Inmarsat-4 Navigation Transponder Test Equipment and Control Software for In-Orbit Tests

A.J. Van Dierendonck, R. Coker, O. Razumovsky, D. Bobyn, H. Kroon

Abstract:	At present the Space Based Augmentation Systems, like the US WAAS (Wide Area Augmentation System) and the ESA EGNOS (European Geostationary Navigation Overlay Service) in Europe, utilize Inmarsat-3 and Artemis Geostationary Earth Orbit (GEO) satellites to provide ranging signals to the end users that also contain integrity and correction data on GPS satellites. This signal is generated on the ground and transmitted via C band uplink to the Inmarsat-3 or K-band to the Artemis GEO satellite. The navigation transponder frequency-translates the received uplink signal to GPS L1 and C-band downlink signals for Inmarsat-3 or GPS L1 and K-band for Artemis satellites. Japan's MSAS system, also an SBAS, has a similar architecture and operates in the similar manner. The new Inmarsat-4 (I-4) GEO Satellites, slated for launch in 2004, are being designed to provide SBAS Signals-In-Space on both GPS L1 and L5 frequencies. Furthermore, the L5 signal will replace the C-band downlink signal broadcast used on the current Inmarsat-3 navigation transponders, and this L5 signal will be controlled completely independent of the L1 signal. Because of these differences in Inmarsat-3 and I-4 GEO design, new test equipment and control software are being developed for the I-4 In-Orbit Tests and to provide SBAS L1 and L5 Signal-in-Space proof of concept demonstrations. The thrust of this paper will be a description of the test system and its interaction with the I-4 Navigation Transponders, with an emphasis on the Control Software algorithms.
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:	1307 - 1319
Cite this article:	Van Dierendonck, A.J., Coker, R., Razumovsky, O., Bobyn, D., Kroon, H., "Inmarsat-4 Navigation Transponder Test Equipment and Control Software for In-Orbit Tests," 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. 1307-1319.
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