In a recently released paper, the respected analytics firm London Economics determined that the presence of backup systems at the Denver and Dallas Fort Worth airports prevented any noticeable impacts on air travel despite each having experienced a disruption of GPS signals for 24 hours or more. By contrast, recent GPS interference at an airport without a backup system caused scheduled air service to be canceled until an alternative to GPS was established.
Also important to the lack of impact at Denver and Dallas was that the signals interfering with GPS, with a few minor exceptions, only impacted aircraft in the air.
GPS is essential for the safe and efficient movement of aircraft and support vehicles on the ground at airports, as well as the transport of crews, passengers, supplies, and cargo to and from airports, communication systems, and numerous other services.
Backups needed for both air and ground
Previous work by London Economics has shown that disruption of GPS for these ground functions would likely cause numerous flight delays and cancellations. Delays in the arrival of flight crews, passengers and supplies, for example, would quickly upset flight schedules. If this happened at a major airport, such as Denver or Dallas Fort Worth, disruptions could ripple through the entire air transport system. Wide-spread delays, cancellations and schedule adjustments would bog down air travel across the nation, if not the world.
The incident in Denver was caused by an accidental transmission from a government installation on Jan. 21. 2022. It impacted aircraft within approximately 50 nautical miles of the airport and lasted 33 hours before the source was identified and turned off.
The Dallas incident began on Oct. 17, 2022, and affected aircraft within about 110 nautical miles. It continued for 24 hours before ending on its own. The source has never been identified.
Reducing aviation backups may be a bad idea
In addition to recognizing the value of terrestrial navigation systems for aviation, the London Economics paper cautions about moves in the United States and Europe to “rationalize” these systems by reducing their number. In the event of longer or widespread GPS disruptions, the impact of an insufficient number of terrestrial systems could be significant. The cancellation of air service to an airport in Estonia because of chronic GPS jamming is used in the paper as a cautionary tale.
Instead of reducing the number of old backup systems, London Economics suggests policymakers consider establishing more widely available sources of terrestrial PNT. Taking a fresh look might identify alternative PNT sources for aviation that could also be used by other critical infrastructures. Perhaps even in consumer applications as well.
U.S. government representatives were approached for consultation and comment for this paper and expressed their willingness to participate. Unfortunately, they were unable to obtain permission to do so.
London Economics’ work on this effort was commissioned by the Resilient Navigation and Timing Foundation.
The paper “Aviation GPS Incidents Show Importance of Backup Systems. Policy Makers Take Note.” can be accessed from the foundation’s online library here.
Join the Resilient Navigation and Timing Foundation for a reception with the President’s National Space-based Positioning, Navigation, and Timing Advisory Board on April 23 at The Antlers Hotel in Colorado Springs. The event begins at 6:00 PM. General David Thompson, U.S. Space Force (retired) will discuss his experience as the first Vice Chief of Space Operations, the state of GPS, and the future of PNT.
For more information and to RSVP, contact [email protected] by April 17.
On December 5, in Houston, at a reception hosted by the Resilient Navigation and Timing Foundation to celebrate GPS’ 50th anniversary, I had the honor of publicly interviewing Dr. Bradford Parkinson for 45 minutes. When I asked him how GPS today differs from the design that emerged from the Lonely Halls meeting he chaired 50 years ago this past September, he replied, proudly, that “there is no fundamental difference.” Recently, he recalled, he pulled out for the first time in 20 years a handheld Trimble EnsignGPS — “It was one of those little devices that got shipped to the Iraq War,” he noted —, cleaned its contacts, changed its batteries, turned it on, and was immediately able to navigate. “The point of the story,” Parkinson said, “is that evidently it still works.”
When I asked him what he considered to be the most significant impact of GPS on society, he said it was “also probably the most perilous: kids today just take it for granted. They know where they are.”
Taking GPS for granted, however, is not limited to kids today. It is a pervasive attitude throughout our society, including sectors of the federal government that ought to know better. That is why a recurrent theme throughout the 29th meeting of the National Space-Based Positioning, Navigation, and Timing Advisory Board, on December 6 and 7, which I attended, was raising the alarm about the fact that GPS is falling behind Galileo and BeiDou.
“We must attack this mindset [that GPS is] the Gold Standard and everything is OK. It is not OK,” said Admiral Thad Allan, a former Commandant of the U.S. Coast Guard, who chairs the PNT Advisory Board. Perhaps, he suggested, it is time to declare that GPS is only meeting “the Pewter Standard” for GNSS. “That will get the attention of somebody who does not understand this.”
Parkinson, in emphasizing the urgency of the problem, said that he currently counts eight areas in which GPS is falling behind its GNSS counterparts, including:
L5, the go-to signal particularly for civilian aviation, is not yet activated and will not be until the next three satellites are activated, which will likely not happen for at least another year.
The Next Generation Operational Control System (OCX), the future version of the GPS control segment, is not yet operational.
GPS does not have a satellite-based high-accuracy service (HAS). On this, he said, “Everyone is moving out except us.”
GPS lacks anti-spoofing authentication, which Galileo has.
Additionally, “every one of these things has an enormous lead time,” Parkinson warned.
“As an advisory group, we are only as effective as the willingness of the system that we are advising to act on what we say,” Allan pointed out. The Advisory Board spent the final portion of its meeting discussing how to structure the agenda and products of its next couple of meetings to get these issues with GPS the attention they deserve and require. Stay tuned.
Dana Goward, President of the Resilient Navigation and Timing Foundation, introducing Brad Parkinson and Matteo Luccio, GPS World EIC. (Image: RNTF)
On December 5, in Houston, Texas, at a gala event to celebrate the 50th anniversary of GPS hosted by the Resilient Navigation and Timing Foundation, Matteo Luccio, Editor-in-Chief of GPS World, interviewed Brad Parkinson.
Here are two excerpts from the interview:
How does GPS today differ from the design that came out of the Lonely Halls meeting 50 years ago this past September?
Well, I’m very proud of what happened because, to my knowledge, there is no fundamental difference. Basically, that fundamental design has held up. … As a matter of fact, I still have one of the old Trimble handhelds, it’s called an EnsignGPS. It was one of those little devices that got shipped to the Iraq War. The other day, I pulled it out, batteries were kind of crummy, I got those squared away and went out, sure enough and navigated. I probably hadn’t pulled it out in at least 20 years. The point of the story is that evidently it still works.
What do you consider the most significant impact of GPS on society?
Well, the most significant impact is also probably the most perilous: kids today just take it for granted. They know where they are.
“Seen & Heard” is a monthly feature of GPS World magazine, traveling the world to capture interesting and unusual news stories involving the GNSS/PNT industry.
UK begins UAV deliveries
Image: Screenshot of video by BBC
Royal Mail and UAV company Skyports have launched the Orkney I-Port operation to distribute letters and packages between the Orkney Islands, Scotland, reported the BBC. In partnership with the council’s harbor authority and Scottish airline Loganair, mail will be transported from Royal Mail’s Kirkwall delivery office to the city of Stromness in Orkney. UAVs will then carry items to the islands of Graemsay and Hoy, where postal staff will complete the delivery routes. The UAV service will initially operate for three months and may continue on a permanent basis under existing regulatory frameworks due to Orkney’s unique landscape and the proximity of the islands to one another. The UAV service aims to improve service levels and delivery times to Graemsay and Hoy, as weather and geography typically cause disruption to delivery services. The use of UAVs to deliver mail also may bring significant safety improvements by ensuring that postal workers can deliver between ports without risk.
GNSS is taking a hike, literally
Image: Aleksandar Georgiev/iStock/Getty Images Plus/Getty Images
In July, officials in Taichung City, Taiwan, launched a GNSS-based app to aid lost hikers and to mitigate risk associated with outdoor activities in the area’s mountainous region, reported Tapei Times. The app was developed by the Taichung Fire Bureau in response to a surge in outdoor activities after the COVID-19 pandemic restrictions were lifted and, subsequently, an increase in medical emergencies linked to mountain activities. Wi-Fi towers have been built at major trailheads such as Toukeshan, Anmashan, Fushoushan and Snow Mountain to supplement the app as well as to help facilitate UAV deployment to find lost hikers.
In a biological preserve in Mexico’s Campeche state, a team of archaeologists have documented pyramids, palaces, a ball court and other remains of an ancient city they call Ocomtún, reported The New York Times. Archeologists surveyed the site for six weeks in May and June, finding 50-foot-tall structures resembling pyramids, as well as pottery and Mayan engravings they believe date to between 600 AD and 900 AD. The team determined the city was likely abandoned more than 1,000 years ago. Surveying of the area has been revolutionized over the past decade by lidar — allowing researchers to survey densely forested areas that are difficult to explore on foot. Archeologists were able to use airborne lasers to pierce through dense vegetation and reveal the ancient structures and human-modified landscapes beneath.
More than 350 UAVs were lost during a practice light display show in Melbourne, Australia, on July 14, ahead of a scheduled performance for the opening of the women’s World Cup. The UAVs appeared to stop mid-show and plummet into the Yarra River. Divers have since fished out hundreds of the UAVs. According to the Resilient Navigation and Timing Foundation, the likely cause of the mass-crash was interference with GPS signals.
More than 350 UAVs were lost during a practice light display show in Melbourne, Australia, on July 14, ahead of a scheduled performance for the opening of the women’s World Cup.
The UAVs appeared to stop mid-show and plummet into the Yarra River. Divers have since fished out hundreds of the UAVs.
According to the Resilient Navigation and Timing Foundation, the likely cause of the mass-crash was caused by interference with GPS signals. This incident shows that having multiple and robust navigation sources is important for safe UAV operation.
The same 91 signers also sent an identical letter to President Biden.
April 24, 2023
Dear Senators and Members of Congress:
Last year, many of the undersigned wrote in reflection of the unprecedented opposition to the Federal Communications Commission’s (FCC’s) Ligado Order(1) across the vast federal and commercial user base of Global Positioning System (GPS), satellite communications and weather forecasting services. Three years after adoption of the Order, as eight petitions for reconsideration remain pending, (2) we again urge you to work together with the FCC to stay and ultimately set aside the Order. (3) Critically, this is now necessitated by the crucial, previously unavailable information that was produced at the direction of Congress: the independent technical review undertaken by the National Academies of Sciences, Engineering, and Medicine (NAS) (4) analyzing the potential interference issues related to the Ligado Order.
We greatly appreciate your administration’s opposition to the Ligado Order and commitment that the National Telecommunications and Information Administration (NTIA), on behalf of the executive branch, will continue to actively pursue its petition for reconsideration of the Order. (5) As you know, the pending petitions for reconsideration convincingly demonstrate that the Ligado Order is legally and factually deficient. In the pending petitions, parties showed that the Ligado Order is fundamentally flawed, incompatible with the FCC’s rules and inadequate in protecting incumbent services from the harmful interference from Ligado’s proposed operations. This substantial documentation, among many other concerns from federal and commercial users, resulted in Congress enacting bipartisan legislation in consecutive years after the FCC’s adoption of the Ligado Order, mandating NAS’s independent technical review and requiring the Department of Defense (DoD) to brief federal representatives across the government “at the highest level of classification” on the potential for widespread harm from Ligado’s proposed terrestrial operations. (6) On this basis alone, the FCC should stay the Order in an acknowledgement that it clearly did not account for the full, real-world risk of harm associated with a nationwide terrestrial deployment in the L-band.
While the pending petitions have a strong likelihood of success on their own merits, the FCC’s rules and the public interest now require the FCC to reconsider the Order in response to the extensive analysis in the NAS Report. (7) This new, previously unavailable information presented in the Congressionally-mandated independent technical review confirms that Ligado’s proposed terrestrial operations would cause harmful interference (8) at significant ranges to incumbent L-band services across a broad range of deployment scenarios. This is consistent with the well-supported and robustly documented analyses and determinations of the federal government, (9) including fourteen federal agencies and departments, (10) and commercial parties (11) alike. Importantly, as concisely stated by DoD and detailed in the NAS Report, “[t]he terrestrial network authorized by [the Ligado Order] will create unacceptable harmful interference for DoD missions. The mitigation techniques and other regulatory provision [sic] in [the Ligado Order] are insufficient to protect national security missions.”(12)
The unequivocal conclusions of the NAS Report constitute the exact type of previously unavailable information that the FCC’s rules (13) dictate must be addressed on reconsideration. Indeed, NTIA stated on behalf of the executive branch that the NAS Report “offers the [FCC] an important opportunity to reconsider Ligado’s Authorization.”(14) We therefore urge you to work with the FCC to address the harm from Ligado’s proposed terrestrial network to critical GPS, satellite communications, and weather forecasting services by staying the Order, addressing the previously unavailable information contained in the NAS Report, and resolving the pending petitions for reconsideration.
Sincerely,
AccuWeather, Inc.
Aerospace Industries Association
Agricultural Retailers Association
Airborne Public Safety Association
Aircraft Electronics Association
Aircraft Owners and Pilots Association
Airlines for America
Alabama Agricultural Aviation Association
ALERT Users Group
Allied Pilots Association
Air Line Pilots Association, International
American Geophysical Union
American Meteorological Society
American Rental Association
American Road & Transportation Builders Association
American Weather and Climate Industry Association
Arizona Agricultural Aviation Association
Arkansas Agricultural Aviation Association
Associated Equipment Distributors
Association for Uncrewed Vehicle Systems International
(1) Ligado Amendment to License Modification Applications, IBFS File Nos. SES-MOD-20151231-00981, SAT-MOD-20151231-00090, and SAT-MOD-20151231-00091, Order and Authorization, 35 FCC Rcd 3772 (2020) (“Ligado Order” or “Order”).
(2) More than twenty parties in total signed petitions for reconsideration of the Ligado Order and all of these petitions remain pending before the FCC. See Petitions for Reconsideration of the National Telecommunications and Information Administration; the Air Line Pilots Association, International; the American Road & Transportation Builders Association, the American Farm Bureau Federation, and the Association of Equipment Manufacturers; the Joint Aviation Petitioners; Iridium Communications Inc., Flyht Aerospace Solutions Ltd., Aireon LLC, and Skytrac Systems Ltd.; Lockheed Martin Corporation; Trimble Inc.; and the Resilient Navigation and Timing Foundation, IB Docket Nos. 11-109 & 12-340 (all filed on or about May 22, 2020). The ten “Joint Aviation Petitioners” consist of the Aerospace Industries Association, the Aircraft Owners and Pilots Association, Airlines for America, Aviation Spectrum Resources, Inc., the Cargo Airline Association, the General Aviation Manufacturers Association, the Helicopter Association International, the International Air Transport Association, the National Air Transportation Association and the National Business Aviation Association.
(3) The Commission should also not proceed with any companion rulemakings causing harmful interference to weather forecasting and hydrology services that could result in Ligado deployments, particularly in light of the analysis and recommendations presented in the “Spectrum Pipeline Reallocation 1675–1680 MHz Engineering Study (SPRES) Program Report. See Allocation and Service Rules for the 1675-1680 MHz Band, Notice of Proposed Rulemaking, 34 FCC Rcd 3352 (2019); U.S. Department of Commerce. National Oceanic and Atmospheric Administration. National Environmental Satellite Data Information Service. Spectrum Pipeline Reallocation 1675–1680 MHz Engineering Study (SPRES) Program Report. Silver Spring, MD: NESDIS, October 2020 (public release August 2022).
(4) National Academies of Sciences, Engineering, and Medicine, Analysis of Potential Interference Issues Related to FCC Order 20-48 (2022), https://doi.org/10.17226/26611 (“NAS Report”).
(5) Letter from Gina Raimondo, Secretary of Commerce, U.S. Dept. of Commerce, to The Honorable James M. Inhofe, ranking member, U.S. Senate Committee on Armed Services (June 22, 2021) (reiterating the NTIA’s position opposing the Ligado Order).
(6) William M. (Mac) Thornberry National Defense Authorization Act (“NDAA”) for Fiscal Year 2021, Pub. L. 116-283, 134 Stat. 4074 § 1663; NDAA for Fiscal Year 2022, Pub. L. 117-81, 135 Stat. 1541 § 1613.
(7) These statements are based on the publicly available portions of the NAS committee’s work. In addition, NAS prepared a classified annex, which further details the risks of Ligado’s proposed terrestrial network and additionally warrants FCC action.
(8) The term “harmful interference” is herein used to describe the results of the NAS Report. In turn, the undersigned believe the results of the NAS Report dictate that the FCC must reach the legal conclusion that Ligado’s operations would cause harmful interference under the FCC’s rules.
(9) See, e.g., National Telecommunications and Information Administration Reply to Ligado Networks LLC’s Opposition to Petitions for Reconsideration or Clarification, IB Docket Nos. 11-109 & 12-340, at 10 n.26 (filed June 8, 2020); U.S. Department of Transportation, Global Positioning System (GPS) Adjacent Band Compatibility Assessment, Final Report (Apr. 2018) (“DOT ABC Report”),
(10) See Memorandum from Thu Luu, Executive Agent for GPS, Department of the Air Force, to IRAC Chairman (Feb. 14, 2020).
(11) See, e.g., Letter from J. David Grossman, Executive Director, GPSIA, to Marlene H. Dortch, Secretary, FCC, IB Docket Nos. 11-109 et al., at 6 (Sept. 17, 2020); Letter from Bryan N. Tramont, Counsel to Iridium Communications Inc., to Marlene H. Dortch, Secretary, Federal Communications Commission, IB Docket Nos. 11-109 et al. (Jan. 19, 2022); Update to 2016 Technical Assessment of Ligado User Terminal Interference to Iridium attached to Iridium Communications Inc. et al., Petition for Reconsideration, IB Docket Nos. 11-109 et al. ( May 22, 2020).
(12) NAS Report at 6, 73.
(13) 47 C.F.R. § 1.106(c)(2).
(14)Press Release, NTIA, NTIA Statement on National Academies of Sciences Report (Sept. 9, 2022).
“Precautionary principle: The principle that the introduction of a new product or process whose ultimate effects are disputed or unknown should be resisted.” — Oxford Languages
Photo: U.S. Fish and Wildlife Service
The Arctic National Wildlife Refuge spans almost 20 million acres. It is home to a vast array of wildlife from tiny pollinating flies to giant grizzly and polar bears.
It also has oil. Lots of oil.
Getting that oil out of the ground and to market would create jobs and benefit commerce. It would also harm the environment. Some wildlife would suffer.
Many argue the long-term harms of drilling outweigh the short-term benefits. The Biden administration agrees and has banned drilling to protect the refuge’s environment and wildlife.
The administration has taken a similarly conservative approach to preserving the spectrum environment for satellites.
Like the previous administration, it has urged the Federal Communications Commission (FCC) to not allow Ligado Networks’ use of frequencies adjacent to spectrum assigned to GPS and Iridium Communications. The concern is that Ligado’s more powerful transmissions will harm some existing users.
A recent report by the National Academies of Sciences, Engineering and Medicine validated that concern. As is the case with many complex environmental issues, the total number of impacted individuals, and the total negative impact to the nation, are unknown. They may be unknowable.
As an independent agency, the FCC gets recommendations from, but does not report to, the administration. To date it has not been swayed by formal appeals from the executive branch, nor by those from numerous industry and non-profit groups, to rescind its decision allowing Ligado to operate.
Like other agencies making environmental decisions, the commission should use the “precautionary principle” when thinking about new uses and users. It is a well-recognized and systematic method of linking science and public policy.
increasing public participation in decision making
shifting the burden of proof to the proponents of an activity
taking preventive action in the face of uncertainty
exploring a wide range of alternatives to possibly harmful actions.
The first three of these were part of the FCC’s process in its Ligado decision, though critics of the outcome might question how rigorously each was applied:
Hundreds of public comments were received before the order was issued.
Critics note that opposition to the FCC’s eventual course of action was expressed by stakeholders across a very a broad spectrum of society.
The applicant, Ligado, was required to bear the burden of proof.
However, as the National Academies report says, different assumptions in Ligado’s analysis led it to an entirely different conclusion from studies done by the Department of Transportation.
The FCC order allowing Ligado to operate includes “preventative actions.”
Yet many see these preventative measures as unworkable window dressing. In the staid and reserved phrasing of the National Academies report, they “may in some cases not be practicable within operationally relevant time and financial parameters.”
Regardless of the virtues or sins of its process to date, the FCC’s path forward must hinge on the final tenant of the precautionary principle: “Exploring a wide range of alternatives in the face of uncertainty.”
The most obvious, simplest, and straightforward of these alternatives is for the FCC to assign Ligado different frequencies, ones more distant from those used by space-based applications.
Admittedly, this path is only “simple and straightforward” in concept. It will require restarting the frequency allocation process nearly from the beginning, detailed analyses, complex negotiations, and difficult decisions.
Yet the current situation means certain harm to an unknown but significant number of GPS and Iridium users. Harm that could, in some instances, be severe. Even life-threatening.
It also means harm for Ligado. As things stand now, the company will always be under a cloud in the minds of federal officials and other GPS and Iridium users. Ligado will also undoubtedly be blamed for a variety of problems not of its doing from solar weather to criminal jamming. And a significant mishap related to company-caused interference could cause it extreme harm. Perhaps even bringing about Ligado’s demise.
The radio frequency spectrum is a limited and critical national resource. The FCC’s desire to use it to best advantage is necessary and appropriate. This, however, requires great care to safeguard the overall environment and existing users.
Resolving the “Ligado issue” will require creativity and a departure from the adversarial approach that has characterized the FCC process to date. Let’s hope that as the commission reconsiders the issue, it finds a way for everyone to come out ahead.
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.
An August 2020 paper published by the journal Sensors revealed China’s plans to expand coverage of its terrestrial Loran positioning, navigation and timing (PNT) system with three new transmitter sites in the western part of the country. The article indicates that this is a part of providing a backup system for GNSS.
According to the paper, “…the vulnerability of GNSS to unintentional and intentional interference signals can be found frequently nowadays. For national security and economic effectiveness, a reliable and complementary navigation system is needed desperately. The suitability of the Loran for a backup navigation system has been evaluated and reported.”
China has operated a Loran system for decades. While the system is capable of operating independently, its signals are also compatible with systems operated by South Korea and Russia. These are coordinated through the Far East Radio Navigation Service (FERNS) to ensure the systems are complementary and reinforce each other where coverage overlaps. The United States and Japan were also members of FERNS until they terminated Loran transmissions in 2010 and 2015, respectively.
Image: RNT Foundation
Little public information about China’s Loran system has been available and our queries have gone unanswered. One of the few documents available in the west is a 2014 paper about Loran-C from the Chinese Academy of Sciences in Shaanxi, China which can be accessed through the RNT Foundation website. It shows substantial Loran coverage in the eastern part of the nation, but only a broken circle indicating “projected coverage” in the west.
Graphic from 2014 Chinese Academy of Sciences paper on Loran showing projected coverage in the western part of the country with a dotted circle. (Image: RNT Foundation)
The single transmitter in that area projected by the 2014 paper could provide a strong, difficult to disrupt timing signal for fixed receivers with known locations.
Three new transmitters will be installed according to the August 2020 paper titled “High-Accuracy Positioning Based on Pseudo-Ranges: Integrated Difference and Performance Analysis of the Loran System.” The increased service in the western part of the country will provide “full coverage” positioning, navigation and timing usable by both fixed and mobile receivers.
The August 2020 paper is the first known documentation in over a decade of specific Chinese intentions regarding its Loran system.
Still, it is not a surprise to many observers. At 2019’s Stanford PNT Symposium, Xiaochun Lu of China’s National Time Service Center described the nation’s plan for a “comprehensive” PNT system. This system will include a wide variety of PNT sources including low earth orbit satellites, inertial systems, local positioning systems, and Loran.
Like Ms Lu, the authors of the August 2020 paper are employed at China’s National Time Service Center, which is part of the Chinese Academy of Sciences.
Last week, 27 members of the U.S. House Agriculture Committee sent a letter to Federal Communications Commission (FCC) Chairman Ajit Pai. In it, they urged him to reconsider the FCC’s decision to allow Ligado Networks to operate a terrestrial nationwide network that the executive branch says will cause harmful interference to GPS signals for many users.
This concern and opposition from a sector not traditionally engaged in GPS or positioning, navigation and timing (PNT) issues is just one example of how the FCC’s decision — rather than putting the issue to rest — has instead recruited a whole new set of actors from across multiple sectors for the opposition.
Many observers don’t see this as surprising.
According to one observer, previously it was easy for many to assume the FCC would reject Ligado’s proposal. The entire executive branch had been vehemently opposed for years. So had aviation groups, the weather community, geospatial interests and some satellite communications concerns. With such opposition from so many important quarters, it was reasonable for many to assume they need not become involved. Now that the FCC has acted to the contrary, these interests have become well energized.
The FCC decision also empowered opponents to educate and recruit others who don’t normally think or worry about GPS and PNT issues, folks like farmers and agricultural interests.
As one insider said, “The existing opposition can now go to just about anyone in any sector and say, ‘This is going to happen and it will harm your operation. There are no ifs, ands, or buts. The FCC has decided’.”
Photo: Avalon_Studio/E+/Getty Images
Agriculture’s reliance on GPS
Agriculture is a good example. While not the sector that first springs to mind when most people think about GPS, farming has become dependent on augmented GPS for precisely and automatically driving machinery, minimizing fertilizer and pesticide use, and a wide variety of other productivity gains over pre-GPS operations.
“GPS is critically important to the commercial agriculture, mining, forestry and rural manufacturing industries. In fact, GPS has become the single most significant technological advancement for American farm equipment in the past two decades… [A 2019 RTI study] found that during planting season, if GPS were interrupted, the economic impact to the agriculture sector could amount to losses of $15 billion due to lower crop yields. Moreover, an earlier study suggested GPS-enabled precision agriculture could save farmers an estimated 10 to 15 percent in operating costs and purchased inputs. This same study estimated the benefits of GPS to precision agriculture between $10 and $17 billion.”
Department of Transportation studies have shown that high-precision GPS receivers, such as those used in agriculture, could be impacted within 3,000 meters of a Ligado transmitters. With tens of thousands of transmitters deployed in a nationwide network, this could pose a real problem for American farming.
Other sectors have also become involved in the opposition. The recently formed Keep GPS Working Coalition has members representing aviation, surface transportation, maritime, agriculture and equipment manufacturing.
This formal and public coalition, though, seems to be just the tip of the opposition iceberg.
Almost 100 dissenting organizations
According to some involved with protesting the FCC’s decision, there are nearly a hundred organizations and companies that are working in some way to have it overturned. These include multiple aviation, delivery service, agriculture, surface transportation, geospatial, weather, maritime, space and technology interests.
One sign of the influence they are having is an increase in concerns being expressed by members of Congress.
In addition to the agriculture letter, some of the most powerful recent examples are statements made during meetings of the influential House Committee on Appropriations. Rep. Ken Calvert (R-CA), ranking member of the Defense Appropriations subcommittee, spoke at length in opposition to the FCC’s action. His comments were followed in a similar vein by the vice chair of the Appropriations Committee, Rep. Peter Aguilar (D-CA).
Many of the questions being asked by the public and members of Congress alike were reflected in the letter from the Agriculture Committee members:
How did the FCC know that “its” tests were representative and valid?
Why does the FCC find that some degradation of GPS reception is acceptable?
Why did the FCC reject the executive branch’s testing criteria?
Was there a cost/benefit analysis?
The letter also asked the question that is on almost everyone’s mind: If and when there are problems, who is going to fix them?
At first it was a flurry of letters and public statements from U.S. senators and members of the house. Then there was a senate hearing on the topic, and the issue was discussed in several other hearings.
The Federal Communications Commission’s (FCC) approval of a long-standing request by Ligado Networks continues to be controversial. The request was to make terrestrial broadcasts on a frequency near that used by GPS. Broadcasts which, according to analyses by the departments of Defense and Transportation, will interfere with GPS reception for many users.
Now it looks as though Congress is ready to move beyond talk and enact one or more pieces of legislation. These would require an independent technical review of the FCC’s decision and place limits on the ability of Ligado Networks to use the license it was granted.
Congressional interest has been fueled both by member concerns and a regular drumbeat of input from constituents. The recently formed Keep GPS Working Coalition is just one example. It was created from a larger group of more than 70 companies and organizations across a broad swath of industries that has gone on record against the decision and has been supporting congressional action.
National Defense Authorization Act
A primary vehicle for congressional action looks to be the National Defense Authorization Act (NDAA) for 2021. Unlike other “annual” legislation that often gets sidetracked or delayed during election years, Congress has passed an NDAA for each of the past 59 years. As such, it is a particularly powerful tool.
This is doubly so in this case, as the member of Congress that has been the most outspoken critic of the FCC’s decision is Senator Jim Inhofe (R-OK). He chairs the Senate Armed Services Committee that has direct responsibility for the NDAA.
Responding to conflicting claims about the findings of government and private tests, the bill requires the Defense department to contract with the National Academies of Science, Engineering and Medicine for an independent technical review.
Evaluating Potential Impact on GPS
Among other things, the review will compare the different methods of evaluating the potential impact on GPS services from Ligado’s transmissions, and determine which of those was the most effective in guarding against any harm.
The bill also prohibits the Defense Secretary from spending any money to comply with the FCC’s order until the Congress has been given an estimate of the total cost to the department of coping with Ligado’s transmissions.
While the FCC order requires Ligado to modify or replace any government receivers impacted by its operations, the Defense department and others have said this is only a small fraction of the overall costs they would incur.
The bill requires the Defense Department estimate to consider a much larger scope of costs including:
To upgrade, repair, or replace potentially affected receivers
To modify, repair, or replace equipment, pares, associated ancillary equipment, software, facilities, operating manuals, training, or compliance with regulations, including with regard to the underlying platform or system in which a capability of the Global Positioning System is embedded; and,
For personnel of the department to engineer, validate, and verify that any required remediation provides the Department with the same operational capability for the affected system prior to terrestrial operation in the 1525 to 1559 megahertz or 1626.5 to 1660.5 megahertz bands of electromagnetic spectrum.
The House version of the NDAA also provides that:
“The Secretary of Defense may not enter into a contract, or extend or renew a contract, with an entity that engages in commercial terrestrial operations using the 1525–1559 megahertz band or the 1626.5–1660.5 megahertz band unless the Secretary has certified to the congressional defense committees that such operations do not cause harmful interference to a Global Positioning System device of the Department of Defense.”
RETAIN GPS and Satellite Communications Act
Senator Inhofe has also announced he will introduce stand-alone legislation when Congress returns from summer recess. His “Recognizing and Ensuring Taxpayer Access to Infrastructure Necessary for GPS and Satellite Communications Act,” or “RETAIN GPS and Satellite Communications Act,” would require Ligado to modify or replace any receiver, including those used by private citizens, that would be impacted by Ligado’s operations.
This modification would be required before the FCC’s order allowing them to transmit could come into force. Most observers opine that the number of impacted civil receivers in the U.S. is so great that this would effectively deny Ligado use of the frequency.
Introduction of the RETAIN GPS and Satellite Communications Act was planned for before the summer recess. Its delay until after was likely to provide more time to recruit co-sponsors.
GPS Interference a ‘Niche’ Issue
One observer commented that “GPS and the FCC Ligado order are really niche issues. As time goes on, more and more members of Congress will hear about it from constituents and be appalled.”
The delay will also allow time for the mammoth NDAA bill to clear Congress. RETAIN GPS would then have more chance for the spotlight.
Many industry observers have opined that regardless of congressional action, Ligado will struggle to find a successful 5G or other business model that will generate a significant revenue stream from the spectrum.
As public concern continues to grow and Congress responds with legislation, it may turn out that Ligado finally won the battle at the FCC but ended up losing the war.
