Spirent Communications announced that the Spirent GSS7000 GNSS simulator has been integrated into Microwave Vision Group (MVG) over-the-air (OTA) and passive antenna test systems.
MVG, an antenna measurement solutions company, enables the characterization and evaluation of antennas for testing wireless connectivity, reliability, and standards compliance. MVG near-field test systems perform fast and accurate measurements for OTA tests of antennas designed for satellite communications and other GNSS-enabled products, systems, and networks.
As connectivity in industries such as automotive, aviation and military becomes ever more sophisticated, the need to ensure that all the pieces of technology work together in the way they should increases. The integration of Spirent into MVG test systems enables R&D engineers to incorporate the antenna and the vehicle in a test environment that represents the real-world signal environment as closely as possible while maintaining full control and repeatability.
“Our integration into MVG over-the-air test systems, such as the multi-probe SG24 or StarLab, delivers a cutting-edge testing solution, helping to accelerate the development of next-generation products and systems,” says Adam Price, VP of PNT Simulation at Spirent.
DIU accelerates commercial GEOINT and NAVWAR tools and capabilities to the warfighter
The U.S. Defense Innovation Unit (DIU) will be testing ways to mitigate disruptions to GNSS signals this fall.
Disruptions include those from intentional sources, such as spoofing, as well as intentional or unintentional jamming. Intentional tactics can be applied by adversarial nation states, criminal networks or privateers.
The shared interests between the government and private citizens alike for awareness of GPS disruptions make commercial solutions ideal; information and insight can be broadly shared not just within the U.S. Department of Defense (DOD), but across agencies, allied partners and the public as needed.
In the Fall of 2021, the DIU launched the Harmonious Rook prototype project to address the need for scalable, persistent awareness of positioning, navigation and timing (PNT) disruptions across the globe.
This September, the Harmonious Rook team will support the U.S. Army 1st Armored Division’s Command Post Exercise (CPX) at the National Training Center (NTC), Fort Irwin, California. The exercise is focused on large-scale combat operations (LSCO) and intended to stress the division headquarters’ ability to deploy to an austere location and command and control its units utilizing a synthetic training environment.
U.S. and multinational maritime forces participate in SEACAT 2021. (Photo: NTC)
Parallel to this training event is the 2nd Brigade, 1st Armored Division’s external validation exercise, also at NTC, in which the 2nd Brigade will be stressed and evaluated on its ability to deploy while contested and conduct LSCO exercises against a live opposing force.
Several DOD and civilian agencies are participating, including the National Air and Space Intelligence Center (NASIC) and the National Space Intelligence Center (NSIC). Multiple non-traditional vendors and non-governmental organizations are also supporting Harmonious Rook, from data delivery, to machine learning analytics, to visualization and contextualization.
Vendor Participation
Several Harmonious Rook vendors will participate in notable DOD and international exercises. In August 2022, prototyping companies will support the Southeast Asia Cooperation and Training (SEACAT) exercise, where more than 20 Indo-Pacific countries will train and collaborate on the common goal of maritime crises and illegal activities response.
During this multinational exercise, commercial firms will provide space-based geolocation reports and maritime analytical services, and integrate the insights into the U.S. Navy’s and Department of Transportation’s shared visualization platform, Seavision.
DIU is also working to explore the use of publicly available PNT data to draw insight from domestic GPS interference events.
“Mapping GPS disruptions and contextualizing patterns of behavior are key to mitigating the effects of degraded PNT as well as enabling safety of navigation under such conditions,” said Lt. Col. Nicholas Estep, Harmonious Rook program manager, USAF. “Instead of developing, building, and deploying hardware tailored for collection of navigation warfare operations, we are accessing currently available commercial data and analytics to address the need for PNT situational awareness. There are billions of GPS users and devices distributed across the world that may be adversely affected and turning the vulnerability into an advantage for discovery, classification and attribution of such malicious activity is a key aspect of this effort.”
“The Harmonious Rook project is a very promising new approach that complements traditional collection methodologies, as it will help our customers by sharing analysis due to the unclassified and commercial nature of the data,” said Scott Feairheller, senior analyst at NSIC.
“While the Army works diligently to acquire relevant equipment to assist in the real-time recognition and characterization of potential adversary interference, we must leverage non-organic, commercially available software and equipment, like Harmonious Rook, as a stopgap to increase awareness, seize digital key terrain and maximize lethality,” said Lt. Col. Patrick Jones of 1st Armored Division’s Space Support Element (SSE). During the exercise, capabilities will be tested to support intelligence, information operations, and command and control elements with commercial geospatial and navigation warfare awareness at the tactical level.
DIU’s Harmonious Rook program is not limited to the DOD and the malicious activity more commonly observed overseas and in combat environments. DIU is also working to explore the use of publicly available PNT data to draw insight from domestic GPS interference events, a mission with interest from the U.S. civil agencies.
With widespread users and subscribers that rely on PNT services, any intentional or unintentional disruption can lead to severe transportation, communication and financial implications. This highlights the importance of bringing both government and private-sector industries together to identify, attribute and mitigate GPS interference as quickly as possible.
Of the 60 exhibitors at the Institute of Navigation’s Joint Navigation Conference (JNC) in San Diego this year, 16 make inertial navigation systems (INS). Many of the other exhibitors integrate INS with GNSS receivers or make simulators to test those integrations. Several exhibitors make a variety of other navigation systems, using active and passive optical sensors, wheel encoders and RF systems that map beacons of opportunity. Only seven manufacturers of GNSS receivers were present.
That’s because the conference — which took place June 6-9 and focused on technical advances in positioning, navigation and timing (PNT) — was hosted by ION’s Military Division for the Departments of Defense (DOD) and Homeland Security. “From an operational perspective,” said the conference program, it focused on “advances in battlefield applications of GPS; critical strengths and weaknesses of field navigation devices; warfighter PNT requirements and solutions; and navigation warfare.” In other words, it was mostly on how to navigate in environments in which the use of GNSS is challenged or denied due to jamming.
The conference program told the story of the GNSS/PNT community’s interests and concerns. Several sessions were on complementary PNT using terrestrial RF signals of opportunity, IMUs, geophysical fields (including gravity and Earth’s magnetic field), celestial objects, ground vision and new commercial sources of space-based PNT, such as satellites in low Earth orbit (LEO).
Other environments in which reliance on GNSS is hard or impossible — such as urban canyons, deep inside buildings, underground and underwater — pose the same navigation challenges to both military and civilian applications. Likewise, jamming is a threat to both. Therefore, several sessions focused on critical infrastructure, demonstrating that the concerns about GNSS vulnerabilities are not just military ones.
Hence the presence among the exhibitors of three manufacturers of atomic clocks, which continue to shrink in size, weight, power and cost (SWaP-C) and are used to assure holdover — that is, the time period required to keep networks synchronized when their primary timing source, usually GNSS, is disrupted or temporarily unavailable. Networks affected include cellphone providers, radio and television broadcasters, financial networks, and the biggest network of all, the Internet.
The JNC “experienced record attendance in both conference participants and exhibitors, hosting more than 1,000 attendees,” Lisa Beaty, ION executive director, told me. She attributed the increase to “the importance of PNT in the nation’s critical infrastructure, current innovation, programmatic funding, and the desire by the DOD community to collaborate and reconvene.” She confidently anticipates additional growth next year.
I am equally confident that much of the cutting-edge technology on display at this conference will find its way into civilian applications in the next few years. Whether in war or in urban canyons, GNSS navigation faces some of the same challenges.
The May 4-5 meeting of the National Space-Based Positioning, Navigation and Timing Advisory Board focused on its mantra to “protect, toughen and augment” (PTA) GPS. The meeting included three great presentations that bear directly on the A of that mantra.
CAST
The electric grid used to be simpler: regional operators flowed power unidirectionally from stations to customers basing the load on past usage. Now, the grid is becoming a wide-area network — with regional inter-connects, multi-directional flows, and load based on real-time data and predictive analysis, requiring sensors time-synchronized within 1 microsecond from UTC. Yet, this critical infrastructure’s timing applications depend entirely on vulnerable GPS technology.
“If we can provide an authoritative, trusted synchronization source across the interconnected grid, its operators have a much better opportunity to understand the interdependencies and movement of power across their networks,” said Carter Christopher of Oak Ridge National Laboratory. He described the lab’s Center for Alternate Synchronization and Timing (CAST), which provides a redundant and resilient satellite-based service backed up by a network of terrestrial master clocks. CAST is precise, traceable and secure from jamming, spoofing, cyberattacks and physical attacks.
HARS
Attila Komjathy and Larry Romans of NASA’s Jet Propulsion Laboratory (JPL) proposed a GPS high-accuracy and resilience service (HARS) based on global differential GPS (GDGPS). It would provide corrections to GPS orbit and clock errors, and encrypted navigation data bits over the internet. It would match Galileo in accuracy, they said, pointing out that Galileo, QZSS and BeiDou provide high-accuracy services in their broadcast signals. HARS would improve the accuracy of consumer GPS receivers of 3–5 m to 1 m and help ensure that multi-constellation GNSS chips would continue to rely on GPS first.
HARS could be implemented by having commercial providers—such as Apple, Google and cellular carriers—distribute GDGPS corrections generated by JPL and supported by government partners. Private industry, Komjathy and Romans pointed out, provide service for RTK, centimeter and decimeter apps, but only governments (the U.S. Coast Guard’s DGPS service and Galileo’s HAS) provide corrections for about one-meter accuracy. Therefore, HARS would not compete with industry and would create additional opportunities for it to create value-added products.
αPNT
David Castiel and Cyrus Langroudi, of Virtual Geosatellite LLC, proposed αPNT, a virtual geostationary satellite system with elliptical orbits that would provide active PNT in a distributed architecture integrated with a blockchain. The system, they said, would be able to provide very accurate geographical position, precise timing and guidance with a minimum number of satellites on the horizon. It would rely on two-way links between transceivers and satellites to protect against jamming or spoofing.
While GPS’s success makes it a critical and ubiquitous infrastructure, its vulnerabilities require and stimulate exciting new R&D. Stay tuned.
ION is now accepting abstracts for the co-located 2023 International Technical Meeting (ITM) and Precise Time and Time Interval (PTTI) Systems and Applications Meeting. The co-located conferences will take place January 23-26, 2023 at the Hyatt Regency Long Beach, in Long Beach, California.
ION strongly encourages authors to present in-person in Long Beach. Authors will be given the option at the point of abstract submission to submit for “in-person presentation with video presentation for remote viewers” or “virtual presentation only.”
The Precise Time and Time Interval Systems and Applications (PTTI) meeting is an annual conference sponsored by ION with a technical program designed to disseminate and coordinate PTTI information at the user level, review present and future PTTI requirements, inform government and industry engineers, technicians, and managers of precise time and frequency technology and its problems, and provide an opportunity for an active exchange of new technology associated with PTTI.
ION’s winter meeting, the International Technical Meeting (ITM), is a more intimate conference with a technical program related to positioning, navigation and timing and includes the ION Fellows and Annual Awards presentations.
Spirent is one of only 226 organizations in the United Kingdom to be recognized with the Queen’s Award, which acknowledges the company’s excellence in international trade.
Spirent is headquartered in the UK, with its positioning business in Paignton, Devon, developing and manufacturing positioning, navigation and timing (PNT) test solutions. It also has a research and development facility in Daventry, Northamptonshire.
“As reliance on PNT technology continues to grow, our positioning technology business is the trusted partner of the world’s foremost PNT developers, delivering maximum performance without compromise through our dedicated test and validation solutions,” said Martin Foulger, general manager, Spirent Positioning. “We are honored to receive the prestigious Queen’s Award accolade, which is testament to the hard work of our employees in enabling us to achieve such tremendous success worldwide.”
Powered by its international trade, its exports outside of the UK represent a significant proportion of its business, serving a global customer base across five continents and more than 40 countries. Its technology has represented the global gold standard for commercial and government research and development facilities since the inception of GPS.
Its core business is the simulation of GNSS signals in laboratories for the development of applications used in advanced aircraft, chipsets, satellites, smartphones, cars, autonomous systems, marine vessels and defense systems, as well as the navigation systems themselves.
“Market leaders who are developing PNT applications have placed their trust in our test solutions for decades due to our unrivaled performance, realism and reliability,” said Foulger. “Furthermore, Spirent expertise is directly enabling and driving innovation in connected and autonomous vehicles and machine learning, as well as helping to make the world more sustainable through working closely with fields such as smart cities and precision agriculture.”
Now in its 56th year, the Queen’s Award are the most prestigious awards for businesses in the UK and a globally recognized royal seal of approval for companies. As a winner of the award, Spirent is permitted to display the esteemed Queen’s Awards Emblem for the next five years.
An expert has warned the government of the United Kingdom that the lack of an alternative to Galileo threatens to put critical infrastructure at risk, according to a report in Daily Express.
Andy Proctor, formerly with the satellite and positioning, navigation and timing (PNT) cabinet office, submitted evidence of his concerns to the UK’s ministers.
“Our critical infrastructure is at risk from the loss of PNT, space-based or otherwise,” he wrote. “We are currently critically dependent upon GPS; the loss of which will have a major impact in capability and economically.”
Proctor is director of Rethink PNT, a consultancy firm.
He pointed out that the government disinvested in the eLoran terrestrial system that could have provided a backup, although this is slowly reversing.
“For 20 or so years there have been calls for action, yet the current status of inaction regarding the PNT strategy puts our systems at increasing risk, especially given the clear and present electronic-warfare systems being used in Europe today,” Proctor wrote.
Britain was removed from the Galileo project following Brexit, and has since been looking for an alternative PNT system.
More than 100 experiments will be conducted with the Navigation Technology Satellite-3 (NTS-3), set to launch next year, according to a U.S. Air Force official and reported by FedScoop.
“We’re really excited to push the state of the art with more than 100 experiments on this little [NTS-3] spacecraft and we’re looking at ways that we can solve warfighters’ problems in the contested environment,” Maj. Gen. Heather Pringle, commander of AFRL, told reporters April 6 at the 37th Space Symposium in Colorado Springs.
Maj. Gen. Heather Pringle
Set to launch in 2023, NTS-3 is designed to push the boundary of today’s position, navigation and timing (PNT) technology to pave the way for a more flexible, robust, and resilient architecture for satellite navigation technology.
NTS-3 is a product of the Air Force Research Laboratory (AFRL) and industry, designed to test advanced techniques and technologies to detect and mitigate interference to PNT capabilities and increase system resiliency for military, civil, and commercial users.
Unlike the GPS medium-Earth-orbit satellites, NTS-3 will operate for one year in geosynchronous Earth orbit. Ultimately, NTS-3 will identify key aspects for new GPS receivers that incorporate multiple signals and readily adapt to warfighter needs.
The NTS-3 experiments will also involve ground equipment and terminals such as command and control stations and software-defined radios. Specific improvements to the ground segment will enable experimentation with automated “lights-out” operations, control station failover, and near-real time environment sensing and generation of error correction and tailored waveforms. Onboard systems will monitor clock accuracy and orbit parameters to mitigate errors and notify the user.
NTS-3 will test a new digital signal generator that can be reprogrammed on-orbit, enabling it to broadcast new signals, improve performance by avoiding and defeating interference, and adding signatures to counter spoofing.
AFRL also will explore antenna configurations to provide Earth coverage and steerable regional beams in multiple frequencies and signal codes. The NTS-3 satellite will be equipped with 110 antennas to help counter attempted GPS jamming.
Ultimately, NTS-3 is expected to provide users with enhanced signal stability, availability, integrity and accuracy.
L3Harris plans to deliver NTS-3 later this year. The company is assembling the satellite at its Palm Bay facility near Cape Canaveral, Florida. The plant was expanded in 2021 to accommodate the NTS-3 program.
the former Loran-C transmission antenna at Værlandet, Norway. (Photo: UrsaNav)
By Alan Grant and Dana Goward
In my “First Fix” editorial in the January 2022 issue of this magazine, I listed 10 questions about eLoran I had received from a PNT expert in response to an article about eLoran I wrote for the November 2022 issue. I encouraged eLoran proponents to address these questions. Two well-known authorities, neither of whom have a financial interest in the technology, stepped forward to help. Below, again, are my 10 questions about eLoran and their answers.
Alan Grant is head of Research and Development for the General Lighthouse Authorities of the United Kingdom and Ireland (GLA). He is an expert in radionavigation systems and leads the team that established the U.K.’s eLoran system, which operated from 2007 to December 31, 2015 in support of maritime users.
Dana A. Goward is president of the Resilient Navigation and Timing Foundation and a retired U.S. Coast Guard Captain. He also served in the federal Senior Executive Service as the maritime navigation authority for the United States. He has decades of experience with navigation policy and leading government policy and programs.
— Matteo Luccio, Editor-in-Chief
Accuracy specifics. While my November article stated that eLoran would have a two-dimensional accuracy of “better than 20 meters, and in many cases, better than 10 meters,” is that RMS, 95%, or some other statistic?
AG: Like any radionavigation system, the achievable accuracy will depend on several aspects, including the user’s location with respect to the broadcast stations and how error sources are modelled. The GLA eLoran service, when in operation in 2015, provided positional accuracy in the order of 8-10m (95%) to seven ports on the east coast of the UK. These ports had local reference stations to help manage temporal errors and the ports had been mapped to correct for additional secondary factors (ASF).i
DG: Others have reported greater accuracies using differential corrections.
Performance standard. GPS provides a commitment to users in a published performance standard. What specific measures of positioning accuracy, integrity and continuity would you recommend the proposed eLoran system be committed to provide (using the architecture described in the answer to Question 6)?
AG: The target performance would need to be tied to the target use cases to ensure the appropriate requirements are met. IALA provides guidance in this area for maritime services with general maritime requirements provided by the IMO within resolutions A.1046 and A.915.
Coverage. Would you recommend this eLoran positioning performance hold for the entire United States (including Alaska, Hawaii, Puerto Rico and other territories), only for the “lower 48” states, or only parts of these 48 states?
DG: The primary goal of any effort to complement and back up GPS/GNSS would be to make the nation and its citizens safer in at least two ways. First, to provide an alternative PNT source or sources in the event that signals from space were not available for any reason. Second to make GPS satellites and signals (and therefore the nation) safer by “taking the bullseye off GPS.” Having one or more alternatives will greatly reduce incentives for malicious disruption. To achieve these two goals the alternatives must be widely available and easily accessed. How widely available and easily accessed the United States or any other country wants to make such systems is a policy decision.
Current users. By number of users, the predominant common current civil uses of GNSS for positioning are consumer devices (mostly cellphones). By contribution to the U.S. economy, the predominant uses are high-precision applications. For what fraction of these uses would eLoran positioning be adequate? Could an eLoran receiver and antenna fit in today’s consumer devices?
DG: Lots of presumptions and assumptions in this question. Several overall thoughts, though. First, determining users’ real requirements can sometimes be difficult. I have a nice new full-size sedan. So, I think that is my requirement even though I could get to work almost as quickly and much less expensively if I owned a used compact car or caught the bus at the corner.
Second, GPS/GNSS will, hopefully, always be the primary source. The questions then are 1) how accurate can eLoran positioning become with additional work, and 2) how accurate does a fallback system need to be?
Durk van Willigen of Reelelektronika b.v. displays a combined GPS, GLONASS and eLoran receiver at the 2017 Munich Satellite Navigation Summit. (Photo: Reelelektronika)
Finally, as to equipment size, I recall seeing a photo of the first GPS receiver sitting on a pallet with two chairs for operators. Today, receivers are made at chip scale. Huge reductions in C-SWAP have been the growth arc for all kinds of technologies as they are implemented more and more widely.
In 2017 the Dutch company Reelektronika showcased a combination eLoran, Chayka, GNSS receiver that was only 6 cm long. This was achieved without a whole lot of investment in research and development. Who knows how low C-SWAP for eLoran receivers will go?
Future uses. Emerging civil uses of GPS for positioning include autonomous ground and air vehicles, navigation to space and in space, and lane-accurate car navigation. Which of these could be served by eLoran?
AG: The overall concept of having a mix of dissimilar position sources remains sensible for all modes. GNSS is expected to remain the primary means of position determination, with different use cases selecting different complementary systems based on their needs. eLoran may support some use cases but may not be the answer for all.
DG: Many believe GPS alone is not sufficient to serve some of the applications cited. This is the basis for language in both the European Radionavigation Plan and a U.S. Presidential Executive Order cautioning against over-reliance on GNSS. Perhaps GPS and eLoran together might be deemed sufficient. Or, perhaps a more diverse and resilient PNT architecture will give rise to additional applications such as precise positioning from 5G that will be sufficient.
Architecture. To maintain accuracy during a prolonged GPS outage, eLoran would require reference stations to calibrate time-varying propagation errors, as well as a certain number of transmitters for good nationwide geometry and for redundancy, ensuring service even if a transmitter is attacked or is taken off-line for maintenance. What architecture would you recommend to achieve this?
AG: The MarRINav projectconsidered a similar question for the UK and the project’s approach could be employed to consider this question for the United States.iv
DG: A good starting point for the United States might be the sites used by the shuttered Loran-C system. The federal government still retains custody of most of them. Also, considerable thought has been given to the questions of eLoran reference stations and integrity in the United States. PNT expert Mitch Narins, formerly of the FAA and now Strategic Synergies, advises that much of this work has been done. The FAA and Coast Guard conducted a study to deploy eLoran in the United States to support aviation non-precision approach, maritime harbor entrance and approach, and precise time and frequency users. The proposed architecture supported aviation’s demanding integrity requirement (1×10-7), maritime’s demanding accuracy requirement (8-20m), and time and frequency users’ precision requirements (100 ns/Stratum 1).
7. Infrastructure cost. What would be the cost of installing the required transmitters, power supplies, reference stations, communication links and control system for the architecture described in the answer to Question 6? Can you reference a recent and independent estimate? To a ballpark figure, what cost fixed-price contract would you accept to implement it? Similarly, what would be the annual costs for operating and maintaining this infrastructure?
AG: The MarRINav project produced a cost-benefit analysis report that addresses some of these questions, albeit aligned to the approach proposed for the UK. The documents are open source and available on the MarRINav website.
DG: To quote President Kennedy, “There are costs and risks to a program of action, but they are far less than the long-range risks and costs of comfortable inaction.”I agree with Dr. Grant that the capital costs in MarRINav are roughly transferrable to the United States. As another data point, the 2010 operating cost for Loran-C in the United States was about $36M/year. That number included several hundred employees, though. Plans to automate the system projected reducing annual costs to $15M/year in 2010 dollars.
Impact. eLoran transmitters are large and high-power. Providing positioning across the United States could require building some of them from scratch or significantly reconstructing old Loran sites. What issues — such as environmental, aviation safety and security — would this raise, and how would you recommend they be addressed?
DG: These issues would be dealt with the same way they are for any construction project. eLoran transmission sites are essentially the same as commercial AM radio stations. Reusing sites still owned by the government could make the process even easier. Compared to the cost and difficulty of putting PNT assets in orbit, these challenges should be relatively easy to overcome.
Receivers. Assuming all the above were achieved, it would accomplish nothing unless eLoran receivers were widely purchased, installed and used. How much would that cost? Who would pay? Should we assume that “if we build it, they will come”?
AG: This is a valid concern and has different answers depending on the planned use case and the level of national/international standardization required. Within the maritime sector, the IMO has approved a multi-system receiver performance standard that supports the use of all GNSS and terrestrial systems within one device, rather than having a separate eLoran receiver.
DG: I completely agree — adoption and use are absolutely key. Fortunately, government leaders have a wide variety of levers to influence adoption and use. These range from education and encouragement to regulation, legislation, and subsidies.
Alternatives. Given the widespread development of other positioning technologies over the past decade, much has changed since the earlier recommendations for eLoran. How do we know that eLoran is the right investment — or even a needed part of the solution or needed system in a system of systems — for the future of U.S. PNT?
AG: The MarRINav project researched and compiled details of different positioning, navigation and timing technologies supporting maritime navigation, within Deliverable D4. The recommended system-of-systems approach recognized that there was no one-fit-all solution, rather it sought to allow for a scalable solution that reflects users moving from location to location and between systems. It considered global, regional and local solutions, recognizing the cost vs. usable coverage tradeoff for each. The proposed solution of GNSS, supported by eLoran in combination with VDES R-Mode and radar absolute positioning, was deemed as the most appropriate mix for the UK, given geographical and political constraints. The approach can be ported to investigate the appropriate options for the United States.
DG: The U.S. Department of Transportation’s January 2021 report to Congress has findings similar to those in MarRINav. It described a system of systems that included fiber, satellites and terrestrial broadcast. The department subsequently said that a critical factor for a terrestrial broadcast system would be the coverage area per unit of required infrastructure. Of the systems discussed, eLoran met this criterion best. This recent finding is consistent with numerous other government reports, two previous government announcements that it would build eLoran, two recommendations from the President’s National Space-based Positioning, Navigation, and Timing Advisory Board and the technology’s on-going use around the world. Likely someday there will be something to replace GPS and other legacy technologies. We must work with the combination of technologies we have now until that day arrives.
Common Threats
Common threats to GNSS and eLoran could include the following:
1. Cyber attacks. Given that GPS’s OCX is said to be the most cybersecure system built by the U.S. Department of Defense, how would eLoran’s control system be even more cybersecure than OCX, to avoid a common cyber-vulnerability?
AG: Cybersecurity is a key concern and one that any navigation and safety of life system must consider. I will leave manufacturers of each system to comment on how secure they are. However, if we consider signal interference and data manipulation within this category, then using a stronger signal at a different frequency to GNSS provides some protection against jamming. While any radio signal can be jammed, the perpetrator would need more power and physically larger equipment to jam at lower frequencies.
DG: Yes, the security of control systems is very important and must be included in the design up front. Authentication and security of signals, and the cybersecurity of receivers must be as well. This is especially true for complementary systems for GPS since GPS signals are so open and vulnerable, and so many receivers are largely unprotected. We will have the opportunity to do better with a new system and avoid the huge expenses of OCX, the new GPS control system.
Additionally, let us not forget that cybersecurity is needed for much more than control systems. Signals and receivers need to be much more secure than civil GPS is right now. A new system, be it eLoran or another technology, will be able to build cybersecurity in from the beginning.
Physical attacks. Given concerns about possible physical attacks on GPS satellites, which move at multiple km/sec 20,000 km from Earth, would it not be easier to physically attack eLoran transmitters, which are stationary, terrestrial, in remote locations, and hundreds of feet tall and require massive power sources?
AG: We should not lose sight that any ground infrastructure can be attacked, regardless of whether it is a satellite uplink station or part of a terrestrial communications or positioning system. Careful selection of the transmitter location, along with suitable site security options should help deter the attack and mitigate the impact where possible.
DG: Every physical asset and every signal is vulnerable to some degree to attack by a host of malicious actors, and damage by a variety of natural occurrences. The key to resilience and making PNT sources less attractive targets is to have diverse sources with the smallest number of common failure modes.
Space weather. GPS is potentially vulnerable to severe space weather that could damage satellites or temporarily hinder signal propagation from space to Earth. However, severe space weather could also damage the power grid upon which megawatt eLoran transmitters rely. How would eLoran service be protected from the effects of severe space weather, such as a Carrington Event?
AG: Space weather has the potential to affect all radio broadcasts. Depending on the type of event it can affect performance several different ways, including ionospheric scintillation, applying forces to satellites or disrupting power networks. The aim is to use systems where the underlying failure modes are as different as possible. Using a combination of satellite and terrestrial signals, at different frequencies, with local power generation where possible can help mitigate the impact. Whether it’s possible to mitigate all the implications of a Carrington type event is not clear and perhaps one for the experts.
DG: With the available warnings about solar events, it is conceivable that both GNSS and terrestrial systems could be powered off or otherwise secured for such an event to minimize damage. A new-build terrestrial system could also be constructed with surviving a Carrington Event in mind. And, of course, terrestrial systems will be easier to access, repair, and replace than those in space. As for other possible issues with the power grid, generators, uninterruptable power supplies, and other backup methods can easily be installed. Before 2010, several U.S. Loran-C transmitters were in such remote locations, they never had grid power and were always powered by generators.
Given that space is increasingly a congested and contested arena, should the U.S. government establish a new office to manage both space-based and terrestrial-based PNT systems?
John Fischer
“The U.S. government already has the National Executive Committee for Space-Based PNT (see gps.gov), which coordinates policy among all the branches of government. There is also a PNT Advisory Board, which includes some international members to inform the committee, and a National Coordination Office to execute the policies. This is in addition to the new U.S. military’s Space Command under which GPS operates. So, space-based issues are being addressed, but maybe more could be done to coordinate terrestrial-based PNT systems with space-based ones.” — John Fischer
Ellen Hall
“As new technology advances, government, along with its policies and laws, struggles to keep pace. This was certainly true of the internet and cybercrime. This is also true of terrestrial-based PNT, where new technology emerges in areas not currently covered. Policy gaps and overlapping technologies need to be addressed and coordinated. It certainly seems that this would be one of those areas that could benefit from oversight. Space-based PNT is currently addressed by the National Executive Committee for Space-Based PNT, among others.” — Ellen Hall
Bernard Gruber
“The threat to U.S. space-borne assets and the signals they generate is very real. Both commercial and military users of GPS continue to seek independent alternatives to current PNT systems that are diverse and robust. The National Coordination Office supports the National Executive Committee (NEC) for Space-Based PNT. I believe the role of the NEC should be broadened to include terrestrial and alternative PNT as a first step to charter/secure a new or expanded program office.” — Bernard Gruber
Editorial Advisory Board
Tony Agresta, Nearmap
Miguel Amor, Hexagon Positioning Intelligence
Thibault Bonnevie, SBG Systems
Alison Brown, NAVSYS Corporation
Ismael Colomina, GeoNumerics
Clem Driscoll, C.J. Driscoll & Associates
John Fischer, Orolia
Bernard Gruber, Northrop Grumman
Ellen Hall, Spirent Federal Systems
Jules McNeff, Overlook Systems Technologies
Terry Moore, University of Nottingham
Mitch Narins, Consultant
Bradford W. Parkinson, Stanford Center for Position, Navigation and Time
The appropriation for fiscal year 2022 enacted this month included $15M for “Position navigation and timing [PNT] technologies and global positioning system [GPS] backup” in the Department of Transportation (DOT) budget. At first glance, this might seem like a small but important step toward establishment of the system or systems President Bush mandated in 2004, the Obama administration promised in 2015, and called for by law in 2018.
Make no mistake, having the issue mentioned in the act is a very positive step. Unfortunately, a careful read of the report that came with the appropriations act shows the funds are not for solving, but for continuing to admire, the problem.
Here’s what the appropriation report says (in italics) and what it means. This is based on our reading of the text and conversations with hill insiders who said they had a tough battle with the administration to get any funding or mention of PNT or “GPS backup” in the budget at all.
“The agreement provides $15,000,000 to establish a program…” – This is not really a lot of funding for any federal effort. It is enough to hire several people, set up an office, and maybe do a few studies.
Notice that the appropriation language talks about “[leading] to wide adoption of multiple technologies.” It makes no mention of establishing any systems or signals.
Theoretically, this might be done by following the path in the Trump administration’s 2020 Executive Order on responsible use of PNT. The order addresses critical infrastructure and encourages such users to protect themselves with alternate PNT services they find on their own.
DOT might try this with all users to achieve “wide adoption,” though there are many obstacles. Principal among these is that GPS is free while commercial services are not. Providers of alternative PNT services have long recognized that it is impossible for them to compete with free GPS and argued that the government needs to be the customer.
“…Funding will enable, among other things…” An interesting turn of phrase that seems to say, ‘you must do all of this, but if you have any money left over you can do other things.’ This is pretty much a throw-away phrase since, with this worklist, they won’t have money left over for anything else. In fact, they will probably come up short.
“…the development of safety-critical PNT requirements and standards…” In other words, study the problem some more. Developing requirements and standards is important, but it doesn’t provide anything for the United States to use when Putin jams GPS or there is a huge solar storm.
“…vulnerability and performance testing…” Again, more study and little to no progress implementing solutions.
“…certification protocols for safety-critical functions”… Still more study.
“…the procurement of services as deemed appropriate by the Department…” Some might see this as a ray of hope. It could, conceivably, allow DOT to contract for PNT signals from space, fiber, or terrestrial broadcast and move toward establishing one or more systems. Unfortunately, $15M isn’t much for such an effort, even if DOT didn’t have to also create an office and do all the required studies and standards. In this context “services” almost certainly means contracted staff to help with administration and hiring think tanks.
“…and user adoption models in order to facilitate the responsible use of resilient PNT services to meet Federal requirements for widespread adoption.”
Since there are no “federal requirements for widespread adoption” to meet, this seems like another throwaway phrase that someone thought sounded actiony and proactive.
Additionally, we are not sure what a “user adoption model” is.
The best translation we can come up with is “DOT must figure out how to get Americans to adopt alternate PNT services that are either expensive or haven’t been invented yet. All in the absence of a government mandate for them to do so.”
Most in the PNT community have long recognized the need to “get the bullseye off of GPS” by making it a less attractive target, while at the same time protecting the nation against a wide variety of threats to satellites and signals. For them, the language in this year’s appropriation bill can be discouraging.
Yet there is some reason for hope. At least the problem was discussed in the bill, and some money was put toward it, regardless of how flawed the underlying assumptions and mandated actions might be.
Maybe we should all take comfort in the old Hollywood maxim – “It doesn’t matter what they say as long as they are still talking about you.” Let’s all keep the conversation going.
Abstracts for the ION GNSS+ 2022 show, “GNSS + Other Sensors in Today’s Marketplace,” are due March 4.
The ION GNSS+ conference will take place September 19-23 at the Hyatt Regency Denver at Colorado Convention Center in Denver. The show will also include a virtual option.
The 2022 conference will bring together international leaders in GNSS and related positioning, navigation and timing fields to present new research, introduce new technologies, discuss current policy, demonstrate products and exchange ideas.
The two tracks covered during the conference will be commercial and policy tracks and research tracks.
The commercial and policy tracks will include high performance and safety critical applications, status and future trends in GNSS, and mass market and commercial applications. The research tracks will include multisensor and autonomous navigation, algorithms and methods, and advanced GNSS technologies.
