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gAGE

gAGE

Location

Jordi Girona 1-3

C3 Building, 08034 Barcelona.

Spain

41° 23' 19.0536" N, 2° 6' 42.8256" E

 

The Research group of Astronomy and Geomatics (gAGE/UPC) is an interdepartmental research group of UPC involving the Departments of Mathematics and Physics. A summary of the gAGE/UPC activities in relation with the UPC structure and organization can be seen in Figure 1. The education activities of gAGE/UPC include both, graduate and post-graduate levels, having created and coordinated several Master and Doctorate courses on GNSS. From 2010 gAGE/UPC members have participated as invited lecturers in the ESA International Summer School on GNSS, organizing that School in Barcelona during 2015.

 

 

Figure 1 Organization of UPC and integrated gAGE activities

 

Concerning research and technology transfer activities, the results achieved in the last years by gAGE/UPC have given to this research group a high international acknowledgment, which has been shown in the adjudication of several competitive contracts from institutions and companies in the satellite navigation and aeronautical sectors such as ESA, Eurocontrol, Galileo Joint Undertaking (GJU), and the European GNSS Agency (GSA). A detailed list of current active projects and projects where gAGE/UPC has been involved in the last 5 years can be seen in the website. Currently, members of gAGE/UPC take part in several international groups of experts; have published more than 90 scientific papers in peer-reviewed journals and more than 220 papers in congress proceedings in the GNSS field. This large number of publications demonstrate the capability and experience of gAGE/UPC in the assessment of the performance of high accuracy and integrity of GNSS services for the end-users of interest in the current activity. gAGE/UPC senior members share 5 registers of patents on GNSS (2 international linked to WARTK and Fast PPP techniques, with 12 associated entries) and four books on GNSS Data Processing, the last one, with two volumes published by ESA. See gAGE/UPC website http://gage.upc.edu.

In this context, the expertise, concepts and products of gAGE/UPC relevant to the present project activities are detailed next.

  1. The innovative concept of Fast-PPP. The advent of multiconstellation and multifrequency GNSSs (Galileo, modernized GPS …) could finally open the door for the extension of High Accuracy Services to Mass Market Users in a standalone mode with fundamental impact on the application domain. Feasibility has been investigated and demonstrated by gAGE/UPC, developing new algorithms and showing that centimeter level of accuracy navigation can be achieved for any worldwide PPP-user with very fast convergence. This new technique is called Fast-PPP. In this context, gAGE/UPC has developed a Central Processing Facility (CPF) with the capability of separating the different effects on actual GPS, Glonass and Galileo signals with accuracies at the level of 1 cm. Indeed, the ionospheric model running in the CPF produces ionospheric determinations at the level of 1/2 TECU (8 cm L1 delay) or better. These values are several times more accurate than the IGS TEC maps and provide a valuable source of ionospheric determinations to assess the GNSS ionospheric models.
  2. Ionosphere for Galileo high accuracy service (HAS).  Starting in 2021, the public will obtain the new and free service provided by Galileo HAS. Currently, different message structures are being developed by ESA and EC at the system level, to broadcast the necessary information for HAS. Namely, ionosphere corrections, differential code biases (DCB), precise satellite orbits and clocks. In this context, the research group (gAGE/UPC) is the responsible of the implementation of the ionosphere and DCB real-time models for the Galileo HAS in the ESA ITT AO/1-9797/19/NL/AF named (IONO4HAS). This is a consequence of more than 15 years of experience developing, testing and improving a Central Process Facility (CPF) that is able to calculate all precise products that are involved in the Galileo HAS. Note that gAGE/UPC patented together with ESA the Fast-PPP technique with centimetre level accuracy in a few minutes of convergence time (see previous point). That is the backbone of the concept implemented in the Galileo HAS.
  3. Integrity and availability for EGNOS. Concerning the field of ionospheric studies, gAGE/UPC has developed a new indicator of ionospheric activity (IAI), the Along Arc TEC Rate (AATR) [Juan et al. 2018a; Sanz et al. 2014]. From an analysis of the behavior of the SBAS systems under different ionospheric conditions, it has been demonstrated that this AATR indicator is a very suitable means to discern if the SBAS service availability anomalies are linked to the ionosphere. In this sense, the AATR indicator has been selected as the metric to characterize the operational conditions of the ionosphere within the framework of EGNOS operations and activities. Likewise, the AATR index has been adopted as a standard tool by the International Civil Aviation Organization (ICAO) for joint ionospheric studies in the different SBAS systems (WAAS, EGNOS, MSAS...). 

On the other hand, gAGE/UPC is giving support to the EGNOS Project Office in the generation of Ionosphere Expert Team Scenarios (IET) for EGNOS. In particular, has generated the IET7 (Halloween storm moved to Europe), IET8, IET9 (Long Duration IET scenarios) and IET10 (ICASES1 and ICASES2 project, see Table 4‑15) and has developed the Feared Events projects for Signal in Space analysis and anomaly investigation.

From 2001 to 2012, gAGE/UPC was an active member of the ESTB/EGNOS Data Collection and Analysis Working Group of Eurocontrol. This working group was devoted to the Operational Validation Activities for EGNOS. gAGE/UPC developed its own tools to analyze the SBAS (EGNOS/WAAS) signal, in both position and Signal in Space domains, including a Global Monitoring System (under an Eurocontrol contract) to analyze the performance of the EGNOS system over Europe on a daily basis.

Finally, gAGE/UPC, in collaboration with ESA, has developed several studies on the transfer of integrity from pseudo-range to position domains that have led to the Stanford-ESA Integrity Diagram (awarded by the US ION GNSS 2006). This technique is used to assess the robustness of the EGNOS system with respect to the integrity bound provision, for all possible satellite geometrical conditions. The Stanford-ESA Integrity Diagram was adopted by the GSA recommendations for the EGNOS safety certification as a tool for the integrity assessment in the position domain.

  1. EGNOS maritime service. Recently, gAGE/UPC has evaluated how EGNOS meets the International Maritime Organization (IMO) requirements established in its Resolution A.1046 for navigation in harbor entrances, harbor approaches, and coastal waters: 99.8% of signal availability, 99.8% of service availability, 99.97% of service continuity and 10 m of horizontal accuracy. Using the GNSS Laboratory Tool Suite (gLAB, see next point) to compute the EGNOS service maps, showing a signal availability of 99.999%, a horizontal accuracy of 0.91 m at the 95th percentile, and the regions where the IMO requirements on service availability and service continuity are met. From that study, a revision of the assumptions made in the EGNOS Maritime Service against those made in EGNOS for civil aviation has been suggested. In particular, the use of the EGNOS Message Type 10.
  2. The GNSS laboratory tool suite (gLAB). Officially developed by gAGE/UPC under several ESA contracts (see Table 4‑15), this software tool provides multi-frequency/multi-constellation PPP as well as standard (mass-market) point positioning in static and kinematic modes. It also provides differential positioning, and EGNOS modernized V3 version, including integrity of ionospheric corrections and monitoring of availability. In the next months, in agreement with ESTEC/ESA, gAGE/UPC will expand the scope of the software to include RAIM and Advanced RAIM tools and, in particular, adding an experimental RAIM for maritime services.
  3. Scintillation mitigation for precise positioning. In the framework of the activities developed under two ESA projects [SCIONAV and CLIMIONO, see Table 4‑15], gAGE/UPC has developed a new methodology to derive reliable scintillation monitoring parameters (S4, σφ and ROTI) using measurements from geodetic receivers operating at 1 Hz sampling frequency. This methodology is known as the geodetic detrending (GD) technique. Thanks to an accurate geodetic and ionospheric modelling, the GD technique allows to analyze scintillation impact on GNSS measurements and to detect small cycle-slips (of one or two cycles) produced by scintillation in individual (uncombined) GNSS signals. This has paved the way to implement suitable mitigation techniques to allow precise positioning (PPP) under scintillation conditions in high and low latitudes.