Table of Content

25 June 2024, Volume 44 Issue 3

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Recent Progress and Applications on Fiber-based Optical Frequency Comb

LI Haonan, CHEN Xinyi, YANG Honglei, GE Jun

2024, 44(3):  1-10.  doi:10.12060/j.issn.1000-7202.2024.03.01

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Invented at the turn of the century,Optical frequency comb has coherently bridged between radio frequencies and optical frequencies.With more than 20-years continuous development,optical frequency comb has revolutionized optical frequency measurement methods and been widely used in precision measurement beyond that.Firstly,the advantages of the fiber optical frequency comb are highlighted,and the technical principle of the fiber optical frequency comb is briefly introduced.Then,the main development directions of the fiber optical frequency comb,namely low noise,high power,and integration,are analyzed.Finally,the application progress of the fiber optical frequency comb in optical frequency measurement,absolute distance measurement,ultra-low noise microwave generation,precise spectral measurement,and astronomical spectral calibration are discussed.

Experimental Study on Pumping Methods of Micro CPT Atomic Clock

BAI Daibing, LIN Zaisheng, WU Chenfei, LV Yutao, LIU Meng, GONG Hang, MA Ming, XV Jie, XUE Xiaobo, ZHANG Shengkang

2024, 44(3):  11-16.  doi:10.12060/j.issn.1000-7202.2024.03.02

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The （Coherent Population Trapping）CPT atomic clock is a compact atomic frequency standard based on the principle of coherent population trapping, which does not require a microwave resonant cavity, which is beneficial for reducing the volume and power consumption of physical systems. In order to explore polarization pumping methods suitable for micro CPT atomic clocks, three pumping methods were selected, including single circularly polarized light, parallel linearly polarized light, and elliptical polarized light, under the limitations of physical system volume, power consumption, and complexity. Based on the 6mm × 6mm × 6mm micro ⁸⁷Rb cell, desktop systems were constructed to measure the linewidth and SNR of CPT resonance signals using three methods. The results show that micro CPT atomic clocks are more suitable for using elliptically polarized light method.

Study on the Development and Characterization of High Density Standard Delay Line#br#

XU Mengjie, GU Yi

2024, 44(3):  17-22.  doi:10.12060/j.issn.1000-7202.2024.03.03

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Transmission Delay is an important source of testing errors in digital integrated circuits.The traditional method of calibrating a testing system with a single standard delay line can no longer meet the metrological requirements of testing systems with hundreds of test channels.A high-density standard delay line integration and setting method based on microstrip line structure is proposed to meet the demand for efficient and accurate measurement of transmission delay time in testing systems.Four specifications of high-density standard delay lines are designed,achieving high-density integration of 512 standard delay lines on a single specification standard board,improving the portability of standard instruments and improving the measurement efficiency of testing systems;A standard delay line calibration method based on time-domain reflection technology has been designed.Through multiple sets of comparative experiments,the measurement result deviation is less than 50 ps,and the delay line meets the on-site measurement requirements of the testing system.

Analysis of Technical Indexes and Research on Testing Methods of Function Generator

AI Hua, WANG Ning, CHEN Ting, LV Xue

2024, 44(3):  23-28.  doi:10.12060/j.issn.1000-7202.2024.03.04

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We comprehensively analyzed the technical indexes of typical function generators at home and abroad.According to the use of instrument functions and the degree of impact on test results,we comprehensively and systematically classified and graded the technical indexes based on functional indexes,performance indexes,and general quality characteristic indexes.And then we developed the research on testing methods and testing experiments.More importantly,we conducted in-depth analysis of various test results,which it not only provides experimental data support for instrument users and manufacturers,but also provides the suggestions for instrument function selection,optimal design,and performance status evaluation.

Digital Simulation Analysis Method of Rayleigh Lidar Uncertainty

YI Hui, FU Tuo, YANG Jian, ZHAO Bo, SUN Hongsheng

2024, 44(3):  29-35.  doi:10.12060/j.issn.1000-7202.2024.03.05

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The uncertainty analysis method of Rayleigh lidar for middle and upper atmosphere detection is studied,the current situation of Rayleigh lidar uncertainty analysis and metrological calibration is systematically sorted out,the problems and challenges faced by Rayleigh lidar calibration are analyzed and summarized,and the digital simulation analysis method of Rayleigh lidar uncertainty is proposed.The digital analysis method,model building method and signal flow simulation building process of Rayleigh lidar are discussed.Using digital,Monte Carlo simulation analysis technology,can effectively asses the system measurement uncertainty,reveal the associated components and index factors on the influence of the measurement results,solve the problem of uncertainty analysis of domestic Rayleigh lidar measurement,support detection activities,data quality,predict the prediction of scientific evaluation.

Research on Continuous Frequency Quantum Electric Field Measurement

JIN Gang, CHENG Yongjie, PENG Bo, HAN Binbin, HUANG Chengzu, ZHAO Peng, LIU Xingxun, QI Wanquan

2024, 44(3):  36-40.  doi:10.12060/j.issn.1000-7202.2024.03.06

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To solve the problem of the limited bandwidth,when measuring the RF electric field using Rydberg atom EIT-AT method,a method of continuous broadband RF field measurement is proposed.The experiment of quantum Rydberg RF electric field measurement is carried out in TEM cell.The fiber-coupled quantum probe is placed in TEM cell,based on the a model of non-resonance interaction between RF field and Rydberg atoms,According to the shifted spectrum frequency of Rydberg in electric field,the electric field can be calculated.The method can be used to the measurement of electric field for the continuous frequency between 50 MHz and 500 MHz,which enlarge the range of application of quantum field measurement,the propose can also be applied in other band electric field measurement,such as frequency above 1 GHz,the fiber coupled atom-based electric probe can also be used for electric field environment detection in narrow and small space,such as pipes and mini case.

High-performance Miniaturised Software Radio Transceiver System Based on ADRV9009

XU Jianxiang, ZHOU Changyi, LIU Ruipeng, JIANG Yaxiang, ZHOU Li

2024, 44(3):  41-47.  doi:10.12060/j.issn.1000-7202.2024.03.07

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To address issues such as the complexity of hardware structure,narrow bandwidth,poor flexibility,and limited scalability in traditional radio transceiver systems,a design and implementation method for a software-defined radio transceiver system based on the high-performance transceiver ADRV9009 and Kintex-7 FPGA is proposed.This high-performance software-defined radio transceiver system primarily consists of three main parts:a high-bandwidth RF unit,a digital signal processing unit,and peripheral units.It allows flexible configuration of transmission and reception parameters such as frequency points and bandwidth,exhibiting excellent RF performance.Compared to traditional software-defined radio platforms,it features small size,strong flexibility and scalability,and versatile application scenarios,making it promising for widespread use in mobile communication,satellite communication,and other fields.

Study on Real-time Imaging Method for Multi-frequency Array Ground Penetrating Radar Data

SUN Changjun, YU Wen, WANG Wei, SHI Xinghua

2024, 44(3):  48-54.  doi:10.12060/j.issn.1000-7202.2024.03.08

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Using multi-frequency array Ground Penetrating Radar (GPR) to detect defects in launch site pavements can obtain target information at different depths and resolutions. However, the vast amount of data generated by multi-frequency array GPR and the inability to merge data from different frequencies pose challenges for imaging and anomaly interpretation. To address this issue, a real-time imaging method for multi-frequency array GPR data is proposed, which utilizes ray projection in both depth and channel directions to more comprehensively display information on underground anomalies at different depths. The processing results of measured data indicate that this method effectively retains the basic information of underground anomalies, achieving rapid and high-precision display, thus meeting the application requirements for the rapid detection of defects in launch site pavements.

Research on Time and Frequency Application Based on RTKLIB Precision Point Positioning

YU Xu, LIU Zhixiang, CUI Guowei, ZHANG Yan, JIANG Wenshuai, MA Chaoran, TAN Jie, ZHANG Ran

2024, 44(3):  55-60.  doi:10.12060/j.issn.1000-7202.2024.03.09

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The traceability comparison device has the function of remote time traceability which is based on satellite navigation system. The device that deployed in two places can trace back to the master laboratory to carry out the clock common view comparison, which helps the construction of the time-frequency traceability comparison system, which realizes high-precision time synchronization between two places. When the traceability comparison device receives satellites’ signals to calculate pseudo range, it is affected by ionospheric delay and other factors, which is not conductive to the positioning. To improve the capacity of traceability comparison and decrease the uncertainty of common view comparison, it is essential to explore the correlation between timing stability of single station and positioning accuracy. According to the calculation of the common view files of the Beijing Institute of Radio Metrology and Measurement (BIRMM) for three consecutive months, it can be obtained that the timing of a single station is stable in the range of 0.6~1.6 ns.Precision point positioning algorithm is used to calculate the navigation files and the precision ephemeris, and the positioning accuracy of East-North-Up directions can be obtained. The positioning accuracy is consistent with the fluctuation trend of the timing stability curve of single station. Linear regression analysis was used to explain 5.7% of the change in timing stability of single station, indicating a weak correlation between the two sites, which means improving the positioning accuracy of a single point has a positive impact on reducing the uncertainty of the common view.

Development of Time Code Equipment Based on Common View Technology

CAI Yongmei, BAO Jihua, ZHANG Yongmin, YANG Zhangjun, LI Dazhen, ZHANG Ran, WANG Xin

2024, 44(3):  61-67.  doi:10.12060/j.issn.1000-7202.2024.03.10

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Time codes have wide applications in various fields such as aerospace, finance, and power. Based on satellite common view technology, the time difference between the central station and the remote station is obtained. By taming the rubidium clock, a long-distance and high-precision time code synchronization method between the central station and the remote station is studied, which enables high-precision timing at the remote station and high-precision time code calibration for general time system equipment. Through experimental verification, the time synchronization standard deviation between the remote station and the central station is better than 5 ns, the accuracy of 1PPS for external timing by the remote station is better than ± 20 ns, the accuracy of B (DC) is better than ± 20 ns, and the accuracy of B (AC) is better than ± 10 μs; Remote station external time code measurement deviation is 1PPS, B (DC) ≤ 20 ns, B (AC) ≤ 10 μs. Based on commonview taming, time code synchronization enables remote stations to have high-precision inspection and support capabilities that cover different support requirements, providing a high-precision and convenient means of time-frequency equipment inspection, testing, and emergency support.

An 852 nm Frequency-stabilized Laser Based on the Ultrastable Cavity PDH Locking Technique#br#

MA Jiyang, SHEN Tong, XUE Xiaobo, ZHAO Weinan, SU Yabei, YANG Honglei, ZUO Yani, ZHANG Shengkang

2024, 44(3):  68-74.  doi:10.12060/j.issn.1000-7202.2024.03.11

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Since the development of laser locking technology in the 1980s,ultrastable lasers have played an important role in high-precision optical quantum time-frequency metrology,such as optical clocks,gravitational wave detection,cavity quantum electrodynamics,and satellite-ground communication.The Pound-Drever-Hall(PDH) technology provides a good way to stabilize free running lasers.Here,by utilizing such method,we lock the 852 nm wavelength laser to the resonance frequency of the ultrastable cavity to achieve the highly-stabilized laser output.In the experiment,the quality factor of the ultrastable resonator reached 10¹⁰,the finesse reached 200,000,and the 1 second frequency stability of the output laser reached 5.2×10^-15 with laser linewidth of 2.3 Hz.This continuous laser with such frequency stability will provide robust technical support for an 852 nm clock laser with good correlation with Cs atoms.

Ultra-long Distance Ranging Technology on LiDAR

WEI Longchao, WANG Pengyu

2024, 44(3):  75-81.  doi:10.12060/j.issn.1000-7202.2024.03.12

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For ultra-long distance ranging RVD Light Detection and Ranging(LiDAR) requirement，the integrated distance measurement and communication module have been developed. Without changing the original radar architecture and signal structure. The distance measurement and communication function has been realized for long-distance and high dynamic cooperative targets. The principle of distance measurement has been derived. Ranging errors caused by dynamic and clock performance factors has been analyzed. The formula for the influence of speed and clock performance on ranging error has been provided. It is concluded that in high dynamic environments, the combined effect of relative velocity, ranging period, and clock bias on both sides results in ranging system errors. A demonstration verification platform has been built to complete algorithm evaluation and principle demonstration.

Throughput Enhancement Method Based on Joint Position and Transmit Power of UAV

CHEN Dan, YANG Hongzhao, XIE Yinghui

2024, 44(3):  82-88.  doi:10.12060/j.issn.1000-7202.2024.03.13

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Unmanned Aerial Vehicles (UAVs) plays an important role in wireless networks due to the advantages of high mobility and high line-of-sight communication probability.Therefore,joint optimization of UAV 3-D position and transmit powers for throughput maximization (JPTM) algorithm is proposed in this paper.In JPTM,joint optimization problem of 3-D placement and transmit power of UAV was established to maximize the throughput.The problem was a nonconvex optimization problem,and the problem is divided into two optimization problem.The first optimization problem is solved by Mean-shift algorithm and the optimal horizontal locations of UAVs are calculated.The second optimization problem are decomposed by divide-and-conquer strategy,and the sub-problem are approximated by first-order Taylor expansion.The sub-problem is formed to be standard convexity problem,which is solved by CVX tool.Simulation results have demonstrated that JPTM results in throughput performance as compared to Circle Packing Theorem-based Deployment (CPTD) of UAVs and Energy-Efficient Variable simultaneous Deployment (EEVD) algorithm.

Thoughts on Promoting Engineering Management of Scientific Research Projects

YU Yanan

2024, 44(3):  89-92.  doi:10.12060/j.issn.1000-7202.2024.03.14

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In recent years,China has experienced rapid growth in R&D investment;however,the low rate of technology transfer remains a significant obstacle to the high-quality development of Chinese science and technology.High-quality engineering management of scientific research projects is crucial for realizing advanced scientific and technological achievements.The core principles of engineering management of scientific research projects were elucidated from the aspects of encompassing project initiation demand management,project initiation coherence and systematic approach,dual-wheel driving management model based on project data,standardization construction of technical supply chain,and comprehensive evaluation of all factors management.Furthermore,the view was put forward that scientific research projects should be managed in an engineering-oriented way to enhance the market sense and problem-solving capabilities of scientific and technological personnel,as well as optimize the talent allocation of research teams.