Computer Augmented Oscilloscope System

The Computer Augmented Oscilloscope System (CAOS) is a laboratory-computer terminal intended for experiments involving waveforms and their interpretation. The terminal is portable and can be used wherever telephone access to a suitably programmed computer is available. The CAOS laboratory equipment includes a sampling oscilloscope with a storage CRT, the terminal proper, and a telephone line connection. The terminal includes alphameric and function keyboards, A/D and D/A converters, a read-only store character generator, sequencing and control logic, and circuits for interfacing to the oscilloscope and the telephone line. CAOS is an interface between the experimenter, the experiment, and the computer. It provides digital acquisition of waveform data, system calibration, data analysis, experiment control, and graphic and alphameric display. CAOS can emulate a number of laboratory instruments and can operate additional X-Y storage oscilloscopes.     

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。     

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。     

一种调制度测量仪的数字化精确评价与溯源方法

提出一种调制度测量仪校准方法,对低频载波情况,直接使用数字示波器进行采集测量,用软件无线电方式解调分析,获得调制域参数。对高频载波情况,首先用下变频技术将其转换成低频载波情况,然后进行测量、解调分析,并给出了详细过程。以此方式,将调制度测量仪的量值溯源到数字示波器的采样速率和幅度上,从而达到校准调制度测量仪的目的。在一种具体型号的仪器上所做的校准验证实验,验证了所述方法的有效性与可行性。     

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.     

脉冲磁场传感器的时域标定

针对脉冲磁场测量的要求，对传感器的时域标定问题进行了研究，组建基于高压脉冲源，ＴＥＭ传输室，数字存贮示波器及计算机的时域标定系统，提出了基于输出误差模型的时域定数据处理方法，利用该模型可方便地获得的传感器的灵敏度，转折频率等参数，成功地利用所建立的误差修正模型对传感器造成的测量失真进行了恢复。     

An Accurate Wide-Band Automatic Waveform Analyzer

This paper presents accurate and quantitative measurements of waveform parameters and eye pattern which is important as an evaluation parameter of digital transmission characteristics in the development of a wide-band automatic waveform analyzer from dc to 10 GHz. The measurements and-error of transfer characteristics by using FFT is also described. New techniques are adopted in averaging, calibrating, and compensating the time axis for the accurate measurements. Relevant software offers a method for quantitative measurement. The methods have made it possible to measure the waveform parameters which are about ten times more accurate than can be obtained through conventional oscilloscopes. In the quantitative evaluation of eye pattern, the measuring error has been improved from 10 down to 2 or 3 percent as compared with measurements by sight using a conventional oscilloscope. An equation which gives the approximate value of the error in the measurement of transfer function in the frequency domain from the time-domain pulse response is shown and confirmed to correspond with the actual case.     

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.     

A look-up-table digital predistortion technique for high-voltage power amplifiers in ultrasonic applications

In this paper, we present a digital predistortion technique to improve the linearity and power efficiency of a high-voltage class-AB power amplifier (PA) for ultrasound transmitters. The system is composed of a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), and a field-programmable gate array (FPGA) in which the digital predistortion (DPD) algorithm is implemented. The DPD algorithm updates the error, which is the difference between the ideal signal and the attenuated distorted output signal, in the look-up table (LUT) memory during each cycle of a sinusoidal signal using the least-mean-square (LMS) algorithm. On the next signal cycle, the error data are used to equalize the signal with negative harmonic components to cancel the amplifier's nonlinear response. The algorithm also includes a linear interpolation method applied to the windowed sinusoidal signals for the B-mode and Doppler modes. The measurement test bench uses an arbitrary function generator as the DAC to generate the input signal, an oscilloscope as the ADC to capture the output waveform, and software to implement the DPD algorithm. The measurement results show that the proposed system is able to reduce the second-order harmonic distortion (HD2) by 20 dB and the third-order harmonic distortion (HD3) by 14.5 dB, while at the same time improving the power efficiency by 18%.     

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。     

仪表着陆信号发生器校准研究

仪表着陆信号发生器是仪表着陆系统机载设备的专用检测设备,目前国内还没有公开发布的关于仪表着陆信号发生器的国家或行业范围内的检定/校准技术标准。本文通过对仪表着陆系统原理进行剖析,从仪表着陆信号发生器工作特点入手,对航向信标、下滑信标、指点信标等信号特点进行分析,给出了计量特性,并基于频谱分析仪直接测量法给出了各项计量特性的校准方法,同时对频谱分析仪引入的测量不确定度进行了分析,用GUM法评定了扩展不确定度。结果表明,给出的校准方法可满足仪表着陆信号发生器关键参数的校准需求,使用频谱分析仪校准符合仪表着陆信号发生器各计量特性的量值溯源要求。     

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。     

A Predictable Subnanosecond Step Generator

Determination of the response of a time domain instrument to a voltage step is preferable to determination in terms of its response to sine waves. Unfortunately the output waveshape of a voltage or current step generator cannot be evaluated as easily as that of a sine wave source. Consequently, investigators rely (or should rely) upon waveform predictability rather than waveform measurement when employing step generators in system characterization. One form of a predictable step generator is discussed that is useful in the subnanosecond to tens of nanoseconds time region after the step edge. A practical realization of this form is given that has predictability to within 1 percent in that time region from 350 picoseconds to 6 nanoseconds after an 80-picosecond rise-time step edge.     

Ohmic drop compensation in voltammetry: iterative correction of the applied potential

A new method of ohmic potential drop correction for use with potential step and sweep voltammetric methods is described. The method, iterative correction of the applied potential (ICAP), essentially replaces an electronic positive feedback correction with a digital positive feedback correction. This paper will present one form of the ICAP procedure, in which voltammetric current data acquired by a high-speed digital oscilloscope are used to iteratively generate a compensating potential waveform that is then synthesized by an arbitrary waveform generator. The ICAP method is advantageous for high-speed measurements, since many of the difficulties caused by electronic positive feedback compensation are eliminated.     

100kA快响应精密冲击分流器研制及特性分析

冲击电流为暂态电流波形,持续时间短且波形不可重复,测量误差影响因素众多难以评估.研制快响应精密冲击分流器,采用同轴管式结构,分析分流器的测量原理及尺寸设计.研究分流器的瞬态响应过程,将输出信号焊接至电阻体外侧,消除趋肤效应的影响.分流器的稳态电阻测量值为0.969 7 mΩ,杂散电感为32 nH,测量额定电流时,电阻温...     

Long-Term Stability of the NIST Standard Ultrasonic Source

The National Institute of Standards and Technology (NIST) Standard Ultrasonic Source (SUS) is a system comprising a transducer capable of output power levels up to 1 W at multiple frequencies between 1 MHz and 30 MHz, and an electrical impedance-matching network that allows the system to be driven by a conventional 50 Ω rf (radio-frequency) source. It is designed to allow interlaboratory replication of ultrasonic power levels with high accuracy using inexpensive readily available ancillary equipment.The SUS was offered for sale for 14 years (1985 to 1999). Each system was furnished with data for the set of calibration points (combinations of power level and frequency) specified by the customer. Of the systems that had been ordered with some calibration points in common, three were returned more than once to NIST for recalibration. Another system retained at NIST has been recalibrated periodically since 1984. The collective data for these systems comprise 9 calibration points and 102 measurements spanning a 17 year interval ending in 2001, the last year NIST ultrasonic power measurement services were available to the public.These data have been analyzed to compare variations in output power with frequency, power level, and time elapsed since the first calibration. The results verify the claim, made in the instruction sheet furnished with every SUS, that “long-term drift, if any, in the calibration of NIST Standard Sources is insignificant compared to the uncertainties associated with a single measurement of ultrasonic power by any method available at NIST.”     

基于VB与9500B示波器校准仪的自动校准系统

介绍了以9500B示波器校准仪为标准器,针对示波器DSO-X3034A为被校对象做主要阐述,采用Visual Basic Studio 2010为上位机人机交互界面开发语言,利用Agilent Connection Expert搭建通信平台,通过SCPI指令来实现上位机对9500B示波器校准仪、数字示波器之间的程控功能,按国家校准规范自动完成上升时间、直流增益、扫描时间系数、频带宽度四大模块校准工作,最后保存数据自动生成报告。     

显示屏闪烁率与响应时间计量标准装置的研制

介绍了显示屏闪烁率和响应时间的测量方法,并根据平板显示行业所特有的溯源需求进行校准装置的设计,研制出内置函数信号发生器的亮度、闪烁率和响应时间可调的标准屏,搭建了包括标准屏、高速光度探头和高精度示波器的显示屏闪烁率计量标准装置,对装置的计量特性进行研究,并对装置的测量结果进行验证。研究结果表明,该校准装置满足计量标准的溯源要求,可用于显示屏闪烁率和响应时间的校准。     

Standard Reference Specimens in Quality Control of Engineering Surfaces

In the quality control of engineering surfaces, we aim to understand and maintain a good relationship between the manufacturing process and surface function. This is achieved by controlling the surface texture. The control process involves: 1) learning the functional parameters and their control values through controlled experiments or through a long history of production and use; 2) maintaining high accuracy and reproducibility with measurements not only of roughness calibration specimens but also of real engineering parts. In this paper, the characteristics, utilizations, and limitations of different classes of precision roughness calibration specimens are described. A measuring procedure of engineering surfaces, based on the calibration procedure of roughness specimens at NIST, is proposed. This procedure involves utilization of check specimens with waveform, wavelength, and other roughness parameters similar to functioning engineering surfaces. These check specimens would be certified under standardized reference measuring conditions, or by a reference instrument, and could be used for overall checking of the measuring procedure and for maintaining accuracy and agreement in engineering surface measurement. The concept of “surface texture design” is also suggested, which involves designing the engineering surface texture, the manufacturing process, and the quality control procedure to meet the optimal functional needs.