America urgently needs alternatives to GPS and the government must fund efforts to make that happen. So say separate documents sent to President Biden and senior members of Congress earlier this month.
On May 6, the government’s National Security Telecommunications Advisory Committee (NSTAC) issued its “Report to the President on Communications Resiliency.” The next day the industry group Alliance for Telecommunications Industry Solutions (ATIS) sent letters to Congress. Both organizations identify the need for alternatives to GPS to support telecommunications and other critical infrastructure. Both also urge government funding for the effort.
NSTAC is a federal advisory committee composed of 18 members from the telecommunications industry. Most are CEOs and very senior leaders in companies such as AT&T, Microsoft, and Iridium.
This month’s NSTAC report highlights the critical role that PNT, especially timing, plays in telecommunications. It notes that widespread use of GPS makes the system vulnerable to a host of threats. To address this, the group recommends the administration consider an approach “similar to that reflected in the Resilient Navigation and Timing Foundation’s paper entitled “A Resilient National Timing Architecture.” Further, to enhance the ability of commercial entities to afford leveraging this architecture, the Administration should appropriate sufficient funds to lay the foundation for creating this timing architecture, with the Federal Government being the first customer for what will ultimately become a resilient, interconnected network for PNT delivery.”
Federal funding is necessary, according to the board, because free GPS services eliminate market demand for alternatives.
ATIS sent letters to leaders in the House and Senate citing an “urgent need” for funding deployment and adoption of GPS alternatives for use in critical infrastructures, including telecommunications.
ATIS develops standards and other technical deliverables for information and communications technology (ICT) and services companies on a broad range of issues, including 5G and the Internet of Things (IoT).
Network and system synchronization is key for telecommunications. At present this is done almost exclusively using signals from GPS. ATIS had previously documented in reports and letters to Congress the vulnerability of GPS signals and the need for complementary and alternative systems to use when GPS is not available.
The letters outline the criticality of precision timing to critical infrastructure, industries, first responders, and U.S. government entities. They cite applications such as E9-1-1 and Assisted GPS used to find wireless handsets, as well as critical infrastructure networks, as some of the applications at risk.
ATIS also endorsed the findings of a recent Department of Transportation (DOT) report to Congress. That report documented that there exist “suitable, mature and commercially available technologies” able to provide alternatives to GPS.
Also mentioned was the appropriateness of government funding. “The role of government in protecting its citizens suggests an imperative to safeguard the capabilities of critical infrastructure industries by facilitating resilient PNT.”
Some in previous administrations had questioned whether it was necessary and appropriate for the government to fund GPS alternatives. According to NSTAC and ATIS, the answer is “yes” to both.
While the Biden administration has not made any official statements on the matter, reports of conversations with recent appointees seem to indicate that they agree with the need for government funding. There also seems to be bipartisan support for this view.
As one example, Ms. Diana Furchtgott-Roth, a conservative economist who served in the Trump administration as the leader for civil PNT issues, supports government funding wholeheartedly. At a recent webinar she indicated that the national need is beyond the business model of any company. “Just as the government funds national defense, it should also provide a complement to GPS,” she said.
The NSTAC “Report to the President on Communications Resiliency” can be found here.
ATIS letters to members in the House can be found here, and to members in the Senate here.
Dana A. Goward is President of the Resilient Navigation and Timing Foundation
Featured image: AnuchaCheechang/iStock/Getty Images Plus/Getty Images
It said policymakers “could consider selecting the most resilient technologies as the cornerstone of the PNT suite for military missions, rather than defaulting to GPS.”
The 51-page report takes a comprehensive view of alternative PNT policy and leadership across the department. Its findings are an interesting and informative look at issues and efforts.
Increasing demands
The report comes at a time when U.S. forces have been seeing increasing interference with their own and allied GPS-enabled systems. The Organization for Security and Cooperation in Europe has regularly reported that its surveillance drones in the Ukraine have been jammed. Chinese press recently bragged that jamming caused U.S. Navy ships in the South China Sea to switch from using GPS to the Chinese BeiDou system. Additionally, U.S. military commanders have regularly described the Middle East as the most contested electronic warfare area on the planet, in large part because of regular interference with GPS signals.
The GAO study also comes on the heels of a provision in the National Defense Authorization Act (NDAA) for this year which directs DOD to provide non-GPS PNT to combatant commanders by 2023. The act says this timeline is consistent with responding to Joint Urgent Operational Needs, a formal method for commanders to communicate with department leadership. According to some sources, this suggests that the Pentagon has been receiving such requirements from field commanders, but has not responded to them in what Congress considers a timely manner.
Alternative PNT “not a priority,” resisted
Despite chronic GPS signal interference across the globe, outside experts and officials across the DOD told the GAO study team that developing alternative sources of PNT was not a priority for DOD. One example cited was the lack of a central program office.
One expert said, “PNT — It’s everyone’s need, but nobody’s business.” Another expert said, “Everyone wants to use [PNT], no one wants to pay or care for [PNT].” One DOD official characterized alternative PNT as an afterthought. DOD’s PNT Roadmap states that PNT capabilities, despite being mission critical, are not normally considered a key requirement, but rather may be treated as “a second-tier requirement.”
Worse, the report indicated that some forces within the department resist alternative PNT efforts.
According to one DOD official cited anonymously in the report “bureaucratic and political obstacles [represent] the biggest challenges for alternative PNT” and “anything that threatens GPS, such as alternative PNT technologies, faces pushback.”
The report cited another DOD official as agreeing that “there is an impression that the GPS program has a lot of political clout within DOD, and that those trying to develop alternative PNT technologies may face political challenges.”
Realistic requirements
Many missions do not need the accuracy provided by GPS, according to the report. Nevertheless. DOD programs often default to GPS performance standards when developing requirements. Many alternative technologies, while more resilient, are unable to achieve the same accuracy as GPS and therefore fail to meet the over-stated requirements.
Open architecture
Both DOD and GAO see development of modular open system architecture (MOSA) as key to PNT success in the future. This will allow addition of new PNT sources to a platform without the need for a major retrofit. With MOSA, all that would be needed is a new sensor module for the desired PNT source.
The GAO report endorsed this approach and encouraged DOD to institutionalize it with dedicated funding.
Working with industry
Decades of civil GPS use have benefited DOD in many ways. Broad academic and commercial research has resulted in a host of applications and improvements in the size, weight, and power requirements of equipment, as well as lowered costs. These benefits would almost certainly not have been realized at the current scale if the market for GPS equipment and apps had been restricted to military users.
The 2021 NDAA directs the department to “…enable civilian and commercial adoption…” of the GPS alternative technologies it develops for field commanders. The GAO report suggests DOD also work to leverage industry advances in technologies.
Scope and recommendations
GAO’s tasking for this effort did not include examining efforts to make GPS signals and equipment more resilient to disruption, nor use of non-U.S. satellite navigation systems. Neither were non-defense uses of PNT, nor improvements in such things as tactics, techniques, and procedures considered.
The study focused solely on department efforts to complement GPS services.
Six recommendations for policymakers are included in the report:
Increase Collaboration — Consider mechanisms to coordinate across DOD to clarify responsibilities and authorities in prioritizing the need for alternative PNT technologies.
Focus on Resiliency — Consider selecting the most resilient technologies as the cornerstone of the PNT suite for military missions, rather than defaulting to GPS.
Clarify Requirements — Consider opportunities to clarify what level of PNT performance is actually needed for missions, rather than defaulting to requirements that match GPS performance.
Coordinate with Industry — Consider ensuring that DOD and commercial industry coordinate so that industry is prepared to meet DOD’s needs, and DOD can leverage industry advances.
Institutionalize Open Architecture — Consider making the open architecture initiative more permanent, including providing funding.
Analyze Vulnerabilities — Consider having DOD conduct ongoing analysis of vulnerabilities of different PNT systems.
The May 2021 GAO report “Defense Navigation Capabilities: DOD is Developing Positioning, Navigation, and Timing Technologies to Complement GPS” is available here.
Projects will advance technology used for secure GNSS, quantum timekeeping and communications
ColdQuanta, which specializes in cold atom quantum technology, has been awarded two development contracts from U.S. government agencies worth $2.55 million. Both projects are based on the company’s Quantum Core technology, which uses atoms cooled to a temperature of nearly absolute zero and lasers to manipulate and control the atoms with extreme precision.
Prototype Atomic Clock
The Office of the Under Secretary of Defense for Research & Engineering (OUSD R&E) awarded ColdQuanta $1.8 million for the development of a prototype atomic clock that could enable reliable, highly accurate position, navigation and timing (PNT) capabilities necessary for the functioning of critical infrastructure around the world. Atomic clocks are used for GPS/GNSS systems as well as for time-distribution services that are the basis of financial networks, computer, TV and radio services and other applications.
Alternative PNT. However, services such as satellite-based GPS can be spoofed, lack encryption or other security features, and often can’t deliver the signal strength required. Because of this, the development and deployment of a PNT system that doesn’t depend on GPS is a critical need across governments and industry, according to ColdQuanta. The company said this is especially true for mobile systems such as aircraft and spacecraft that need to know their position with great precision even when GPS is unavailable.
Under this project, ColdQuanta will deliver a state-of-the-art atomic clock with “instant on” capability if a GPS signal is lost, with a timing accuracy comparable to the best commercial clocks. It will also be ruggedized, portable and compact to enable its use in aircraft, and will minimize the power draw in between periods of demand.
“High-performance atomic clocks are the backbone of the internet, electrical power grids, financial networks, and autonomous navigation. Combining this with ColdQuanta’s development of related inertial navigation devices — such as gyroscopes, accelerometers and gravimeters — will lead to the first Quantum Positioning Systems,” said Dan Caruso, executive chairman and CEO of ColdQuanta. “We’re excited to work closely with the Department of Defense to meet their urgent needs, while also advancing the capabilities needed for future, unassailable global positioning technology.”
This velocity-distribution data for a gas of rubidium atoms confirmed the discovery of the Bose–Einstein condensate in 1995. In these three snapshots in time, atoms—cooled to near absolute zero—condensed from less dense areas on the left (red, yellow, and green) to very dense areas at the center and the right (blue and white). (Image: NIST/JILA/CU-Boulder)
Miniaturized Ion Trap System
Also, the Air Force Research Laboratory (AFRL) awarded ColdQuanta $750K for the development of a high-performance miniature ion trap system. Compact ion trap systems are applicable to a spectrum of quantum applications including quantum networks, computing, metrology, and timekeeping.
ColdQuanta previously developed a prototype miniaturized ion trapping system with performance that is competitive with traditional, large-footprint vacuum systems. The system maximizes performance and robustness while minimizing size, weight, and power consumption (SWaP). The new AFRL award will build on the success of this prototype to increase performance, reduce cost, and create a robust architecture for deployable quantum platforms.
Bose-Einstein Condensate
The story of ColdQuanta began in 1924 with the discovery of the Bose-Einstein condensate (BEC) — also known as the fifth form of matter — by Satyendra Bose and Albert Einstein. Seventy years later, BEC was first synthesized at the University of Colorado at Boulder in collaboration with the National Institute of Standards and Technology (NIST), for which Eric Cornell and Carl Wieman won a Nobel Prize in 2001. Their colleague, Dana Anderson, co-founded ColdQuanta, which is using the fifth form of matter as the foundation for its cold atom quantum technology.
When atoms are cooled to a few millionths of a degree above absolute zero, they take on quantum properties. Lasers are used to arrange the atoms, hold them in place, run computations on them, and read out the results. Quantum calculations, communications and sensing are the result.
ColdQuanta is collaborating with global customers including major commercial and defense companies; the U.S. Department of Defense; national laboratories operated by the Department of Energy, NASA, and NIST; major universities; and quantum-focused technology companies to advance products and services development with Cold Atom Quantum Technology. ColdQuanta is based in Boulder, with offices in Madison, Wisconsin, and Oxford, United Kingdom.
New technologies use a variety of inputs to help ensure seamless navigation, even when GPS reception fails because of interference or jamming.
Honeywell has successfully demonstrated multiple alternate navigation technologies for military aircraft. These new products are intended to help ensure seamless navigation — even when GPS signals are blocked, interrupted or unavailable.
For military operations, GPS-jamming — intentional or not — can block vital signals from conveying critical information regarding positioning, navigation and timing (PNT). In these instances, it’s important for military vehicles and aircraft to be equipped with alternative navigation technologies, like celestial or vision navigation, to maintain operational readiness.
“For military operations, not having access to critical positioning and timing information can make or break a mission,” said Matt Picchetti, vice president and general manager, Navigation & Sensors, Honeywell Aerospace. “We’re very excited to roll out this robust lineup of alternate navigation solutions, which are specifically designed to address the needs of our military customers and give them the added layers of redundancy needed to successfully carry out their operations, even if they lose access to GPS signals.”
Illustration: Honeywell
Alternate navigation technologies provide a different means of measuring position, velocity and heading when GPS is disrupted. These technologies include:
Vision-aided navigation. This technology uses a live optical or infrared camera feed and compares it with maps to provide a passive, not jammable, highly accurate alternative PNT solution that provides GPS-like accuracy in GPS-denied or jammed conditions.
Celestial-aided navigation. Honeywell’s celestial-aided navigation technology observes stars and “reference objects” orbiting the earth such as satellites, which have known positions and velocities. This technology compares those reference objects to stars and can determine position and velocity, the same way a GPS receiver can.
Magnetic anomaly-aided navigation. This navigation technology measures magnetic strength using sensors and compares this data with known geographical magnetic maps to accurately identify the position of the aircraft relative to the Earth.
Prototypes of these alternate navigation systems will be available in 2022, with initial deliveries expected to start in 2023.
Honeywell navigation systems are used by nearly every aircraft flying to guide millions of passengers to their destinations. Since 1914 when the first autopilot used Honeywell gyroscopes to hold the plane stable during flight, Honeywell has delivered more than 500,000 high-performance inertial sensors across several platforms on land, in the air and at sea.
In separate letters to members of the House of Representatives and the Senate, seven companies and a non-profit urged Congress to support alternative positioning, navigation and timing systems (PNT) with the “necessary funds and other appropriate policy tools.”
The letters focus on and endorse the system-of-systems approach outlined in the Department of Transportation’s (DOT) recent report to Congress on the results of its GPS Backup Technology Demonstration. The report found an adequate and robust American PNT system should include space-based L-band signals, low-frequency (LF) and ultra-high-frequency (UHS) signals, and fiber connections between the terrestrial LF and UHF transmitters.
“Our country depends on GPS for critical infrastructure, and there is an urgent need for resiliency being built into our critical infrastructure. Before the report came out, some of us had different ideas of how the U.S. should go forward,” said Ganesh Pattabiraman, CEO of NextNav. “But the DOT report provided the data to make it very clear that it is a combination of technologies that need to come together to truly enable nationwide backup to GPS, and it was good to see we could get industry alignment on the findings.”
The letters describe many of the threats to GPS, both natural and malicious; its vulnerabilities; and the dire consequences of disruptions. They go on to state that robust, more reliable PNT is needed for emerging and future systems like E911, 5G, resilient electrical grids, drones and other automated systems.
Monty Johnson, CEO of OPNT, a provider of time-over-fiber services, praised the findings of the DOT report. “The key to resilience and reliability in a system-of-systems is including technologies that deliver the same information using starkly different means. It is hard to imagine a combination of technologies that are more diverse than fiber, satellites, LF and UHF.”
According to Pattabiraman, the signers of the letter agree that the DOT report made clear that there are mature technologies available today that can address the GPS backup issue. DOT and Congress now have the data to act to enable a much-needed resilient infrastructure for the country.
Dana A. Goward, president of the non-profit RNT Foundation, agreed. He also observed that deciding on the technologies and congressional funding were important, but only first steps. “The goal of this effort is not to just implement systems,” he said. “it’s to make America safer. Establishing the services quickly and efficiently will be key, as will ensuring they are widely adopted.”
“Protecting the nation from the consequences of a space-based PNT disruption will require that these systems be accessed and used by a wide variety of users from first responders and delivery services, to all forms of critical infrastructure,” Goward said. “This means the government will need to eliminate as many barriers to adoption as possible. One or more of these alternatives has to be available to every American. And a basic level of service has to be free, just like the GPS utility it is reinforcing. Fortunately, we estimate this can be done relatively inexpensively. It will be only a small fraction of the $1.7B we spent on GPS last year.”
The alternative to making this relatively modest investment, according to Goward, is unacceptable.
“There are lots of threats to GPS,” he said. “Take the sun for example. The most recent study I saw estimates a 70% chance solar activity will damage the GPS constellation in the next 30 years and a 20% chance it will destroy a big part of it. And the sun is just one of the threats we face. We can’t keep playing this kind of Russian Roulette with the fate of our nation. Especially when other countries like Russia and China have already taken steps to protect themselves with terrestrial systems.”
A copy of the letter sent to Senators can be found here, and the one to members of the House of Representatives here.
In its closing days, the Trump administration issued several new policy documents affecting positioning, navigation and timing (PNT) issues.
Some have questioned the long-term impact of these, given the significant policy differences between the previous and current administrations. Yet policies in relatively non-controversial areas such as PNT are generally developed by career personnel who tend to remain in place from administration to administration. While they must adhere to the philosophical tenets of extant elected officials, these policies tend to endure longer than others.
Even if this weren’t the case, considering the wealth of other issues the new administration is grappling with, these new policies could remain in force for some time, even if the new regime ultimately decides to change them.
Several themes run through many of the documents. These include:
Space-based PNT is vulnerable and must be protected.
The first of these late-term documents to be published was the National Space Policy issued on Dec. 9, 2020. Highlights and possible impacts for the PNT community include:
A goal to “Promote and incentivize private industry” could have implications for low-Earth orbit (LEO) PNT services.
A goal to “Increase the assurance of national critical functions” could include GPS/PNT resilience.
A pledge to “Safeguard space components of critical infrastructure” undoubtedly includes GPS. The section also has ominous statements about U.S. responses to purposeful interference and tasks the Defense and Homeland Security secretaries with having those responses ready.
Another pledge to “Maintain and Enhance Space-based Positioning, Navigation and Timing (PNT) Systems” is followed by eight explanatory paragraphs, many of which repeat previous policy. One new item is a promise to invest in detection and mitigation of harmful interference. A mention is also made of the need for multiple and diverse PNT sources, and responsible use of PNT, echoing the February 2020 Executive Order on the subject. Both of the latter two mentions were in the context of critical infrastructure and mission essential functions versus the security of the nation and economy as a whole.
Congress mandated a GPS backup technology demonstration in 2017, and $10 million was subsequently provided for that purpose. Various internal government delays resulted in the project not getting underway until March 2019. It concluded about a year later.
While some people have been critical, it is important to remember the report documents 11 vendor demonstrations, not engineering tests. Technologies were demonstrated in different locations and under differing conditions.
There is no silver bullet for meeting the nation’s needs. It must be a system of systems.
Also, the amount of effort and equipment in the demonstrations depended in some cases upon infrastructure available and the amount of money the government and vendors were able to spend. This meant that at least one technology was “demonstrated” mostly by explaining the concept, and other vendors were able to only partially demonstrate their technologies.
All of that said, the report offers valuable information about how America should make its national PNT much more resilient and reliable. First, it reinforces DOT’s message that there is no silver bullet for meeting the nation’s needs. It must be a system of systems. Second, the report goes further and says what that system of system should look like: “Those technologies are LF and UHF terrestrial and L-band satellite broadcasts for PNT functions with supporting fiber-optic time services to transmitters/control segments.”
From a policy perspective, this is a huge step forward. It resolves previous ambiguity and positions the nation to establish a resilient PNT architecture, one that will do more than be a “GPS backup.” It will be an architecture that will better support current applications and better enable emerging ones like autonomy, 5G and “NextG.”
Published one hour and fourteen minutes before the end of the administration on inauguration day, this plan was mandated as part of the February 2020 Executive Order on responsible use of PNT. By taking a comprehensive look at how we can do better, it provides an interesting outline of the challenges associated with America’s current over-reliance on GPS. While not a policy or directive document, it does suggest two or three departments and agencies that might be tasked with addressing each challenge.
It also addresses the need for interference detection and monitoring, and diverse sources of PNT.
This directive was published five days before the end of the administration and replaced the previous policy, 2004’s NSPD-39.
While the old policy calls for performance monitoring of GPS signals, the new one also has investment in interference detection and monitoring as a goal.
Perhaps the most significant change in the new policy was the absence of the words “backup capability” and the lack of a mandate for DOT to lead its establishment. Yet the policy hammers home multiple times the need for more than GPS as a source of PNT. And it doesn’t abandon the idea of government involvement in making that happen.
In addition to reinforcing Executive Order 13905 on responsible use of PNT, the directive defined a new (for presidential policies) term. “Alternative PNT Service” was described as “a PNT service that has the capability to operate completely independent of, or in conjunction with, other PNT services.” The directive goes on to say that “Multiple, varied PNT services used in combination may provide enhanced security, resilience, assurance, accuracy, availability and integrity. An alternative PNT service allows a user to transition from the primary source of PNT signals in the event of a disruption or manipulation.”
And while the policy does not say the government will establish or support an alternative PNT service, it comes pretty close. One of its goals is “Invest in… as appropriate, alternative sources of PNT for critical infrastructure, key resources, and mission-essential functions.”
It goes on to task the departments of Defense, Homeland Security and Transportation with making that happen.
So “backup” is out, “alternative PNT” is in. We agree words are important and are happy to have the new words. Let’s hope the new administration will match the new words with action (as appropriate).
What should the new administration’s priorities be to make PNT more resilient?
We asked Brad Parkinson, the “Father of GPS” and a GPS World Editorial Advisory Board member, what the new U.S. administration’s priorities should be to make positioning, navigation and timing (PNT) more resilient. For more answers from board members, see below.
Brad Parkinson
Protect the Spectrum. Reverse FCC authorization for relatively high-powered Ligado transmitters that have been proven to degrade GPS and other GNSS operation for thousands of PNT users. All U.S. government departments and major user groups affected have pleaded with the FCC to reverse this terrible decision. There is little benefit from it to the American public.
Protect the rapidly evaporating and self-proclaimed Gold Standard of GPS. The GPS satellite designs are showing their age. They need to go to multiple launch (three at a time) and revert to simpler designs without the spot-beams and other weighty add-ons that greatly increase complexity and cost. The Chinese have added to BeiDou (a) inter-satellite precision ranging and wide-band communications, (b) geosynchronous satellites, probably with good spot-beam acquisition aids, and (c) a WAAS-like correction directly on the satellites, which may have accuracies down to real-time kinematic (RTK, perhaps a few centimeters). Also, they claim their basic accuracies to be better than GPS (it might be true!) — I think they already have operational retro-reflectors.
Allow and encourage export of the basic and quickest fix to jamming and spoofing for high-value PNT users. More than 40 years ago, we demonstrated, in hardware, a high anti-jamming receiver that could fly directly over a 10 kW GPS jammer and not be affected. We know that high-gain, digital beam-steering antennas will create close to immunity, but our manufacturers will not move this way because we cannot sell or use them on the international market.These devices, combined with inexpensive inertial components and the newer signals, would make PNT virtually immune to current threats of interference — both jamming and spoofing.
Move the military focus from alternative PNT techniques to seriously upgrading their receivers and useful signals. No current or reasonably anticipated alternative can provide the accuracy (3D), availability or integrity of GPS. The new M-code and L1C signals have been in the queue for about 20 years. (Loran for ground operations probably is very vulnerable to direct attack in a fluid battlefield operation. Loran’s main value is to distribute time and for maritime users.) In those 20 years, we now have cellphone chips costing less than $5 that can listen to about 200 ranging signals and process RTK, as well as use all the corrections available (WAAS, EGNOS, etc.). Such capability cannot be found in military receivers. The Defense Department must improve its acquisition strategy in terms of both speed and competition, and ncorporate existing civil capability into military user equipment.
Take government actions to rapidly identify, shut down, and prosecute GPS jammers. Some believe this problem is much larger than recognized already. All cellphones should be required to report extraordinary spectrum noise levels or apparent attempts at spoofing. This should be fed to a dynamic national database, perhaps maintained by the Coast Guard. GPS users should have an automated way to find out whether there are substantial threats in their operating area.
Brad Parkinson is the Edward Wells Professor, Emeritus, Aeronautics and Astronautics (recalled) and co-director of the Stanford Center for Position, Navigation and Time at Stanford University.
Editorial Advisory Board PNT Q&A
Here are additional responses to the question from more GPS World Editorial Advisory Board members.
John Fischer
“We hope the new administration continues on the path established with the Executive Order last year for resilient PNT, supporting progress made by DHS and NIST in establishing resilient and cybersecure frameworks. It will be important for them to maintain an open market concept toward future innovative solutions and not mandate a particular PNT approach. Awareness of the criticality for trusted PNT in our mobile connected society is established and we must not lose this.” John Fischer Orolia
Jules McNeff
“Resilient PNT should be a national security priority. Its continuity is vital to both military and economic/social activities of all kinds. Its qualities of spatial awareness and synchronization enable the efficient functioning of the most sophisticated modern technologies in the physical and cyber worlds while also simply getting people and things from point A to point B on schedule. In that context, the elements which comprise resilient PNT should be protected from natural or hostile disruption.” Jules McNeff Overlook Systems Technologies
Greg Turetzky
“Truly resilient PNT requires combining multiple positioning technologies to maximize resiliency. However, the government’s influence in many of the augmentation technologies (sensors, vision, etc.) is limited. What the administration can do is make GPS itself more resilient by speeding up the launch and acquisition schedule of GPS Block III. The new signals, particularly at L5, are invaluable for improved resiliency to jamming and spoofing as well as providing a significant improvement in accuracy.” Greg Turetzky Consultant
Positioning, navigation and timing (PNT) orbs guide 50-ton robots carrying containers at the Ports of Auckland.
In a world-exclusive report, GPS World visited with officials at the Ports of Auckland, New Zealand, and the Australian company Locata to reveal a revolutionary port automation system. Locata’s navigation system could change the way containers are handled around the globe, and open the floodgates for next-generation automation of Critical National Infrastructure sites.
Global shipping lines, ports and container terminals are at the heart of the immense, multi-trillion-dollar global logistics market, and ports are classed as critical infrastructure in many nations.
Much of the world’s port infrastructure is old, has no space to expand, and strains at the seams as it faces the reality of handing larger cargo volumes and massive new container ships —some with more than 22,000 containers on board. Efficiently managing the huge spike in container moves caused by the arrival of these gigantic new vessels is a critical requirement for container terminals and their logistics chains, and the problem will only become more acute.
Once arriving at port, container vessels are offloaded by ship-to-shore (STS) cranes. (Photo: bfk92/E+/Getty Images)
Automating operations at ports and intermodal hubs to accelerate their throughput is an obvious solution. “Automate or die” is now an accepted industry mantra, and indeed a small number of terminals around the world have been automated in the past. Early attempts at using GPS for positioning autonomous machines promptly fizzled, however. A chaotic environment of gigantic moving metal machines and constantly changing metal container stacks creates insurmountable blockage and multipath position errors. The environment makes it impossible to guarantee ultra-reliable, centimeter-level GNSS positioning.
In the past, the industry had to resort to providing basic-level positioning by drilling holes to install (with no exaggeration) between 50,000 and 500,000 RFID transponders or magnets in the port’s pavement. This was extremely tedious and labor intensive, and came with serious downsides. The transponders do not work well for differing machine sizes because they usually require reader antennas, the size of two regular house doors, under the machine. Furthermore, the drilling deteriorates the pavement — the ports’ most valuable asset.
The biggest problem, however, was that for a fully operational site like Auckland — known as brownfields in the industry — the port often would have to be closed for years to allow the transponders and pavement to be installed. Such a shutdown isn’t feasible for most operating ports; hence, brown-fields were considered next-to-impossible to automate.
Although this may seem to be less of an issue for new greenfields ports (those built from scratch), buried transponders essentially lock in the mobility and usage patterns for any port, requiring another shutdown to make changes. In all, the logistics industry and its machine manufacturers urgently need a viable, flexible, reliable positioning solution for terminal automation — and soon.
A New Solution
It’s now been revealed that a new solution for this urgent requirement had, in fact, been in stealth mode development for many years. Due to commercial competitive considerations, all the work had taken place under the radar and without publicity. Konecranes, the largest port machine manufacturer, had been developing fully autonomous straddle carriers specifically to address this market, in partnership with Australian company Locata Corporation.
This totally new automation system is being rolled out now at multiple terminals around the world. The first port to emerge with this trailblazing capability is the Ports of Auckland.
Locata’s ground-based GNSS-like positioning system is changing the game for logistics terminals. The Ports of Auckland is the first of many ports and logistics hubs around the globe currently operating or installing Locata (see Figure 1). In the process, the port is delivering the global logistics industry a raft of world-first capabilities.
Figure 1. The Ports of Auckland covers 140 acres at the doorstep of Auckland’s central business district. The outline shows the approximate coverage of the LocataNet local positioning system (landside only). (Photo: Ross Clark/Ports of Auckland)
Partners on this project — the government owners of the Ports of Auckland; its system supplier Konecranes; and Locata — are breaking new ground and in the process opening the floodgates for next-generation machine automation of critical national infrastructure sites.
Groundbreaking Capabilities
Living on an island means every-day items are delivered via cargo ships. That’s certainly the case in Auckland, New Zealand’s largest city, which has a harbor on the Pacific Ocean.
The Ports of Auckland is the largest terminal for commercial freight that arrives in New Zealand. Its 140-acre international trade port is in the heart of the city and surrounded by water, so expansion by reclaiming land is out of the question, even as the country continues to grow.
With this situation, the port’s operator was faced with the seemingly impossible: double the handling capacity of the port in a few years without reclaiming any more land. They turned to automation and cutting-edge technology to find a solution.
Everything that arrives at the port is in a standardized shipping container. The port’s plot of land is usually crammed with the maximum number of containers it can hold. The Ports of Auckland had to seek out automation that increases the terminal’s capacity by stacking containers higher, stacking them close together, and generally making things move faster and more efficiently.
For inbound cargo, once a container is unlocked from its ships, ship-to-shore (STS) cranes unload them to ground level. Straddle carriers then lift and move each container to a ground-level holding area, where it is stored and then transferred to a truck or a train that will deliver it to its ultimate destination.
Export cargo arrives at the port via truck or train, and the straddle carriers handle them through the port’s storage areas to be loaded onto a ship.
The port also handles trans-shipments; containers that arrive via a ship destined to be loaded onto another ship. These handling processes are repeated over and over around the clock, operating pre-automation at a capacity of around 900,000 containers per year.
Straddle carriers are the workhorses of the operation, moving containers within the port. Manual straddles are operated by trained onboard drivers and can stack containers two high. In a traditional manual environment, a driver’s time is divided between tasks that require skill such as picking up a container from the STS crane, or on repetitive work — like organizing containers for efficient loading onto ships, trains and trucks — which are tasks that can readily be automated.
By adding automation, the Ports of Auckland created a mix of manual and automated straddles working together at the terminal. Drivers are assigned the more interesting and skillful tasks, while the automated robotic straddles carry out the repetitive, “boring” tasks.
“Very soon, when the automation system is fully implemented, our straddle carrier fleet will consist of 27 Konecranes Fully-Automated Straddle Carriers (A-STRAD), and 24 manned straddle carriers,” said Ross Clarke, program manager of Auckland’s Port Automation Project. “This interaction of manned and automated machines, without any physical infrastructure separating them, is a world first.”
The A-STRADs are bigger than the manual straddles. The 50-ton, four-story-high machines can move 40-foot containers weighing 50 tons around the port at up to 30 kilometers per hour. Each can stack containers up to three high and closer together.
Five fully autonomous Konecranes A-STRADs at work in the Ports of Auckland. The Locata VRay Orb antennas can be seen at the top of each straddle. (Photo: Photo: Ross Clark/Ports of Auckland)
With the new automated system, the Ports of Auckland will almost double the capacity of the terminal to 1.7 million containers per year once automation is fully implemented in early 2021.
The Ports of Auckland chose Konecranes to supply the fully-autonomous straddle carriers. With no cab, A-STRADs are uniquely identifiable as autonomous. A-STRADs can drive around the port, lifting and moving containers in the same way as their manual predecessors, using their spreader and assisted by the onboard sensors. A critical difference is how they position themselves and how they safely operate in an environment with many other objects, manual straddles, A-STRADs and container stacks.
At the heart of this capability is the Locata local positioning system. It allows A-STRADs to reliably position themselves to centimeter-level accuracy throughout the terminal work area. Every A-STRAD has two Locata antennas, each attached to a Locata Rover receiver, that enable an A-STRAD to accurately determine its position and orientation.
Driver Assistance. Both the A-STRADs and the manual straddles at the Ports of Auckland are positioned using Locata technology. The manned straddle carriers are fitted with a driver-assistance system, which is also positioned by Locata, so their operations can be monitored and coordinated in lock-step with autonomous A-STRADs.
“The driver assistance system operates a lot like the auto-parking system in a car,” Clarke said. “When manned straddles are near the interchange area where they interact with A-STRADs, operators change to driver-assist mode and can take their hands off the steering wheel, allowing the system to autonomously guide the straddle carrier to the correct stack location with an accuracy of +/–3 cm.”
Roots of a New Strategy
The groundbreaking positioning system has been in the works for several decades.
“Locata has been working on this ‘terrestrial replica of GNSS’ capability for 25 years,” Locata CEO Nunzio Gambale told GPS World. “It didn’t spring up one day just because co-founder David Small and I thought, hey, we’d like to replace the GPS satellites.
“Our driving vision has been to provide accurate performance in myriad environments where we always knew GNSS was going to fail to deliver,” Gambale continued. “Importantly, what you see today is not just ‘a lab experiment’ or a prototype test system. It’s operationally deployed, enabling some of the most demanding positioning applications on Earth. Our team has been laser-focused on developing real technology which improves on GPS-like positioning, and delivering solid solutions for real-world problems modern applications now face.”
The Locata System
Two LocataLite transmitter antennas, installed 23 meters up a light pole, provide high-accuracy positioning coverage over part of the Ports of Auckland. (photo: Photo: David Small/Locata)
LocataLites. Locata is a local positioning system that uses a network of synchronized transmitters, known as LocataLites, installed in and around the port to cover all straddle work areas. The LocataLites work like miniature GPS satellites, transmitting GPS-like signals using two frequencies in the 2.4-GHz ISM band.
LocataLites are strategically installed and configured to deliver reliable centimeter-level accuracy, with particular attention paid to the geometry available from the network when the installation layout is designed. This LocataLite network (called a LocataNet) enables the equipment on each straddle carrier to trilaterate its position using a method similar to GNSS positioning.
Locata technology is built upon two critical proprietary capabilities developed and perfected over many years: TimeLoc and multipath mitigation. To date, Locata has been granted more than 160 patents on these core advances.
Sub-Nanosecond TimeLoc. First, LocataLites use their own broadcast signals to time synchronize with each other using a proprietary technology called TimeLoc. This allows all the LocataLites in a LocataNet to time synchronize with each other to sub-nanosecond levels without requiring atomic clocks.
Mutipath Mitigation. Second, Locata’s proprietary multipath mitigation technology enables Locata receivers to correctly track direct signals, even in an environment filled with reflected signals. Multipath is the main reason GNSS can’t deliver the accuracy and reliability required at a port.
Locata’s multipath mitigation technology has two components: the Locata receiver and the VRay Orb antenna.
Locata receivers. The receivers incorporate a proprietary signal-processing technique, correlator beamforming (CBF), which delivers beam-forming capability comparable to advanced phased-array antennas.CBF allows the Locata receiver to combine signal samples from its multiple antenna elements to form virtual “beams,” and any signal outside of a given virtual beam is ignored.
Unlike traditional phased arrays, however, the Locata CBF system is markedly less complex and orders of magnitude less expensive. CBF uses only one RF front end, yet it can form millions of individually-steered beams per second.
VRay Orbs. The straddle carriers at the Ports of Auckland are the first commercial operating deployment of Locata’s VRay Orb antennas, with two orbs atop every A-STRAD as well as the manual straddles (Opening Photo).
A row of Locata VRay Orb60 antennas atop Konecranes A-STRAD machines stretch into the distance toward Auckland’s business district. (Photo: David Small/Locata)
Bespoke Positioning
The placement of LocataLite positioning transmitters on any site is entirely within the control of the LocataNet designer. “Our partners can place them where they want, in as high a density as they want, and as accurately as they need to get their job done,” Gambale said. “The LocataNet delivers rock-solid, super-reliable positioning in environments where that wasn’t possible before.”
With GNSS, users have no control over the geometry of the satellites in view. “That’s a huge problem in many of these high-accuracy applications because it can greatly affect your DOP [dilution of precision] geometry,” he added. “Engineers trying to rely on GNSS can see huge variability — or complete failure — in a machine’s position. Unreliable positioning is not acceptable when an enterprise is relying on 50-ton autonomous machines, doing critical work that you cannot afford to stop.”
According to Clarke, “Locata is well-suited to our requirements as it offers high precision, high resistance to interference, and high reliability.”
Breakthroughs at the Port
Locata’s enabling technology has brought multiple breakthrough advantages to terminal automation. Critical among them is the ability to automate a terminal while in full operation.
“Because our container terminal is working at high utilization, with no spare space to operate, we are deploying the automation in two phases,” Clarke said. “The first phase started commercial operations in August 2020, and we have now handled more than 35 ships using the automated system. The next phase, with the entire terminal running fully operational automation, is scheduled to enter service in early April 2021.”
Flexibility. The new system also provides extreme flexibility to alter the layout of operations in real time, something never possible with transponders embedded in the ground. A-STRADs drive around using a digital map. With Locata, this map can be changed as often as needed without having to change anything in the infrastructure.
Reduced Wear and Tear. Before automation, line markings on the pavement guided operators on paths and in storage areas. While this kept operations orderly, following the marked lines caused ruts in the pavement that eventually require costly and time-consuming repairs.
“With A-STRAD positioning being so precise and repeatable, this accuracy could have caused serious ruts and also become a problem,” Clarke said. “With Locata and the ‘invisible’ digital pavement markings, we came up with a cool solution to this that we call ‘stack shuffling.’ We shift the digital drive paths and storage plots over time so that wear and tear on the pavement is spread more evenly, requiring fewer repairs to the tarmac.”
The shuffling is imperceptible to a human, but the A-STRADs are spreading the wear across the entire tarmac and greatly extending the service life of the terminal surface, according to Clarke.
Less Fuel. The automation also brings significant environmental benefits. “A-STRADs use approximately 10% less fuel, which means they are indeed cheaper to run,” Clarke said.
Locata-enabled manned straddles near STS cranes unload a ship at dusk. (Photo: Photo: David Small/Locata)
Autonomous and Manned
Ensuring the safety of workers, machinery and cargo is a critical requirement at any port. All parts of the Ports of Auckland’s new system were tested for two years, including system software from both Konecranes and Locata.
The software was tested in pieces as it was developed. Then, full system functionality was delivered and tested. Both automated and manual straddles are centrally monitored and coordinated by this terminal operating system.
Working Together. Auckland’s port is the first in the world to use autonomous and manned machines together without a physical separation. This allows skilled operators to manually handle operations in specific areas, while the autonomous A-STRADs are tasked with monotonous and time-consuming jobs with no practical limitation on the machine’s repeatability.
Within the access-controlled premises in Auckland, all work areas are constantly monitored by the centralized system. The Locata system tracks the location of all straddle carriers at all times.
Training. All manual straddle drivers go through virtual and hands-on training with specific attention paid to safety protocols.
“Once they’ve first learned what to do in a simulator,” Clarke said, “they then carry out the same tasks with an instructor in a real straddle carrier. We also train our control room staff in a virtual training environment that’s a bit like a container terminal version of a flight simulator.” Figure 2 shows the screen of the operator training simulator.
Figure 2. The straddle carrier simulator used for manual straddle operator training shows (top left) the container drop-off location, designated path, and open and restricted zones. (Photo: Ross Clark/Ports of Auckland)
Laser Scanners. As a last line of defense, autonomous A-STRADs are equipped with laser scanners that detect obstacles and automatically engage collision prevention measures, if required.
More Locata Applications
Port machinery automation is the most recent industrial sector to reveal the adoption of Locata technology. However, Locata is already used by large industry partners for deep-pit mining where mine pit walls act like deep urban canyons and severely limit the sky view. (See GPS World, March 2017.)
Locata also is being used as the core truth reference positioning system at the U.S. Air Force (USAF) White Sands Missile Range. There, it is independently providing high-accuracy non-GPS-based positioning when GPS signals are heavily jammed; this is practically the Holy Grail for alternative PNT, and the USAF has been using the system operationally at White Sands since 2016. (See GPS World, January 2020.)
NASA is another Locata user, working with the Federal Aviation Administration on research for next-generation air traffic control. Numerous other applications are currently in stealth development.
Gambale said the company’s technology is not representative of a solution just for ports, mines, aviation, military or any other specific application. “Our ground-based technology has myriad advantages in the many environments where satellite-based positioning was never designed to work. We can change the game for many modern applications because Locata allows users to have total control over where transmitters are placed, the power they transmit, the design of their network structure, and much more.”
For more than 10 years, the company worked to develop technology to reduce multipath — the bane of high-accuracy GNSS positioning in urban, industrial, indoor and occluded areas.
“Those are all real-world environments where satellite-based signals cannot be tracked reliably enough for next-gen, extremely demanding applications like fully-autonomous operations,” Gambale said. “Our business is the direct result of GPS changing the world, and the industry then fueling a largely unqualified public expectation that centimeter-level positioning would be available everywhere. Clearly, that is not correct.
“The growing roster of huge, globally significant companies adopting our technology for applications that go beyond GPS limitations shows our developments deliver real benefits to many markets. Auckland is living proof that Locata is a true, terrestrial, centimeter-accurate alternative-PNT system.”
“In some specific cases, e.g., for critical infrastructures and applications requiring both continuous availability and fail-safe operations, GNSS cannot be the sole means of positioning and timing information.” European Radionavigation Plan, 2018
The Joint Research Center in Ispra, Italy, is the preferred demonstration site. (Photo: European Commission)
The European Commission is undertaking a GNSS backup technology demonstration, much like the one completed by the U.S. Department of Transportation earlier this year. Companies from many countries outside the European Union, including the United States, are eligible to participate. Responses are due by Jan. 13, 2021.
A tender issued on Oct. 26 says that the goal is for the commission to better understand available non-GNSS PNT technologies. Also, they are interested in services that can provide positioning and navigation, and/or time.
Completely Independent from GNSS
Since the intent is to provide a backup for GNSS during an outage, all offered technologies must be completely independent. Specifically, they must have “no common points of failure with GNSS.”
Some industry observers have opined that this eliminates any space-based capabilities from consideration. Coronal mass ejections from the sun have long been considered a threat to satellites. Others have wondered if networked-based solutions could be also excluded because of frequent use of GNSS for synchronization, billing and other applications.
Another requirement is that offered technologies be capable of covering the entire EU territory, including inland waters. While this might seem to rule out fiber-based timing systems, advocates say that is not necessarily the case. They contend a fiber network supporting dispersed transmitters would serve both fixed and mobile applications, and reach users for whom connecting to a fiber node is not feasible.
Other requirements listed in the tender for offered technologies include:
Resilience to GNSS jamming, spoofing, and unintentional interference
Technical readiness levels of 5 or more for positioning and navigation, 6 or more for timing
Able to perform for at least a day during a loss of GNSS
Positioning accuracy < 100 m horizontal, or timing accuracy < 1 microsecond relative to UTC
If timing is included, it must be traceable to UTC
The Demonstration
A webinar for potential offerors was held on Nov. 4. Although it was not recorded, the slides shown are available at the RNT Foundation website. One update to the slides is a new email replacing the one of the first slide. All inquiries should be sent to the project leader at [email protected].
Up to seven companies, presumably each demonstrating different technologies, will be accepted into the program.
The preferred demonstration site is the European Commission’s Joint Research Center in Ispra, Italy. Recognizing that transporting equipment and traveling to Italy might be a challenge for many companies, the tender states’ commission personnel are willing to travel to other locations to see systems demonstrated.
The JRC Ispra campus covers 170 hectares with 100 buildings and 36 km of roads. It provides state-of-the-art laboratories, smart city infrastructure (grids, homes, mobility), and varied topography with urban, semi-urban, rural and woodland areas. (Image: EC)
Information on All Technologies Sought
Unlike the European Space Agency’s Navigation Innovation and Support Programme (NAVISP), companies from outside of the EU are invited to respond to the tender and could be selected. This reflects the commission’s desire to include as many technologies and collect as much information as possible.
Limited funding for the demonstration, pandemic travel restrictions, the need for infrastructure to support wide-area signals, and other obstacles may prevent some companies from participating in this effort. The commission’s overall goal, though, is to get information about as many technology options as possible.
So, while not stated in the tender, the commission is eager to hear from technology companies, even if they do not want to be considered as a part of demonstration project. All are invited to contact project leader Ignacio Alcantrailla-Medina. All information is welcome, though most important are a technology’s performance, technical readiness level (TRL), and if it can be deployed in the European Union.
We understand that, as is the case in the United States, solutions delivering timing are of particular interest.
Combining the data from the demonstration project with other information gathered, the commission hopes to be able to identify a way forward with alternative PNT in Europe by the end of 2021.
The eLoran transmission site at Incheon, South Korea. (Photo: UrsaNav)
South Korean is in the early stages of evaluating its eLoran system, but great results are expected based on the UrsaNav-supplied station in Incheon.
In August 2018, the Korea Research Institute of Ships and Oceans Engineering (KRISO) awarded UrsaNav, through its agent Dong Kang M-Tech, a contract to supply and install an eLoran transmitter testbed system in South Korea. UrsaNav is the exclusive, worldwide distributor of Nautel’s NL Series transmitters, provided eLoran transmitter technology, as well as timing, control and differential reference station equipment for the testbed. The contract represented the first phase in a broader program to upgrade Korea’s Loran-C stations to be the foundation of a sovereign Enhanced Loran (eLoran) positioning, navigation and timing (PNT) service.
“The Republic of Korea recognizes the challenges associated with relying solely on space-based signals, the relative ease with which those signals can be jammed or spoofed, and the necessity to provide trusted time and trusted position to its citizens and critical national infrastructure,” said Charles Schue, CEO of UrsaNav.
The 35-meter eLoran transmit antenna in Incheon. (Photo: UrsaNav)
Many critical infrastructure sectors rely on accurate time and position, including maritime, aviation, electrical distribution, telecommunications, finance/banking, and digital broadcast. A complementary PNT (CPNT) service provides continuity of operations through alternative and diverse timing and positioning information. CPNT is a vital element in ensuring national security and assuring trusted time and position.
KRISO, in conjunction with the Korea Ministry of Oceans and Fisheries (MOF), is developing an Initial Operating Capability eLoran system to provide complementary PNT services as a part of its Electronic Navigation (E-Navigation) mission. KRISO selected UrsaNav Inc. as its prime eLoran systems contractor through a competitive tender offer.
UrsaNav provided, installed and tested an eLoran transmission system at a temporary location near Incheon, South Korea, in November 2019. The company also provided ancillary equipment for Additional Secondary Factor (ASF) map measurements and map-generation software, as well as differential reference station equipment to KRISO. Because of land size restrictions at the temporary site at Incheon, the eLoran transmission system was paired to a small footprint 35-meter top-loaded monopole antenna.
In addition to the equipment provided by UrsaNav, MOF separately contracted a local Korean firm to provide an interim GPS receiver set to synchronize the existing Loran-C sites at Pohang and Kwangju to UTC.
KRISO is in the early stages of measuring the performance of the Korea eLoran system, but results are expected to show better than 20-meter navigational accuracy within 30 kilometers of the differential reference station at the port of Pyeongtaek.
Once the eLoran performance has been proven, MOF plans to move the Incheon eLoran equipment to a permanent site, potentially on the island of Socheongdo, and pair it with a larger “Tee” antenna to increase the output power and coverage area of the system.
MOF also plans to upgrade the existing UTC synchronized Loran-C transmission sites at Pohang and Kwangju with new eLoran transmission equipment systems. The ministry will potentially add two additional transmission sites to provide complete coverage of the land and territorial waters of South Korea.
The U.S. Department of Homeland Security “did exactly what was required by Congress” in issuing its report in June on positioning, navigation and timing (PNT), according to a letter sent by numerous PNT companies to the DHS.
The July 17 letter to Chad F. Wolf, acting secretary of Homeland Security, refutes a previous letter from Congressional representatives that the report contained numerous errors and failed to address many of the things Congress had required.
“We believe that some key claims made in the members’ letter of June 9 are either exaggerated, irrelevant to the report’s Congressional tasking, or simply wrong,” states the July 17 letter, which is signed by senior executives of Satelles, Orolia, Iridium, Navsys, Jackson Labs, Seven Solutions and Qulsar.
The group takes on the claims of the representatives point by point, finding them exaggerated, irrelevant or incorrect.
For instance, the letter critical of the DHS report states:
“The report focuses on the needs of ‘industry’ largely ignoring the needs and impacts on public services (including first responders), government operations, and individual citizens.”
In response, the industry representatives state:
“The focus of the report, as directed by the NDAA, is on the requirements of the owners and operators of national critical infrastructure. This includes “public services, government operations,” and its beneficiaries, “individual citizens.” To the extent that the report focuses on incentivizing the industry, it is in order for it to be able to meet these requirements.
“While the report only highlights PNT use cases from a subset of the 16 critical infrastructure sectors, their pragmatic recommendations address a range of requirements across all sectors. With respect to PNT needs for backing up GPS, DHS acknowledges the differences between and commonalities among the sectors and offers exceptional guidance for leveraging the capabilities of diverse forms of commercially available alternative PNT rather than endorsing a single, anti-competitive, government-imposed solution.”
There are many ways to navigate. For most applications, none surpass the accuracy, affordability and convenience of satellite navigation.
However, given the threats to GNSS from spoofing and jamming, and the possibility that GNSS satellites could be destroyed accidentally by space debris or intentionally during a war, the search is on for alternative sources of positioning, navigation and timing (PNT) data.
Potential alternative PNT (APNT) approaches include computer vision, terrain contour matching (TERCOM, which was used to guide cruise missiles in the 1970s and 1980s), and using magnetic anomalies (MAGNAV).
Diverse animals — such as sea turtles, spiny lobsters, and birds — use magnetoreception for orientation and navigation. However, while animals likely perform wayfinding using the direction of the magnetic field, similarly to how humans use a compass, high-resolution maps used in conjunction with atomic instruments enable us to perform absolute positioning to tens of meters, explained Major Aaron Canciani.
Canciani, an assistant professor of electrical engineering at the Air Force Institute of Technology, has been designing algorithms for MAGNAV flight testing for several years.
Earth’s crustal magnetic field varies from location to location as much as topographic features do and, like them, it changes very little over time. However, unlike topographic features, which only occur on the third of the planet’s surface covered by land, magnetic variations also occur on the oceans. This makes them potentially very useful as landmarks to the Navy and Air Force. Magnetic variations have the additional benefit that they cannot be jammed or spoofed.
NOAA’s EMAG2 World Digital Magnetic Anomaly Map. (Image: NOAA National Geophysical Data Center)
Just like other features of Earth, magnetic fields can be mapped, using scalar magnetometer sensors to measure their strength and direction. In fact, government agencies and mining companies have been making these maps for many decades, for geological exploration and other purposes, though mostly on land.
Conversely, these maps can be used to navigate by comparing the data from magnetometers to the map, just like cruise missiles used to use on-board radar altimeters to match the contours of the land beneath them to contour lines on a digital map and navigators on vessels in shallow waters compare the depths reported by their fathometers to those marked on a chart.
Before this approach to navigation can be widely implemented, however, magnetic maps need to greatly improve in coverage and quality. In addition to magnetic maps and sensors, MAGNAV also requires sophisticated algorithms and careful calibration, to do such things as subtract errors from space weather and the local magnetic field of the aircraft or ship.
The greater the platform’s speed, the greater MAGNAV’s accuracy, because the magnetometers can collect more varying magnetic information per unit of time of INS drift, Canciani explains. On a platform moving fast and at low altitudes, MAGNAV could achieve 10-meter accuracy. In less ideal conditions and relying on lower quality magnetic maps, the accuracy could be as low as one kilometer — which is sufficient for many missions, such as navigating ships at sea.
Off-the-shelf scalar magnetometers about the size of a quarter have already been flight tested. Corporations, the military and civilian government agencies such as NOAA, NASA and NGA already have suitable magnetic maps, though they need to be improved and expanded, particularly at sea. This would require gathering new data using calibrated sensors on airplanes, ships and submarines.
Could magnetic sensors be installed on thousands of aircraft, land vehicles and sea vessels to collect magnetic data during their routine operations? “With proper calibration, yes, but it should not be downplayed how difficult it is to get 1 nanoTesla measurements on a platform,” Canciani said. “Mapping and navigation are inverse problems so any platform that has been calibrated well enough to navigate could, in turn, also be used for mapping.”
However, he points out, the task is much more complicated than just putting a magnetometer on a platform. “Getting clean data on complex platforms remains the largest challenge for magnetic navigation,” Canciani said, “although we are making excellent progress with projects like the Air Force Accelerated AI program with MIT and Lincoln Lab. In this project we are using state of the art scientific machine learning approaches to calibrate complex magnetic fields on operational platforms. Without excellent calibration algorithms the only sure-fire way to get clean magnetic data is putting a sensor out on a boom or wing-tip, which might not be practical for all use cases.”
Two F-16 Fighting Falcons fly over Edwards AFB during a 2009 air show. (Photo: U.S. Air Force/Chad Bellay)
Canciani admits that MAGNAV is often met with skepticism but hopes that realistic testing on realistic platforms will lead to more interest and funding for this approach.
While some such testing has already been performed using private survey aircraft, a much more important test will take place in September, when F-16s from the Air Force Test Pilots School will fly MAGNAV sensors and software over a test range next to Edwards Air Force Base in Nevada.
