L1/L5 SBAS MOPS Ephemeris Message to Support Multiple Orbit Classes

Tyler Reid, Todd Walter, and Per Enge

Abstract:	New satellite orbits ranging from highly eccentric inclined geosynchronous (IGSO), medium (MEO) to low Earth (LEO) orbits are being proposed for future Global Navigation Satellite Systems (GNSS) and Satellite Based Augmentation Systems (SBAS). This paper addresses the challenges associated with designing a message for the L5 Minimum Operational Performance Standards (MOPS) ephemeris and almanac data which can handle this broad spectrum of proposed orbital regimes. In the past, the MOPS message used Earth fixed Cartesian position, velocity, and acceleration (9 degrees-of-freedom (DOF)) to describe the motion of the geostationary (GEO) SBAS satellites. The proposed next generation MOPS message will have to be much more sophisticated in order to encompass potential navigation and augmentation satellites ranging from GSO to LEO. A method of optimally fitting orbital elements has been devised which allows for a wide variety of orbital elements to be employed. With this, a 9 DOF set of orbital elements has been selected for the ephemeris message and a 7 DOF set for the almanac which function amicably for the range of orbits in question. Case studies show the effectiveness of the proposed message for GPS, GLONASS, BeiDou, WAAS, EGNOS, QZSS, Iridium, and other proposed orbits such as Molniya. Quantization and detailed message structure will also be discussed.
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:	78 - 92
Cite this article:	Reid, Tyler, Walter, Todd, Enge, Per, "L1/L5 SBAS MOPS Ephemeris Message to Support Multiple Orbit Classes," Proceedings of the 2013 International Technical Meeting of The Institute of Navigation, San Diego, California, January 2013, pp. 78-92.
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