Initial Functional Verification Tests of RESSOX with MICHIBIKI (QZS-1)

T. Iwata, T. Matsuzawa, T. Kawauchi, S. Fukushima, Y. Fukuhara, T. Hiroshima, Y. Takahashi, J. Amagai, K. Saito

Abstract:	The First Japanese positioning satellite, MICHIBIKI, Quasi-Zenith Satellite-1, was launched successfully on September 11, 2010 from the Tanegashima Space Center of Japan Aerospace Exploration Agency (JAXA). The first three months after the launch were devoted to initial functional verification tests. The National Institute of Advanced Industrial Science and Technology (AIST) has been developing the remote synchronization system of an onboard crystal oscillator (RESSOX) for the Quasi-Zenith Satellite System (QZSS), and planned initial functional verification tests to be conducted at the Time Management Station (TMS) in Koganei (Tokyo) in November and at the TMS in Onna (Okinawa) in December of 2010. Those TMSs are facilities of the National Institute of Information and Communication Technology (NICT). RESSOX reduces overall cost, satellite power consumption, and onboard weight and volume. Moreover, RESSOX has a longer lifetime than a system with onboard atomic clocks. However, MICHIBIKI carries rubidium atomic clocks and RESSOX will be used in the experiments to examine its potential use in future QZSS. Six basic functional capability tests were planned: (1) measurement of time difference between RESSOX control signal and a space vehicle clock, (2) feed-forward capability of RESSOX Experiment One, (3) feedback capability of RESSOX Experiment One, (4) control performance during communication interruption (CI) of RESSOX Experiment One, (5) capability of RESSOX Experiment Two, and (6) control performance during CI of RESSOX Experiment Two, and (1), (2), (4), (5), and (6) were verified. In Experiment One, the RESSOX control signal that includes information on the standard time is sent from ground stations, and the onboard crystal oscillator of MICHIBIKI is controlled to synchronize the arrival of the RESSOX control signal. This is similar to such time calibration signals as WWV or JJY, but compensates the delay. In Experiment Two, on the basis of the results of a time comparison between the onboard crystal oscillator and the standard time conducted by NICT, the voltage applied to the onboard crystal oscillator is calculated at the ground station and is transmitted to MICHIBIKI to control the crystal oscillator. In the actual operation, 35- minute CI occurs twice a day because of the need to avoid interference with other GEO satellites. Therefore, the control performance during CI should be considered. In this paper, first, Experiments One and Two will be described. Second, the results of actual initial functional verification tests are demonstrated. Finally, issues for real experiments are discussed.
Published in:	Proceedings of the 2011 International Technical Meeting of The Institute of Navigation January 24 - 26, 2011 Catamaran Resort Hotel San Diego, CA
Pages:	1124 - 1132
Cite this article:	Iwata, T., Matsuzawa, T., Kawauchi, T., Fukushima, S., Fukuhara, Y., Hiroshima, T., Takahashi, Y., Amagai, J., Saito, K., "Initial Functional Verification Tests of RESSOX with MICHIBIKI (QZS-1)," Proceedings of the 2011 International Technical Meeting of The Institute of Navigation, San Diego, CA, January 2011, pp. 1124-1132.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In