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的校准

介绍了用于校准宽带取样示波器的详尽模型法和脉冲标准法 ,并指出了它们的缺陷。着重介绍了可以进行自校准的“NTN”技术 ,该技术的基本设计是将三台取样示波器以“NTN”形式两两对接 ,其中一台对直流进行采样 ,用反卷积分离另一台取样示波器的响应波形 ,并通过解方程组可得到示波器的冲激响应。最后给出了用反卷积分离取样示波器冲激响应的计算机仿真。     

基于NTN校准技术的脉冲标准法

脉冲标准法是校准宽带取样示波器的一种行之有效的方法,但它需要波形参数已知的脉冲信号源,当取样示波器的带宽很宽时,这种脉冲信号源是很难得到的。近年来发展起来的NTN校准技术可以不受带宽的限制,但是它只限于对某些结构的取样示波器的校准。提出了一种基于NTN校准技术的脉冲标准法,该法克服了上述限制,可以实现更多种类的宽带取样示波器的校准。实验结果表明,该方法是非常有效的。     

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。     

带有连接电缆的"NTN"校准技术

在利用“NTN”校准技术对取样示波器进行校准时，为保证校准精度，要求两台取样示波器的输入端直接对接。但在实际运用中，为方便起见，常常将两台取样示波器的输入端用电缆连接在一起。显然，电缆的接入。将对“kick-out”脉冲的响应波形产生影响，这就要求在数据处理中扣除电缆的影响。详细介绍了带有电缆的“NTN”校准技术的实验设置、数据预处理算法(包括去时基抖动处理、消除取样电路的非对称性的方法等)、“kick-out”脉冲的反卷积分离以及扣除电缆影响的算法。最后，给出取样示波器阶跃响应的波形并进行了评价。     

数字存储示波器上升时间的测量不确定度评定

介绍了用阶跃响应法评价数字存储示波器上升时间的测量不确定度分析与评定过程。讨论了主要的不确定度来源,包括信号源上升时间及其误差、示波器时基误差、示波器幅度测量误差、上升时间区间端点处波形曲线随变化率的影响,以及测量重复性等,给出了不确定度模型,以及减小不确定度的主要措施,并结合实例,给出了上升时间的不确定度评定结果。     

数字示波器直流电压测量及其不确定度评定

依据数字示波器校准规范,使用Fluke 9500B示波器校准仪对TDS 3032B数字示波器直流电压测量结果的不确定度进行了评定。分析了系统的不确定度来源,给出了用于现场校准结果的不确定度评定方法,并结合实际测量数据给出了数字示波器直流电压校准的不确定度分析。     

数字示波器参数示值误差的测量不确定度评定

示波器是一种直观、通用、精密的测量工具,对示波器校准的不确定度分析具有重要的意义。文章根据数字示波器校准规范提供的方法,对数字示波器脉冲幅度、周期、频带宽度、上升时间进行测量,并对测量结果的不确定度来源进行了分析,给出了用于现场校准结果的不确定度评定方法,并结合实际测试数据给出了数字示波器脉冲幅度、周期、频带宽度、上升时间校准的不确定度分析。经实践证明该方法准确、有效,可供撰写示波器检定装置建标报告和示波器脉冲幅度、周期、频带宽度、上升时间不确定度评定方面参考。     

非精确性测量数据的不确定度评定

基于D—S理论，提出了一种对非精确性的测量数据进行不确定度评定的方法。该方法首先计算非精确性数据的总不确定性，包括不具体性与冲突性之和，然后参照香农熵不确定度评定方法，建立总不确定性与不确定度的联系公式，最后计算不确定度。该评定方法同时适用于精确性和非精确性测量数据，是传统香农熵评定方法的广义形式，文中给出实例验证了其有效性。     

数字存储示波器垂直系统测量结果不确定度评定方法探讨

文章主要对数字存储示波器误差来源进行了分析,对测量方法及测量原理进行了阐述,探讨性的给出了数字存储示波器垂直系统关键技术指标测量结果不确定度评定的方法,并就整个不确定度的评定过程进行分析给出结论。     

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     

Broadband sampling oscilloscope characterization with the“Nose-to-Nose” calibration procedure: a theoretical andpractical analysis

In the past the “nose-to-nose” calibration procedure has been introduced as probably the most accurate method to determine the impulse response of broadband sampling oscilloscopes like the HP54124T. The method is based on the hypothesis “sampler kick-out equals oscilloscope impulse response”. This hypothesis was originally based on an intuitive approach and was later verified experimentally (comparison with power measurements) as well as with SPICE simulations. Until now, however, there was no generalized mathematical evidence supporting this basic hypothesis. In this paper a mathematical theory is developed, which starts from a generalized sampler equivalent scheme, and which shows that, under conditions which are valid in practice, the sampler kick-out indeed equals the sampler impulse response. Experimental results are reported concerning the accuracy and precision of the calibration procedure. These experiments involve the investigation of experiment repeatability, noise, sampler linearity and timebase effects     

Traceable Waveform Calibration With a Covariance-Based Uncertainty Analysis

We describe a method for calibrating the voltage that a step-like pulse generator produces at a load at every time point in the measured waveform. The calibration includes an equivalent-circuit model of the generator that can be used to determine how the generator behaves when it is connected to arbitrary loads. The generator is calibrated with an equivalent-time sampling oscilloscope and is traceable to fundamental physics via the electro-optic sampling system at the National Institute of Standards and Technology. The calibration includes a covariance-based uncertainty analysis that provides the uncertainty at each time in the waveform vector and the correlations between the uncertainties at the different times. From the calibrated waveform vector and its covariance matrix, we calculate pulse parameters and their uncertainties. We compare our method with a more traditional parameter-based uncertainty analysis.     

取样示波器nose-to-nose校准技术中kick-out脉冲的研究

研究了nose-to-nose校准技术中关键信号kick-out脉冲产生的机理以及影响因素,并通过将两台Agilent86100系列的50GHz的取样示波器对接,获得了kick-out脉冲的响应波形.     

Nose-to-Nose校准技术的仿真研究

Nose-to-nose校准技术可以对任意带宽的取样示波器进行自校准．早期的研究工作集中在对关键信号hick-out脉冲的仿真．本文从不同的角度对微波二极管取样头电路进行了全面的仿真,得到了结论：hick-out脉冲是由于在取样电路的不平衡时选通脉冲的泄漏造成的．并对NTN校准技术从仿真实验到物理实验做了介绍．     

宽带取样示波器时基误差补偿的新方法研究

时基误差严重影响宽带取样示波器的高精准测量,但对时基误差进行精确估计和补偿极为困难。针对宽带取样示波器的时基误差(含时基失真与抖动引起的误差),首次运用正交距离回归算法对宽带取样示波器时基误差进行估计。对比多相位、多频率最小二乘法,该方法仅用一组近似正交的正弦信号对宽带取样示波器的时基误差进行有效估计,实现了对测量信号的时基补偿,得出了低于0.3ps的时基误差,显著提高了宽带取样示波器测量准确度。     

Calculation of Pulse Parameters and Propagation of Uncertainty

The fundamental starting point for the analysis of all two-state waveforms is the determination of the low- and high-state levels. This is a two-step process. First, the data are grouped into points belonging to each state, and second, the value of each state is determined from the group mean, the mode, the median, or some other statistic. Once the state levels are determined, pulse parameters such as transition duration, amplitude, overshoot, and undershoot can be calculated. The IEEE 181-2003 Standard on Transitions, Pulses, and Related Waveforms recommends methods for grouping the data, determining the state levels, and determining pulse parameters, but gives no guidance for propagation of uncertainty, particularly in the presence of systematic and/or correlated sources of error. Correlations are important because certain pulse parameters, such as transition duration and pulse duration, are invariant with respect to, e.g., multiplicative error, which is correlated highly. We propose a new procedure for determining the pulse states that involves clustering the data and then using a robust location estimator to determine the state level. This technique allows the propagation of uncertainty from the covariance of a sampled waveform representation all the way to the calculation of pulse parameters. We use Monte Carlo simulations to verify the proposed procedure for some canonical pulse waveforms.