Clocks, eLoran, quantum navigation and best practices – UK PNT forging ahead

Saying the government must focus on “delivering an operational resilient positioning, navigation and timing (PNT) system for the UK as soon as we can,”  the British Science Minister, Lord Patrick Vallance, announced several initiatives in his opening remarks to the Royal Institute of Navigation’s UK PNT Leadership Seminar on Nov. 20.

Among them was a funding increase for the National Physical Laboratory’s National Time Centre (NTC) project, from £30 million to £62.7 million, and a plan to have NTC and the first of the nation’s new eLoran towers at initial operating capability by January of 2027.  

Plans for all efforts beyond next year were necessarily caveated with “subject to spending review.”  

Still, seminar attendees were gratified to hear the minister endorse the ten-point PNT policy framework published by the previous administration in 2023. It was particularly encouraging that he also committed to operationalizing it with implemented systems.

The minister did not mention the UK’s significant investment in quantum research, which was discussed later in the seminar. This research has the potential to contribute to PNT with better timekeeping and inertial and gravimetric sensing. Three quantum hubs — one each in Scotland, the Midlands and the South — are part of this effort.

Lord Vallance and Shabana Haque, Ph.D., the head of the National PNT Office, who spoke later, also mentioned two important non-technology themes.

The first theme was that the PNT office is fully funded, staffed and very active. It was created last year as a cross-government effort and included representation from the Ministry of Defence. In addition to pushing the nation’s PNT efforts forward, the office has been engaged with numerous other governments, including those of the United States, Canada, Australia, New Zealand, Europe, Japan and Korea.

Secondly, the PNT initiatives are necessary for the nation’s resilience and security but will also be a source of economic benefits. This goes beyond PNT resilience, enabling Britain’s economy to function during local and potentially widespread GNSS disruption events. As the nation develops the technology stack to support its own resilient PNT architecture, along with enabling and supporting policies, devices and services will become marketable to others.

A sovereign PNT capability that can both stand independently and cooperate with GNSS is becoming increasingly attractive to many nations. Being able to source such a capability from a respected and trusted ally such as Great Britain could make acquiring and implementing such a system much easier for many.

The UK government has been working with several partners to advance its understanding and planning implementation of an eLoran capability. Haque highlighted work with the ESA’s F)!NAVISP program, resulting in the UK’s Roke developing an eLoran antenna for handheld devices. She also discussed the integration of the National Timing Centre’s clock and fiber network with eLoran signals and the development of GNSS/eLoran receivers. Of particular interest to many was an “eLoran Effectiveness Report” that the government commissioned and received from the General Lighthouse Authority’s Research and Development (GRAD) team. GRAD has had extensive experience with the technology, having operated and evaluated a differential eLoran system along Britain’s east coast for more than a year.

In a related move that helped signal the UK’s commitment to the technology, the Ministry of Defence issued a request for information (RFI) about a deployable eLoran capability in September. The RFI indicated that the document was a prelude to an acquisition.

The UK Science Minister also praised the RIN’s work and publication of a series of tools to help explain PNT and the need for resilience to those outside the community. The tools will also help organizations evaluate their readiness for GNSS disruptions.

Available from the RIN’s Resilient PNT Portal, they are:

• A PNT Explainer that outlines risks from over-dependence on GNSS and provides links to other informative resources.
• A Best Practices “placemat” describing a “Prepare, Act, Recover” framework for PNT disruptions.
• A PNT Resilience Checklist for organizations to use to self-evaluate their risk from GNSS disruptions.

The RIN recommends that PNT experts use these tools to work with customers, suppliers and partners and act as a “guiding hand.”

The RIN sees these all as a “phase 1 release.” Feedback on the tools is encouraged and should be sent to rpnt@rin.org.uk The RIN team say they are eager to know what works, what could be improved, and to receive suggestions for other efforts.

As a “learned society,” the RIN has a significant influence on government policy and direction. Lord Vallance recognized this, saying that “the Royal Institute has played a really important role in recent years to highlight the PNT opportunity and risk, to provide expertise, and to work with government on solutions.”

The RIN’s director, John Pottle, and RIN Fellows Ramsey Faragher, Guy Buesnel and Andy Proctor were all recognized during the seminar for their contributions to the organization’s resilient PNT efforts.

Commercial eLoran to be offered in the UK

Hellen Systems, Inc. and Arqiva have partnered to develop a commercial eLoran service in the United Kingdom. The announcement was made on the Hellen Systems LinkedIn page.

The partners seek to support critical national infrastructure, government, and military users by citing the need for “sovereign, independent, resilient” PNT alternatives.

eLoran is deployed and operating across China and South Korea. Older versions of Loran are operating in Russia and Saudi Arabia. Yet, aside from a single transmitter in the UK being used as a timing signal, operating Loran systems have been off the air in the West since the European system shut down in deference to Galileo in 2016.

In recent years, increasing interference with GNSS signals has rekindled Western interest in the technology. The European Space Agency (ESA) recently sponsored a project that produced an eLoran antenna suitable for mobile devices. Three transmitters are on-air in the U.S., presumably for testing, and the UK Ministry of Defence has issued a request for information, which is expected to lead to the purchase of a deployable eLoran system (the U.S. Air Force operated a deployable capability called Loran-D in the 1970s).

Originally developed and used in World War II, some still view Loran as old technology. Its advocates counter that today’s telephones and televisions are vastly improved over 1940s technology, and the same is true for eLoran over its older Loran-A and Loran-C versions.

A high-power terrestrial system operating at 100kHz, UK demonstrations with differential eLoran in 2014 showed an accuracy of 10 m positioning and 50 ns timing. The positioning accuracy for the previous version of Loran, Loran-C, was approximately 460 m absolute accuracy, 90 m repeatable accuracy and 5 µs.

Hellen Systems’ President, Bridge Littleton, says the partnership is “… excited to bring commercial eLoran to the UK as a unique resilient PNT capability” and cites its advantages as a secure signal able to penetrate deep indoors without the need for an external antenna. The UK frequency regulator, Ofcom, proposed offering commercial eLoran licenses in 2022 and began the process in 2023. Hellen was granted a UK spectrum license for eLoran earlier this year.

The announcement also lists Microchip, Chronos Technology, Ltd, Continental Electronics, and CGI as team members in the project.