harmonic distortion model is used to account for amplitude nonlinearity of the sampling channel. Use of an independent method for estimating the channel noise and jitter allows an accurate estimate of the harmonic order. Methods are presented for separating the harmonics generated by the sampling channel from those generated by the time-base distortion. The use of an iterative sine-fit procedure gives accurate results in a short time. A new weighting procedure is described, which minimizes the error in the estimates. Guidelines are given for selecting good sets of test frequencies. Results are shown for both simulated and real data     

Noniterative waveform deconvolution using analytic reconstructionfilters with time-domain weighting

A new deconvolution approach is described for reconstructing fast, step-like, or impulsive signals that have been measured with a sampling oscilloscope for which an impulse response estimate is available. The approach uses analytic reconstruction filters to control noise amplification and a new noniterative filter optimization that is based on a calculated “indicated error” function that is similar in shape to the true error. The new method aids in reporting uncertainties of the deconvolution results and it permits the use of time-domain weighting to optimize the measurement of different waveform features, The performance of the proposed approach is compared with that of the error energy/regularization approach that is currently popular     

On the determination of dynamic errors for rise time measurementwith an oscilloscope

The dynamic behavior of an oscilloscope is usually described by its bandwidth, which is not sufficient for well-founded error estimation for rise time measurement. Two rules of thumb have become most common that describe (a) a relation between bandwidth and rise time of an oscilloscope and (b) an estimation of the error resulting from the rise time limitation of the oscilloscope. Although it is well understood that these rules are approximations, no information on their accuracy and extent of validity appears in the literature. In this paper, we analyze these rules of thumb with their underlying assumptions and respect a more realistic model for oscilloscope behavior. We give accurate error estimates for a selection of typical input signals, show how well the rules perform for these signals and that, although the rules provide good upper bounds for the error, they can not be reliably used for error correction     

Improved Bias Supply for Tunnel-Diode Picosecond Pulse Generators

An improved bias supply for tunnel-diode (TD) picosecond-pulse generators is described. The supply is stable with temperature and, in a commercial 35-ps (nominal) risetime tunneldiode pulse generator/sampling oscilloscope system, has produced a 4:1 reduction in time-base jitter and 2:1 reduction in time-base drift. Also described is a tunnel-diode pulse generator, which, when used with the bias supply, produces a stable pulse having a flat-top sag of no more than 2 percent in 1 ?s.     

Measuring Time Base Distortion in Analog-Memory Sampling Digitizers

High-frequency digital oscilloscopes are often prone to systematic errors in sampling time or time base distortion (TBD). This error greatly affects the quality of the acquisition of fast signals, but its systematic nature makes measurement and correction possible and greatly advantageous. Existing techniques for measuring TBD exhibit good performance with equivalent-time sampling digitizers, but they are not able to measure the distortion in real-time analog-memory systems - a technology of widespread use in modern gigasamples/second sampling scopes. This paper illustrates the correct measurement technique that was developed according to the hardware peculiarities of analog-memory sampling digitizers. The performance of the developed techniques are theoretically evaluated and practically demonstrated in the experimental characterization of an actual real-time analog-memory scope.     

Improved time-base for waveform parameter estimation

An improved gated oscillator time-base and associated auto-calibration algorithm for use in a high-accuracy sampling waveform acquisition system are described. The time-base architecture consists of a stable 100 MHz gated oscillator, 24-bit counter chain, and a clock period interpolator. The nominal, uncorrected linearity of the time-base is approximately ±30 ps. By using an iterative, sine-fit based algorithm, the linearity has been improved to <5 ps. Details of the performance and major sources of error of the time-base and correction algorithm in an equivalent time sampling system are also discussed     

A fast-pulse oscilloscope calibration system

A system is described for calibrating high-bandwidth oscilloscopes using pulse signals. The fast-pulse oscilloscope calibration system (FPOCS) is to be used to determine the step response parameters for digitizing oscilloscopes having bandwidths of ~20 GHz. The system can provide measurement traceability to standards maintained at the U.S. National Institute of Standards and Technology (NIST). It comprises fast electrical step generation hardware, a personal computer (PC) and software, and a reference waveform, i.e., a data file containing an estimate of the step generator output signal. The reference waveform is produced by prior measurement by NIST of the step generator output signal (calibration step signal). When the FPOCS is in use, the calibration step signal is applied to the device under test, which is an oscilloscope sampling channel. The measured step waveform is corrected for timebase errors, then the reference waveform is deconvolved from it. The results are impulse, step, and frequency response estimates, and their associated parameters (e.g., transition duration, transition amplitude, -3 dB bandwidth) and uncertainties. The system and its components are described, and preliminary test results are presented     

相关时延估计误差对测频误差的影响

声学多普勒测速技术采用宽带编码信号进行多普勒频移估计时会产生测频误差,该误差来源主要分为两种：（1）宽带信号频谱不对称;（2）相关时延存在估计误差。文章主要讨论相关时延估计误差对测频误差的影响,分析了其产生的原因以及该误差对测频误差的影响。忽略相关函数简化误差以及滤波后频点不对称,推导得到由相关时延估计误差导致的测频误差的解析式。进行了仿真和湖试数据分析,不同频移下的测频误差与理论测频误差一致,不同填充系数下的实际测速误差与理论测频误差变化趋势相同。该对比结果验证了相关时延估计误差会对测频误差产生影响,证明了由相关时延估计误差导致的测频误差的解析式可信。