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.     

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.     

卫星导航接收机时延测定技术研究

利用卫星导航接收机进行高精度授时同步是一种简单有效的授时同步手段。导航接收系统时延的精确测量是进行高精度授时的前提,其输出秒脉冲信号的时延更是影响远距离授时、时间同步的关键。围绕卫星导航接收系统时延的测定,通过分析卫星导航接收机的时延构成及特点,建立了卫星导航接收机的时延构成模型,制定了便于操作的卫星导航接收机时延测定的方法,搭建了一套完整的卫星导航接收机时延测定系统,并对系统进行了标定和实验验证。     

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。     

SATRE Modem发射时延的一种高精度测量方法

在高精度远距离时间传递中,设备时延是影响时间传递精度的重要因素之一.本文以卫星双向时间传递的SATRE Modem发射时延的测量为例,给出了一种BPSK调制系统时延的高精度测量方法.并对国家授时中心卫星双向比对所采用的SATRE Modem的发射时延进行了测量,测量结果与国外同行的测量结果符合度优于3.5 ns.     

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。     

Investigation of the Optimum Trigger Level in Time Interval Measurement

Measuring the time interval (TI) with an accuracy in the picoseconds range requires having an accurate measurement system and minimizing the sources of errors contributed by the signal being measured. Trigger level timing error is one of the main sources of error that dramatically affects the measurement accuracy. In this article we study the effect of changing the trigger level on the TI measurement accuracy for sinusoidal signals, introduce a laboratory method for determining the optimum trigger level that leads to the highest measurement accuracy, and make a method validation.     

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.     

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。     

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.     

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。     

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。     

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.     

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.     

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.     

延期药延期时间的p-t曲线测试新方法

利用测压组件、高压电弧点火器、压力变送器、示波器等建立了一种新型的、适用于延期药燃速测试的p-t曲线测试系统。利用高压电弧点火器在金属针与延期体金属管壳间产生电弧,点燃延期体;用示波器记录燃烧过程中测压组件内部的p-t曲线,通过适当的取点,得到延期药的燃烧时间。分别用p-t曲线法和光电法测试了秒级及毫秒级延期体的延期时间,并对所得结果进行了对比。对于秒级延期体,光电法、p-t曲线法测试后计算得到的延期精度分别为3.35%、3.43%;对于毫秒级延期体,光电法、p-t曲线法测试后计算得到的延期精度分别为12.21%、18.96%。结果表明:该p-t曲线测试系统应用于秒级、毫秒级延期药延期时间的测试是可行的,体现延期体的真实燃烧状态,满足高低温下延期体测试的保温需求。     

时延系统中T-LSSVR动态软测量建模方法研究

针对工业过程中由于系统存在延时导致软测量模型难以建立、模型精度偏低等问题,提出将系统延时(T)与最小二乘支持向量回归机(LSSVR)相结合,构建一种基于T-LSSVR的动态软测量建模方法;该方法在建模过程中利用互相关函数与一阶广义差分算法辨识得到“静态响应延时”和“动态响应延时”,通过软测量手段对变量进行预测以实现辅助变量对主导变量的最佳估计。对某化工企业具有此类双延时性质的系统进行实验,实验结果表明该建模方法在动态和稳态数据预测方面都有良好的预测效果。     

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 Fictitious Time Integration Method for Solving Delay Ordinary Differential Equations

A new numerical method is proposed for solving the delay ordinary differential equations (DODEs) under multiple time-varying delays or state-dependent delays. The finite difference scheme is used to approximate the ODEs, which together with the initial conditions constitute a system of nonlinear algebraic equations (NAEs). Then, a Fictitious Time Integration Method (FTIM) is used to solve these NAEs. Numerical examples confirm that the present approach is highly accurate and efficient with a fast convergence.