QZSS L1-SAIF Supporting GPS/GLONASS Multi-Constellation Augmentation

Takeyasu Sakai, Hideki Yamada, Kazuaki Hoshinoo, and Ken Ito

Abstract:	QZSS (quasi-zenith satellite system) is a Japanese satellite navigation program with a regional service coverage. The orbits for QZS (quasi-zenith satellite) are 24-hour elliptic orbit inclined 43 degrees in order to broadcast radiosignals from high elevation angle into urban canyons. With a full constellation of QZSS, one of QZSS satellites always exists at around the zenith so that it helps the first acquisition of navigation signals and quick start of GNSS receiver as well as it provides GPSlike and SBAS-like ranging signals. The first QZSS satellite, QZS-1 “Michibiki”, was launched successfully on 11th Sept. 2010 from Tanegashima Space Center, Japan, and settled to the intended inclined elliptic orbit. By the end of November, initial functional checkout for satellite bus and mission equipment was completed without any major problems. Since then, technical validation experiments have been conducted by some participating organizations. QZSS is broadcasting GPS augmentation information on the GPS L1 frequency for experiments. For this purpose L1-SAIF (submeter-class augmentation with integrity function) signal has been developed based on SBAS standard. The ENRI has been responsible for development of L1-SAIF Master Station (L1SMS). The facility was successfully developed and tested with expected performance. Following initial functional checkout, the initial experiment has been conducted using a combination of QZS-1 on orbit and L1SMS. In order to provide the better availability to users, it is a natural way to extend the augmentation system so to support the multi-constellation environment. The L1- SAIF message is, in fact, capable of augmenting GLONASS as well as GPS in terms of the message contents defined based on the SBAS specifications. In order to confirm the possibility to augment both GPS and GLONASS simultaneously by the single L1-SAIF signal, the authors made an upgrade to the L1-SAIF Master Station to be capable of augmenting both constellations. The output L1-SAIF message stream is broadcast over Japan and surrounding regions via QZSS L1-SAIF augmentation signal on GPS L1 frequency. Both GPS and GLONASS are augmented simultaneously by the single L1-SAIF signal; Also, the QZS-1 itself is augmented by the same signal. According to the experiment, it is confirmed that broadcast message stream containing information on both GPS and GLONASS satellites is fully functional and the user positioning performance is improved by using both constellations.
Published in:	Proceedings of the 2013 International Technical Meeting of The Institute of Navigation January 29 - 27, 2013 Catamaran Resort Hotel San Diego, California
Pages:	209 - 358
Cite this article:	Sakai, Takeyasu, Yamada, Hideki, Hoshinoo, Kazuaki, Ito, Ken, "QZSS L1-SAIF Supporting GPS/GLONASS Multi-Constellation Augmentation," Proceedings of the 2013 International Technical Meeting of The Institute of Navigation, San Diego, California, January 2013, pp. 209-358.
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