JAPAN: The latest update on Quasi-Zenith Satellite System (QZSS) Program

Satoshi Kogure, Hiromichi Moriyama, Akihiro Matsumoto, Shinichi Sakabe, Taku Sato, Koji Nakaitani, Hisanori Emura, Johta Awano, Motoyuki Miyoshi, Kazuhiro Yoshikawa

Abstract:	The first satellite of Quasi-Zenith Satellite System called as “Michibiki” was launched in 2010. Alert flag of Michibiki’s ranging signals was removed in July 2016, as the tuning of the Kalman Filter was accomplished. Consequently, the performance of civil open service achieved Signal in Space User Range Error (SIS-URE) as less than 2.6 meter (95% probability) which is defined in its interface specification document. Based on this stable performance, Michibiki lead a wide variety of technical verifications and application demonstrations into successful results. In September 2011, the Government of Japan decided to implement the Michibiki system developed by Japan Aerospace Exploration Agency (JAXA) and other Japanese national research institutes as infrastructure consists of four satellites until the late 2010s. The implementation of the whole system including additional satellites and ground control segment are now ongoing under QZSS program administrated by Cabinet Office (CAO). The manufacturing and integration of ground control segment as well as its operation with regard to navigation service, to be commenced from April 2018, are assigned to QZS System Service Inc., which is Special Purpose Company (SPC) established under Private Financial Initiative (PFI) enterprise. Two Inclined Geo-Synchronous Orbit (IGSO) satellites and one Geo-Synchronous Orbit (GSO) satellite are being developed with slight modifications based on Michibiki’s developments experience as well as predicated on new user requirements. For instance, lighter weight and higher efficiency solar array panel is applied and it facilitates to maintain Yaw Steering attitude control mode even in lower Beta angle which is defined as the angle between Earth-Sun vector and the orbit plane of satellite. Additional Rubidium Atomic Frequency Standard (RAFS) is added to improve the redundancy longer lifetime requirement, 15 years. The two way communications link is added on the GSO satellite for the safety confirmation just after the huge earthquake which ground communications are damaged or limited. GSO satellite has a patch array antenna replacing helical array antenna, otherwise two IGSO satellites maintain as same antenna design as Michibiki. Regarding to the services, the GPS complementary service and GNSS augmentation service are designed based on the past demonstration activities. The Early Warning Service on L1S and QZSS Safety Confirmation Service (Q-ANPI) through S-band link. Satellite Based Augmentation System (SBAS) service through the GEO satellite has been included in the program in 2015. The Interface Specification and Performance Standard for new QZSS can be downloaded at the QZSS web site. (http://qzss.go.jp/en/technical/ps-is-qzss/ps-is-qzss.html) Some documents have been already opened to the public as of November 2016. Rest of documents will be published soon. While the preparation to launch 24/7 service provision are getting progress, the procurement of replacement satellite for the first one. Since its design life is 10 years, the replacement satellite will have to be on the orbit in 2020. In this paper, the latest update on the QZSS program is presented. The system architecture, modifications on the newly built satellites are introduced. Moreover, future evolution of the QZSS is briefed.
Published in:	Proceedings of the ION 2017 Pacific PNT Meeting May 1 - 4, 2017 Marriott Waikiki Beach Resort & Spa Honolulu, Hawaii
Pages:	627 - 652
Cite this article:	Kogure, Satoshi, Moriyama, Hiromichi, Matsumoto, Akihiro, Sakabe, Shinichi, Sato, Taku, Nakaitani, Koji, Emura, Hisanori, Awano, Johta, Miyoshi, Motoyuki, Yoshikawa, Kazuhiro, "JAPAN: The latest update on Quasi-Zenith Satellite System (QZSS) Program," Proceedings of the ION 2017 Pacific PNT Meeting, Honolulu, Hawaii, May 2017, pp. 627-652. https://doi.org/10.33012/2017.15015
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