David Calle Calle, Laura Martínez Fernández and Guillermo Tobías González, GMV, Spain

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Abstract:

Currently, many European Space Missions, for which the Copernicus Programme is the main representative, rely on precise GNSS products for achieving their goals. These GNSS products comprise, among others, precise GNSS orbits, GNSS clock corrections and Earth Orientation Parameters. Most of these aforementioned missions comprise Atmospheric, Oceanic, Land, Climate Change monitoring among others, each of them enabled by the specific technologies on board different Low-Earth Orbit satellite families, including the most recent cubesats. The GNSS product provision for the aforementioned missions has become more and more demanding over the past years, in particular in terms of accuracy, supported constellations and latency. The missions’ requirements regarding GNSS product provision has progressively shifted from decimetre accuracy, hourly latency and sole GPS processing, to cent metric accuracy, near real-time product provision and multiGNSS support. Two clear examples of mission evolutions are EUMETSAT’s Polar System Second Generation (EPS-G), comprising six satellites in total, and EU/ESA’s Copernicus Sentinel-1, -2, -3 missions, comprising currently six satellites, and more to be launched in the following years. Although the scope of these missions are completely different, the enhanced capabilities regarding their GNSS payload with respect to previous missions, together with the input GNSS products requirement needs, are in line with the trend described previously. In this regard, the Radio Occultation (RO) instrument receiver on board EUMETSAT’s next generation of polar-orbiting satellites (EPS-SG) will be able to observe, acquire and track signals from both the modernised GPS and from the Galileo navigation systems. Being mandatory the provision of precise (not only GPS, but also Galileo) products for the success of the MetOp program. Moreover, the expected accuracy of these GNSS products is one order of magnitude higher that the ones provided for the first generation of EPS; the GRAS Ground Support Network (GSN) Service. Another clear example of the aforementioned mission evolution are the Copernicus Sentinel missions. In this case, the current Sentinel-1, -2 and -3 A&B satellites have already receivers tracking L1 C/A, L1P(Y), and L2P(Y). The receivers on-board the B satellites track as well L2C-M and L2C-L. The receivers on-board the future C&D satellites and Sentinel-6 will add L5 I/Q signals of the GPS constellation, and the E1 B/C and E5a I/Q of Galileo constellation. Consequently, it is foreseen that the necessary input GNSS products will comprise Galileo before the end of 2020. Over the last 2 years, and with the aim of providing an answer to these challenges, GMV has evolved its magicGNSS service for being able to provide highly accurate multiGNSS products in a near real-time basis. This new magicGNSS service is being currently provided to EUMETSAT to support various EUMETSAT Radio Occultation missions, and also used as a backup for the Copernicus Precise Orbit Determination (CPOD) service. The objective of this paper is to provide an overview of this new magicGNSS service for LEO POD applications. The paper will describe the high-level architecture of GMV’s solution, the different algorithms and techniques which support it, and the main challenges faced over the last year. The results and statistics of the achieved product accuracy and timeliness will also be presented and analysed. To conclude, insights about future needs and challenges to be undertaken to cover future mission needs will be presented.