As the world moves towards greater levels of autonomy and automation, it is expected that wide-area safety systems and services will become the norm including both terrestrial and GNSS-based safety services. Other major developed economies in the United States/Canada (WAAS), Europe (EGNOS), Japan (MSAS), India (GAGAN), South Korea (KASS), and Australasia (SouthPAN) have now or will soon have access to high-integrity GNSS-enabled aviation procedures, largely implemented via Satellite-Based Augmentation Systems (SBAS).

Currently, the UK does not have access to such services, previously provided via EGNOS, for UK airspace flight operations. In this current situation, it is a priority for the UK to evolve national GNSS capabilities, implementing navigation and timing resilience and integrity, for (a) aviation, (b) maritime, and (c) other growing sectors using GNSS safety applications. As an important first step, there is a need to establish a UKSBAS testbed, broadcasting a GNSS Signal-In-Space (SIS) to begin to address the non-availability of EGNOS safety-of-life services.

As a result, the UKSBAS Phase 1 activity was successfully proposed to the NAVISP element 3 programme during 2021 and resulted in the deployment of the initial testbed capabilities, focused on the broadcast of an ICAO SARPS compliant SBAS signal in space (SIS) using PRN code 158 via the Inmarsat-3F5 navigation transponder (54 degrees West), uplinked from the testbed Ground Uplink Station (GUS) at Goonhilly Earth Station (GES) UK, with the navigation data overlay frames being generated using magicSBAS software installed at the UKSBAS testbed augmentation processing centre (APC) in Nottingham, UK (GMVNSL). A stable, continuous L1 SBAS signal in space has been delivered, provided via the initial testbed platform. The maritime integrity service interface platform has been established with a view to extending the maritime integrity user trials in Phase 2A along with live aviation trials.

The top-level objectives of the UK SBAS Testbed Phase 2A, identified by UK Department for Transport and UK Space Agency, are as follows:

1. To investigate complete SBAS system architectures to de-risk and inform any potential fully operational system
2. To investigate and demonstrate regulatory compliance for safe and secure operation of SBAS in United Kingdom
3. To execute live trials to develop and deliver demonstration of :

1. maritime IM at sea
2. aviation IM (piloted)
3. aviation PPP and IM (UAV) in Phase 2B (TBC)
4. PPP and IM in driver/driverless cars in Phase 2B (TBC)
5. IM in rail use case in Phase 2B (TBC)

4. To explore IM in fixed critical national infrastructure (CNI) for high-integrity timing resilience.