Ranging Quality of QZSS L1-SAIF Signal

T. Sakai, H. Yamada, K. 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 GPS-like 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) for the experiment. It 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. RF characteristics of L1-SAIF signal is identical with GPS L1 C/A signal so that L1-SAIF can be used for ranging. For this purpose, the L1SMS has been upgraded to be capable of generating and broadcasting ephemeris information on L1-SAIF signal via Message Type 58. The authors have tested ranging quality of L1-SAIF signal including the accuracy of ephemeris information. The result shows ranging accuracy of L1-SAIF is better than 0.5m RMS which is comparable to GPS. It is confirmed that using L1-SAIF signal as an additional ranging source improves position accuracy and reduces the maximum position error both horizontal and vertical directions.
Published in:	Proceedings of the 2012 International Technical Meeting of The Institute of Navigation January 30 - 1, 2012 Marriott Newport Beach Hotel & Spa Newport Beach, CA
Pages:	1255 - 1264
Cite this article:	Sakai, T., Yamada, H., Ito, K., "Ranging Quality of QZSS L1-SAIF Signal," Proceedings of the 2012 International Technical Meeting of The Institute of Navigation, Newport Beach, CA, January 2012, pp. 1255-1264.
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