• Title/Summary/Keyword: Low earth orbiting satellite

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Command and Telemetry System Design for Low earth orbiting satellite considering the PUS concept (PUS 개념을 이용한 차세대 저궤도위성의 원격명령어 및 텔레메트리 시스템 개발)

  • Lee, Na-Young;Lee, Jin-Ho;Suk, Byong-Suk
    • Aerospace Engineering and Technology
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    • v.6 no.1
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    • pp.92-96
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    • 2007
  • The conventional commands & telemetry system of Korean low-earth orbiting satellites has certain limitations in accommodating various missions. As the payload becomes complex, it requires very complicated operational concepts in terms of commands and telemetry. With the current design, commands and telemetry formats have to be rebuilt whenever new payloads or operation concepts are involved, and many constraints in operation shall be produced due to the lacks of its flexibility. In this paper, a new strategy for commands & telemetry development partially derived from PUS (Packet Utilization Standard) of European Space Agency, which provides enhanced features for the accommodation of payloads & operational requirements, is presented.

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The Geolocation Based on Total Least Squares Algorithm Using Satellites (위성을 이용한 Total Least Squares 기반 신호원 측위 알고리즘)

  • 박영미;조상우;전주환
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.2C
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    • pp.255-261
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    • 2004
  • The problem of geolocation using multiple satellites is to determine the position of a transmitter located on the Earth by processing received signals. The specific problem addressed in this paper is that of estimating the position of a stationary transmitter located on or above the Earth's surface from measured time difference of arrivals (TDOA) by a geostationary orbiting (GSO) satellite and a low earth orbiting (LEO) satellite. The proposed geolocation method is based on the total least squares (TLS) algorithm. Under erroneous positions of the satellites together with noisy TDOA measurements, the TLS algorithm provides a better solution. By running Monte-Carlo simulations, the proposed method is compared with the ordinary least squares (LS) approach.

Gravity Estimation by Using Low-Low Inter-Satellite Tracking Data (저궤도 위성간 추적데이터를 이용한 지구중력장 측정)

  • Kim,Jeong-Rae
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.31 no.8
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    • pp.58-68
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    • 2003
  • Accurate estimation of the Earth gravity field plays an important role in understanding the Earth geodynamic activities. After brief discussion on the objective of the gravity estimation, dedicated satellite missions for this purpose are described. Recently launched NASA/DLR Gravity Recovery and Climate Experiment (GRACE) mission, which consists of two co-orbiting low altitude satellites, is described. For the performance analysis, full numerical simulation was performed. The simulation procedure and its key instrument modelings are described. From the simulation results, a significant improvement on the Earth gravity field accuracy is expected.

Development and Testing of Satellite Operation System for Korea Multipurpose Satellite-I

  • Mo, Hee-Sook;Lee, Ho-Jin;Lee, Seong-Pal
    • ETRI Journal
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    • v.22 no.1
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    • pp.1-11
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    • 2000
  • The Satellite Operation System (SOS) has been developed for a low earth orbiting remote sensing satellite, Korea Multipurpose Satellite-I, to monitor and control the spacecraft as well as to perform the mission operation. SOS was designed to operate on UNIX in the HP workstations. In the design of SOS, flexibility, reliability, expandability and interoperability were the main objectives. In order to achieve these objectives, a CASE tool, a database management system, consultative committee for space data systems recommendation, and a real-time distributed processing middle-ware have been integrated into the system. A database driven structure was adopted as the baseline architecture for a generic machine-independent, mission specific database. Also a logical address based inter-process communication scheme was introduced for a distributed allocation of the network resources. Specifically, a hotstandby redundancy scheme was highlighted in the design seeking for higher system reliability and uninterrupted service required in a real-time fashion during the satellite passes. Through various tests, SOS had been verified its functional, performance, and inter-face requirements. Design, implementation, and testing of the SOS for KOMPSAT-I is presented in this paper.

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Engineering Test Satellite, KITSAT-3, Program (저궤도 기술시험용 소형위성 우리별 3호 개발)

  • Park, Sung-Dong;Kim, Sung-Heon;Sung, Dan-Keun;Choi, Soon-Dal
    • Proceedings of the KIEE Conference
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    • 1995.07b
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    • pp.907-909
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    • 1995
  • The SaTReC is to develop, deploy, and operate a low Earth orbiting small satellite system, KITSAT-3, carrying a remote sensing payload, a space science payload, and a data collection system. Through the development of KITSAT-3, the SaTReC is to demonstrate the small satellite system which provides highly accurate attitude control, high speed data transmission, and a unique spacecraft configuration and to provide educational opportunities to Korean space industries and research institute. The KITSAT-3 is expected to be launched in the beginning of 1997 by Chinese Long March IV as a secondary payload into about 800 km's sunsynchronous orbit.

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Mission Analysis and Planning System for Korea Multipurpose Satellite-I

  • Won, Chang-Hee;Lee, Jeong-Sook;Lee, Byoung-Sun;Eun, Jong-Won
    • ETRI Journal
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    • v.21 no.3
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    • pp.29-40
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    • 1999
  • The Mission Analysis and Planning System (MAPS) has been developed for a low earth orbiting remote sensing satellite, Korea Multipurpose Satellite-I (KOMPSAT-I), to monitor and control the orbit and the attitude as well as to generate mission timelines and command plans. The MAPS has been designed using a top-down approach and modular programming method to ensure flexibility in modification and expansion of the system. Furthermore, a graphical user interface has been adopted to ensure friendliness. Design, Implementation, and testing of the KOMPSAT is discussed in this paper.

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Flight Performance Analysis of the GRACE Inter-Satellite Ranging Instrument (GRACE 위성 간 거리측정기 비행성능 분석)

  • Kim, Jeong-Rae
    • Korean Journal of Remote Sensing
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    • v.22 no.4
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    • pp.255-264
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    • 2006
  • GRACE (Gravity Recovery and Climate Experiment) is the first dedicated gravity mapping mission. Its primary measurements are the distance changes between two co-orbiting low earth satellites. GRACE is a joint development by NASA and German DLR and was launched in March 2002. GRACE improves the Earth gravity model accuracy by nearly two factor of magnitude over pre-launch models. After brief description of the GRACE primary instrument, inter-satellite ranging system, its flight status and preliminary performance evaluation is presented. Ranging system error models, which were not included in the pre-launch performance model and design specifications, are identified through analyzing the flight data. Base on this analysis, future research topics on the GRACE instrument performance analysis are discussed.

The Real-Time Determination of Ionospheric Delay Scale Factor for Low Earth Orbiting Satellites by using NeQuick G Model (NeQuick G 모델을 이용한 저궤도위성 전리층 지연의 실시간 변환 계수 결정)

  • Kim, Mingyu;Myung, Jaewook;Kim, Jeongrae
    • Journal of Advanced Navigation Technology
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    • v.22 no.4
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    • pp.271-278
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    • 2018
  • For ionospheric correction of low earth orbiter (LEO) satellites using single frequency global navigation satellite system (GNSS) receiver, ionospheric scale factor should be applied to the ground-based ionosphere model. The ionospheric scale factor can be calculated by using a NeQuick model, which provides a three-dimensional ionospheric distribution. In this study, the ionospheric scale factor is calculated by using NeQuick G model during 2015, and it is compared with the scale factor computed from the combination of LEO satellite measurements and international GNSS service (IGS) global ionosphere map (GIM). The accuracy of the ionospheric delay calculated by the NeQuick G model and IGS GIM with NeQuick G scale factor is analyzed. In addition, ionospheric delay errors calculated by the NeQuick G model and IGS GIM with the NeQuick G scale factor are compared. The ionospheric delay error variations along to latitude and solar activity are also analyzed. The mean ionospheric scale factor from the NeQuick G model is 0.269 in 2015. The ionospheric delay error of IGS GIM with NeQuick G scale factor is 23.7% less than that of NeQuick G model.

Simulation Modeling of Range and Acceleration Measurement Instruments for Satellite Formation Flying (편대비행 위성용 거리 및 가속도 관측기 시뮬레이션 모델링)

  • Kim, Jeong-Rae
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.33 no.2
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    • pp.75-83
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    • 2005
  • NASA/DLR Gravity Recovery and Climate Experiment (GRACE) mission, which consists of two co-orbiting low altitude satellites, is to measure the Earth gravity field with unprecedented accuracy. Its key instruments include inter-satellite ranging systems and three-axis accelerometers. For the preliminary design and requirements analysis, extensive instrument simulation models are developed. These modeling techniques and orbit-gravity field estimation techniques are described.