RO-SISMON: Results and Multi-SBAS Fusion at user Level for Non-SoL Applications

Alexandru Pandele, Antonia Croitoru, Mihnea Ion, and Simon Buehler

Abstract:	The European Geostationary Navigation Overlay Service (EGNOS) enables the usage of GNSS signals for safety critical applications like aviation, maritime and fluvial navigation through the addition of integrity information for the augmented signals. While EGNOS’ Open Service already completely covers Romania, APV-I and LPV200 Availability requirements set in collaboration with civil aviation are not met in Eastern and South-Eastern Romania. The upcoming releases of EGNOS aim at extending, amongst others, the availability of services towards the Eastern members of the EU28 group. Romania will greatly benefit from this extension, as the aviation authorities are highly interested in increasing the number of APV-I and LPV200 procedures at Romanian airports. Romania is ideally located to play a strategic role in assessing the performances of two other SBAS: the Russian System for Differential Corrections and Monitoring (SDCM) and the Indian GPS Aided Geo Augmented Navigation system (GAGAN) and potential future combined use with the European SBAS. Keywords: SBAS, EGNOS Introduction The Romanian Signal In Space MONitor (RO-SISMON) project is an activity financed in the scope of the ESA Romanian Industry Incentive Scheme. Considering the framework described above, the project focuses on monitoring the EGNOS, SDCM and GAGAN coverage over Romania. The activities developed consist of: • 4 GNSS monitoring receivers deployed at carefully chosen Romanian airports to derive typical user level performance • FTP data storage server for storing all data collected by the receiver network and make it available online • automatic reports created for monitoring EGNOS performance over Romania and the comparison of SBAS corrections between EGNOS, SDCM and GAGAN. Site selection The installation of the monitoring stations was guided based on the following criteria: geographical location (towards the Eastern border of the EGNOS coverage area), infrastructure availability at the airports and local environment (minimizing antenna masking). Using the SBAS Simulator tool developed by IGUASSU, we were able to determine four suitable locations: Bucharest, Constanta, Bacau and Suceava. For each selected site, a RFI analysis was performed together with an assessment of the local environment especially with respect to physical masking. Hardware development The main components of the receiver platform used for every station are the following: a Septentrio PolaRx 5 multi-frequency multi-constellation receiver, PolaNt-X MF/ Chocke Ring antenna, TNC Antenna cable, battery back-up, back-up hard-disk, 4G modem and a Mini PC Intel NUC. After the validation of the prototype monitoring station at Bucharest site, the other three stations were integrated at the above mentioned locations. SBAS Performance Report To enable on-demand as well as automatic report generation, a web platform was developed in order to create a system for data collection and storing, automatic reporting and SBAS performance assessment. The EGNOS performance analysis is mainly performed in real-time by EVORA, a dedicated software developed by IGUASSU. The assessment contains ESA All Stanford plots, accuracy, availability, continuity and protection levels. While initial investigations were able to show that deploying EGNOS ground stations to one or more selected locations would actually enhance EGNOS performance over Romania, the automatic reporting provides valuable information about the performance of EGNOS at user level in Romania, as it can be observed in the LPV200 availability map. Due to the location of the stations installed, it is also possible to acquire SDCM and GAGAN messages. Their ionospheric and satellite corrections are continuously compared with the ones broadcasted by EGNOS. A first assessment of the ionosphere corrections show that there are nine common IGPs between the three SBAS, twelve common IGPs between EGNOS and GAGAN and 108 common IGPs between EGNOS and SDCM. Further comparison of actual ionospheric corrections are the subject of ongoing investigation. Also, regarding the satellite corrections, the UDREi evolution of each GPS PRN monitored by the three SBAS has been analyzed. Preliminary results of these comparisons have shown that the combined use of these systems (by selecting the best values for the ionospheric and satellite corrections out of all three available) could enhance the SBAS availability and accuracy at user level and increase its service area towards the Eastern part of Europe (as a first step for non-SoL services). Final results shall be presented in the full paper and ION 2018 presentation. The output data of the reports are found to be a valuable asset for Romanian authorities involved in designing new approach procedures.
Published in:	Proceedings of the 31st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2018) September 24 - 28, 2018 Hyatt Regency Miami Miami, Florida
Pages:	1124 - 1143
Cite this article:	Pandele, Alexandru, Croitoru, Antonia, Ion, Mihnea, Buehler, Simon, "RO-SISMON: Results and Multi-SBAS Fusion at user Level for Non-SoL Applications," Proceedings of the 31st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2018), Miami, Florida, September 2018, pp. 1124-1143. https://doi.org/10.33012/2018.15937
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