Galileo System Performance Trends Towards Full Operations Capability, a TGVF-X Perspective
G. Galluzzo, S. Circiu, D. Ibañez, G. Lopez, S. Wallner, J. Hahn, ESA-ESTEC; C. García, L. Domínguez , F. J. Sobrero, A. García, GMV
Date/Time: Thursday, Sep. 14, 1:50 p.m.
With a constellation of 24 operational satellites providing navigation services, the Galileo system has already secured a key role in the multi-GNSS scenario. The user community has been following the acceleration in the system deployment and service provision enhancements since the declaration of Galileo Initial Open Service on 15th December 2016. The increasing number of Galileo-enabled devices, including the proliferation of smartphones and IoT devices, has boosted the usage of Galileo signals as never before in the history of the Programme. The European Space Agency (ESA), as the Galileo System Design Authority, is responsible for the development and qualification of new Galileo system releases (known as System Builds), and is also contributing to the continuous and independent monitoring of the system navigation and timing performance.
In 2023 ESA and all Galileo Programme stakeholders celebrate a historical milestone, the tenth-year anniversary of the very first positioning fix on 12th March 2013, when the first determination of a ground location was possible relying solely on European infrastructure, from the four In Orbit Validation satellites in space to the ground control centers in Italy and Germany, as well as the worldwide network of sensor and uplink stations.
This first Galileo only based position computation took place at the Navigation Laboratory at ESA’s technical heart, the European Space Research and Technology Center (ESTEC), in Noordwijk, The Netherlands.
The Time and Geodetic Validation Facility (TGVF), with its core infrastructure integrated in the Navigation Laboratory at ESA-ESTEC, was one of the main tools used to validate the first positioning fix.
TGVF, and the latest version TGVF-X for system eXploitation phase following the Galileo Initial Services declaration in December 2016, is the main system prototyping, experimentation, monitoring and troubleshooting platform operated at ESA-ESTEC. TGVF-X is a culmination of a project that dates to the early 2000s, to the early inception of the Galileo project, targeting the early prototyping experimentations of the Orbit Determination and Time Synchronization (ODTS) and Galileo System Time (GST) generation algorithms, to confirm their technical feasibility and de-risk large scale industrial procurements.
This paper provides an update on the latest system performance trends towards the Galileo 1st Generation Full Operational Capability phase, as well as TGVF-X independent monitoring of new system capabilities and services, such as I/NAV improvements, High Accuracy Service, and OSNMA.
One of the latest improvements introduced in the Galileo Open Service signal are the so-called I/NAV improvements. Within this additional information transmitted in the I/NAV message, new parameters (Secondary Synchronisation Pattern (SSP), Reduced Clock and Ephemeris Data (RedCED) and Forward Error Correction (FEC2) based on Reed Solomon) are broadcasted with the main purpose of reducing the time to first fix for the Galileo users. The TGVF-X was upgraded in order to support the live tests campaign of these improvements during summer 2022. During this testing phase, the TGVF-X provided instrumental support and confirmed the achievement of the expected performance of the new functionalities, allowing ESA to deploy these features in more satellites. At the time of writing this abstract, 11 Galileo satellites have been upgraded to transmit the SSP, RedCED and FEC2 parameters within the INAV pages and the TGVF-X is routinely monitoring these transmissions. Specifically, the performance of the reduced clock and ephemeris data is monitored, using the Fitting Range Error (FRE, in comparison with the navigation data) and SISRE (using the internally generated E-OSPF orbits and clocks as reference). The correctness of the transmitted SSP and Reed Solomon is verified and reported to ESA by the TGVF-X. In case any anomalous behavior is detected, an automatic alert is sent to ESA.
This monitoring is done using the data provided by the Galileo Experimental Sensor Stations (GESS) network, operated by the TGVF-X. Owning its own global stations network has given the TGVF-X the possibility of becoming a key participant in other important milestones of the Galileo system: the Galileo Open Service Navigation Message Authentication (OSMA) and the High Accuracy Service (HAS). Regarding OSNMA, the GESS network has been upgraded in the past years to process the authenticated signal, giving ESA the possibility to monitor the OSNMA, which is currently under testing, worldwide. The TGVF-X is routinely monitoring and reporting the performance of the authenticated PVT computed at each receiver.
Another very important milestone in Galileo´s history is the declaration of Galileo HAS Initial Service beginning of 2023, in which the TGVF-X has been a key player in terms of monitoring. Already during the testing phase, the TGVF-X platform has monitored real time the HAS service through different aspects. On one hand, the broadcast corrections (orbit and clock corrections to the broadcast ephemerides and the satellite biases) are being monitored real time, verifying that their accuracy fulfills the expected one. On the other side, the performance at user level is also monitored by running several Real time PPPs and analysing the performance in terms of positioning accuracy. After service declaration, all these monitoring activities continue running routinely within the TGVF-X and are included in the visualization dashboard so that ESA can always access the latest status of the service. Additionally, regular reports are being generated for more detailed analysis.
In the tenth anniversary of the first positioning fix, this work provides a comprehensive view of the performance trends and evolution towards the full operational capabilities of the Galileo system, with special focus on the new system capabilities which have boosted the usability of the Galileo satellites and based on the powerful monitoring tools of the TGVF infrastructure.
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