UK SATNAV signal boosts efforts toward sovereign PNT capabilities

A satellite navigation signal is broadcasting as part of efforts to explore the creation of a sovereign national capability in resilient positioning, navigation and timing (PNT) for the aviation and maritime sectors.


The signal, broadcast in coordination with the US Federal Aviation Administration, the European Space Agency (ESA) and the European Union Space Programme Agency (EUSPA), is said to be stable and operational, which will allow on-going testing and validation by industry, regulators, and users. 

Inmarsat and partners Goonhilly Earth Station Limited and GMVNSL Limited, is delivering the UK Space Agency-funded tests with the European Space Agency via the latter’s Navigation Innovation and Support Program (NAVISP). 

According to Inmarsat, UKSBAS – UK Space-Based Augmentation System – generates an overlay test signal to the US Global Positioning System (GPS). This enables the assessment of more precise, resilient and high integrity navigation for maritime and aviation users in UK waters and airspace. It increases accuracy in positioning to a few centimetres compared to the few metres provided by standard GPS.

Since leaving the EU the UK is no longer part of the Galileo satnav system and cannot use the European Geostationary Navigation Overlay Service (EGNOS) safety of life (SOL) services, which enable the use of GPS for airport approach and landing.

The UKSBAS signal – enabled via the repurposed SBAS transponder on Inmarsat’s I-3 F5 satellite – allows testing of this potential alternative system to begin. Built by Inmarsat’s Athena partner Lockheed Martin and launched in 1998, I-3F5 covers the UK as part of its Atlantic Ocean region service overlay.

In a statement, Todd McDonell, president, global government at Inmarsat, said: “The Inmarsat team is inspired by delivering solutions to new problems through technology and innovation. Repurposing a transponder on a long-serving satellite to deliver a new capability to the UK, potentially a vital and enduring one, certainly lives up to that core Inmarsat ethos. Working with our fellow British companies at Goonhilly and GMVNSL to deliver such a capability for the country is very rewarding and we look forward to reporting on the results.” 

Tests will assess whether UKSBAS can develop into a full operational capability to support safety-critical applications, particularly at night and in poor weather conditions. Goonhilly provides the signal uplink for the system from Cornwall and software from Nottingham-based GMVNSL generates navigational data.

As well as aviation and maritime operations, the project could extend to any UK user requiring accurate, high-integrity navigation capabilities including rail and road operators.

Congratulations to Inmarsat, Goonhilly and GMVNSL on this impressive achievement,” said Paul Bate, CEO of the UK Space Agency. “This project is a great example of the innovation found throughout the UK space sector and demonstrates how we can work effectively with the European Space Agency to strengthen our national space capabilities.”