Error vector magnitude (EVM) is a key parameter that characterizes the communication quality of RF communication systems, and digital mobile communication measurement equipment need to pay attention to the measurement error of this parameter during calibration. At present, in terms of equipment metrology calibration, the error at the zero point is mainly detected through closed-loop detection of vector signal generators and vector signal analyzers that are close to the ideal. There is a lack of relevant research on other value ranges in evaluating uncertainty.This article investigates the traceability of impaired EVM parameters under baseband and RF output conditions, and analyzes their measurement uncertainty through Monte Carlo analysis, which forms a performance evaluation of digital modulation transmission and measurement equipment.

An ac shunt calibration system based on digitally assisted current transformer bridge is developed. The impedance bridge measurement method is introduced based on the circuit of the system. The electronic Wagner network is designed to reduce the capacitive leakage current. The compensated zero-flux current transformer is constructed to provide high accuracy current ratio for the calibration system. The voltage of the ac shunt to be calibrated is compared with that of an ac standard resistor adjusting by a two-stage inductive voltage divider with four decades arrangements to realize the quasi-balance state for the bridge. The simultaneous digital sampling system is used to measure the difference voltage of the bridge. The calibration system can measure both ac resistance and phase angle of the ac shunts with nominal current smaller than 100 A in the 20 Hz to 3 kHz frequency range. The optimal uncertainty is 6.5 mu Omega/Omega for ac resistance and 10 mu rad for phase angle. Calibration results of ac shunts at different currents and frequencies are showed. The comparisons of measurements of ac resistance and phase angle are performed to verify the accuracy of the system.

UV LED has been widely used in various fields such as medical disinfection and biochemical detection, especially in UV curing. Compared with traditional high-voltage mercury lamp, UV LED shows large differences both in the spectral power distribution and irradiance, which may cause up to 20% error in calibration. A 365 nm UV LED source has been developed and measured, which is made of UV LEDs, temperature control module, integrating sphere, circuit and monitoring module. The experiment results indicate that the irradiance of about 884 mW/cm2 meets the actual requirements of the curing industry, and the stability of 1.0% (15 min) and uniformity of 1.6% are in compliance with the calibration regulation.

The sun protection factor (SPF) is a measure of the fraction of sunburn-producing UV rays that reach the skin. A xenon arc solar simulator with appropriate filters has been usually used to produce the required UV radiation for the SPF determination. The measurement accuracy of the SPF is dependent on the spectral characteristics of the UV solar simulator. A typical UV solar simulator used for in vivo determination of the SPF has been measured and evaluated. The experiment results indicate that both of its UVA+B and UVA spectrums fall within the acceptance limits.

结合电能表在射频电磁场辐射抗扰度试验(RS)中出现频繁自动重启的案例,分析产生该异常现象的原因,给出了消除该干扰的解决方法.在该案例中,射频电磁场在电源电路中引起的电压波动触发了掉电检测信号,引起自动复位重启.通过在电压基准源芯片的参考引脚和地之间并接旁路电容,滤除来自空间射频电磁场在环路中引入的干扰电压,有效解决了该问题.

The total luminous flux is one of the most important characteristics of LEDs. The total luminous flux measurement of traditional LEDs with low power (0.05W@20mA), low heat and single package must conform to the specifications of CIE 127: 2007 Measurement of LEDs. Compared to traditional low-power LEDs, the latest LEDs have higher power (1W@350mA), higher heat and exhibit more complex packages. Because of their own characteristics, high-power LEDs have put forward some new measurement requirements for standard light source, heat dissipation structure, special fixture and integrating sphere. Therefore, a new type of 2π standard light source has been designed and used for the total luminous flux calibration of high-power LEDs.

With the development of LED technology research, more and more UV LED light sources have been used in UV curable coatings industry, instead of traditional UV lamps. Compared with the traditional UV fluorescent lamps, UV LEDs have many advantages, such as single peak, more energy saving, longer life, less thermal diffusivity. In the process of actual application, we need to monitor the intensity and energy of UV LED light sources regularly; therefore it is very important to make sure that the ultraviolet energy meter we adopted is accurate. In this paper, we firstly introduce our UV energy meter calibration device. We obtain the relative spectral distribution of UV LEDs and traditional curing UV light sources through spectrometer. By the analysis of spectral differences between the two, combined with the standard ultraviolet energy meter spectral response curve, we improve the measurement method to adapt to UV LED energy meters calibration. In this paper, the attention in the relevant calibration method is put forward for the characteristics of UV LEDs and the corresponding measurement uncertainty analysis is also evaluated to provide guidance for daily calibration.

Specular gloss is the perception by an observer of the mirror-like appearance of a surface. The primary gloss standard and glossmeter of China is maintained in Shanghai Institute of Measurement and Testing Technology (SIMT), which were originally developed in 1998. Recently, the instrument has been updated in several aspects, such as source arm, optical system and sample holder. The experiments and intercomparison measurements have been performed. The measurement results validate the measurement accuracy of our improved instrument.

Specular gloss is the perception by an observer of the mirror-like appearance of a surface. The glossmeter provides a quantifiable way of measuring the specular gloss. A setup for determining the specular gloss of non-textured coatings on plane, opaque substrates has been introduced. The measurement results using our apparatus have been compared with that obtained by NRC. The comparison results validate the accuracy of our instrument.

介绍了一套自行研制的直流电能表校准装置,对输出的直流功率信号中的电压、电流分别变换后进行采样并卷积,得到一段时间内的平均功率标准值,采用相同的外触发信号同步采样测量被检直流电能表的脉冲输出,得到与被检直流电能表输出相关的频率值,并用LabVIEW编写了自动测试计算软件得到测量结果.该方法利用3458A数字多用表直流信号采样准确度高的特性,有效地克服了测量信号稳定性、测量噪声和分流器发热不稳对测量结果的影响,为建立高准确度的标准直流电能表校准装置提供了一种技术解决方案,为直流电能量值溯源提供了技术保障.

A reference system for the calibration of electronic transformer tester based on the digital sampling method is described. The calibration software is designed in conformity to the IEC 61850-9-2/LE standard. The extended uncertainties estimation to the current function of the electronic transformer testers are 5.4E-5 for magnitude and 64prad for phase displacement with coverage factor k=2. Corresponding to the voltage function, the extended uncertainties are estimated to within 2.2E-5 and 50prad separately.

The Keysight 3458A is a common digitizer because of the great accuracy and small integration time. The bandwidth of its DC input path varies depending on the magnification of input amplifier of different ranges, which causes time latency of input signal. A method to measure the latency based on aperture time is introduced. When the aperture approximately equals to the period of the signal under test, extremum of sampling value reflects signal's initial phase. Experiments at 1V and 10V ranges with input signals of 25kHz and 50kHz were carried out and the time latency were measured. Then the bandwidth were calculated which were the same of about 120kHz for these two ranges.

Specular gloss is the perception by an observer of the mirror-like appearance of a surface. Specular gloss is usually measured by a glossmeter, which can be calibrated by a group of gloss plates according to JJG 696-2015. The characteristics of a gloss meter include stability, zero error, and error of indication. The characteristics of a gloss plate include roughness and spectral transmissivity of a high gloss plate, spectral reflectivity of a ceramic gloss plate. The experiment results indicate that calibration of both gloss meters and gloss plates should be carefully performed according to the latest verification regulation in order to reduce the measurement error.

The total luminous flux is one of the most important characteristics of a LED. According to the CIE standard, the luminous flux for LEDs can be measured by an integrating sphere equipped with a spectroradiometer. The luminous flux of LEDs has been measured in the 4π geometry, which is suitable for LEDs with different luminous intensity distributions. The results between NIM and SIMT validate our calibration ability. The experiments indicate that the standard LEDs and the measurement repeatability play important roles in the uncertainty analysis.

The method of precision measurement of AC resistance and time constant based on a kind of quasi-balance resistance bridge is studied. A two-stage inductive voltage divider is used as the ratio reference of the bridge. The unbalanced bridge voltage is transferred to winding of a transformer by electronic circuits, realizing the quasi-balance status automatically of the bridge. The quasi-balance state also makes the voltage ratio of inductive voltage divider unaffected by internal loading of ratio winding. The digital synchronous sampling method is used to measure the small complex voltage ratio. To reduce influence of lead wire connecting two resistors when measuring small resistors, amplifiers are used to eliminate voltage drop on the wire together with a Kelvin network. The measurement system designed in this paper can measure resistance from 1 Ω to 10 000 Ω. Experimental results at frequency of 1 kHz show that the measurement system deserves high accuracy and stability.

Specular gloss has been widely used to characterize the ability of a surface to reflect light specularly. Specular gloss is theoretically related to the physical properties of a surface, such as roughness, directionality and uniformity. Specular gloss, mainly determined by incident angle and refractive index of a surface, is a relative measurement quantity. Specular gloss is usually measured by a glossmeter. The topographical and optical properties of a surface have been analyzed on how to affect the measurements. The experiment results indicate that a less rough/flatter, more isotropic and more uniform surface will result in a more accurate measurement value. Therefore, physical properties of a surface must be carefully inspected before the specular gloss measurement in order to acquire a satisfied result.

Dissipation factor of the capacitor can be measured precisely by capacitance bridge. A kind of transfer circuit containing the auxiliary balancing circuit is used to compare the four-terminal resistor and the standard capacitor. Voltages of the two kinds of impedance are sampled synchronously by a two-channel digitizer. The phase difference of the voltages is computed by improved DFT algorithm. Based on the dissipation factor of the standard capacitor, time constant of the resistor can be computed. Experiments show the uncertainty of 8 ns with this method.

Specular gloss is the perception by an observer of the mirror-like appearance of a surface. The measurement of specular gloss consists of comparing the luminous flux reflected from an object to that reflected from a gloss reference standard. The accuracy of specular gloss measurements depends not only on the characteristics of the instrument but also on the properties of the gloss reference standard. Experiments have been performed to analyze the possible sources of error such as gloss reference standard variation, photodetector linearity and measurement repeatability, which are three most important components of uncertainty. The results indicate that the instrument should be carefully examined before the specular gloss measurement in order to acquire a satisfied result.

The calibration of electronic transformer (ET) with digital output can be realized using reference digital voltage multimeter(DVM) with synchronized sampling. However, there are time related errors of DVM which affect the result of phase displacement of ET under calibration. Such errors include the trigger latency, bandwidth limitation and aperture time of the DVM. This paper estimates the errors and makes a correction to the calibration result. The accuracy of the correction is verified using an arbitrary waveform generator (AWG) with dual synchronized channels with satisfactory results.

Digital sampling method is widely used in precision electromagnetic measurements based on DFT algorithms. The accuracy of phase difference measured by sampling method influences a lot to power, energy and so on. The active phase shifter is constructed to get stable 90° phase standard. To obtain the error of the phase shifter, two calibration steps are carried out in which a 1:-1 two-stage inductive voltage divider (IVD) is used. The calibration uncertainty for the 90° phase difference is 0.0006°. With the 90° phase standard, phase difference measured by a synchronous sampling digitizer using an improved DFT algorithm is calibrated.