Enhanced Space Based Quasi-Zenith Augmentation System

I. Petrovski, S. Kawaguchi, M. Ishii, H. Torimoto, H. Kishimoto, T. Furukawa, T. Tanaka

Abstract:	Japan Quasi-Zenith Satellite System (QZSS) is a new generation space based augmentation system with regional navigation capabilities. The main purpose of implementation of the new system is to improve GPS availability in urban and mountainous environment. Apart from extended availability, the QZSS will also supply user with real-time corrections, which include atmospheric corrections, GPS clock and orbital corrections and possibly corrections related to other satellite systems such as GLONASS, and GALILEO in future. The geometry of the QZSS should guarantee specified satellite availability above the certain elevation mask angle. The paper describes QZSS concept, proposals and studies, performed by Advanced Space Business Corporation, which was formed by the leading Japan companies to facilitate public participation in QZSS development, Mitsubishi Electric Corporation, Hitachi Ltd. and GNSS Technologies Inc. The presented paper provides one with analysis of such characteristics as visibility, availability, availability and geometry for the different types of QZSS constellation. Paper analysis different approaches for QZSS time keeping and synchronization with GPS time. Direct synchronization to the GPS time and synchronization through the local UTC are compared. Different options for onboard clock are now under consideration and the related issues are highlighted. Paper presents criterions and proposals for the design of QZSS monitoring network. The proposals for the variety of services, which QZSS can deliver, are presented. These services include differential correction services, and assisted data service. The special simulation software was developed for the feasibility study to assist in the QZSS concept development. The software allows to simulate orbits and raw data for monitoring network and analyze monitoring network configuration, ephemeris and clocks observability for the proposed QZSS constellation and given monitoring network. The software also allows to estimate impact QZSS on availability and accuracy of the GPS positioning. The paper also highlights differences and similarities between QZSS and MSAS. The proposed paper describes work that had been conducted as QZSS feasibility study for NASDA, and Advanced Institute of Science and Technology, Japan.
Published in:	Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003) September 9 - 12, 2003 Oregon Convention Center Portland, OR
Pages:	437 - 444
Cite this article:	Petrovski, I., Kawaguchi, S., Ishii, M., Torimoto, H., Kishimoto, H., Furukawa, T., Tanaka, T., "Enhanced Space Based Quasi-Zenith Augmentation System," Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003), Portland, OR, September 2003, pp. 437-444.
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