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Session B3: Future Trends in GNSS Augmentation Systems

A UK SBAS Testbed Capability
David Hill, George Newton, Claudio Soddu, Inmarsat; Mark Dumville, Madeleine MacCreadie, Smita Tiwari, William Roberts, GMV NSL; Julián Barrios Lerma, GMV AD; Chris Emes, Goonhilly Earth Station Ltd.
Date/Time: Thursday, Sep. 22, 11:03 a.m.

The United Kingdom’s (UK) withdrawal from the European Union (EU) affected the way that the UK participates in the EU Space Programmes. In the context of Space-Based Augmentation Systems (SBAS), this event ended UK participation in the EGNOS programme, removed UK access to the EGNOS Data Access Service (EDAS) and prevented the use of EGNOS Safety of Life (SOL) services in UK airspace as from June 25th, 2021 which directly-affected 18 UK airports.
Following this, a new UK national SBAS demonstrator has been established, to aid in assessing the options for a future operational capability to provide augmentation services for users of GPS and potentially other GNSS. This is the “UKSBAS Testbed”, developed under the European Space Agency’s “Positioning, Navigation and Timing: Innovation, Competitiveness and Support for Institutional Projects” (NAVISP) programme. The project is led by Inmarsat, with support from GMV NSL and Goonhilly Earth Station.
The UKSBAS Testbed makes use of a current in-orbit Inmarsat geostationary (GEO) satellite navigation transponder, a commercial-off-the-shelf navigation signal generator, SBAS message generation, Message Type 0 (MT0) checks and service performance monitoring through GMV’s magicSBAS suite, and a UK ground station at Goonhilly for the signal uplink to the GEO navigation transponder. The testbed architecture will use a dense network of existing Continuously Operating Reference Stations (CORS) made available by UK Ordnance Survey and IGS real time services as sources of GPS observations and navigation data.
A primary objective of the testbed is the establishment of a UK SBAS L1 test Signal in Space (SIS) that may form the basis for the provision of a future SBAS services. The test signal will at all times be marked as being not operational (and therefore not to be used for any safety-critical applications) through the regular transmission of SBAS Message Type 0 (MT0) in compliance with ICAO SARPS. Also, the testbed enables the assessment of the interoperability between UK SBAS and EGNOS signals within their respective coverage areas. A further key objective is the delivery of a system performance assessment in relation to the monitoring of GPS via the dense, high-redundancy CORS network.
Additionally, the testbed also hosts a prototype, web-based Maritime Integrity Service Interface (MISI), a platform on which alternative approaches to integrity bounding may be tested, using approaches potentially more appropriate to maritime communities than the aviation-centric conventional SBAS algorithms.
Finally, the infrastructure includes a performance monitoring platform able to compute the system performances not only in terms of aviation services (e.g. APV-I, LPV-200 availability) but also at user level (e.g. performances at dedicated CORS stations). The uksbas.org website provides live information on the performance of the UKSBAS Testbed.



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