• Title/Summary/Keyword: Space Synchronization

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Improvement of Time Synchronization over Space Wire Link (스페이스와이어 링크의 시각 동기 성능 개선)

  • Ryu, Sang-Moon
    • Journal of Institute of Control, Robotics and Systems
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    • v.15 no.11
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    • pp.1144-1149
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    • 2009
  • This paper deals with the time synchronization problem over SpaceWire links. SpaceWire is a standard for high-speed links and networks between spacecraft components, which was invented for better, cheaper, faster on-board data handling in spacecraft. The standard defines Time-Code for time distribution over SpaceWire network. When a Time-Code is transmitted, transmission delay and jitter is unavoidable. In this paper, a mechanism to remove Time-Code transmission delay and jitter over SpaceWire links is proposed and implemented with FPGA for validation. The proposed mechanism achieves high resolution clock synchronization over SpaceWire links, complies with the standard and can be easily adopted over SpaceWire network.

Improvement of Time Synchronization of SpaceWire Network through Time-Code Extension (타임코드 확장을 통한 스페이스와이어 네트워크의 시각 동기화 성능 개선)

  • Ryu, Sang-Moon
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.21 no.4
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    • pp.724-730
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    • 2017
  • SpaceWire invented for spacecrafts has Time-Code defined for time synchronization over SpaceWire network. A Time-Code suffers transmission delay of 14[bit-period] and jitter up to 10[bit-period] whenever it passes through a SpaceWire link, which is the primary cause of time synchronization error. This work presents a simple method to improve the time synchronization which uses two extended Time-Codes. Nodes on a SpaceWire network can find how much delay and jitter a received Time-Code has suffered while it passes through the network, and they can correct time synchronization error with this information. The proposed method was validated in a simulation environment developed based on OMNeT++. The simulation result showed that time synchronization error less than a few bit-periods can be achieved. The proposed method is cost effective and suitable for small-scale SpaceWire network systems.

Technical Trend of Time Synchronization Equipment in Naro Space Center (나로우주센터 표준시각 동기화장비 기술동향)

  • Han, Yoo-Soo;Choi, Yong-Tae
    • Current Industrial and Technological Trends in Aerospace
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    • v.6 no.1
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    • pp.116-123
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    • 2008
  • In the launch mission, mission control systems and tracking systems need time synchronization for data monitoring and data analysis. There are several standards for time synchronization and an adequate standard is selected according to the requirement of time accuracy and cost among time synchronization standards. Oscillators are used to maintain time accuracy. There are some kinds of oscillators with diverse characteristics and an adequate oscillator can be adopted according to time accuracy. In this paper, we will specify characteristics of several oscillators and standards generally used for time synchronization. And we will also introduce TSDN(time synchronization and display network) for time synchronization in Naro Space Center.

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The Classification of Game Spaces and the Notations for Spatio-Temporal Synchronization on a Scenario (게임 공간의 분류와 시나리오의 시간 및 공간 동기화 표현법)

  • Ha, Su-Cheol;Seong, Hae-Gyeong
    • The Transactions of the Korea Information Processing Society
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    • v.6 no.10
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    • pp.2630-2641
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    • 1999
  • Most of the previous game development has proceeded in the approaches of the temporal-oriented synchronization because of producing game objects by using general authoring tools, and ad hoc or trial and error methods has been devised for representation of spatial concept. This paper is a study on the unification notation for spatio-temporal synchronization to conquest this fault. First of all, we classify game space as temporal object, spatial object, absolute/relative spatio-temporal space. The spatio-temporal relationships are divided into temporal extent, temporal location, spatial extent, and spatial location. In the paper the temporal and spatial relationships of game scene are defined to represent the synchronization, and we propose new unification notation by temporal and spatial concept to represent two concepts putting emphasis on space. Their relationships are presented on 3D by creating time axis related with time in scene unit of the two dimensional plane in the pivot on space. The usability of this representation method are shown by applying examples of game scenario.

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Time Synchronization over SpaceWire Network using Hop Count Information (홉 카운트 정보를 이용한 스페이스와이어 네트워크 시각동기화 방안)

  • Ryu, Sang-Moon
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2016.10a
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    • pp.715-718
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    • 2016
  • SpaceWire invented for on-board data handling in a spacecraft has Time-Code defined for time synchronization over SpaceWire network. Delay and jitter of the transmission of Time-Code caused when a Time-Code travels through a network are the main reasons of time synchronization error. This work proposes a scheme that can reduce the time synchronization error by using extended Time-Codes. The proposed scheme can remove both transmission jitter and transmission delay. The scheme will be validated in a simulation environment built with OMNeT++.

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Analysis of transmission delay of timecode over SpaceWire network using OMNeT++ (OMNeT++을 이용한 스페이스와이어 네트워크의 타임코드 전송 지연 분석)

  • Ryu, Sang-Moon
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.19 no.9
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    • pp.2022-2028
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    • 2015
  • SpaceWire is a standard for high-speed links and networks between spacecraft components, which was invented for better, cheaper and faster on-board data handling in spacecraft. The standard defines timecode and its distribution which can be used for time synchronization among the nodes in a SpaceWire network. A timecode output from the time master which provides standard time over a SpaceWire network travels through links and routers to reach every nodes. While traveling, a timecode suffers from transmission delay and jitter which cause some difference in time synchronization among nodes. In this work, a simulator was developed using OMNeT++ to simulate the operation of a SpaceWire network and some analyses were performed on the transmission delay and jitter accompanied with a transmission of a timecode. The result will be used in the near future for the research of a precise time synchronization technique over a SpaceWire network.

The Time Synchronization Signals of the GNSS Receiver for KSLV-II and Their Performance Assessment (한국형발사체 위성항법수신기의 시각동기신호 생성 및 성능 평가)

  • Kwon, Byung-Moon;Shin, Yong-Sul;Ma, Keun-Su;Yun, Kwang-Ho;Seo, Hung-Seok
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.47 no.11
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    • pp.812-820
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    • 2019
  • The GNSS receiver for KSLV(Korea Space Launch Vehicle)-II provides real-time navigation data as well as precise time and time interval. The precise time signals provided by the GNSS receiver that can be used for the time synchronization between onboard systems, and between the onboard systems and ground stations have the forms of the 1PPS(One Pulse Per Second) and IRIG-B(Inter-Range Instrumentation Group Time Code B) which are synchronized with UTC(Coordinated Universal Time). A signal for timing faults also informs whether the time synchronization signals are available or not. This paper describes the time synchronization signals of the GNSS receiver for KSLV-II and their performance assessment.

Directed Identification, Synchronization by Aesthetic Recognition of Animation Field (애니메이션 분야의 심미적 인식에 의한 동일시와 동기화 연출)

  • Lee, Hyun Woo;Ryu, Chang Su
    • Journal of Korea Multimedia Society
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    • v.25 no.10
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    • pp.1475-1482
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    • 2022
  • Mickey Mousing perfect match between animation sound and image was an aesthetic in the field of animation, but since the 2000s, works such as and released by producers such as DreamWorks and Pixar have expanded the perfection of synchronization to irony. It also influenced the identification system of sentiment. It is time to view the directing attempt of these elements as a factor that changed the new paradigm of narrative, and related research is needed. In this study, the scene of was analyzed as a case study for the synchronization of animation sound and image components and the boundary direction on the recognition of identification between reality and fiction. Aesthetic recognition of the research work is based on the premise of real time and space perception, and the audience can recognize in the conceptual world as an integrated art by playfully producing fictional time and space. The direct antithesis of synchronization and identification was drawn to maintain the curiosity of the next scene by repeating selective concealment and disclosure of information in the direction of conveying an unfamiliar and heterogeneous feeling to the audience.

A Synchronization Technique of Mobile XML Documents using the Message Digest Tables (메시지다이제스트 테이블 기반의 모바일 XML 문서 동기화 기법)

  • Park, Seong-Jin
    • Journal of Information Technology Services
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    • v.8 no.2
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    • pp.157-171
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    • 2009
  • In mobile XML environments, the efficient synchronization technique is required to maintain the consistency of replicated XML data because the same data can be replicated between so many different XML documents. In this paper, we propose a message digest based synchronization technique to maintain the consistency of replicated data between client XML documents and a server XML database in mobile XML environments. The proposed an XML data synchronization technique(XSA) has the advantage of model generality aspect and storage space aspect by using the tuple-based message digest table to detect the data conflicts. The proposed technique can be applicable to the application requiring the consistency of replicated XML data without any restrictions in the heterogeneous(between hierarchical XML documents and relational XML databases) mobile environments.

A Study on the Construction of Ground Test Segment for the Time Synchronization System Using the Geostationary Satellite (정지궤도 위성을 이용한 시각동기 지상시스템 시험장비 구축에 관한 연구)

  • Lee, Sang-Cherl;Kim, Bang-Yeop
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.32 no.5
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    • pp.104-108
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    • 2004
  • The most of the CDMA mobile communication depends on the GPS for the time synchronization. Then, we must prepare alternative system against the unusable GPS like a unexpectable accident or strategic purpose by the USA government. In this study, we have constructed ground test segment for the time synchronization system using the geostationary satellite. In addition. we have designed, manufactured and tested the transmitting and receiving board to receive 1 PPS signal from atomic clock for transmitting stored data in buffer to satellite modem and to produce 1 PPS signal from satellite modem for measuring time delay.