CPI Electron Device Business – TMD Technologies Division has successfully completed sea trials of its cquantum-hybrid inertial navigation system (INS) aboard the THV Galatea, operated by Trinity House, the General Lighthouse Authority for England, Wales, the Channel Islands and Gibraltar.
This milestone shows that quantum-enabled sensing hardware can operate stably in maritime conditions, with the potential to provide resilient positioning without continuous reliance on GNSS.
Research indicates that a 24-hour GNSS outage could cost the UK economy £1.4 billion through cascading effects on logistics, transportation and critical infrastructure, underscoring the need for GNSS-independent solutions. By proving that quantum sensors can operate in operational conditions aboard a working vessel, CPI TMD is advancing technologies that reduce reliance on satellite navigation and improve resilience across maritime, defense and commercial sectors.
The Harlequin System: Quantum-Enhanced INS
The Harlequin system is a quantum-classical hybrid INS designed to extend GNSS holdover — the ability to maintain accurate position when satellite signals are unavailable or unreliable. Developed under an Innovate UK funded project, with partners from industry and academia, including the University of Strathclyde, and Joseph Cotter’s group at Imperial College London, Harlequin integrates classic INS components (a precise clock, a ring laser gyroscope, and a MEMS accelerometer) with CPI TMD’s gMOT-based quantum accelerometer.
Onboard team for the sea trial. (Photo: CPI TMD)
The gMOT cold atom source, developed by CPI TMD, the University of Strathclyde and Kelvin Nanotechnology, is a grating-based magneto-optical trap that provides a source of ultra-cold atoms that forms the basis of a portable, rugged quantum sensor.
Conventional INS technology accumulates errors over time, causing position estimates to drift. By integrating its cold-atom accelerometer technology with classical INS technology, Harlequin leverages quantum-enhanced sensing to perform periodic drift corrections, extending the period over which a vessel can maintain accurate position in the absence of satellite-derived timing and positioning.
Real-world trials: Operating around a working vessel
The Harlequin trial demonstrates that quantum sensors can operate reliably outside the lab, functioning in the harsh conditions of real-world maritime operations—a crucial validation step toward field-deployable systems.
The sea trial took place aboard the THV Galatea, which is not a scientific test vessel but an operational ship with a demanding day job: keeping shipping routes safe by ensuring buoys and lights are correctly placed and maintained, surveying the seabed for hazards, marking wrecks, and supporting marine-infrastructure projects such as cables and pipelines.
The Harlequin system had to be loaded, tested and unloaded around the Galatea’s regular operational schedule, adding complexity to the trial and underscoring the system’s ability to integrate into real-world maritime workflows.
Next Steps: System Upgrades and Second Trial
Data gathered during the trial will inform a program of system upgrades aimed at improving performance and enhancing suitability for long-term shipboard operation. A second field trial is planned for the end of 2026 to validate improvements and bring it closer to operational readiness.
The General Lighthouse Authorities (GLA) of the United Kingdom and Ireland has named Alan Grant to the top post of its research and development team. Grant assumed his new role on Nov. 1.
As part of his duties, he heads the GLA’s research and development program, considering existing and future maritime requirements and operational strategy. GLA Research and Development (GRAD) is tasked with improving maritime safety by developing innovative and cost-effective maritime aids-to-navigation (AtoN).
GRAD projects have included all aspects of AtoN including human and machine interaction, operational life and environment. The team has deep technical expertise and experience with automatic identification systems (AIS) , the VHF Data Exchange System (VDES) , eLoran, e‑navigation, GNSS, SBAS and visual signaling.
The organization is well known for its expertise in electronic navigation aids and was an important contributor to the MarRINav project. The project effort was funded by the European Space Agency and examined what combination of electronic aids to navigation are needed to ensure uninterrupted UK shipping.
Grant joined the GLA in 2003 and has worked on a variety of systems during his time with GRAD. He led a series of successful GPS jamming trials and the development of the multi-system radionavigation receiver performance standards, from initial concept to international recognition at the IMO. He continues to support resilient positioning, navigation and timing in maritime navigation at both technical and strategic levels.
Grant is a Fellow of the Royal Institute of Navigation, where he is a member of the council and served as vice president, 2019-2021. He is also a member of the U.S. Institute of Navigation and served on the ION Council, 2013-2017.
Grant chairs the International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA) radionavigation services working group and is a member of several international standards bodies. He is a chartered engineer, a chartered physicist, and author of more than 120 journal papers, magazine articles, and conference papers.
Martin Bransby, the prior GRAD leader, has taken a position with Telespazio in the UK.
Longstone Lighthouse is situated on the Outer Farne Islands on the Northumberland Coast in Northern England. (Photo: ad_foto/iStock/Getty Images Plus/Getty Images)
The official portrait of HRH The Duke of Edinburgh as Master of Trinity House. (Image: Trinity House)
Prince Philip, technology advocate, championed both GPS and alternative navigation methods during his lifetime.
Prince Philip — the Duke of Edinburgh and husband of Queen Elizabeth II of the United Kingdom — died on April 9 at Windsor Castle in England. He was 99. His funeral will take place April 17.
As the Master of Trinity House, Prince Philip was the U.K.’s authority for lighthouses in England, Wales, the Channel Islands and Gibraltar. Trinity House is also responsible for the provision and maintenance of other navigational aids, such as light vessels, buoys and maritime radio/satellite communication systems.
In its extensive coverage of his death, the BBC aired a radio program in its World Service that mentioned the prince’s knowledge and concern about GPS. “As Master of Trinity House, he was infuriated that people didn’t understand what would happen if GPS were shut down,” said the narrator.
Real Admiral Sir Jeremy de Halpert was Prince Philip’s deputy master at Trinity House. “ Prince Philip from the very beginning understood that it was a single point of failure,” de Halpert told the BBC. “GPS can be jammed very easily… He encouraged us to move ahead and make sure the country has a failsafe backup, which we have done, and it is now operational,” he said.
Below is the section of the documentary where the prince’s support for GPS and a GPS backup is discussed.
GPS World thanks Innovation editor Richard Langley for sharing the material.
An electronic pelorus is poised to become a useful tool in any mariner’s toolbox of resilient PNT systems. Learn how it works, and the benefits it brings to position fixing at sea.
INNOVATION INSIGHTS by Richard Langley
POP QUIZ: What do a character from Greek mythology, a point on the coast of Sicily, the pilot of Hannibal’s ship, a fizzy wine from New Zealand, and a navigation instrument have in common?
They are all called Pelorus or pelorus in the case of the instrument as it’s not a proper noun (grammar lesson over). And while a discussion of each of the uses of the word could be quite educational, this month’s column, perhaps predictably, will be about the pelorus or rather a modernized version of it.
If you are a landlubber, like me, you may not have heard of the pelorus. Yet, in one form or another it has been around for hundreds of years although not always going by that name. In appearance and use, it resembles a compass with sighting vanes.
But it has no magnetic components of any sort. And while a compass is used to get a magnetic bearing of a charted feature such as a tower or lighthouse or the magnetic heading of a vessel, a pelorus is used to measure a relative bearing between a feature and a reference direction such as the heading of the vessel, commonly called the ship’s head.
If a line is drawn on a chart through the sighted feature at an angle equal to the measured bearing, the vessel must be somewhere along this so-called line of position. If a second bearing on another feature significantly displaced from the first is measured in quick succession, a second line of position can be drawn on the chart, crossing the first.
The intersection point gives the (two-dimensional or horizontal) location, or position fix, of the vessel. Since the measured bearings will have some error, generally at least three lines of position are established with their intersections forming a small triangle, sometimes called a “cocked hat.” The location of the vessel is either inside the triangle or nearby depending on the similarity of the bearing errors.
Position fixes can also be obtained from instruments that measure ranges. In this case, the lines of position are circles for terrestrial systems providing two-dimensional fixes or spheres of position in the case of three-dimensional fixes obtained from GNSS measurements.
But let’s get back to the pelorus. Most vessels of a certain size are equipped with a pelorus. Frequent use of the pelorus helps to maintain situational awareness and being a completely passive device, it is not dependent on receiving an electronic signal of any kind. Only an acceptable level of visibility is required. And it can provide a manual check on any automated ship’s systems such as a GNSS receiver.
However, determining position fixes using a pelorus and a paper chart is laborious and time consuming and it is cumbersome to manually add lines of position to an electronic chart. What is needed is an electronic pelorus, which measures bearings electronically and automatically generates a line of position on an electronic chart.
The General Lighthouse Authorities of the United Kingdom and Ireland, the agencies responsible for aids to navigation in the U.K. and Ireland, have developed such an instrument. Dubbed the BinoNav, it is poised to become a useful tool in any mariner’s toolbox of resilient PNT systems and in this month’s column, we learn about its genesis, how it works, and the benefits it brings to position fixing at sea.
The overreliance on GNSS is well known and widely publicized. While GNSS is generally available, concerns remain on how maritime operations, and safe navigation in particular, are affected should GNSS not be usable, or become denied for any reason.
The General Lighthouse Authorities of the United Kingdom and Ireland (GLA) have been working on resilient positioning, navigation and timing (PNT) for many years. This work has included a comprehensive review of different potential solutions and their availability. One option proposed is the development of a ship-based positioning system that makes use of a modernized pelorus to work with a modern bridge.
Pelorus systems work by providing bearings from fixed positions, normally on the vessel bridge wings, to specific targets visible to the mariner and identified on the navigation chart. By taking several bearings in quick succession, intersecting lines can be drawn on the navigation chart, providing a position estimation. Clearly, there are limitations to this approach — these are explored within this article, but can be summarized as:
Automation. The time taken to measure the bearings can limit the achieved accuracy.
Visibility. Performance is limited by the mariner’s ability to see unique targets.
Paperless bridges. Many vessel bridges are moving away from paper, limiting the mariner’s ability to take bearings and plot them.
e-Navigation. More bridge systems require electronic values of latitude and longitude.
In an attempt to resolve most of these limitations, the GLA has been working on the development of an enhanced pelorus, or ePelorus, with its name registered to the Research and Radionavigation Directorate (R&RNAV) as BinoNav.
Prototype BinoNav systems have been developed and installed on all GLA vessels for trial. They enable the navigator to take visual bearings to known targets, from anywhere on the bridge using a handheld device — they are no longer confined to the bridge wings and targeting port or starboard objects.
Measured bearings are automatically registered and drawn on an electronic chart. Multiple bearings can then be made with ease, each of which is displayed on the chart and the intersecting “cocked-hat” position (to be discussed later), calculated automatically. This information can then be used to feed other bridge systems and confirm the vessel’s position.
In this article, I will provide a comprehensive overview of the BinoNav system, provide the results of initial trials and explain the planned development of the proposed resilient PNT solution.
e-NAVIGATION
Much has been written about e-Navigation elsewhere, but briefly, it is the International Maritime Organization’s (IMO’s) concept for the future of navigation, instigated by the U.K. Department for Transport in 2004. It will lead to the integration of systems and data — for the exchange of relevant geolocated information — faster and more cost effectively, and it will do this in the context of larger, faster vessels operating in ever more constricting shipping lanes and increasing offshore obstacles such as renewable energy infrastructure as well as the legacy of non-renewable energy infrastructure.
e-Navigation is designed to enhance safety of life for the mariner, improve protection of the environment, and increase energy efficiency in terms of shorter routing for fuel-efficient shipping. Moreover, it will allow more effective use of resources and integration across transport modes, including the more effective provision of integrated port operations.
Since its inception in 2004, development and delivery of e-Navigation services has been slow. Even now, some 14 years later, only a few prototype projects have delivered anything like what was anticipated in the original e-Navigation vision. This sluggishness has been caused by minimal leadership and drive from the IMO.
Despite this, some initiatives have been successfully delivered on a local or regional basis. These initiatives have come largely through projects such as Accessibility for Shipping, Efficiency Advantages and Sustainability (ACCSEAS), Efficient Safe and Sustainable Traffic at Sea (EfficienSea) 1 & 2, Motorways and Electronic Navigation by Intelligence at Sea (MonaLisa) 1 & 2, and Sea Traffic Management (a MonaLisa project), all of which have been supported by funding from the European Union.
Resiliency in PNT has been identified by the IMO as a lead area in the delivery of e-Navigation, and all these projects have used resilient PNT as the basis of what they have delivered.
REQUIREMENT FOR RESILIENT PNT
FIGURE 1. Ships’ systems affected by GPS jamming. (Data: Author)
It is now well recognized that all GNSS are vulnerable to interference, whether these interferers are from natural causes such as space weather or from synthetic sources such as jamming or spoofing devices. GNSS receiving units and satellite failures also occur. There are many examples of each of these problems affecting GNSS worldwide.
Resilient PNT information is needed to ensure continuity of maritime operations and safe navigation — especially for e-Navigation, management of sea traffic, and autonomous vessels.
GPS jamming trials were conducted by GLA’s R&RNAV in 1994, 2008, 2009 and 2012. These trials showed the real-time vulnerability of maritime systems to jamming. They identified that many ships’ systems were affected by GPS jamming. However, some systems we did not expect to be affected actually were (see Figure 1). Devices such as the helicopter-deck stabilization system and the ship’s gyrocompass are good examples.
GLA Work on Resilient PNT. GLA, through R&RNAV, has conducted a program of work that has looked at the issues of GNSS vulnerability and what they can do about it through a series of studies. These have looked at a number of systems such as
enhanced Loran, absolute radar positioning (two different methods)
ranging mode or R-mode, which is the use of ranging signals from existing marine infrastructure (two different methods)
signals of opportunity (many methods)
hybrid systems
dead reckoning
inertial
other on-board systems.
The timeline for the introduction of some of these systems into operational use, as well as current and new GNSS, can be seen in Figure 2. This article deals with equipment that falls into the “other on-board systems” category.
FIGURE 2. Timeline for resilient PNT (GNSS and complementary systems). (Diagram: Author)
A DRIVER FOR OPTICAL NAVIGATION SYSTEMS
The need for new optical navigation systems has been driven by a number of marine incidents, one of which I will discuss in detail.
MV Tricolor Incident. On Dec. 14, 2002, in early morning thick fog, on its way from Zeebrugge to Southampton, the MV Tricolor, with a load of almost 3,000 BMW, Volvo and Saab cars, collided with a Bahamian-flagged container ship named Kariba, about 20 miles north of the French coast in the Dover Strait Traffic Separation Scheme.
Albeit damaged above the water line, the Kariba could continue, while the MV Tricolor remained wedged on her side in 30 meters of water in a busy area of navigation. No lives were lost and the crew were rescued by the Kariba and a tugboat. Nevertheless, approximately 2,862 cars and 77 units of cargo, consisting mainly of tractors and crane parts, could not be salvaged.
The shipping lane, being the busiest in the world, was marked by buoys and guarded by the French police vessel Glaive and HMS Anglesey, thereby warning other vessels of the MV Tricolor’s presence. Despite the marking and patrolling, only two days later a cargo ship, Nicola, followed by another vessel, Vicky (carrying 70,000 tonnes of highly flammable gas oil) collided with the wreck of the Tricolor, after failing to heed several French naval warnings. In between the two further collisions, more buoyage and patrol vessels were deployed. On Jan. 22, a third accident happened when a salvage tug knocked a safety valve off the Tricolor, resulting in a massive oil spill.
Besides the heavy economic losses, including the estimated operation cost of around £25M (roughly $40M), the incident caused massive marine pollution and environmental contamination by spilling large quantities of oil. The Royal Society for the Protection of Birds estimated more than 1,000 birds were found dead or damaged by oil spilled from Tricolor.
Why Did It Happen? The incident was blamed on declining professional standards among seafarers, which was leading to scores of near misses in the area every day. Indeed, Andrew Linnington of the National Union of Marine Aviation and Shipping Transport Officers is quoted as saying that ship owners had been cutting costs by reducing use of deep-sea pilots to guide vessels through the world’s most crowded shipping lanes. Ships were increasingly crewed by one trained officer and a few poorly paid sailors from parts of the developing world.
“We know of at least four cases in the past year of ships going the wrong way in shipping lanes against the flow of traffic,” Linnington said. “Complaints are made to the states where the ships are registered, but they are often small countries used as flags of convenience and don’t have the resources to take action.”
It is clear from the incident and the ensuing investigation that navigators were not looking out the window, despite various radio navigation warnings and other methods, not the least of which was deploying wreck-marking buoys and virtual aids to navigation.
A very good way of mitigating the failure of any navigation system is by using reversionary methods of navigation, like looking out the window! This was a big driver in the GLA development of the BinoNav.
WHAT IS BINONAV?
FIGURE 3. A pelorus. (Photo: Author)
BinoNav is an electronic pelorus. A pelorus is a device that is completely independent of any other system or electronic position fixing system (EPFS), and this is important for providing resiliency.
Pelorus. A standard pelorus (see Figure 3) is used to take relative (to the vessel’s head) bearings to charted objects in the vicinity. The navigator then draws a line on the relevant navigation chart through the charted object. It is clear now that the vessel lies somewhere on this “line of position” from the charted object. This process is then repeated several times using different charted objects, with a minimum of three iterations.
This process then creates a “cocked hat” (a triangle in the case of three lines of position) generated from the intersection of the lines. Accounting for systematic errors, the vessel should lie somewhere within this cocked hat (see Figure 4 for an example).
This process is laborious and time consuming, but it does have the advantage of getting the navigator to look at real features outside the vessel — not just a red line on an electronic chart that they follow without question.
FIGURE 4. An example of positioning using a pelorus. (Chart: Author)
What about Electronic Chart Display? Electronic Chart Display and Information Systems (ECDISs) are excellent, when used correctly, and have driven innovation in the shipping industry. However, they do have disadvantages: If you are using a pelorus, you cannot very easily draw on a screen. You can generate an electronic bearing line (EBL) on an ECDIS, but it is a very long, convoluted way of providing a position not derived from an EPFS, such as a GNSS fix.
Any system that needs to generate an EBL on an ECDIS needs to do it electronically. Moreover, it needs to do this without having to rely on GNSS for position or time to avoid the issues of GNSS vulnerability: it should be completely independent. It should also be able to carry out optical to electronic integration to ensure that the mariner is looking out the window. Another GLA requirement was that it should be relatively low cost to make and distribute to enable take up across all users. So the idea of BinoNav was born. BinoNav fulfills all these criteria easily, intuitively and quickly, updating the electronic position of the vessel. Furthermore, with its wireless connection, bearings can be taken anywhere on the bridge of a vessel.
BINONAV FEATURES
In this section, I will describe the BinoNav and how it is used.
FIGURE 5. The BinoNav configuration. (Photo: Author)
Easy to Use. BinoNav comprises two parts: the “Bino” unit, which is a modified pair of binoculars, and a “base” unit that performs the communication link between the Bino unit and the electronic chart. Pick up the Bino unit from the base unit (see Figure 5 for overall configuration of the BinoNav).
Line up the graticule inside the Bino unit with a charted feature of use, press either of the buttons to automatically generate a line on the displayed electronic chart, which is relative to the ship’s head. As with a standard pelorus, one needs at least another two of these EBLs to generate a cocked-hat position on the electronic chart. Using either the touch screen or the mouse, “hover” over the cocked hat to generate a triangle. Now, right click to drop a marker at the center of the cocked-hat position and delete all lines. Once the vessel has moved (and dictated by the operating environment at the time), this process can be repeated. When two or more of the markers have been dropped, a line is drawn between the marks, thereby showing a track on the chart.
Features. From the use of the BinoNav unit as described above, a track is produced on an electronic chart that is not derived from an EPFS. This is important as it shows the integration of visual navigation into e-Navigation, something which e-Navigation has tried to do from the very beginning, as described by Brian Wadsworth in his earliest vision of e-Navigation (see Further Reading).
Another feature of BinoNav is “radar mode” for charted feature recognition. This feature draws a continuously moving line on the display that points at the position relative to the ship’s head. This is useful for the recognition of charted features when in unfamiliar territory.
The BinoNav is very easy to install, with only a connection for power and a connection for a suitable National Marine Electronics Association (NMEA) protocol data feed for heading. Many of its electronic components are available off the shelf and are widely available commercially with bespoke printed circuit boards. Some modification to the binocular unit has been necessary, with the addition of a bespoke unit, which links to the base unit for both orientation measurement and power when the unit is docked. The binoculars are readily available for around $500. The gyros incorporated in both the base unit and the binocular unit are high-grade microelectromechanical systems (MEMS) devices giving an angular resolution of 0.25-0.5 degrees, similar to that of a standard pelorus.
Currently, the BinoNav is 3D-printed, which allows for the quick production of one-off units. However, this approach is clearly not a suitable solution for long production runs and would require a different method of production.
FIGURE 6. The BinoNav installation on THV Alert. (Photo: Author)
Something for the Future. R&RNAV has received a lot of interest in the BinoNav not only from our own mariners, but also from a variety of influencers in the maritime world. We have had a great deal of positive feedback on potential improvements and additional features that we plan to develop.
We will also seek to gain approvals through IMO and the International Electrotechnical Commission to integrate BinoNav with ECDIS, so there will be no need for separate displays (unless being used on non-SOLAS vessels; that is, ones to which the International Convention for the Safety of Life at Sea does not apply.)
CURRENT GLA INSTALLATIONS
FIGURE 7. Using the BinoNav on ILV Granuaile. (Photo: Author)
The BinoNav has been installed on all six GLA vessels: ILV (Irish Lights Vessel) Granuaile, NVL (Northern Lighthouse Vessel) Pharos, NVL Pole Star, THV (Trinity House Vessel) Alert, THV Galatea and THV Patricia. The installation on Alert is shown in Figure 6 and BinoNav use on Granuaile is shown in Figure 7.
CONCLUSIONS
The key points made in this article can be summarized as follows:
e-Navigation is based on the premise of electronic navigation from “berth to berth.”
Many accidents happen because crews do not look out the window.
There is a need for electronic positioning from non-GNSS sources.
The BinoNav integrates visual navigation and electronic navigation through an ECDIS.
The BinoNav provides an independent verification of position with or without EPFS.
INTELLECTUAL PROPERTY
BinoNav is a registered trade mark and carries unregistered design rights. BinoNav has patents pending.
ACKNOWLEDGMENTS
The author thanks the masters, officers and crews of all the GLA vessels for their help and for the benefit of their experience throughout the whole process of the BinoNav development. Special thanks go to those who helped during the various development trials on ILV Granuaile and THV Alert prior to the mainstream installations.
This article is based on the paper “BinoNav® – A New Positioning System for Maritime” presented at ION GNSS+ 2018, the 31st International Technical Meeting of the Satellite Division of The Institute of Navigation, Miami, Florida, Sept. 24–28, 2018.
MARTIN BRANSBY is the head of the Research and Radionavigation Directorate at the General Lighthouse Authorities of the UK and Ireland, stationed in Harwich, Essex. He is responsible for the delivery of its program portfolio in research and development in technically diverse areas such as resilient PNT, e-Navigation, GNSS, Automatic Identification System (AIS) and visual signaling. He is a fellow of the Royal Institute of Navigation, and holds memberships in the Institute of Engineering and Technology and The Institute of Navigation. He is also a member of the International Association of Marine Aids to Navigation and Lighthouse Authorities’ AtoN (Aid to Navigation) Requirements and Management Committee.
FURTHER READING
Author’s Conference Paper
“BinoNav® – A New Positioning System for Maritime” by M. Bransby in Proceedings of ION GNSS+ 2018, the 31st International Technical Meeting of the Satellite Division of The Institute of Navigation, Miami, Florida, Sept. 24–28, 2018, pp. 1728–1735.
“Marine eNavigation: An Orientation Paper” by B. Wadsworth, document WEND9-INF4, presented to the 9th meeting of the International Hydrographic Organization World-wide Electronic Navigational Chart Database (WEND) Committee, Monaco, April 7–8, 2005.
“The Impact of GPS Jamming on the Safety of Navigation” by S. Basker, A. Grant, P. Williams and N. Ward, presented at the 48th meeting of the Civil GPS Service Interface Committee, Savannah, Georgia, Sept. 15–16, 2008.
Table 1. Capability and status of complementary positioning technologies. (Chart: GLA)
The General Lighthouse Authorities of the U.K. and Ireland (GLA) reached Initial Operational Capability for eLoran on the East coast of the U.K. Although it was shown to work well technically, it has not been possible to implement the system in Europe on a regional basis.
The GLA have also been involved in the potential development of other, non-satellite based, alternative systems. These may now form the basis of positioning resiliency either individually, or as a tapestry of systems serving the maritime navigator in Europe, unless current plans for commercial operation of eLoran come to fruition.
Here we consider the technical and regulatory status of eLoran in comparison with the other options, and explore necessary steps to protect the maritime navigator in the face of increasing GNSS outages. Several alternative backup technologies could be considered complementary to GNSS for future introduction into ships’ Integrated Navigation Systems. They have varying capabilities, and different limitations and levels of maturity, summarized in Table 1. Figure 1 shows estimated timescales for development and implementation.
Figure 1. Timeline for resilient PNT. (Image: GLA)
Conclusions
■ eLoran is the only complementary backup system that can be implemented within the timescale envisaged for the introduction of e-navigation; however, there are political obstacles to implementation, at least in Europe.
■ R-mode and possibly radar positioning could be introduced by about 2030; however, both have inherent coverage limitations. Feasibility studies are needed to assess their economic viability.
■ Other options, such as inertial systems and signals of opportunity, might emerge as viable alternatives by 2030, but there are large uncertainties about technical and regulatory matters.
■ Quantum devices and options such as bathymetric and geomagnetic positioning can only be considered as longer term and uncertain possibilities.
■ A multi-system solution may offer the best approach. The IMO concept of the Integrated Navigation System aboard vessels, incorporating a multi-system receiver, provides flexibility for the inclusion of the above positioning technologies, if and when they become available, at an affordable cost.
Bridge of the Galatea, a GLA vessel that carries a eLoran receiver and conducted tests of the new system. Photo: GLA
Back-up to Vulnerable GPS Signals Required for Busy Shipping Lanes
The General Lighthouse Authorities (GLAs) of the UK and Ireland announced October 31 the initial operational capability of UK maritime eLoran. Seven differential reference stations now provide additional position, navigation, and timing (PNT) information via low-frequency pulses to ships fitted with eLoran receivers. The service will help ensure they can navigate safely in the event of GPS failure in one of the busiest shipping regions in the world, with expected annual traffic of 200,000 vessels by 2020.
Ships carry 95 percent of UK trade, accounting for its strongly expressed concerns regarding GPS vulnerability to jamming and spoofing, and the leadership role it has taken in eLoran research and testing. The UK is the first country in the world to deploy the technology along its coastline, thronged with both passenger and cargo services. Deployment involved replacing the existing radio receiver equipment in two prototype reference stations at Dover and Harwich, and the creation of five new reference stations in the Thames, Humber, Middlesbrough, and Firth of Forth and Aberdeen in Scotland, on the North Sea where oil-laden vessels come from deep-sea drilling rigs.
Entirely independent of GPS, eLoran can provide navigation information for vessels as well as the timing data necessary to maintain the power grid, cell phones, financial networks, and the Internet in the event of an outage. Unlike space-based navigation, eLoran signals can also reach inside buildings, underground, and underwater.
Captain Ian McNaught, deputy master of Trinity House, commented, “eLoran provides a signal around 1 million times more powerful than those from satellite signals, providing resilience from interference and attack. The achievement of initial operational capability for the system at Dover and along the east coast of the UK is a significant milestone, providing for improved safety aboard appropriately equipped vessels. The maritime industry would now benefit from the installation of eLoran receivers on more vessels to take advantage of improved navigational safety.”
“Telecoms, finance, energy, and other industries, which are subject to significant issues caused by the loss of timing signal provided by GPS, are recommended to take advantage of the enhanced reliability now available to address the over-dependence of key national infrastructure on vulnerable satellite systems,” McNaught said.
eLoran technology is based on longwave radio signals and is independent and complementary to GPS.
Several other nations are consulting with the UK GLAs on eLoran. South Korea wants to establish an eLoran alliance with the UK while it pursues its own rollout of differential eLoran reference stations and new eLoran transmitters based on the latest technology. In 2012, South Korea was the victim of a 16-day GPS jamming attack by North Korea.
Full operational capability covering all major UK ports is expected by 2019.
Galileo Roving High
The fifth Galileo navigation satellite, one of two left in the wrong orbit in August, made a series of November maneuvers as a prelude to its health being confirmed. The aim was to raise the lowest point of its orbit — its perigee — to reduce the radiation exposure from the Van Allen radiation belts surrounding Earth, as well as to put it into a more useful orbit for navigation purposes.
Should the two-week operation prove successful, the sixth Galileo satellite will follow the same route, according to the European Space Agency (ESA).
The Galileo pair, launched together on a Soyuz rocket on August 22, ended up in an elongated orbit traveling out to 25,900 kilometers (km) above Earth and back down to 13,713 km. The target orbit was a purely circular one at an altitude of 23,222 km. Also, the orbits are angled relative to the Equator less than originally planned.
The two satellites have only enough fuel to lift their altitude by about 4,000 km — insufficient to correct their orbits entirely. But the move will take the fifth satellite into a more circular orbit than before, with a higher perigee of 17,339 km.
“The new orbit will fly over the same location every 20 days,” said Daniel Navarro-Reyes, ESA Galileo mission analyst. “The standard Galileo repeat pattern is every 10 days, so achieving this will synchronize the ground track with the rest of the Galileo satellites.”
“In addition, from a user receiver point of view, the revised orbit will reduce the variation in signal levels, reduce the Doppler shift of the signal, and increase the satellite’s visibility,”Navarro-Reyes said. “For the satellite, reducing its radiation exposure in the Van Allen radiation belts will protect it from further exposure to charged particles. The orbit will also allow Galileo’s Earth Sensor to hold a stable direction for the satellite’s main antenna to point at Earth. Right now, when the satellite dips to its lowest point, Earth appears so large that the sensor is unusable. The satellite relies on gyroscopes alone, degrading its attitude precision.”
The recovery is being overseen from the Galileo Control Centre in Oberpfaffenhofen, Germany, with the assistance of ESA’s Space Operations Centre, ESOC, in Darmstadt, Germany. France’s CNES space agency is providing additional ground stations so that contact can be maintained with the satellite as needed, ESA said.
Welcome IIF-8
The U.S. Air Force launched the eighth GPS IIF satellite on October 29, aboard an Atlas V 401 rocket. With this new arrival on orbit, only four more Block IIF satellites remain to be placed aloft. Three are in storage awaiting launch, and one is in production.
The Boeing-built GPS IIF-8 (SVN-69/PRN-03) will replace SVN-51 in the E plane slot 1. SVN-51 will be re-phased from E1 to an auxiliary node at E7 somewhere around SVN-54 currently on station at E4, according to the Air Force Second Space Operations Squadron (2 SOPS).SVN-38/PRN-08 will be taken out of the operational constellation prior to SVN-69 payload initialization and sent to Launch, Anomaly Resolution and Disposal Operations (LADO).PRN-08 will be assigned initially to SVN-49 and set to test.
SVN-51 will remain in an auxiliary node once it completes its re-phase journey. The SVN-51 re-phase will take about six months after the initial burn occurs.
eLORAN Initial Operational Capability at the Port of Dover
An overview of the work of the General Lighthouse Authorities of the United Kingdom and Ireland on the implementation of Enhanced Loran Initial Operational Capability (IOC) in the waters around Great Britain. eLoran is the latest in the longstanding and proven series of low-frequency, LOng-RAnge Navigation systems. It evolved from Loran-C in response to the 2001 Volpe Report on GPS vulnerability. It vastly improves upon previous Loran systems with updated equipment, signals, and operating procedures.
By Paul Williams and Chris Hargreaves
GPS/GNSS is everywhere! It is used in many ship’s systems (Figure 1), but it is vulnerable to interference both intentional and unintentional.
Its output is displayed on the electronic chart display and information system; is transmitted to other vessels using the Automatic Identification System (AIS); is used to calibrate the gyro compass; is used in the radar; is connected to the digital selective calling, its reported position transmitted at the push of the emergency button for search-and-rescue; is in the vessel data recorder, the dynamic positioning system, surveying equipment, the ship’s entertainment system for aiming the satellite dish; and it even synchronizes the ship’s clocks!
28 days worth of ship-traffic data for the Strait of Dover.
GNSS is also used in marine Aids-to-Navigation (AtoN) provision, for deploying buoys and lights, AIS transponders, and AtoN position monitoring, and its precise timing capabilities are used to synchronise the lights along an approach channel to improve conspicuity.
GNSS (effectively GPS) has become the primary Aid-to-Navigation (AtoN) used by all professional and most other mariners. The vulnerability of GNSS to space weather and interference (unintentional and criminal jamming) means that a backup system is needed to achieve resilient Position, Navigation, and Timing (PNT) for e-Navigation. Though the probability of losing GNSS may be low, the consequential impact could be very high, and maintaining an appropriate balance of physical and radionavigation AtoNs is vital for e-Navigation.
Figure 1. GPS is used in many ship’s systems.
The International Maritime Organisation seeks to develop a strategic vision for e-Navigation, integrating existing and new navigational tools in an all-embracing system, contributing to enhanced navigational safety and environmental protection, while reducing the burden on the navigator. One of IMO’s requirements for e-Navigation is that it should be resilient — robust, reliable and dependable.
The General Lighthouse Authorities of the United Kingdom and Ireland (GLAs) have the statutory responsibility to provide marine AtoNs around the coast of England, Wales, Ireland, and Scotland. It has become clear over recent years that if the GLA chose to implement eLoran, it could rationalize its physical AtoN infrastructure, removing some lights and other physical aids, and on balance actually reduce costs by implementing eLoran. Indeed, compared to other possible resilient PNT options such as GNSS hardening, radar absolute positioning, increasing physical AtoN provision, eLoran would save the GLAs £25.6M over a nominal system lifespan of 10 years from the introduction of e-Navigation services in 2018 to 2028.
Not So Old-Fashioned. How does the new eLoran differ from the old, outdated, Loran-C system? The core signal of eLoran is pretty much the same as Loran-C, but tolerances have been tightened up. Things like carrier zero crossing points, half-cycle peaks, ECDs, transmission timing, signal power, signal availability, power supply resilience have all been upgraded, taking advantage of improvements in technology allowing us to better appease the so-called four horsemen of navigation: accuracy, availability, continuity, and integrity.
SAM control is a thing of the past, and eLoran transmitters are synchronised directly to UTC. This means that their times of transmission can be predicted. Having stations independently synchronised to UTC means that the mariner no longer has to rely on old-fashioned hyperbolic navigation. Charts with hyperbolic lines of position on them are also a thing of the past. A modern eLoran receiver works just like a GPS receiver, employing signals from all available transmitters in its position solution. With GPS those transmitters are moving in space; in eLoran the transmitters are fixed onto the surface of the Earth.
Reelektronika LORADD receiver, only 3 centimeters tall.
Modern receivers are small (photo). They use off-the-shelf, high-performance processors, and the receiver is written in software, allowing a lot of flexibility.
Three transmitters are sufficient to give you position; four or preferably five signals are better for integrity. But for timing and frequency applications you only need one transmitter. The Anthorn station in the UK can cover the entire UK and Ireland with a radio signal that has stability enough to satisfy the Stratum 1 frequency source requirement for steering the clocks of telecom networks, and Anthorn has not even been upgraded to full eLoran standard yet!
One of the big differences between Loran-C and eLoran is that eLoran now has a data channel. Some of the Loran pulses of each pulse group are modulated so that data can be sent over the 100kHz signal. This allows service providers to send integrity alerts, and application-specific data, like UTC time, and differential-Loran (DLoran) and DGPS corrections. In Europe this is implemented by the already internationally standardised Eurofix system.
A parallel can be drawn with GPS signals, which contain a navigation component (pseudorandom noise code and/or carrier phase) and modulated data. Some options for data channel technology are still evolving with 1500 bits per second demonstrated, and 3000 bps possible. That may not sound very much to salt-of-the-earth communications engineers, but for Loran it’s pretty impressive, especially when you consider prototype attempts at Loran data communications in the past have been limited to 30 to 250 bps.
Maritime Applications Services
How do we apply eLoran to something like the maritime application of port approach? It is important to remember that the receiver operates by measuring how long it takes a groundwave radio signal to travel over the surface of the earth. An eLoran receiver assumes that the world is made entirely of seawater, for which it has a very accurate propagation model built in. The receiver does not, and indeed cannot, know about any land along the propagation path; and land slows the signal down, perhaps by as much as a few microseconds, over typical propagation distances.
So the service provider must survey the effects of the land masses in the area of coverage. The Additional Secondary Factors (ASFs) of all the stations across the proposed service area are therefore mapped. The ASF survey is a once-and-for-all task, but it needs to be done and the ASFs published. In the old days, hyperbolic lines would be “grid warped,” or tables would be published on paper for the navigator to enter values manually. But with modern eLoran receivers containing large amounts of memory, quite detailed ASF maps can be stored in the mariner’s receiver.
ASFs depend on the electrical conductivity of the surface over which the eLoran signal travels. The conductivity changes with the constitution and moisture content of the earth. This means that the ASF along a path varies over a period of time —perhaps by as much as a few hundred nanoseconds over a year. Because the ASFs in a receiver are fixed, a method is needed to correct for this temporal ASF variation. In order to monitor this variation, a reference station is installed close to the harbor or point of use of the eLoran service. This DLoran reference station measures the temporal changes in the signals’ arrival times due to changing ASFs, transmitter variations, and weather effects.
The phrase “reference station” conjures up images of expensive buildings, amenities, and hordes of personnel and associated support services. However, a DLoran reference station is a small box sitting in the corner of a room connected to a small eLoran receive antenna on the roof, and to the Internet. It sends differential corrections over the Internet to an eLoran transmitter, which then broadcasts them to the mariner’s receiver over the Loran Data Channel, for example Eurofix.
Note that a DLoran reference station does not transmit a radio signal. It does not need a transmitter itself; it uses the Internet and the eLoran signal to disseminate its real time data. The mariner uses the same eLoran receiver to receive both the navigation signal AND the differential corrections.
So the process is: map ASFs once; run a reference station; and broadcast corrections. That’s it! With good signal-to-noise ratio and transmitter geometry, 10-meter or better accuracy can be obtained.
Measuring ASFs
The GLA have had the ability to measure ASFs for several years, using a combination of commercial hardware and proprietary software (Figure 2).
Figure 2. GLA-produced software for ASF survey, processing, and validation.
The software, written in Matlab, shows a real-time plot of the survey as it progresses. The ASF values are color-coded according to magnitude. The software can also process the ASF data once it has been measured, to get the best performance out of it. The real-time capabilities of the software allow the determination of the quality of the data while aboard the ship, rather than having to wait until back in the laboratory. Statistical analysis of the data can also show where the ship should go to gather more data in a particular area.
Once the survey is complete, the software can be used to generate interpolated grids of ASF data — the most convenient and accurate form of ASF data storage.
It is important with any scientific or engineering measurement to establish the error on that measurement. The same can be said of ASFs, and so the software can calculate the error bounds on ASF measurements. This “ASF error” data can again be published in grid form alongside the ASF database. This allows it to be used as one component of an Integrity Equation, implemented within the mariner’s receiver, to calculate Horizontal Protection Level (HPL).
After processing, the ASF data should be validated by performing a harbor approach or other maneuver that requires a particular positioning accuracy. For this, the software can be switched to “Validation” mode. Once the validation is successful, the data can be output in a publication format (RTCM SC-127 format for example).
The plot in Figure 2 shows part of an ASF database for Harwich and Felixstowe, major ports on the east coast of the UK. Using this data and DLoran in the Harwich and Felixstowe approach provides 10-meter (95 percent) positioning accuracy.
UK eLoran Prototype
This prototype eLoran system works alongside GPS. It has been in operation 24 hours a day since May 2010. It is “prototype” because it demonstrates the concept of eLoran using signals from existing Loran-C stations in Norway, the Faroe Islands, Germany, and France plus the UK’s station at Anthorn; see Figure 3.
Figure 3. Relevant European Loran-C stations for prototype eLoran.
These stations, together with ASF measurements and DLoran, can deliver a high-precision eLoran service in ports where 10-20 meter accuracy is needed, across the area enclosed by the green contour in Figure 4.
Figure 4. Coverage of prototype eLoran over the UK and Ireland.
It is very impressive, yet the full availability and accuracy benefits of eLoran are still to come as these stations are eventually upgraded to full eLoran capability. And for the last year or so, the GLA have begun to move beyond the confines of the Harwich and Felixstowe approaches and implement initial eLoran services in other regions around the GLA service area.
The GLA aim to do this in two stages. In the first stage Initial Operational Capability (IOC) service will be installed by mid-2014, with the second stage Full Operational Capability (FOC) service covering all major ports in the UK and Ireland, plus Traffic Separation Schemes, installed by 2019 or so in time for e-Navigation.
Initial Operational Capability
IOC involves upgrading the installation at Harwich and Felixstowe and new installations in the approaches to another six of the busiest ports in the UK: Aberdeen, Grangemouth, Middlesbrough, Immingham, Tilbury, and Dover. For each of these areas an ASF survey and a DLoran reference station will be required.
The corrections for these reference stations will be broadcast using the Anthorn Loran Data Channel. There is also the need for a Monitoring and Control System for the network of DLoran Reference Stations, and it is envisaged that this will be based in Harwich. Figure 5 illustrates the architecture of the Initial Operational Capability system. The diagram shows the major components: eLoran transmitter, DLoran reference station network, monitor, and control system. Also shown are the interfaces between the components, which provide not only operational data but also include the ability to monitor the integrity of the system. Also note that the Loran Data Channel is capable of supporting third-party messaging applications using a client “logon” facility. This is already being done at Anthorn.
Figure 5. The architecture of the UK GLA’s eLoran Initial Operational Capability.
The European tender process for seven operational reference stations and the control system is almost complete.
The aim of IOC is to provide areas for demonstrations and trials, so that the mariner can gain experience of the system and its capabilities and provide feedback to the GLA on its performance.
eLoran at the Port of Dover
In the absence of the final operational reference stations, the GLA decided to perform an early implementation using prototype equipment that was already available at the GLA. The choice for this implementation was obvious: the iconic Port of Dover, a major port on the southeast coast of the UK and the Dover Strait, one of the busiest seaways in the world. Some 500-plus vessels travel through the Strait each day on their way to or from the North Sea region; see Opening Figure.
The GLA have, with the agreement of Port of Dover Operations, installed a prototype DLoran Reference Station within the port’s Terminal Control building. The roof of the building is an ideal location for the reference station receiver antenna as the location demonstrates low noise in the eLoran band and has easy access to mains power, cable runs, antenna mounts, and Internet access.
The ASF survey took place in March 2012, and covers the area outlined by the yellow polygon in Figure 6.
Figure 6. Area of March 2012 ASF survey.
Accuracy Performance Validation
Once the ASFs had been measured and the prototype reference station installed, the performance needed to be tested. This was accomplished through a validation run of the vessel through the area.
Figure 7 shows a screenshot of the GLA ASF measurement software running in validation mode. The colored track shows the path of the vessel, with the color indicating the positioning error compared to differential GPS. The vessel travels through an area of extrapolated and interpolated ASF data, so the positioning error at the northern end of the track is higher than the lower end of the track.
Figure 7. Screenshot of GLA ASF measurement software running in validation mode.
Figure 8 shows a comparison of eLoran positioning against DGPS positioning along the route as a scatter plot. The associated Cumulative Distribution Function (CDF) is shown on the right of the diagram. From this it can be seen that the positioning accuracy obtained along this particular route was 12.5 meters (95 percent).
Figure 8. eLoran positioning accuracy scatter plot and cumulative distribution function of positioning error. Accuracy: 12.5 m (95%)
Dover to Calais Ferry Installation. Further validation and demonstrations will take place aboard a cross-Channel ferry. P&O Ferries in the UK has installed a receiver aboard their vessel, The Spirit of Britain. This relatively new vessel is one of the largest passenger ships to operate along the iconic Dover to Calais route. Data will be collected and feedback obtained on the eLoran service’s performance over the coming months.
Other Areas
The GLA continue their work towards IOC-level eLoran. Dover was the first port of call for the GLA eLoran Initial Operational Capability — the ASFs have been mapped and a prototype DLoran reference station has been installed. The final operational DLoran reference stations should be available this time next year.
The next area the GLA have concentrated upon is the Thames Estuary up to Tilbury. Although the GLA have not yet installed a permanent DLoran reference station, the ASF survey was performed in November 2012 using a temporary reference station installed at Medway. Along the route shown in Figure 9, a validation trial demonstrated 8.3 meters (95 percent) accuracy (Figure 10). The GLA have also recently surveyed the River Humber, including its approaches, up to the port of Hull. The data is currently in the process of being validated.
Figure 9. ASF map validation route from the port of Medway heading out of the River Thames estuary.
Figure 10. eLoran positioning accuracy scatter plot and cumulative distribution function of positioning error. Accuracy: 8.3 m (95%).
Status and Next Steps
The next steps are to continue the implementation of IOC eLoran at the remaining port approaches for this phase. It is the aim that all ASF surveys will have been performed by the middle of 2014 in readiness for the installation of the operational DLoran reference stations at each candidate port. Licence agreements are being established with the various port authorities involved in order to allow this.
All ports that have been approached are positive and are keen to assist in the GLA eLoran implementations. eLoran noise surveys have been performed at all ports and locations for all DLoran reference stations have been found.
The Port of Dover has prototype eLoran up and running and has demonstrated 12.5-meter (95 percent) accuracy during the limited validation performed so far; however, further validation continues aboard the Spirit of Britain ferry.
The Thames Estuary ASF Survey has been performed, and 8-meter (95 percent) accuracy has been demonstrated in the area. The River Humber and its approaches have also been surveyed with validation in progress.
IOC-level DLoran reference stations should be available mid-2014, ready for installation.
The methods and processes employed during this work will be proposed for inclusion within the next version of the eLoran receiver Minimum Performance Specification as determined by Radio Technical Commission for Maritime Services (RTCM) Special Committee 27. These include techniques and algorithms used for ASF measurement processing, the preferred ASF file format, guidelines on the usage of ASF data, and integrity computation.
Acknowledgments
The GLA acknowledge the assistance of the crew of THV Alert, the Dover Harbour Board, Peel Ports (Medway), Associated British Ports (Humber), Aberdeen Harbour Authority, Forth Ports, PD Ports (Middlesbrough).
This article is based on a presentation made at the Institute of Navigation International Technical Meeting, January 2013, in San Diego, California.
Paul Williams is a principal development engineer with the Research and Radionavigation Directorate of the GLA, and technical lead of the GLA’s eLoran Work Programme, responsible for the ongoing roll-out of the GLA’s eLoran Initial Operational Capability (IOC). He holds a Ph.D. in electronic engineering from the University of Wales.
Chris Hargreaves is is a research and development engineer with the Research and Radionavigation Directorate Directorate of the GLA. His work focuses on eLoran in measurement trials, software development, and data analysis. He holds a masters’ degrees in mathematics and physics from the University of Durham and in navigation technology from the University of Nottingham.
