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Quasi-Zenith Satellite System (QZSS)-Outline and its time related mission
Hama, shinichi,Takahashi, Yasuhiro,Amagai, Jun,Ito, Hiroyuki,Morikawa, Takao,Yokota, Shouichirou,Fujieda, Miho,Kimura, Kazuhiro 통신위성우주산업연구회 2005 Joint Conference on Satellite Communications Vol.2005 No.-
Japan has started a project of Quasi-Zenith Satellite System (QZSS) since FY2003. QZSS will be highly useful not only for communications but for complement of the modernized GPS in urban canyon and mountainous area with its high visibility brought out by its inclined orbits. National Institute of Information and Communications Technology, Japan (NICT) is to develop a Space-borne Hydrogen Maser (SHM) and time management system, and carry out experiments using them. A breadboard model (BBM) of the SHM was developed to overcome the issues such as size, weight and life time, which are required in space environment. Basic design was carried out for time management system to achieve nano second level time transfer. The design and the manufacturing of the engineering models (EM) of the on-board equipment have been carried out since 2004. The first satellite is planned to be launched in FY 2008.
Nakazawa, Isao,Kimura,, Kazuhiro,Ishida, Hitoshi,Hama, Shinichi 통신위성우주산업연구회 2006 Joint Conference on Satellite Communications Vol.2006 No.-
The receiving revel of mobile satellite communication using the communication and broadcasting engineering test satellite(COMETS) was found to a deep fading characteristic when the satellite elevation angle was between 78 and 81 degrees. We conducted a detailed field study on high satellite elevation angle propagation on 2GHz and 2.5GHz bands in urban area there are many high buildings. We measured the receiving level of uplink/downlink transmissions between pseudo-satellite equipment and pseudo-terminal equipment (on-board antenna included). The equipment was set so that the satellite elevation angle from the horizontal was between 70 and 88 degrees. The results showed that left handed circular polarization (LHCP) receiving levels had a characteristic deep fading of 20-30dB due to the signal being reflected off a wall. When the terminal equipment moves near the building wall, we report on the result of review of the validity of the proposed high satellite elevation angle wall reflection model by the analytical result of the receiving level variations.