First UK-generated satnav signal coming in test project

Satellite communications company Inmarsat is working on a United Kingdom Space Agency-funded test project with the European Space Agency to deliver the first UK-generated satellite navigation signal. The project provides a potential platform for the UK to enhance its post-Brexit positioning, navigation and timing (PNT) capabilities.

Other partners are British companies Goonhilly Earth Station Limited and GMV NSL Limited.

Repurposing a transponder from the Inmarsat-3 F5 satellite, the test project — known as UK Space-Based Augmentation System (UK SBAS) — will provide an overlay signal to augment the U.S. GPS, refining its accuracy from a few meters to a few centimeters.

UK PNT without EGNOS

The UK no longer has access to the European Geostationary Navigation Overlay Service (EGNOS) Safety of Life services since leaving the European Union (EU) and is not involved in the EU’s Galileo programme for similar reasons. Therefore, this new national capability supported by current and future Inmarsat satellites could offer a new option for high-integrity, precision navigation across the country, in its airspace and within surrounding waters.

UK SBAS will provide a basis to assess its future development into an operational capability to support safety-critical applications such as aircraft approaching and landing at airports or navigating ships through narrow channels, especially at night and in poor weather conditions.

Goonhilly will provide the uplink for the system from Cornwall. Software from GMV NSL, based in Nottingham, will generate the ground-based navigation signal. This is a similar system to that already in use in Australia and New Zealand, supported by Inmarsat.

The project could be crucial for UK users who need accurate, high-integrity navigation capabilities to enable their operations. It will initially cover aviation and maritime operations, but has the potential to extend into rail and other land-vehicle applications. For example, UK SBAS will comply with International Civil Aviation Organization (ICAO) standards.

“It is very welcome news to hear that UK-based companies have teamed up to deliver this ground-breaking project, with help from government funding,” said Transport Minister Trudy Harrison. “From flying planes to steering ships, reliable and precise navigation support is a crucial part of travel. This development is a significant step forward for our world-leading space sector, as we accelerate towards a net-zero transport future.”

Best satellite candidate

Artist’s impression of an Inmarsat-3 satellite. (Image: Inmarsat)

The Inmarsat-3 F5 satellite is in geosynchronous orbit at 54° west, ensuring that its signal covers the UK as part of its Atlantic Ocean region service overlay. This makes it an ideal candidate to participate in the test. The satellite was manufactured by Inmarsat’s Athena partner Lockheed Martin and launched in 1998.

“This project demonstrates British innovation at its best,” said Nick Shave, vice president of Strategic Programmes for Inmarsat Global Government. “Working with Goonhilly Earth Station and GMVNSL, supported by UK funding via the ESA Navigation Innovation and Support Programme (NAVISP), enables us to extend the long life of Inmarsat’s I-3 F5 satellite with additional new services designed two decades after launch.

“We look forward to exploring the potential for this project and the benefits it could deliver to the UK with more precise, high-integrity, resilient navigation services, whilst also exploring future capabilities on new satellites through Inmarsat’s fully funded technology roadmap,” Shave said. “This work also has the potential to be exported to other nations around the world, benefitting the UK economically as well as technologically.”