A Study on the EURAMET Comparison of Time Interval Measurement

At April 2003 there were 25 National Metrology Institutes in 25 countries that are members in the European Association of National Metrology Institutes (EURAMETs) agreed to participate in an inter-laboratory comparison for time interval measurement (TIM). The main target of this comparison, as mentioned by EURAMET, was to support the current calibration measurement capabilities for TI and to gain better understanding of the TIM. Cable delay measurement was taken as an example. The time delay of three different length coaxial cables (short, medium, and long) was measured. The majority of the laboratories used the Counter Method. There was a large span between the measurements for all cables (about 1 ns). Consequently, the measurement results that had been published at 2007 were not satisfied for the participant laboratories. In this article, we study the probable reasons for this considerable span between the different measurements for the same artifact.     

A Digital Interpolation Technique in Time Measurement

The problem of measuring a time interval using a crystal oscillator as a time base is discussed. A statistical analysis is made of the free-running oscillator and gated counter when the time interval to be measured is repetitive. Using the equivalent circuit of a quartz crystal, the difficulties involved in using a pulsed crystal oscillator as a time base are investigated. A method is described to measure, at a random instant, the instantaneous phase of a free-running oscillator and use this information as the last significant figure in a time interval or pulse delay method. The method consists of sensing the coincidence between oppositely-traveling pulses on a delay line. A digital-delay generator was constructed using this technique. The accuracy of the delay was measured as ±0.01 us ±crystal time-base accuracy. The construction and testing of this device is discussed.     

基于CPLD的时间间隔测量仪

介绍了一种根据量化时延原理 ,基于CPLD器件 ,测量分辨力达到 4 3ns的高精度时间间隔测量仪 ,此测量仪巳应用在GPS锁定的高稳晶振中。同时探讨了利用双量化时延法实现更高测量精度的可行性 ,给出了设计框图。     

浅谈生产工艺对延期体秒量的控制

本文讨论了延期体生产中秒量的工艺控制问题，通过改进硅的粉碎，延期药的配比及延期体引拔等工艺措施，显著地稳定和提高了延期体的秒量精度，解决了生产中延期体秒量工艺控制的实际问题，得出了一些指导生产的有效结论。     

基于时空关系的超高分辨率时间间隔测量方法

在量化时延原理的基础上,提出了一种基于时空关系的超高分辨率时间间隔测量方法.利用时频信号在特定媒质中传播的时延稳定性这一自然现象,将被测时间间隔量化,结合相位重合检测技术,使对时间量的测量转化为对空间长度量的测量,大大提高了测量的分辨率和测量系统的稳定性.实验结果表明被测时间间隔的测量分辨率取决于作为两路延时单元的长度差,当两路延时单元的长度差设置在毫米级或亚毫米级时,可达到10 ps级至ps级的超高测量分辨率.     

多端口技术在插入相位延迟测试中的应用

基于多端口电路模型,推导出了被测双端口网络散射参数与检测端口测量值的映射关系,提出了相位传输特性测量的电路优化方案.给出了传输特性测量方法和误差估算方法,并结合多状态技术成功应用于微波雷达天线罩插入相位延迟(IPD)设计.研制开发的测试装置在实际应用中重开机无需校准即可达到测量精度要求,相位测量稳定度可长时间维持在士0.05°之内.     

高精度高分辨力时间间隔测量的技术实现

介绍1 ns分辨力时间间隔测量的技术实现和总体方案设计,并对高分辨力频率测量所采用的模拟内插技术和实现的技术途径进行了简要分析.研究证明采用模拟内差计数方法能够满足高精度、高分辨力的时差测量,提高实现1 ns的时间间隔测量能力.     

点火方式和气室长度对延期元件延期时间的影响研究

为研究点火方式和气室长度对民用雷管延期元件延期时间的影响,将延期元件装配在石英玻璃管中,模拟延期体在雷管中的状态,铅延期体点火采用普通导爆管点燃和电引火药头点燃两种方式。利用高速摄影观察延期体的发火状态并得到了不同点火方式和气室长度对铅芯延期体延期时间和的影响规律。实验发现:点火后,延期体点火端会喷出正在燃烧的延期药;相同条件下,采用引火药头点火方式时,铅延期体延时时间更短;采用导爆管点火时,气室长度的改变对延期时间影响不显著;采用电引火药头式点火时,气室长度从12 mm增加至20 mm的过程中,2段和4段延期体延时时间均增加。     

脑电图机电压测量、时间间隔测量值的不确定度评定

本文依据JJG1043-2008《脑电图机检定规程》,对脑电图机电压测量、时间间隔测量值的不确定度评定进行分析。     

基于TDC-GP1的时间间隔测量系统设计

本文针对时间测量技术的现状及应用需求,介绍了高精度时间-数字转换器TDC-GP1的技术特性,提出了一种高精度时间间隔测量的实现途径,设计了高精度时间间隔测量系统,并通过实验验证了该系统的可行性。     

Random Errors in Time Interval Measurement Based on SAW Filter Excitation

This paper deals with the time interval measurement method that makes use of a surface acoustic wave (SAW) filter as a time interpolator. The method is based on the fact that a transversal SAW filter excited by a short pulse can generate a finite signal with highly suppressed spectra outside a narrow frequency band. If the responses to two excitations are sampled at clock ticks, they can be precisely reconstructed from a finite number of samples and then compared to determine the time interval between the two excitations. We have analyzed noise contributions to the overall uncertainty of the interval measurement. The following four noise sources have been considered: (1) noise of excitation; (2) noise of amplifier; (3) quantization noise of the analog-to-digital converter; and (4) clock and sampling jitter. The main goal of the analysis was to determine the uncertainty of the measurement in dependence on the variances of contributing noises, and the magnitude of the frequency response of the filter. First, each uncertainty component has been analyzed under general assumptions. Second, a general narrow-band filter has been investigated. Finally, we have found the solution for an ideal narrow-band filter where we have obtained simple illustrative results. The results have been compared to Monte-Carlo simulations. Good agreement between theory and simulation has been demonstrated except for the outliers due to the false ambiguity solution that occurs with large measurement errors and small relative filter bandwidth.     

A Simulation Model for Time Measurement

A proposed simulation measurement model is developed which does not rely on the assumption that elements are random variables; therefore, it is based on the assumption that different times exist for the elements, depending upon their sequence of occurrence. By recognizing the sequential arrangement of elements, the interdependence among the elements is recognized. The proposed model includes a learning factor which reduces initial times in relation to the learning which occurs with each subsequent cycle. The model also provides flexibility for expressing the time values themselves. The mean value can still be used, but a randomly selected distribution of values or the operator's own times can be relied on whenever the analyst so desires.     

Numerical Study of a Multilayered Target for Muonic X-Ray Generation by Taking Time Delay of Muonic Atoms

The μd energetic atoms are produced by injection of fast muons into a solid hydrogen target of H ₂/D ₂, which contains a small amount of deuterium. A?solid layer of D ₂ has been frozen on H ₂/D ₂ for ion implantation. The target has been kept at low temperature ～3 K. Once ions are implanted into such a target in experiment, characteristic muonic X-rays are generated. Analyzing such X-rays is very useful for understanding nuclear shape of implanted ions. Here, X-ray yields have been determined by taking time delay of energetic μd(1s) atoms using an alternative kinetic approach. The introduced kinetic model describes recent experimental data well. There are reasonable agreements between obtained X-ray yields and those experimentally reported by Strasser et al.     

A TRA Bridge Technique for In-Circuit Impedance Measurement

A bridge technique is given for the measurement of impedances of two-terminal passive components in an arbitrary network without opening the circuit connections. It is ideally suited to the in-circuit measurements of passive elements in hybrid integrated circuits (HIC's) and printed circuit boards (PCB's). The method employs a new type of bridge, basically improvised from a transformer ratio-arm (TRA), a quadrature amplifier (QA), and two standard capacitors. All the measurements are in terms of the capacitors and the turns ratios of the TRA, and provide results with good accuracy. The range of measurement, together with the sources of error and their minimization, are discussed. Experimental results are found to be in good agreement with the theory.     

区间距离测量方法研究

区间测速是基于距离和时间测量机动车行驶速度的测速方式,其中监控终端触发拍照、车辆信息识别、数据处理运算是其关键要素.中国现阶段道路区间最短距离是计算固定车道机动车行驶所获得的区间道路最短长度,此计算方法忽略了机动车变道行驶,因此这个距离并不是机动车可能行驶的最短距离.本研究采用了一种新的方法来计算区间测速系统中机动车可能行驶的最短距离,并探讨了其工作原理及关键技术.     

区间测速浅议

从设置区间测速的必要性出发,分析了区间限速的目的与意义。根据区间测速的原理,剖析了区间距离与时间同步对区间测速误差的影响,提出了道路线型对于区间测速测量结果存在正偏差的可能,进而引入具体路段,得到了正偏差的取值范围。     

基于高斯光脉冲延迟技术的光纤长度精确测量方法

提出了一种基于高斯光脉冲延迟技术的无盲区、高精度光纤长度测量方法。借助光纤延迟环的作用,在高速示波器上可以观察两路具有相对时延的高斯脉冲序列。通过调节脉冲频率可使两路高斯脉冲完全重合,依据此时脉冲频率可计算出光纤长度。脉冲未完全重合则会引入频率测量的误差,而利用脉冲时延与幅度的转换关系,通过脉冲幅度极大值的测量可以精确判断脉冲是否重合。脉冲频率的分辨力达到0.1 Hz,从而提高光纤长度测量的精确度。实验中当光源波长为1296nm时,该方法测量2284.34m G.652单模光纤长度的不确定度为0.04m,测量12726.57m的不确定度为0.24m。     

A Precision Ultrasonic Phase Velocity Measurement Technique for Liquids

Present paper reports the design and developmental aspects of a new technique for ultrasonic phase velocity measurement in liquids, which is based on the studies carried out on frequency dependence of ultrasonic velocity in pure, binary and ternary liquids/mixtures. The design and developmental aspects of the experimental set up are reported along with optimisation of data acquisition software developed in LabVIEW. Finally, the developed technique is used to measure phase velocity in water (W), aqueous solution of mannitol (M), binary mixture of tertiary butyl alcohol (TBA) in water and a tertiary mixture of TBA + W + M. The results are reported within frequency bandwidth from 3 to 7 MHz. The main reason for selecting these liquids was to identify some of the liquids which can be used as reference liquids for metrological applications. Although, reporting the systematic studies to find out the reference liquid is beyond the scope of the present paper due to obvious reasons, and will be dealt separately, but the studies certainly demonstrate that the technique can successfully be used for phase velocity measurement as a function of frequency and temperature.