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The European GNSS Agency (GSA) organised an online workshop on 3 March to provide an in-depth analysis of the performance of Galileo and show how this performance is evaluated and how it is crucial for service provision in every user application.

The workshop focused in particular on the Galileo Open Service (OS) as defined in the OS Service Definition Document (SDD) and the Programme’s needs for performance monitoring against the defined Minimum Performance Levels (MPLs) and Key Performance Indicators (KPIs). Attention was also paid to publicly available data, products and tools that can be used for GNSS monitoring. In addition to the GSA, the workshop involved representatives of the European Commission, the European Space Agency (ESA) and of the EU Member States and gathered nearly 500 participants. 

Workshop outcome

At the workshop, a number of technical topics were addressed.

• All presenters confirmed that the Initial Services commitments as described in the OS SDD are met, some events were observed and discussed, but the Galileo performance, also compared to other GNSS, especially in terms of accuracy is good. 
• When monitoring the performance of Galileo, it is important that the satellite health status should be verified for F/NAV and I/NAV ephemerides using broadcast navigation data consolidated from a global network. However, there is no standard on how to generate a consolidated navigation message from publicly available data– the quality and availability depends on latency of this data. 
• It is important for users to check the status of the navigation messages as specified in the Galileo OS Signal-in-Space (SiS) Interface Control Document (ICD) and the SDD. This requires that the receivers monitor the Signal-in-Space health flags: signal health status (SHS), data validity status (DVS) and Signal-In-Space accuracy (SISA). The Galileo system uses these three SiS health flags to protect users, and all of them need to be monitored and appropriate actions taken as specified in the ICD. Both the ICD and SDD are available for download on the website of the European GNSS Service Centre (GSC).

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• With respect to using reference stations for performance monitoring, it is recommended to use a geodetic grade receiver connected to a geodetic antenna. This generates high-quality data using multiple frequencies and signals. 
• Real-time data provides an overview of GNSS status in nominal situations. However, not all information from the signals required for monitoring is available in the real-time streams using the RTCM standard. Some sources also provide real-time broadcast orbit and clock corrections in the state space representation (SSR) format, yet unusual events and anomalies might not be reflected properly in these streams, as the underlying processing software might not be able to handle those events well.
• The Galileo Service Operator runs the system to maintain the performance specified in the SDD. Performance may vary within set margins due to operational, maintenance or deployment constraints. In light of this, interpretation of results is key for proper GNSS performance monitoring. It is good practice to make use of redundancy and always to confirm results with other sources, when possible. 

Galileo Reference Centre

The GSA has established the Galileo Reference Centre (GRC) with a primary mission of providing an independent means to monitor and evaluate the performance of the Galileo services and the quality of the Signal-in-Space. The GRC is the European hub for these activities, integrating contributions from European national entities, such as research centres, timing laboratories, and national space agencies.

Watch this: Galileo Reference Centre

Performance is measured against Key Performance Indicators (KPIs), the computation of which depends on GNSS data measurements and derived reference products (e.g. precise orbits, satellites clock corrections). It can also be assessed based on publicly available data and products, which exist with various levels of quality, reliability and latency. To be able to compare results obtained by independent sources, it is important to have a common understanding, guidelines for monitoring and a sound assessment methodology. This is what the Galileo performance workshop aims to provide.

All the presentations delivered during the workshop are now available here.

Media note: This feature can be republished without charge provided the European GNSS Agency (GSA) is acknowledged as the source at the top or the bottom of the story. You must request permission before you use any of the photographs on the site. If you republish, we would be grateful if you could link back to the GSA website (http://www.gsa.europa.eu).

Under the management of the European GNSS Agency (GSA), a collision avoidance manoeuvre for satellite GSAT0219 was performed over the past weekend. This manoeuvre was conducted following a collision risk alert received from EU Space Surveillance and Tracking (EUSST).

On 25 February, the Galileo Service Operator (GSOp) received from the EUSST a collision risk alert between GSAT0219 and an inert Ariane 4 upper stage launched in 1989. Following this warning, GSOp started to closely monitor the risk, in close cooperation with EUSST that was refining its predictions. 

In line with operational procedures, GSOp informed the GSA of the situation. In a joint effort with the European Commission, the GSA managed the follow-up activities. The effective cooperation between EUSST and the GSA/GSOp was instrumental to the success of the mission and bears testimony to the need for efficient cooperation between different organisations in the space sector.

Manoeuvre authorised

Following refinement of the Ariane 4 orbit, the risk of collision was still unacceptably high, so, after assessment of different strategies and associated risks on the service provision, the GSA authorised the execution of an avoidance manoeuvre. The satellite was taken out of service on 5 March, and users were informed via NAGU #2021009. The collision avoidance manoeuvre was performed shortly thereafter, by temporarily relocating the satellite away from its nominal position. Satellite GSAT0219 is expected to be reintroduced into service in Calendar Week 11 (15.03 – 21.03) after the completion of two station keeping manoeuvres to reposition it into its nominal operational orbit. Users will be kept informed via NAGUs.

This is the first time a collision avoidance manoeuvre has been performed for a satellite in the Galileo constellation.

After smartphones, wearables are the second most sold GNSS device, with 70 million shipments in 2019 alone. Given this trend, the European GNSS Agency (GSA) was motivated to test smartwatch devices under various conditions. Three devices were selected that, to a certain extent, characterise the Galileo-enabled device offering on the market in 2020: the Suunto 9, Samsung Galaxy Watch Active 2 and Garmin Fenix 6X PRO. The tests delivered some interesting results.

The tests were carried out by the Airbus Systems Engineering and Technical Assistance (SETA) team under a Galileo System Support contract with the GSA. The main objective was to evaluate the navigation performance of the wearables in different receiver configurations and environments. To evaluate the devices’ performance, the tests assessed positioning accuracy and PVT availability. 

All the tests were carried out close to an Airbus site south of Munich, and included an open sky static test, an open sky pedestrian test, and an open sky bike test. In addition, there were three suburban dynamic tests (two pedestrian – one with the watch worn on the wrist and one on a backpack, and one bike test), an urban static test, and two forest dynamic tests (pedestrian and bike), both of which had alternating vegetation of broadleaf trees and conifers. 

Read this: Point.IoT 2021 – another year of exciting Galileo-powered IoT innovations

Each test was executed three times in order to cover all the possible GNSS receiver configurations. Subtests with the corresponding GNSS receiver configurations are presented in the table below. 

Figure 1: Data collection of forest dynamic pedestrian test case

After smartphones, wearables are the second most sold GNSS device, with 70 million shipments in 2019 alone. Given this trend, the European GNSS Agency (GSA) was motivated to test smartwatch devices under various conditions. Three devices were selected that, to a certain extent, characterise the Galileo-enabled device offering on the market in 2020: the Suunto 9, Samsung Galaxy Watch Active 2 and Garmin Fenix 6X PRO. The tests delivered some interesting results.

The tests were carried out by the Airbus Systems Engineering and Technical Assistance (SETA) team under a Galileo System Support contract with the GSA. The main objective was to evaluate the navigation performance of the wearables in different receiver configurations and environments. To evaluate the devices’ performance, the tests assessed positioning accuracy and PVT availability. 

All the tests were carried out close to an Airbus site south of Munich, and included an open sky static test, an open sky pedestrian test, and an open sky bike test. In addition, there were three suburban dynamic tests (two pedestrian – one with the watch worn on the wrist and one on a backpack, and one bike test), an urban static test, and two forest dynamic tests (pedestrian and bike), both of which had alternating vegetation of broadleaf trees and conifers. 

Read this: Point.IoT 2021 – another year of exciting Galileo-powered IoT innovations

Each test was executed three times in order to cover all the possible GNSS receiver configurations. Subtests with the corresponding GNSS receiver configurations are presented in the table below. 

Figure 1: Data collection of forest dynamic pedestrian test case