• Title/Summary/Keyword: Synchronization error

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An Analysis of Error Factors for Software Based Pseudolite Time Synchronization Performance Evaluation (소프트웨어 기반 의사위성 시각동기 기법 성능평가를 위한 오차 요소 분석)

  • Lee, Ju Hyun;Lee, Sun Yong;Hwang, Soyoung;Yu, Dong-Hui;Park, Chansik;Lee, Sang Jeong
    • Journal of Advanced Navigation Technology
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    • v.18 no.5
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    • pp.429-436
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    • 2014
  • This paper proposes three methods of the time synchronization for Pseudolite and GPS and analyzes pseudolite time synchronization error factors for software based performance evaluation on proposed time synchronization methods. Proposed three time synchronization methods are pseudolite time synchronization station construction method, method by using UTC(KRIS) clock source and GPS timing receiver based time synchronization method. Also, we analyze pseudolite time synchronization error factors such as errors of pseudolite clock and reference clock, time delay as clock transmission line, measurement error of time interval counter and error as clock synchronization algorithm to design simulation platform for performance evaluation of pseudolite time synchronization.

PTP Management Node-based Time Synchronization Error Detection and Recovery System (PTP Management Node 기반 시각동기 오류 검출 및 대응 시스템)

  • Kim, Yoon Hyun;Son, Kyou Jung;Seo, Young Duk;Chang, Tae Gyu
    • Journal of IKEEE
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    • v.24 no.1
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    • pp.248-253
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    • 2020
  • This paper proposed PTP(Precision Time Protocol) management node-based time synchronization error detection and recovery system. The proposed system is to maintain the preciseness of time synchronization under time synchronization error situations on IEEE 1588-based network environment. To demonstrate the proposed time synchronization error detection and recovery system, PTP implemented EVM(Evaluation Module)-based experiments were performed. As a results of the experiments, it is shown that the proposed system effectively maintains the preciseness of time synchronization under time synchronization error situations.

Residual Synchronization Error Elimination in OFDM Baseband Receivers

  • Hu, Xingbo;Huang, Yumei;Hong, Zhiliang
    • ETRI Journal
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    • v.29 no.5
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    • pp.596-606
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    • 2007
  • It is well known that an OFDM receiver is vulnerable to synchronization errors. Despite fine estimations used in the initial acquisition, there are still residual synchronization errors. Though these errors are very small, they severely degrade the bit error rate (BER) performance. In this paper, we propose a residual error elimination scheme for the digital OFDM baseband receiver aiming to improve the overall BER performance. Three improvements on existing schemes are made: a pilot-aided recursive algorithm for joint estimation of the residual carrier frequency and sampling time offsets; a delay-based timing error correction technique, which smoothly adjusts the incoming data stream without resampling disturbance; and a decision-directed channel gain update algorithm based on recursive least-squares criterion, which offers faster convergence and smaller error than the least-mean-squares algorithms. Simulation results show that the proposed scheme works well in the multipath channel, and its performance is close to that of an OFDM system with perfect synchronization parameters.

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Software-based Performance Analysis of a Pseudolite Time Synchronization Method Depending on the Clock Source

  • Lee, Ju Hyun;Hwang, Soyoung;Yu, Dong-Hui;Park, Chansik;Lee, Sang Jeong
    • Journal of Positioning, Navigation, and Timing
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    • v.3 no.4
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    • pp.163-170
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    • 2014
  • A pseudolite is used as a GPS backup system, and is also used for the purpose of indoor navigation and correction information transmission. It is installed on the ground, and transmits signals that are similar to those of a GPS satellite. In addition, in recent years, studies on the improvement of positioning accuracy using the pseudorange measurement of a pseudolite have been performed. As for the effect of the time synchronization error between a pseudolite and a GPS satellite, a time synchronization error of 1 us generally induces a pseudorange error of 300 m; and to achieve meter-level positioning, ns-level time synchronization between a pseudolite and a GPS satellite is required. Therefore, for the operation of a pseudolite, a time synchronization algorithm between a GPS satellite and a pseudolite is essential. In this study, for the time synchronization of a pseudolite, "a pseudolite time synchronization method using the time source of UTC (KRIS)" and "a time synchronization method using a GPS timing receiver" were introduced; and the time synchronization performance depending on the pseudolite time source and reference time source was evaluated by designing a software-based pseudolite time synchronization performance evaluation simulation platform.

Chaos Synchronization Using Error Feedback Coupling

  • Khademian, Behzad;Haeri, Mohammad
    • 제어로봇시스템학회:학술대회논문집
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    • 2005.06a
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    • pp.1632-1636
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    • 2005
  • This paper presents synchronization of two identical Modified Chua's circuits using two strategies of error feedback coupling. In the first method the synchronization is achieved by linear unidirectional and in the second one by linear bidirectional error feedback coupling. Both proposed methods can make the states of the Modified Chua's circuits globally asymptotically synchronized. Numerical results are provided to show the effectiveness of the proposed approaches and to compare them together based on different criteria.

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Analysis and Compensation of Time Synchronization Error on SAR Image (시각 동기화 오차가 SAR 영상에 미치는 영향 분석 및 보상)

  • Lee, Soojeong;Park, Woo Jung;Park, Chan Gook;Song, Jong-Hwa;Bae, Chang-Sik
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.48 no.4
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    • pp.285-293
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    • 2020
  • In this paper, to improve Synthetic Aperture Radar (SAR) image quality, the effect of time synchronization error in the EGI/IMU (Embedded GPS/INS, Inertial Measurement Unit) integrated system is analyzed and state augmentation is applied to compensate it. EGI/IMU integrated system is widely used as a SAR motion measurement algorithm, which consists of EGI mounted to obtain the trajectory and IMU mounted on the SAR antenna. In an EGI/IMU integrated system, a time synchronization error occurs when the clocks of the sensors are not synchronized. Analysis of the effect of time synchronization error on navigation solutions and SAR images confirmed that the time synchronization error deteriorates SAR image quality. The state augmentation is applied to compensate for this and as a result, the SAR image quality does not decrease. In addition, by analyzing the performance and the observability of the time synchronization error according to the maneuver, it was confirmed that the time-variant maneuver such as rotational motion is necessary to estimate the time synchronization error adequately. In order to reduce the influence of the time synchronization error on the SAR image, the time synchronization error must be compensated by performing maneuver changing over time such as a rotation before SAR operation.

Time Synchronization of the Monitoring Data for the VoIP User Assessment of Voice Quality Measurement (인터넷전화 이용자 체감품질 측정을 위한 측정데이터 간의 시간동기화)

  • Kweon Tae-Hoon;Hwang Hyae-Jeong;Lee Seog-Ki;Song Han-Chun;Won Seung-Young
    • The Journal of the Korea Contents Association
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    • v.5 no.4
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    • pp.227-236
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    • 2005
  • We study, in terms of VoIP user assessment of voice quality, the synchronization of measurement system is important. Commonly the synchronization system uses NTP(Network Time Protocol) or GPS(Global Positioning System), these synchronization method has time error of distance, system overhead of data processing, and system specialized clock error. we propose and implement the synchronization method to correct time error between two measurement system in the internet. So the time synchronization of systems can get time error, then user assessment of voice quality become reliable.

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An Implementation of Clock Synchronization in FPGA Based Distributed Embedded Systems Using CDR (CDR을 사용한 FPGA 기반 분산 임베디드 시스템의 클록 동기화 구현)

  • Song, Jae-Min;Jung, Yong-Bae;Park, Young-Seak
    • IEMEK Journal of Embedded Systems and Applications
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    • v.12 no.4
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    • pp.239-246
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    • 2017
  • Time synchronization between distributed embedded systems in the Real Time Locating System (RTLS) based on Time Difference of Arrival (TDOA) is one of the most important factors to consider in system design. Clock jitter error between each system causes many difficulties in maintaining such a time synchronization. In this paper, we implemented a system to synchronize clocks between FPGA based distributed embedded systems using the recovery clock of CDR (clock data recovery) used in high speed serial communication to solve the clock jitter error problem. It is experimentally confirmed that the cumulative time error that occurs when the synchronization is not performed through the synchronization logic using the CDR recovery clock can be completely eliminated.

A SES Alarmed Link Encryption Synchronization Method Having Optimized Threshold Value for High-Speed Video Data Encryption

  • Kim, Hyeong-Rag;Lee, Hoon-Jae;Kim, Ki-Hwan;Jung, Ju-Hyun
    • Journal of the Korea Society of Computer and Information
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    • v.22 no.9
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    • pp.57-64
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    • 2017
  • CCSDS Standard is widely used in the international space telecommunication area. But standard recommendation of CCSDS is not restrictive, so, we can select an appropriate encryption protocol among the layer. For synchronization, encryption sync is attached in the beginning of the encrypted data. In the exceptional environmental condition, although the receiver can not decrypt the normal data, the sender have no conception of that situation. In this paper, we propose a two-stage SES alarmed link encryption synchronization method having optimized threshold value necessary to decide whether the receiver has a correct decryption or not. first, through the experiment of mutual relations between error rate and encryption synchronization detection error, we can predict worst communication environment for the selected encryption synchronization pattern. second, through the experiment for finding what number of consecutive frame synchronization error is an appropriate reference value and analysis of that experiment, we suggest an optimized threshold value for resynchronization request. lastly, through the output images we can predict the probability error that should be guaranteed by channel coder.

An Error Synchronization running on Gateway Software Stack based on CoAP (CoAP 기반 게이트웨이 소프트웨어 스택에서의 오류 동기화)

  • Ko, Eung-Nam
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.9 no.1
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    • pp.114-119
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    • 2016
  • The necessity of IoT(Internet of Things) and Multimedia CSCW is described, and error control for multimedia CSCW(Computer Supported Cooperated Works) based on CoAP stack is suggested. This paper describes an error synchronization running on gateway software stack based CoAP. This system consists of an CS_EDA, and CS_ESA. CS_EDA is an agent that detects an error for multimedia distance system based on gateway software stack based CoAP environment. CS_ESA is an agent that is an error synchronization system for multimedia distance control based on gateway software stack based CoAP environment. From the perspective of multimedia collaborative environment of gateway software stack based CoAP, an error application becomes another interactive presentation error is synchronized with participants engaged in a cooperative work.