在JJG 777-1992检定规程中,电平测量准确度的检定需要使用一台电平振荡器加上一台标准零电平表来完成.本文提出了选频电平表不平衡输入电平测量准确度校准的新方法,此方法不再需要使用电平振荡器和标准零电平表,只使用无线电实验室均具有的通用标准仪器,并给出了校准结果和测量不确定度评定结果,并将此研究结果应用于国家计量技术规范《选频电平表校准》.

本文通过矢量信号发生器输出信号EVM的计算公式,计算出矢量信号发生器ZigBee信号I/Q幅度不平衡调整和信噪比改变时可调EVM值时的参数设置,并使用N9030A中内置的矢量信号分析软件对此结果进行了测量验证,测量结果证明方法可行.在文章的最后介绍了I/Q幅度不平衡调整和信噪比改变的溯源情况.

文章提出了在不使用电平振荡器和标准零电平表校准选频电平表平衡输入电平测量准确度的新方法,对给出的新方法进行了不确定度评定,并将此方法应用于国家计量技术规范《选频电平表校准规范》中.

As the clock frequency and data rate of digital circuit become much higher, signal integrity has become increasingly important. Impedance mismatch of signal transmission paths can cause signal reflection, decrease the signal quality, so the impedance in the signal transmission paths needs to be understood and controlled. During impedance measurements, the preferred method is time domain reflectometry (TDR), which uses high performance digital communication analyzer equipped with TDR modules. A lot of digital communication analyzers equipped with TDR modules in those enterprises need to be calibrated, sent to Shanghai Institute of measurement and testing technology every year. But so far, relevant verification regulation or calibration specification of TDR module has not issued domestic. In order to meet the calibration requirements of our customers, combined with our many years of experience in pulse parameters calibration, carefully studying the technical specifications of TDR module produced by Tektronix, Inc. and Agilent technologies, making full use of the standard instruments in our pulse parameter laboratory, we calibrate the TDR module of digital communication analyzer and meet requirements of customers.

High accuracy of time scale is established and maintained by atomic clocks. During the continuous measurement, the measurement data may get lost due to the delay of the equipment or the sudden change in the outside environment. The quadratic polynomial model can be used to predict and correct the lost data, but it’s not good when dealing with continuous lost data. This paper uses grey model and another two combined models to predict and correct the lost data, and also com-pares the four models’prediction accuracy. It turns out that using the two combined models has higher accuracy over the quadratic polynomial model and grey model, so the combined models are effective and feasible.

<正>本期话题:根据国家标准化管理委员会《关于成立全国电磁屏蔽材料标准化技术委员会(SAC/TC323)的批复》(国标委综合[2008]34号),全国电磁屏蔽材料标准化技术委员会主要负责电磁屏蔽材料领域的标准化工作。该技术委员会的编号为SAC/TC323,英文名称为

Stability is an important factor to measure the quality of an atomic clock. The random factor that affects atomic clock includes five kinds of noise. The random noise can be expressed by spectral density function. In a certain smooth time, only one or two types of noise can influence the atomic clock’s stability. Through the relationship between spectral density function and atomic clock stability analysis variance, such as Allan variance, it’s possible to distinguish the kind of noise on different smooth time. When lacking of data, there is a way that can increase the amount of data by mapping extensions, and it can also improve the degree of confidence in the larger smooth time.

This article describes the calibration program and method of the electrical safety protective equipment in nuclear power plant daily using, such as computer relay test systems, series resonance test systems and high-voltage switching mechanical testing system. Author focuses on the technical difficulties in the calibration method, and the uncertainty analysis of calibration results. This will effectively increase the field of nuclear power equipment, electrical safety to protect the reliability and accuracy to ensure the operational safety of nuclear power.

As the clock difference data received by GPS receiver has a strong signal noise,a Kalman filter model is established with LabVIEW software,which is useful for processing and forecasting the sequence of discrete clock difference data and more accurately reflect the performance of the frequency source.Experimental data show that the parameters selection is reasonable,errors caused by noise are effectively reduced,and calibration accuracy is improved.

In JJG501-2000 Verification Regulation of Spectrum Analyzer, the calibration of input attenuator adopted the method of achieving displayed average noise level readings. But in fact we found that the readings were still fluctuating after 100 times averaging which its dynamic range reached over ±0.3dB and also needed more time to accomplish 100 times averaging. Currently input attenuator of spectrum analyzer has improved much more than before, but the calibration method of JJG501-2000 does not meet the requirements. This paper presents the new calibration method of input attenuator of spectrum analyzer which has more accuracy than the calibration method of JJG501-2000. Meanwhile, this calibration method takes less time and never adds new standard devices so that it is convenient to realize automation calibration of spectrum analyzer.

长三角地区已经成为我国电磁屏蔽材料行业发展的核心地区,标准化在促进电磁屏蔽材料发展的过程中发挥着重要的作用。本文介绍了长三角地区电磁屏蔽材料发展概况,提出了以提升长三角地区电磁屏蔽材料产业发展为目的,必须立足我国国情,建立电磁屏蔽材料标准体系,积极推动企业参与标准化。文中总结了基于科技创新行动计划、公益性行业科研专项等重大科研项目促进标准化及产业发展的实践经验。

Brace medium is used to support the outer and inner conductor in coaxial line.According to the rules of consistent characteristic impedance,low return loss in discontinuous sections and the least effect on electrical properties caused by machining error,this paper aims at optimizing the characteristics of brace medium in SE(Shielding Effectiveness) coaxial tester including the sizet,he thickness of coplanar compensation and mechanical tolerance.It solved the serious problem of step capacitances when using brace medium,and finally compensated the return loss caused by step capacitances in maximum.The less than-32dB return loss can meet industrial requirement.

Tapering transitions were commonly used to connect coaxial fixtures and N-type coaxial interfaces in SE(shielding effectiveness) coaxial testers.Now,it has been optimized by shifting the inner conductors moderately,setting the ratio of inner and outer diameters of the brace mediums,and digging small rings in the brace mediums contact with the air to compensate the step capacitances.An SE coaxial tester with a wider frequency range from 10 MHz to 3 GHz was developed and its stable characteristics were validated by commercial soft HFSS at the sheet resistance of shielding material of 5 Ω.This tester not only overcomes the narrow operating band of the ASTM D4935 testing method but also matches well.

Based on the JJG 1206-2006 frequency standard and the digital clock,the remote calibration standard and existing hardware in Time and Frequency Departments of Shanghai Institute of Measurement and Testing Technology,the calibration of remote frequency source was realized through the calibration data analysis software program and algorithm design method.The results of a database were established and the two algorithms in calibration standards were compared.Results in the final calibration proved to be reliable.

The standard instruments used and calibration approaches of digital modulation quality parameters for WLAN tester are introduced in this paper first, following gives the analysis of the digital modulation quality parameters, finally gives the check parameters and check methods for 802.11a/b/g/n digital modulation signals.

Until now, no national calibration specification or certification has been issued on calibration of WLAN Tester. Based on years of experience in calibration of digital mobile communication instruments, with reference from standards of WLAN technology, the writer defines the parameters, approaches and equipments for the calibration of the WLAN test set. The parameters and approaches are certified to be rational and accurate after calibration on several sets of WLAN test set and fulfill the customer requirement as well.

Based on JJG1206—2006 Frequency standard and digital clock,remote calibration standard,A set of time-frequency remote calibration system device is designed.GPS common-view method for large standard frequency source is used in the system for remote calibration.A database which contains the compared result is established and calibration standard in the two algorithms are compared,Examples are given in the final calibration.

A review on the theories and techniques for weak electrical signal detection.It put great emphasis on the weak electrical signal that was buried in strong noise.The route that was arranged in the paper based on the property of the system that was linear or nonlinear.The linear system was divided into time domain method which contained correlate detection,lock-in amplifier,sampling integrator,digital multipoint average and time averaging method,frequency domain method which pays attention to the power spectrum analyzing,and time-frequency domain method including wavelet analysis and fractional Fourier transform.The nonlinear system introduced higher order spectrum,neural networks method,chaos theory,difference resonator and stochastic resonance.The tendency of weak signal detection is towards the combined methods mentioned above and with the help of professional software such as LabVIEW.

Auto-calibration system is a group of programs that can berun to drive measurement standards and instruments to carry out the calibration automatically and gain or save the calibration results under the control of computer commands.The speed and accuracy can be highly improved.In this paper,a method for linking auto-calibration system to Laboratory Information Management System(LIMS) with its database interface was promoted.A set of calibration programs for MT8801 Radio Communication Analyzer had been built,so all the information including calibration datas were merged into LIMS and PDF report could be shown here.The function for schedule were also tried to make a comprehensive conclusion.

Bluetooth analyzer is used widely in the R&D and production of Bluetooth devices, yet until now no national calibration standard or validation criteria has been made on certifying of Bluetooth analyzer. Based on years of experiences in calibration of digital mobile communication equipment, with reference from version 1.2 and 2.0 standard of Bluetooth technology, the writer defines the parameters, approach and equipment for the calibration of the Bluetooth analyzer. The parameters and approach are certified to be rational and accurate after calibration on several sets of Bluetooth analyzer and fulfills the customer requirement as well.