• 제목/요약/키워드: space communications

검색결과 2,119건 처리시간 0.023초

SERVICE AND NETWORK OPERATION OF THE MULTIBEAM SWITCHING SATELLITE COMMUNICATIONS SYSTEM

  • Choi Kyung Soo;Sin Cheon Sig;Jo Jin Ho;Lee Yong Min;Lee Seong Pal
    • 한국우주과학회:학술대회논문집(한국우주과학회보)
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    • 한국우주과학회 2004년도 한국우주과학회보 제13권2호
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    • pp.351-355
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    • 2004
  • A multibeam switching satellite system technology have started localized development to overcome the limitation of the frequency resource and geostationary orbit existing relay type satellite transponder and the required performance of the spot beam, and looked around the configuration and functions of the multibeam switching satellite communication system. This paper proposed that operation scheme and network control features for service definition, network architecture, transmission method of the natural disaster service network and public communication service network using this system.

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ENVIRONMENTAL TEST OF THE EQM PAYLOAD SYSTEM FOR THE COMMUNICATIONS AND BROADCASTING SATELLITE

  • Choi Jang Sup;Park Jong Heung;Eun Jong Won;Lee Seong Pal
    • 한국우주과학회:학술대회논문집(한국우주과학회보)
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    • 한국우주과학회 2004년도 한국우주과학회보 제13권2호
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    • pp.368-371
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    • 2004
  • ETRI has developed the EQM (Engineering Qualification model) payload system for the communications and broadcasting satellite (CBS) with Korean local companies. This paper describes a series of environmental tests such as vibration, thermal/thermal vacuum, and EMC tests. All the development processes including the design, implementation, integration and workmanship were verified and evaluated by these tests. The results of the functional tests and the compliance to the requirements are also presented. The technologies and heritage obtained from this development will be applied to the development of the payload system for the Korean communication satellite in the near future.

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DESIGN AND FLIGHT SOFTWARE EMBEDDING OF KOMPSAT-2 SIMULATOR

  • Lee, Sang-Uk;Cho, Sung-Ki;Kim, Jae-Hoon
    • Journal of Astronomy and Space Sciences
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    • 제19권2호
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    • pp.97-106
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    • 2002
  • The design feature of KOMPSAT-2 simulator based on object oriented design methodology in terms of unified modeling language (UML) has been discussed in this paper. Also, we present how to embed flight software into the simulator. Flight software em-bedding for KOMPSAT-2 simulator is compared to that of the KOMPSAT-1 simulator.

KA-BAND ANTENNA PERFORMANCE ANALYSIS OF COMS SATELLITE

  • Lee Jeom-Hun;Choi Jang-Sup;Lee Seong Pal
    • 한국우주과학회:학술대회논문집(한국우주과학회보)
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    • 한국우주과학회 2004년도 한국우주과학회보 제13권2호
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    • pp.316-320
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    • 2004
  • This paper describes Ka-band antenna performance analysis of COMS satellite. The key parameters of the antenna system are optimal antenna diameter, feed horn type and horn size, F/D, and the coordinate of offset horns. The paper deals with the method to determine design core parameters of optimal antenna diameter, feed horn type and horn size, F/D, and the coordinate of offset horns, and the performances of design result.

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3D DISPLAY OF SPACECRAFT DYNAMICS USING REAL TELEMETRY

  • Lee, Sang-Uk;Cho, Sung-Ki;Kim, Jae-Hoon
    • Journal of Astronomy and Space Sciences
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    • 제19권4호
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    • pp.403-408
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    • 2002
  • 3D display of spacecraft motion by using telemetry data received from satellite in real-time is described. Telemetry data are converted to the appropriate form for 3-D display by the real-time preprocessor. Stored playback telemetry data also can be processed for the display. 3D display of spacecraft motion by using real telemetry data provides intuitive comprehension of spacecraft dynamics.

An Approach to Eliminate Ambiguity of Blind ML Detection for Orthogonal Space-Time Block Codes

  • Pham, Van-Su;Le, Minh-Tuan;Mai, Linh;Kabir, S. M. Humayun;Yoon, Gi-Wan
    • 한국정보통신학회:학술대회논문집
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    • 한국해양정보통신학회 2007년도 추계종합학술대회
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    • pp.83-86
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    • 2007
  • In the blind Maximum-likelihood (ML) detection for Orthogonal Space-Time Block Codes (OSTBC), the problem of ambiguity in determining the symbols has been a great concern. A solution to this problem is to apply semi-blind ML detection, i.e., the blind ML decoding with pilot symbols or training sequence. In order to increase the performance, the number of pilot symbols or length of training sequence should be increased. Unfortunately, this leads to a significant decrease in system spectral efficiency. This work presents an approach to resolve the aforementioned issue by introducing a new method for constructing transmitted information symbol. Thus, by transmitting information symbols drawn from different modulation constellation, the ambiguity can be easily eliminated in blind detection. Also, computer simulations are implemented to verify the performance of the proposed approach.

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Novel Approach for Eliminating BER Irreducible Floor in the Enhanced Blind Cyclic Detection for Space-Time Coding

  • Pham, Van-Su;Le, Minh-Tuan;Mai, Linh;Kabir, S.M.Humayun;Yoon, Gi-Wan
    • Journal of information and communication convergence engineering
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    • 제6권2호
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    • pp.150-153
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    • 2008
  • In the blind Maximum-likelihood (ML) detection for Orthogonal Space-Time Block Codes (OSTBC), the problem of ambiguity in determining the symbols has been a great concern. A possible solution to this problem is to apply semi-blind ML detection, i.e. the blind ML decoding with pilot symbols or training sequence. In order to increase the performance, the number of pilot symbols or length of training sequence should be increased. Unfortunately, this leads to a significantly decrease in system spectral efficiency. This work presents an approach to resolve the aforementioned issue by introducing a new method for constructing transmitted information symbols, in which transmitting information symbols drawn form different modulation constellations. Therefore, the ambiguity can be easily eliminated. In addition, computer simulation is implemented to verify the performance of the proposed approach.