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An Algorithm to Estimate time offset between Measurement Devices

The Journal of China Universities of Posts and Telecommunications 2004年第Z1期11卷 8-13页

作者： HUANG Zhou-song LEI Zhen-ming ATM Center of Beijing University of Posts and Telecommunications Beijing 100876 P.R.China ATM Center of Beijing University of Posts and Telecommunications Beijing 100876 P.R.China

This paper analyzes the necessity of the measurement of one-way delay, and it also points out the errors caused by the time offset between measurement devices. Then we propose an algorithm to estimate time offset between measurement devices in network. With the estimated time offset, we can correct our measuring results. Simulation shows the effectiveness of our algorithm.

关键词： time offset Network time Protocol(NTP) one-way delay

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System time offset based RAIM in combined GPS/Beidou navigation system

System time offset based RAIM in combined GPS/Beidou navigat...

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第三届中国卫星导航学术年会

作者： XU LongXia1,2,3*1, LI XiaoHui1,2, XUE YanRong1,2,3, CAI ChengLin4& GUO MeiJun1,3 1National time Service Center, Chinese Academy of Sciences, Xi’an 710600, China 2Key Laboratory of Precision Navigation and Timing Technology, Chinese Academy of Sciences, Xi’an 710600, China 3Graduate University of Chinese Academy of Sciences, Beijing 100039, China 4Guilin University of Electronic Technology, Guilin, 541004, China

Compatibility and interoperability of GNSS （Global Navigation Satellite System） are becoming the main trend of future navigation. However, each navigation system has a time scale. When users positioning with not only one system, the time offset between them must be considered. There are several ways to acquire system time offsets. By adding unknown variables in the combined position equation to solve this variable is the commonly used way. For positioning with multi-constellations, system time offsets are some kind of burden which must be taken into account. This paper takes full use of the obtained offsets and proposes a new fault detection method for RAIM （Receiver Autonomous Integrity Monitoring）. Simulations are made to estimate the ability of this new method. This new method takes the high stability of system time offsets of GPS/Beidou system and applies it to assistant fault detection. This method has no additional requirements for navigation system and is fit for applied in receivers. It can be expected this method will be one means of RAIM for Beidou navigation system when integrated with other GNSS in future.

关键词： Compatibility and Interoperability time offset Receiver Autonomous Integrity Monitoring Fault Detection.

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New Preamble Sequence for WiMAX System with Improved Synchronization Accuracy

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Intelligent Automation & Soft Computing 2023年第3期35卷 3187-3197页

作者： Suma Sekhar Sakuntala S.Pillai S.Santhosh Kumar Department of Electronics and Communication Engineering LBS Institute of Technology for WomenThiruvananthapuramKeralaIndia Mar Baselios College of Engineering and Technology ThiruvananthapuramKeralaIndia Department of Electronics and Communication Govt.Engineering CollegeIdukkiKeralaIndia

Worldwide Interoperability for Microwave Access(WiMAX)trusts Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing(MIMO-OFDM)combination for the deployment of physical layer functions and for connecting the medium access control to the wireless *** though Orthogonal Frequency Division Multiplexing(OFDM)facilitates reliable digital broadband transmission in the fading wireless channels,the presence of synchro-nization errors in the form of Carrier Frequency offset(CFO)and time offset(TO)adversely affect the performance of OFDM based physical *** objective of this work is to improve the accuracy of the frequency and the time offset estimation in the WiMAX physical layer.A method to enhance the synchro-nization accuracy byﬁne-tuning the merit factor of the preamble sequence is sug-gested in this ***,a new preamble with improved synchronization accuracy is proposed for the WiMAX *** performance of the proposed preamble is evaluated in a Rayleigh fading channel and the results of simulations show that the Mean Square Error(MSE)in offset estimation is signiﬁcantly reduced and it outperforms the standard WiMAX preamble.

关键词： WiMAX MIMO OFDM time offset carrier frequency offset preamble sequence integrated sidelobe level merit factor

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The Development of the Calibration System for the Clock Tester

The Development of the Calibration System for the Clock Test...

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第43届中国控制会议

作者： Bing Bai Yu Zhang Chang Liu Keyi Liu Marketing Service Center of State Grid Liaoning Electric Power Supply Co Ltd

This article uses NI-VISA technology combined with image recognition technology of OPENCV and Tesseract to develop a set of automatic calibration system for clock *** system uses PC to control general-purpose counter,function signal generator,RF switch and camera through USB interface,GPIB interface and RS232 *** has realized effective traceability of daily clock time difference rate,frequency,warm-up characteristics,frequency offset and time offset parameters of clock testers according to ***,this system has been in use for one year,which effectively solves the problems of low efficiency and high error rate in traditional manual *** article first analyzes and compares similar systems,then elaborates the hardware structure and the implementation method of key technologies of this *** then shows the data and curves tested by this system,and finally summarizes the advantages of this system.

关键词： calibration clock tester daily clock time difference rate frequency warm-up time offset

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