Initial results of GPS orbit and clock estimation by Japanese GNSS test system

In Japan, MTSAT (Multi-functional Transport Satellite) Satellite-based Augmentation System (MSAS) which augments GPS for civil air navigation is planned. The Electronic Navigation Research Institute (ENRI), Ministry of Transport of Japan is developing the GNSS Test System for fundamental study on MSAS feasibility and basic technique for wide area augmentation. Mainly in the aspect of accuracy, estimation technique of satellite position, clock and clock of monitor stations is developed and a feasibility of user navigation accuracy using this information is studied. The initial results on estimation of satellite position, clock and clock of monitor stations by the GNSS Test System will be presented. For evaluation of results, the precise position and clock data of the IGS are used as a reference. Because of geographical restriction of Japan, it is difficult to keep long baseline, and GDOP value for GPS satellite position estimation will be greater than several hundreds or one thousand. However, the results show meaningful estimation on GPS satellite position and clock including SA component by using filtering technique. Also, from the results on estimation of clock of monitor stations, the time transfer with high accuracy will be possible.