Table of Content

25 February 2021, Volume 41 Issue 1

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Reviews in Interferometric Test Technology of Wide Spectrum Surface Profile

GAO Zhi-shan, ZHAO Yu-qing, MA Jian-qiu, YUAN Qun

2021, 41(1):  1-8.  doi:10.12060/j.issn.1000-7202.2021.01.01

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China’s advanced manufacturing industry is developing rapidly.Among them,the optical component manufacturing is becoming larger(the diameter of monomer is several meters) or smaller(the scale is in the micro nano level),which brings new challenges to the non-contact optical detection technology.Taking the detection technology and instrument of optical surface wide spectrum profile as an example,this paper analyzes the development overview and trend at home and abroad,and shows independent research and development of series of optical interference detection instrument in China,which have scientific significance for solving the problem of neck sticking.

Research Progress of Infrared Radiation Characteristic Calibration Technology

DING Wen-hao, ZHANG Xia, FANG Qi

2021, 41(1):  9-14.  doi:10.12060/j.issn.1000-7202.2021.01.02

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Infrared radiation characteristic test is widely used in military and civilian fields,especially for military weapons and equipment against the infrared detection strike.Therefore,the research on calibration technology to improve the measurement accuracy of infrared radiation characteristics becomes the key.In this paper,the research progress at home and abroad is summarized from three aspects,such as standard blackbody radiation sources,calibration methods and radiometer calibration techniques.The methods and results of measurement and calibration involved in the research are discussed and compared to provide technical reference for related personnel,and the future research direction is proposed too.

Analysis of Long Wave Propagation Delay Characteristics and Differential Timing

YAN Bao-rong, LI Yun, GUO Wei, HUA Yu

2021, 41(1):  15-19.  doi:10.12060/j.issn.1000-7202.2021.01.03

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Due to the complexity of long wave propagation path and the real-time change of meteorological conditions,it is difficult to predict the long wave propagation delay accurately and affect the accuracy of long wave timing.These factors have the characteristics of slow change in a certain spatial range.In view of this,the difference method can be applied to long wave timing.By means of the calibration long wave receivers,the path delays are tested statically at different propagation distances.The adjacent test points simultaneously collect data for the characteristic analysis of propagation delay and the feasibility analysis of differential time.The measured data show that the propagation delay of the test point is not constant,and there will be some fluctuation in a day.This is due to the real-time [JP2]variation of meteorological conditions and electrical parameters of the propagation medium on the propagation path.The adjacent test points have the same trend of change[JP] [LM]in the same time period,and the correlation coefficient after fitting is greater than 0.7,which reflects a high degree of linear correlation.Comprehensive analysis shows that within a certain range,meteorological conditions,electrical parameters of the medium and topographic fluctuations are almost the same,which makes the long-wave propagation delay have certain spatial correlation.Differential method can be used to eliminate common errors in the propagation path and improve the timing accuracy of the long-wave.

Development of Multi-channel Time Interval Real-time Analyzer

DENG Zhi-feng, LIU Ya, LIU Yin-hua, XIAO Bo, WANG Jia-cheng

2021, 41(1):  20-26.  doi:10.12060/j.issn.1000-7202.2021.01.04

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In order to meet the requirement of large range,multi-channel and real-time analysis,an 8-channel time interval real-time analyzer is designed and realized.In this paper,the coarse counter is used to measure the time interval in a large range,and the interpolators is constructed with the time-digital-converter chips to measure the time interval in a precise way.At the same time,a low-cost miniaturized microcontroller is used to display,analyze and store the time interval measurement results in real time.The test results show that the standard deviation of the measured second pulse signal interval is better than 45ps,and the measurement stability can reach 5.68ps@1 000s.Allan deviation and Time deviation can be analyzed in real time from 1s to 10 000s.

Design of Beidou High Precision Time Service System based on TDC and ARM

SUN Xue-lin, QIN Ming-wei, HU Gui-lin

2021, 41(1):  27-32.  doi:10.12060/j.issn.1000-7202.2021.01.05

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Aiming at the low accuracy of the existing power,communication and other timing systems,a TDC-based high-precision Beidou timing system is designed.The system uses STM32F2xx/STM32F4xx chips as the core signal processor,compares the phase difference between standard 1PPS and synchronous 1PPS,combines TDC’s high-precision measurement technology for time delay,uses PID algorithm to adjust the local OCXO voltage control value,so that OCXO output is stable Clock frequency to achieve high-precision timing.At present,the timing accuracy of Beidou receivers is generally better than 50ns,and the timing accuracy is less than 20ns to achieve high-precision timing standards.Experimental results show that the timing accuracy of this method can reach 13ns,which can realize Beidou high-precision timing.

Development of Low-frequency Three-dimensional Magnetic Field Measurement System

LI Xiang-lin, WU Jing, JIN Hai-bin, LI Yi-meng

2021, 41(1):  33-37.  doi:10.12060/j.issn.1000-7202.2021.01.06

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Electromagnetic waves in the range of 10 Hz to 20 kHz are widely used in meteorological observation,geological exploration,long-distance communication and other fields.In order to monitor the electromagnetic radiations in this band,a three-axis orthogonal loop antenna is designed.A two-stage amplifier circuit based on AD797 and OP27 is used to condition and amplify the voltage signal of induction coil.The NI-9222 data acquisition card is used to acquire magnetic field signal,and the short-time Fourier transform is used to analyze the time-frequency characteristics of the signal.The developed system can measure time-varying magnetic field of 0.15 pT~340 nT.The circuit simulation and practical test results show that the system has a good amplitude-frequency characteristic and can effectively monitor the weak low-frequency electromagnetic radiations near the power substation.

Research on Influence of Pulsed Current Junction Temperature Measurement Method by Device Series Resistance

ZHENG Shi-qi, LI Hao, ZHAI Yu-wei, LIU Xia-mei, HAN Wei, WU Ai-hua

2021, 41(1):  38-42.  doi:10.12060/j.issn.1000-7202.2021.01.07

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During the measurement of junction temperature by electrical method,states of thermal distribution in temperature calibration and temperature measurement are different,which lead to the inconformity of the value of series resistance,is an important factor which affects the accuracy of the pulsed current junction temperature measurement method.With power diode as research object,pulsed current junction temperature measurement system was built,and electrical measurement on the whole device temperature and series resistor temperature was conducted,which were compared with infrared testing data.Result indicates that temperatures of the bonding wires and chip are quite different,and the change of the bonding wires resistance will cause remarkable deviation in the junction temperature result.

Research on Measurement of Very Low Gas Flow based on Static Cumulative Method

FENG Tian-you, CHENG Yong-jun, CHEN Lian, ZHAO Lan, SUN Dong-hua, ZHANG Rui-nian

2021, 41(1):  43-47.  doi:10.12060/j.issn.1000-7202.2021.01.08

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He standard gas flow in the range of(10^-9~10^-14) Pam³/s were obtained by static expansion method and constant conductance method.The generated very low gas flow was measured by static cumulative method where the corresponding He ion current increase rate varied from 10^-10 to 10^-15 A/s.The experimental results show that the wave motion of the ion current increases with the decrease of gas flow rate.When the flow drops to 1.69×10^-14Pam³/s,several data points have deviated from the increase rate fitting line indicating that the lower limit of measurement has been reached.For gas flow rates from 10^-9 Pam³/s to 7.66×10^-12Pam³/s,their corresponding He ion current rates displayed good consistency with theoretical value,where the maximum deviation from linearity is 6.8%.However,once the flow rate drops below 7.66×10^-12Pam³/s,the collected ion current increase rate data clearly diverge from the linear fitting.

Realization of Laser System for Precision Measurement of Microwave Electric Field Using Rydberg Atoms

CHENG Yong-jie, JIN Gang, LIU Xing-xun, QI Wan-quan, HE Jun

2021, 41(1):  48-52.  doi:10.12060/j.issn.1000-7202.2021.01.09

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The new microwave electric field quantum measurement method based on Rydberg atoms has the advantages of high sensitivity,large dynamic range and small measurement uncertainty.It is expected to form a new generation of microwave electric field standard that can lead to a direct SI-traceable approach for microwave electric field metrology.A miniature green laser system for precision measurement of microwave electric field based on Rydberg atoms is proposed.The single-frequency 509nm green laser system was mounted in the littrow configuration with 80mW output power.We investigated the electromagnetic induced transparency(EIT) spectroscopy of 50D and 50S for microwave electric field precision measurement through the application of homemade laser system.The realization of the laser system provides a feasible scheme for the miniaturized and expandable green laser system,which is beneficial to the realization of the practical precise measuring equipment of electric field based on atomic dielectric.

Improved BigBand Algorithm based on Adaptive Threshold

PANG Jian, QIN Ming-wei, WANG Huan, YAO Yuan-cheng

2021, 41(1):  53-57.  doi:10.12060/j.issn.1000-7202.2021.01.10

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The BigBand algorithm is an under-sampling algorithm that uses the general sparseness of the signal.The traditional BigBand algorithm relies on experience to set a fixed threshold threshold.In the case of low signal-to-noise ratio and noise uncertainty,the value of noise is superimposed and amplified by spectrum aliasing,and the signal and noise are difficult to distinguish clearly,and the spectrum sensing ability is poor.Aiming at this problem,an improved BigBand algorithm based on adaptive threshold is proposed,the initial noise threshold and signal threshold are obtained by using the preset signal false alarm probability,and dynamically adjusts the threshold threshold according to the perceived environmental signal-to-noise ratio,and then selects noise or The signal threshold is used as the threshold threshold for signal judgment and perception.Experimental analysis shows that compared with the traditional BigBand algorithm,the improved algorithm can adapt to the environment with low signal-to-noise ratio and drastic noise changes,and has good anti-interference performance and better spectrum sensing capabilities.

Research on Influence of Modifications and Applicability for the ITU-R P.1546 Model

CHEN Zhen-yuan, YAN Tian-feng, SUN Yu, GAO Rui

2021, 41(1):  58-63.  doi:10.12060/j.issn.1000-7202.2021.01.11

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In order to analyze the accuracy and applicability of the ITU-R P.1546 propagation model in Lanzhou,based on the ITU-R P.1546 proposal,the correction method mentioned in the proposal was modified by Matlab,and the actual test was carried out in Lanzhou,and compared with the traditional Okumura-hata model.The analysis results show that the ITU-R P.1546 propagation model in Lanzhou has a higher accuracy than the traditional model,and after correcting the terrain clearance angle,transmitter clearance angle and receiver antenna height,the mean square error of the model loss is reduced by 16.6% in Anning area and 18.6% in Baiyin area.When there are higher obstacles above the transmitter and receiver paths,there is a big difference between the correction of the model’s terrain clearance angle and the actual loss.The results of this study may provide a reference for the propagation prediction and localization study of the ITU-R P.1546 model.

Design of Simulator for LORAN-C Navigation System based on CPU+FPGA Platform

CUI Ke, LI Jia-ying, LU Hui

2021, 41(1):  64-70.  doi:10.12060/j.issn.1000-7202.2021.01.12

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According to the basic characteristics of Loran-C navigation system signal,based on SDR(Software Defined Radio) theory,a kind of signal simulator of Loran-C navigation system is designed.Building the architecture of the upper system and the lower system with General-purpose computer and FPGA chip,and using PCIE bus as the information communication media,the signal simulator can produce sky-wave signal,the station chain and the band interference signal and the noise jamming signal.The simulator can be applied to the research of Loran-C signal characteristics and the maintenance of receiving equipment.

Simulation Model and Experimental Research on Ramsey Transition of Cesium Atoms

YAN Yu-fei, CHEN Hai-jun, FENG Jin-jun

2021, 41(1):  71-76.  doi:10.12060/j.issn.1000-7202.2021.01.13

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Based on the exiting theory,this paper establishes a simulation model of the Ramsey transition of cesium atoms.This model can not only simulate the transition line shape that occurs in the microwave cavity under ideal conditions,but also can simulate the effects of the common phenomena in the cesium beam frequency standard,such as adjacent σ transitions,the phase difference between the two interaction regions of the microwave cavity and the C field unevenness on the transition line shape.The comparison between experimental test and simulation shows that this model can highly restore the transition line shape measured by the cesium beam frequency standard experiment and give specific parameter deviations,which has an important guiding role in the frequency shift control of the cesium beam frequency standard.

Design and Research on Tissue Equivalent Radiological Anthropomorphic Phantom

WANG Fei-fei, GAO Fei, XU Yang, LIU Yun-tao, LIU Chuan-feng, NI Ning

2021, 41(1):  77-82.  doi:10.12060/j.issn.1000-7202.2021.01.14

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For the research of the absorbed dose of radiation in human body,a tissue equivalent radiological anthropomorphic phantom was established by using 3D printing technology.The effective atomic number and electron density per unit mass of the phantom materials were calculated,the density,element composition ratio and mass attenuation coefficient were verified by experiments,and the mass attenuation coefficient was obtained based on Monte Carlo simulation,and the above parameters were compared with the standard values.The results show that the materials are tissue equivalent.The absorbed dose in organs were measured by a finger ionization chamber in a ⁶⁰Co radiation field.Based on MCNP software,part of the correction factors and the ratio of mass energy absorption coefficient of organ materials to air were simulated,and the absorbed dose of each organ were obtained,providing reference for the quality assurance for radiotherapy.

Research on Measurement Method of Microwave Attenuation of Motor Plume

CAO Yue, SUN Xiao-xu

2021, 41(1):  83-88.  doi:10.12060/j.issn.1000-7202.2021.01.15

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In this paper,a measurement method of microwave attenuation of motor plume is researched.A microwave attenuation measurement system is built based on the motor experimental environment,and this system can realize multi-frequency point measurement.The studying way,test principle,hardware composition,field layout,calibration technology,uncertainty of measurement equipment and experimental results of the system are introduced.The experimental results show that the measurement system has a good measuring effect,and the precision meets the requirements.A large number of measurement data were obtained after field tests,we can estimate the influence of motor plume on microwave signal transmission through effective data processing.

Research on Ground Calibration System for the On-orbit Measuring Instrument of Quality

LIAO Hang, PENG Jian-guo, ZHOU Xin

2021, 41(1):  89-94.  doi:10.12060/j.issn.1000-7202.2021.01.16

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In order to verify the index performance and measurement accuracy of the On-orbit Measuring Instrument of Quality in the space microgravity environment,this paper describes its ground calibration method,establishes a ground calibration system,and implements a ground calibration device by engineering.By simulating the horizontal two-dimensional microgravity environment,the measurement accuracy is verified.The experimental results show that the measurement errors of the calibration technique and calibration system are within the range of the qualified indicators.The above model can be applied to the ground calibration of similar quality measuring instrument in a special environment,and has strong popularization.At the same time,it has a better engineering application value and various prospects.

Method for Acquiring Ship Underwater Noise Source Level based on Measurement of Shallow Sea Acoustic Channel Characteristics

LIU Yu-cai, CHEN Yi, YI Wen-sheng

2021, 41(1):  95-100.  doi:10.12060/j.issn.1000-7202.2021.01.17

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This paper introduces a ship noise source-level engineering test method based on the propagation characteristics of the water acoustic channel to solve the problem of ship underwater radiated noise measurement in the shallow water channel environment.The method is realized by the multi-element space energy averaging.the energy average sound pressure level curve is used to express the characterize of underwater sound propagation in shallow water,and a calculation experience formula suitable for the law of sound propagation in shallow water is proposed.The feasibility and accuracy of the proposed measurement method are verified by simulation and lake experiments.The results prove that the space energy average processing method can suppress the high measurement error caused by the fluctuation of the sound field in shallow water,this method has certain reference value for improving the accuracy of ship radiated noise measurement.