The Indian government is pushing smartphone makers to sell devices that receive NavIC signals along with GPS.
India originally stated NavIC would be required in smartphones sold starting in January 2023, according to Reuters, but strong reaction from smartphone manufacturers Apple, Xiaomi and Samsung apparently caused the government to push back or remove the deadline.
A deadline of January 2023 would not allow enough time for smartphone makers to integrate NavIC-enabled receivers to their devices. Steps include redesign, securing parts, testing and assembly. Many smartphones sold in India by the companies are economy-level devices priced under US$200.
The three tech giants met with government officials, seeking an extended target date of 2025, Reuters reported.
However, India’s Ministry of Electronics & IT issued a statement via Twitter :
A media report has claimed citing a meeting that mobile cos were asked to make smartphones compatible with NavIC within months. This is to clarify: (1) No timeline has been fixed. (2) The cited meeting was consultative; and (3) the issue is under discussion with all stakeholders.
NavIC (Navigation with Indian Constellation) is the operational name for the Indian Regional Navigation Satellite System (IRNSS) developed by India’s space agency for military and commercial purposes. NavIC consists of eight satellites that cover the Indian mainland and the region extending up to 1,500 km from its boundaries.
“NavIC can help in navigation on land, air, sea and also in disaster management,” Science & Technology Minister Jitendra Singh said in a press release. “NavIC satellites are placed at a higher orbit than the GPS of United States. NavIC satellites are placed in geostationary orbit (GEO) and geosynchronous orbit (GSO) with an altitude of about 36,000 km; GPS satellites are placed in medium earth orbit (MEO) with an altitude of about 20,000 km.”
“NavIC uses dual-frequency bands, which improves accuracy of dual-frequency receivers by enabling them to correct atmospheric errors through simultaneous use of two frequencies,” Singh said. “It also helps in better reliability and availability because the signal from either frequency can serve the positioning requirement equally well.”
The Google Smartphone Decimeter Challenge (SDC) competition, co-sponsored by the Institute of Navigation (ION), took place this summer. For the competition, teams developed high-precision GNSS positioning using a pool of smartphone GNSS + inertial measurement unit (IMU) datasets accompanied by high-accuracy ground truth. Teams competed to achieve the best location accuracy with the datasets provided. Winners received cash prizes and sponsored attendance at the ION GNSS+ 2022 conference in Denver, Sept. 19-23, to present their results.
Origins
The SDC has its origins in the Android Operating System, which is an open-source platform. In 2016, Google made GNSS raw measurements available as a public application programming interface (API) on all Android phones. Since then, the available measurements have become more sophisticated and more accurate. For example, dual-frequency carrier-phase data is now available on many Android phones. This enables new areas of research.
Goals
The competition had two goals:
• Stimulate the research and development of high-accuracy algorithms that can produce submeter position accuracy on phones.
• Establish a publicly accessible repository of labeled data so that all future research on location algorithms can be judged in a consistent way against a standard set of data.
The first goal was met beyond our expectations. A total of 1,381 teams participated in the two competitions of 2021 and 2022. Discussion among competitors on the competition platform (kaggle.com) was wide-ranging, incredibly collegial, and beneficial to the entire community.
Competitors have written and shared detailed descriptions, and these have been reviewed and commented on by other competitors. Moreover, winners have written formally peer-reviewed papers and made presentations at the ION GNSS+ conferences, which are available from ion.org.
The second goal is a work-in-progress and is intended to be the legacy of the events.
Legacy
Disciplines such as machine learning have established benchmarks that make it possible to compare new approaches to previous ones in a proper quantitative way. In the GNSS community, this convention has been missing — a glance across papers at conferences will show that different algorithms tend to be presented with different test data and different metrics. Usually, the authors collect this data, and it is often fairly sparse (one or two drive tests, for example). Also, the reader never knows whether the data was cherry-picked (were bad results not mentioned?).
The SDC data provides:
• 206 different drive tests
•86 total hours of dual-frequency (L1, L5) data with code and carrier-phase measurements
•All labeled with ground-truth positions and velocities collected using NovAtel SPAN ISA-100C, with precise lever-arm compensation and validated with Google’s analysis tools.
The Kaggle site allowed users to submit their results, then automatically scored them against the ground-truth data. We advocate that all GNSS researchers use this resource to measure their location algorithm improvements in a standard way. This creates trust in published results, accelerating the recognition and adoption of truly great improvements for the benefit of the entire industry and GNSS users worldwide.
The top three winners of this year’s Smartphone Decimeter Challenge described their projects to Matteo Luccio, GPS World editor-in-chief.
Suzuki
Taro Suzuki, Chiba Institute of Technology
1st Place Winner: Two-Step Optimization of Velocity and Position using Smartphone’s Carrier Phase Observations
What is your research focus and how does it relate to the contest?
My current research focuses on the accurate positioning of vehicles and mobile robots in urban environments where GNSS multipath occurs. I usually use commercial GNSS receivers for my research. This competition is very relevant to my current research, except that the smartphone is replacing a receiver.
How long have you been developing the technology or approach you used to win the contest?
The competition was held for three months, but I concentrated my efforts on the past three weeks. However, I used technologies and resources developed in my previous research (for example, source code developed in last year’s competition).
Have you participated in previous editions of this contest?
Yes, I participated in the last competition and won. The approach used in this year’s competition is based on the method used to win last year’s competition, with additional innovations and improvements.
Where, in what GNSS signal conditions, and at what speeds were the test data collected?
The competition provides a training dataset, which contains raw GNSS observations from a smartphone installed on a vehicle as it travels on real roads. In addition to GNSS observations, the training dataset contains the ground truth of the smartphone’s position. The training dataset includes a wide range of GNSS signal conditions, such as driving on highways around San Francisco and Los Angeles, driving on tree-lined urban streets, and driving in tunnels and under overpasses. I have developed an algorithm that uses a training dataset containing ground truth to accurately estimate the location of smartphones in a variety of GNSS signal reception environments.
What accuracies were you able to obtain?
The competition metric was “average of 50th and 95th percentile horizontal errors.” The metrics are computed for each of the 36 runs in the test dataset, which are divided into public and private groups, then the metrics are averaged in each group to compute the final score. My final score was 1.382 m for public and 1.229 m for private. The best score given after the competition was 1.372 m for public and 1.197 m for private. The final result achieved sub-meter accuracy in the median (50th percentile).
What are the key features of your approach?
The key point of my method is global optimization using graph optimization, unlike a conventional Kalman filter or least-squares-based positioning methods. In addition, highly accurate relative position estimation using the time difference of carrier wave phases of smartphones contributed to the accuracy. Because the competition dataset included environments such as tunnels and elevated structures in which GNSS cannot be received at all, I devised an algorithm with two optimization steps (first velocity optimization, then position optimization) and applied it to the competition. This method enables highly accurate position estimation for vehicle driving data in various GNSS signal reception environments using only smartphone GNSS observation data.
What end-user applications are you expecting your approach to enable?
Decimeter-accurate location estimation could lead to lane-level navigation for vehicles, pedestrian navigation, and advanced location-based smartphone games.
Dai
Shubin Dai, Kaggle Community
2nd Place Winner: Improving Smartphone GNSS positioning using Gradient Descent Method
What is your research focus and how does it relate to the contest?
I am a data scientist and one of the top competition grandmasters on Kaggle. My research interests include computer vision, natural language processing, autonomous driving, and reinforcement learning. I placed in the top three in 14 related competitions (13 of which were solo). So, despite my lack of background knowledge in the GNSS field, these methods, skills and experiences helped me find a solution.
How long have you been developing the technology or approach you used to win the contest?
I spent about 50 days on this competition, including learning principles of GNSS and understanding all kinds of algorithms by reading books, papers and source codes. The Kaggle platform is very helpful when we want to get started in a new field.
Have you participated in previous editions of this contest?
I did not participate in the competition held last year, but I learned a lot from solutions of recent years, particularly the third-place solution.
Where, in what GNSS signal conditions, and at what speeds were the test data collected?
The benchmark datasets include raw GNSS measurement and raw readings from inertial sensors, using smartphones (Xiaomi Mi 8, Google Pixel 4, etc.) enabled with dual-frequency and ADR (accumulated delta range) in driving scenarios, collected in the San Francisco Bay area.
In the GSDC2021 dataset, there are 29 drives with 73 phone GNSS logs in the training set and 19 drives with 48 phone logs in the test set. Compared to 2021’s competition, in the GSDC2022 dataset we can see more data overall and a wider variety of routes: 62 drives with 170 phone logs are provided in the training set and 36 drives with only one phone per drive are provided in the test set.
The drives in the training set took 15 to 60 minutes at an average speed of 18 m/s.
What accuracies were you able to obtain?
According to the metric of this competition, the score is calculated as the mean of the 50th and 95th percentile distance errors. The score on my local validation set is 1.929 m, the score on the public test set is 1.608 m, and the score on private test set is 1.499 m. When we calculate the mean error, the score is 1.401 m on a validated set, the mean error of 40% of the trips are under 1 m. I think the competition metric is more reliable as the 95th percentile distance error is also important.
By the way, my local validation set is more difficult to optimize than the test set, so the mean error on the test set is expected to be lower than 1.401 m.
What are the key features of your approach?
The competition data is noisy due to multipath effects, non-line-of-sight receptions, receiver noise and missing data, therefore it’s quite challenging. I found that the optimal estimation for each point locally is not stable and can be affected by noise at that point on the track. If we can find a solution to a whole track globally, the noise can be reduced as the model must follow all kinds of constraints, such as geometry constraints, speed constrains, and global acceleration constraints.
Although we could extend the WLS and Kalman filter solution to take more points on a track into consideration, it’s not so easy to model all kinds of constrains. On the other hand, if we use a global optimization method, such as factor graph optimization and neural networks, we can add the constrains easily, which makes it more efficient to conduct experiments.
Following the solution of the third-place winner in last year’s competition, I used the global optimization method by taking into account gradient descent, pseudorange, pseudorange rate, accumulated carrier phase (ADR), phone speed and acceleration constraints of every time epoch on a track. When optimizing the track using gradient descent, the losses are designed to filter out abnormal data and reduce the noise by a series of physical and geometrical rules. I spent much time searching for the constraints, proving them and turning them into losses that can be used to update the coordinates iteratively during the competition.
What end-user applications are you expecting your approach to enable?
According to the setting of this competition, we can post-process data collected using Android phones, which is easily obtained. The track obtained can then be optimized using the solutions from this competition. The solutions from the first and the second place can both be considered as a framework that can be extended by adding more constrains to it to improve accuracy.
Everett
Tim Everett, RTK Consultants LLC
3rd Place Winner: An RTKLIB Open-Source-Based Solution
What is your research focus and how does it relate to the contest?
I develop and maintain the demo5 fork of the popular RTKLIB open-source GPS/GNSS software tool. I have optimized this software for low-cost precision GNSS solutions, so it is very closely related to the goals of this competition. My background is in control system theory and I worked in product and technology development for servo systems in the disk drive industry for 25 years before switching to the GNSS field. The mathematics turns out to be quite similar between the two as both are problems in precision positioning, just different in scale. In disk drives, it is nanometers over centimeters and in precision GNSS, it is centimeters over kilometers.
How long have you been developing the technology or approach you used to win the contest?
I have been developing and maintaining low-cost precision GNSS solutions in the RTKLIB software for about six years but have only worked with smartphone solutions in the last year or two.
Have you participated in previous editions of this contest?
I did not participate in last year’s competition but I did work with the data after the contest was over and shared a solution using RTKLIB that would have placed fifth in the competition.
What accuracies were you able to obtain?
I achieved a score of 1.648 m on the private leaderboard. This represents the average of the 50th percentile and the 95th percentile of the errors as scored by Kaggle. Kaggle does not provide any further breakdown of this number but, based on the training data for which ground truths were provided, this corresponded to a 50th percentile error of roughly 0.9 m and a 95th percentile error of roughly 2.3 m. With a small tweak to my solution after the competition was over, I was able to improve my private leaderboard score to 1.593 m, which would have been within 1 cm of the third-place solution.
What are the key features of your approach?
My approach was to use the existing post-processing kinematic (PPK) solution algorithm in RTKLIB but to reoptimize it for the unique characteristics of the smartphone observation data. A PPK solution is the post-processing equivalent of a real-time kinematic (RTK) solution and is a differential solution that relies on differencing the receiver observations with observations from a nearby base station to cancel out most of the largest error sources — including atmospheric, orbital and clock errors — since these errors are common between the two sets of proximate observations.
Because smartphones have very poor GNSS antennas and they were mounted inside vehicles, the signal quality is much lower and the multipath much greater than those for which the RTKLIB algorithm was optimized. In addition, the smartphones were using the L5 frequency band, whereas RTKLIB was optimized for the more commonly used L2 frequency band. One of the main goals of my optimization process was to include many low-quality observations in the solution that would normally be discarded, but to de-weight them appropriately.
What end-user applications are you expecting your approach to enable?
RTKLIB software is currently used to provide precision solutions for many end-user applications such as surveying, drone photogrammetry, sports tracking, precision agriculture, utility location, marine navigation and ground subsistence monitoring. Although smartphones won’t replace dedicated low-cost GNSS receivers, the challenging nature of the smartphone data severely stresses the RTKLIB algorithms and exposes numerous opportunities for improvement that are much less obvious with more typical, higher quality data. I have pulled these improvements into the main branch of the demo5 version of RTKLIB, and hence this work should immediately improve the quality of all these applications and extend their use into more challenging environments.
Photo: Google
Acknowledgements: Thanks to the Institute of Navigation (ION) for co-sponsoring the 2022 Smartphone Decimeter Challenge. Thanks to Luke Walcher and Tolu Ojelade for their contributions to the photos used in this article.
Full-power UHF TV stations in view in the continental United States: yellow (1—3 stations), green (4—6), red (7—10), orange (11 or more). (Image: NAB)
Over the years, we have seen several proposals to use television broadcasts for positioning, navigation, and timing (PNT). This idea was taken one step further in a paper by the staff of the National Association of Broadcasters (NAB). We talked with one of the authors, Robert Weller, NAB’s vice president for spectrum policy, to find out more.
Goward. Bob, your paper calls the notional system the “Broadcast Positioning System” or “BPS.” What is new about your proposal? And what led you and your colleagues to develop this idea and publish the paper?
Weller. Television broadcasters are transitioning to a new transmission standard, ATSC 3.0, that plays well with other industry protocols, has more robust operating points, stricter timing requirements, and is much more flexible. There are already more than 50 US markets with a station transmitting ATSC 3.0. Our paper began to analyze PNT in the context of ATSC 3.0 and confirmed that there was a good match. So, the idea of “broadcast positioning” was born.
Goward. In general, how would BPS work?
Weller. TV stations transmit from towers at known fixed locations. A TV station can transmit its precise location (geographic coordinates and antenna elevation) along with a time-stamp. For fixed receivers using the timing service, only one TV signal is required. Receivers would know their location a priori and would simply calculate their distance from the TV station and use that distance to determine the corresponding time that it takes for the signal to travel from the TV transmitting antenna. That time difference is then added to the received time-stamp to determine the present time at the receiver.
Both fixed and mobile users could access positioning and timing services when at least three TV stations are within range.
Goward. GPS and other GNSS are ubiquitous. What advantages do you see BPS having over space-based navigation systems?
Weller. BPS is not intended to replace GPS. BPS can provide an independent timing and/or position determination, which can provide confidence and help detect spoofing or other problems with GPS. BPS also has the advantage of high power and strong signal levels. Most UHF television stations radiate 1 megawatt of power, which does a good job penetrating buildings and is difficult to jam or spoof.
Goward. There have been many proposals for terrestrial systems to complement GPS. In general, what advantages would implementing BPS have over other non-space approaches?
Weller. There are several advantages. The cost to deploy will be less since the broadcast infrastructure is already in place. Also, because of our high power, the number of nodes necessary is fairly small. I’ll add that TV stations are built to operate 24/7, so most of them are fairly “hard” with back-up power and redundant transmitters. Additionally, the modulation and coding we propose for BPS is intended to provide service well above the noise floor, making it quite robust. Finally, low-cost receivers that are used in televisions can be used to decode the BPS information.
Goward. Your paper says that using the television stations we have today, geographically about 85% of the contiguous United States by land area would be able to get PNT services from BPS. The number is 99% for just timing services. Do you have any thoughts about those not in range for services?
Weller. Those percentages were intended to be conservative and only considered full-power UHF TV stations. There are also hundreds of VHF stations and thousands of low-power TV stations. If you include those stations, the coverage percentages are even higher. It’s certainly possible to add more stations if needed to reach the most remote and unpopulated parts of the United States.
Goward. What about user equipment? Have you done any work in that area? How small do you think receivers could be eventually?
Weller. There are compact GPS and Loran receivers out there, and the technology for BPS isn’t much different. Some Korean companies have already built very small ATSC 3.0 receivers to carry RTK corrections to GPS for use in drones. There are also already ATSC 3.0 USB receivers that weigh less than an ounce.
Goward. Are there other services that BPS could provide?
Weller. BPS can be one element of a PNT system-of-systems that also improves other PNT services. In my opinion, the most valuable service BPS can provide is an alternative reference for critical infrastructure if GPS is compromised. However, BPS would occupy a tiny fraction of ATSC 3.0 signal capacity. So, there could be additional services such as transmitting ephemeris data for expedited GPS acquisition, RTK data for improved PNT accuracy, or even map information.
Goward. Have you thought about what you would be using as a time source?
Weller. Most TV stations already have GPS, but since the point of BPS is to provide redundancy and resilience to GPS, we’re looking at cesium clocks, optical fiber, and eLoran as possibilities.
Goward. NAB is a trade association. How do you see this project benefiting your members?
Weller. This project affirms the public service mission of broadcasters as well as our designation as critical infrastructure. If broadcasters are compensated for the equipment and resources required for deploying and operating BPS as a public service, I expect high participation and user adoption.
Goward. Where do you think you and your colleagues will take the project from here?
Weller. We’re working with possible users to determine their requirements while also trying to identify funding sources to enable the development. We hope to build prototypes and launch market trials as next steps towards commercialization.
GNSS receivers face the same old challenges (extremely weak received signal, orbit and satellite clock errors, ionospheric and tropospheric delays, multipath, dilution of precision, urban canyons, etc.) and new ones (increased interference). However, compared with just a few years ago, they benefit from new signals, many more satellites, a panoply of options for corrections, and improved integration with inertial navigation systems (INS).
For example, pole-tilt compensation is quickly becoming standard. This feature enables users to locate dangerous or hard-to-reach points by measuring them at an angle with just the tip of the pole to which the receiver is attached.
Pole-tilt compensation also makes surveying and mapping easier by removing, in many situations, the need to use total stations or offsets. Together with improvements in work processes, this makes GNSS receivers more user friendly. This is particularly welcome now that more surveyors are retiring than there are new surveyors entering the profession.
The greater accuracy of GNSS receivers enabled by the increase in the number and quality of satellites, signals, corrections services and integration of GNSS with other sensors is also increasing the number of use cases, especially at the high end of the accuracy requirements, such as lane-level vehicle navigation. (Next month’s cover story will center on this year’s Google Smartphone Decimeter Challenge contest, in which competing teams aim to bring smartphone location down to the decimeter or even centimeter resolution using raw location measurements from Android smartphones. This could enable services that require lane-level accuracy, such as estimated time of arrival when using a high-occupancy vehicle lane.)
This month’s cover story highlights what has changed “inside the box” to improve the accuracy and resilience of GNSS receivers for surveying, mapping and a variety of other applications. Read the success stories from five different companies below.
Galileo launch 11 from Europe’s spaceport in French Guyana sent satellites 27 and 28 into orbit. (Photo: ESA/CNES/Arianespace)
News from the European Space Agency (ESA)
Europe’s latest Galileo satellites in space have joined the operational constellation, transmitting navigation signals to three billion users across Earth as well as relaying distress calls to rescuers.
Their entry into service follows a summer test campaign and will result in a measurable increase in positioning accuracy and improved data delivery performance of the overall Galileo system.
Galileo satellites 27-28 were launched at the end of 2021 and underwent in-orbit test review at the end of April. The review was conducted by ESA, satellite manufacturer OHB, and navigation payload maker Surrey Satellite Technology Ltd (SSTL).
Key findings showed both satellites’ payloads are performing extremely well — among the best in the entire constellation — and the satellites entering into service increase the position accuracy and robustness of the overall Galileo system.
A successful system and in-orbit operations review followed, co-chaired by ESA and the EU Agency for the Space Programme (EUSPA), which is in overall charge of commissioning.
Improved navigation message
The two satellites are the first to broadcast an improved navigation message, resulting in three key improvements for Galileo’s public Open Service users:
faster navigation data acquisition, allowing users to establish a first position fix more rapidly
better robustness in challenging environments, such as urban centers
easier access to timing information in the navigation message for users possessing only a rough estimate of timing of the order of 1-2 seconds.
For the testing and broadcasting of this new navigation message, new software for the Navigation Signal Generation Unit was developed by Thales Alenia Space in Italy, SSTL, OHB and ESA, and was uploaded to the two satellites.
During the summer, an extensive test campaign was conducted by ESA to ensure the compatibility of the entire Galileo system at unit, payload, satellite, ground and system levels with the enhanced message. As part of this effort, EUSPA oversaw receiver testing to ensure this compatibility extended to Galileo receivers and chipsets in the market.
These latest launched satellites made ideal test cases for the software and the improved navigation message. Transmission of the upgraded signals from Galileo satellites 27-28 allowed the team to confirm its correct implementation and characterize its long-term performance.
Following a successful Test Review Board, the satellites were brought back into service on Aug. 29
Something big happened to GPS service in the Denver area on Jan. 21.
On that day, Air Traffic Control issued a notice advising pilots of problems with GPS reception spanning about 8,000 square miles in the Denver area.
The advisory, posted at 10:33 p.m. Denver time, said GPS was unreliable within a 50-nautical-mile radius of the Denver International Airport. Interference was likely to be experienced by aircraft on the ground and as high as 40,000 feet above sea level.
The advisory also said the Wide Area Augmentation System (WAAS) and Ground-Based Augmentation System (GBAS), both designed to make navigation with GPS more precise, as well as the ADS-B collision avoidance and traffic management system, would be unreliable.
Pilots reported other systems affected such as transponders that help radar controllers keep track of aircraft, traffic alert and collision avoidance (TCAS) equipment, autopilots, electronic flight bags and terrain warning systems.
Pilots trying to land at Denver International and the much small Centennial Airport 20 miles to the south reported a variety of problems.
I flew in there (Centennial Airport) last night and I’m about to fly out. One second everything was fine, and then next second we completely lost GPS for the rest of the flight, probably coming through ~14,000 [feet] on the arrival from the northwest.
In addition to verbal reports to air traffic controllers, formal reports were filed with NASA’s Aviation Safety Reporting System (ASRS) by pilots flying into Denver International. (Note that ASRS only lists the month reports were submitted, not the day, to preserve anonymity.) Nineteen ASRS reports about GPS in Denver during January match well with comments on Reddit and an Airliners.net forum for the 21st and 22nd of the month.
The ASRS reports tended to focus on problems during approaches to the airport and landings. The most minor included distracting cockpit alerts and warnings.
Cleared ECAM (Electronic Centralized Aircraft Monitor) and emergency cancelled the repetitive nuisance messages. Additionally, received a GPS Lost message on FMC [Flight Management Computer].
More concerning were incidents that could more directly impact safety of flight.
One aircraft’s collision avoidance system, which normally reports issues as they develop, abruptly directed action to avoid another aircraft.
…we received a “LEVEL OFF” TCAS RA with no prior notification. The offending target was to our 2-3 o’clock and climbing…
Two aircraft reported confusing navigation displays on final approach to the airport. One pilot flying in limited visibility (instrument conditions) was sufficiently concerned that they aborted a landing attempt at the last minute.
We were about 1000 AGL [1,000 ft above ground level] – not sure about the exact altitude – and our RA [anti-collision warning] turned into an amber color… We were about 300 – 200 AGL and our autopilot failed… It was very unexpected… I called the go-around.
So, what happened to GPS?
At first, Air Traffic Control told pilots 5G telecommunications systems were causing the interference. That stopped at some point, though, according to an online comment:
As a [air traffic] controller… they haven’t told us anything. I was at work when it all started yesterday and they told us to make broadcasts about 5G interference. Today, they said it wasn’t 5G and not to make those broadcasts, but they still haven’t said what the issue is. There’s obviously rumors and speculation, but at this point, nothing concrete.
The first mention of the incident in traditional media seems to have been in an August 2022 journal article by a group of researchers at Stanford University. It focused on using the aviation ADS-B system to geo-locate GPS interference. The U.S. Department of Transportation provided the exact location and signal strength of Denver’s interfering transmitter to assist the Stanford study.
Requests in August and early September to the departments of Transportation, Homeland Security and Defense for more information on the incident went unanswered.
Mike Roskind from the Department of Homeland Security (DHS) provided some information and promised a formal report would be forthcoming. He said:
the incident lasted for 33.5 hours
impacts varied across infrastructures and applications; some users who were physically shielded from the interference source were able to maintain service
wireline and cellular providers had timing backup systems and were unaffected
a radio system with no backups suffered, as did a simulcast radio system that used rubidium backup clocks; the clocks drifted away from each other over the course of the outage and caused towers to isolate.
Responding to a question about the source of the interference, Roskind confirmed that 5G telecommunication was not the cause, but refused to say more.
He also declined to identify other systems, applications and infrastructure impacted by the disruption. He said that the department is very concerned about protecting the identity of affected users cooperating with the government analysis.
More information will be provided in a DHS report on the incident titled “GPS Interference Happens.” The report is in final review now, according to Roskind, and is expected to be released in October.
“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.
Transportation Secretary Pete Buttigieg made a surprise appearance at the DOT roundtable on complementary PNT. (Screenshot: DOT)
“If this is a problem, the government should act like it.”
Citing more than 10 years of government studies, warnings and promises, representatives from a wide variety of industries criticized the government recently for doing little to address an important national security problem.
At issue was the need for national backup capabilities for GPS and the essential positioning, navigation, and timing (PNT) signals it provides.
GPS signals are weak and easy to block or imitate. At the same time the signals are used by most technologies including networks, telecommunications, electrical grids, broadcast, mobile radios, transportation, and other critical infrastructures.
After Russia threatened to destroy all GPS satellites in 2021 in its run-up to invading Ukraine, a member of the White House National Security Council told a public meeting “GPS is still a single point of failure” for the nation.
The government was criticized for inaction at a “Complementary PNT Roundtable” hosted by the Department of Transportation (DOT) in early August. The department is the federal lead for civil GPS and PNT issues.
Eight attendees interviewed after the event reported a surprising unanimity of comments and concerns expressed by industry reps at the meeting.
Enough with the studies
A repeated theme was that the government has done enough studies to understand the problem and available technologies.
“They have been studying this for over twenty years,” one attendee observed. “The Volpe [Transportation Systems Center] report came out in 2001. And there have been lots of studies since then. All have just been refinements of those original findings.”
Another consistent theme was disdain for the idea that industry and the free market will solve the problem without government leadership and active support.
“GPS is free,” said one attendee from a company that provides PNT services. “We can and do sell to meet niche demands, but it is laughable to suggest we can ever sell enough subscriptions to be enough of a backup for GPS.”
A major telecommunications company rep echoed the sentiment. Wireless telecom is especially reliant on PNT. “We use GPS and would use Loran and low Earth orbit satellites if they were available, but we are not going to build it on our own. There is just no business case.”
“We have a big list of things we could do that would increase our resilience and/or cut costs,” said another telecom provider. “There is no big driver for most, though. No competitive pressure, no government mandates.”
Government must walk the walk
“The government has been telling us for over a decade that this is a problem,” said one attendee. “If that’s true, why aren’t they acting like it? Transportation is critical infrastructure and needs a GPS backup, for example. So why hasn’t DOT done something?” Of all the criticisms expressed, this was predominant, according to interviewees.
A 2021 Executive Order on responsible use of PNT services encouraged critical infrastructure providers to not rely on GPS.
The government needing to be a lead customer was mentioned a number of times at the event. This would help raise awareness, set an example, and signal to users the issue is important enough to act on.
Government action was also seen by users as key to creating confidence that a technology or service will be around for the long haul. This point seemed to resonate with many of the government representatives as well.
“I am not going to go to the time and expense of adopting something unless I know it is going to be around for 20 years or more. The only way I can be assured of that is if one of the biggest users is the government.”
Adversaries not idle
Of particular concern to some was that America’s adversaries have better, more resilient PNT, and are constantly working against us.
They are building PNT “…systems of systems. Space-based, ground-based, and everything in between-based. They are doing it. We need to get out in front and lead,” said one. China has been particularly active building multiple integrated PNT systems.
“Our adversaries are not stupid” and are going to try to stay in the lead. “They will try to interfere with any frequency, system, or combination of systems selected. We must test and build something that is survivable and resilient.”
“If China, Russia, and Iran had the ability to protect themselves from nuclear attack,” said one attendee, “we would be frantically trying to get the same capability. Yet those countries have backup and complementary systems for PNT, and the United States does not. And we’re not doing anything,” said a participant reflecting upon the event.
Hopeful signs
Several attendees said there were signs the event might not have been “just another government meeting.”
As part of his opening remarks, the event host, DOT Deputy Assistant Secretary Dr. Robert Hampshire, mentioned the bipartisan infrastructure law and affirmed that PNT is infrastructure. This led some to believe funding from the infrastructure legislation could be immediately available if the government decided to act.
Others were cheered by DOT Secretary Buttigieg’s cameo appearance and comments at the event. One remarked it was the first time they had heard a DOT Secretary say “PNT” in over 20 years.
Uncertain outcome
Despite the consistent messaging and potentially hopeful signs, some attendees questioned whether anything would change because of the two-and-a-half-hour event.
“There were about 120 people from industry and a wide variety of government agencies, but what was the point?” asked one. “We all told the government the same things we’ve told them before, often in writing.”
Another was concerned that the event didn’t discuss the most important questions.
“We were talking about individual systems and critical infrastructures,” this person said. “This is a strategic national security issue. We need to get the bullseye off GPS and ensure the United States can’t be blackmailed by having GPS held hostage.”
“And what if there is a major coronal mass ejection? China will come out much better than us because they have survivable PNT. The United States will become a second-rate power to China in an instant. We keep talking about the trees and ignoring the forest!”
One attendee whose company has a very active government relations program reported they hoped the event would help sway those in government still opposed to action.
“It is pretty clear to us that almost everyone in the departments who understand the issues is in favor of doing something as soon as possible. The same with Congress. But even though the National Security Council is worried about this, there are some folks in the Office of Management and Budget who have opposed action for over a decade.”
While some came away buoyed by what they saw as an action-oriented tone to the event, others doubted much would change. “It remains to be seen whether criticism from industry and threats from China and Russia are enough to get the government to finally do something.”
Dana A. Goward is President of the Resilient Navigation and Timing Foundation and serves on the President’s National Space-based Positioning, Navigation, and Timing Advisory Board.
SouthPAN early Open Services coverage. (Image: Geosciences Australia)
The government of Australia has awarded Lockheed Martin a $1.18 billion contract to establish the Southern Positioning Augmentation Network (SouthPAN) to enhance precision.
The system is expected to be fully operational by 2028, and will be provided as a service for 19 years with an option to extend.
The program will use a unique, Lockheed Martin-developed, second-generation satellite-based augmentation system (SBAS) broadcasting on two frequencies to augment signals from two GPS and Galileo.
The SouthPAN initiative
The SouthPAN initiative will deliver a signal augmenting GPS and Galileo over the Australasia region, improving accuracy from 5-10 meters to within as little as 10 centimeters.
The greater positioning accuracy and integrity of the SouthPAN signal has applications across a range of users, including civil aviation, vehicle guidance, precision agriculture for efficiencies in crop management, tracking maritime shipments, and enabling navigation for drones and other unmanned vehicles.
Lockheed Martin Australia will work with the SouthPAN project team to establish a network of GNSS reference stations and satellite uplink facilities that will enable communications and transmissions with the SouthPAN space infrastructure.
SouthPAN is a partnership between Geoscience Australia and Toitū Te Whenua Land Information New Zealand (LINZ) under the Australia New Zealand Science, Research and Innovation Cooperation Agreement.
2017 testbed
Lockheed Martin tested a second-generation SBAS testbed in partnership with Geoscience Australia in 2017.
Lockheed Martin’s second-generation SBAS technology receives and monitors basic signals data from multiple GNSS through widely distributed reference stations. This data is collected by a SBAS testbed master station, which computes corrections and integrity bounds for each GNSS satellite signal, and generates augmentation messages.
The new messages are sent to an SBAS payload hosted aboard an Inmarsat geostationary Earth orbit satellite via an uplink antenna in Uralla, New South Wales. The Inmarsat satellite rebroadcasts the augmentation messages containing corrections and integrity data to the end users’ GNSS receivers. The whole process takes less than six seconds.
Lockheed Martin provided the systems integration expertise in addition to the Uralla radio frequency uplink; GMV-Spain provided its “magicGNSS” processors; Inmarsat provided the navigation payload hosted on the 4F1 geostationary satellite. The Australia and New Zealand Cooperative Research Centre for Spatial Information coordinated the demonstrator SBAS test-bed SBAS test-bed projects.
The SouthPAN contract will expand Lockheed Martin’s investments toward sustainable business growth in Australia. Currently, Lockheed Martin programs support 4,000 Australian jobs in advanced manufacturing and technology industries. The contract will grow that footprint with additional jobs in at least four states.
News from the European Space Agency (ESA). Europe’s first generation Galileo constellation is already the world’s most precise satellite navigation system — delivering meter-scale positioning to more than 3.5 billion users worldwide. The Galileo Second Generation will enable even better performance and an expanded range of services.
Essential elements of the G2 system are being evaluated in ESA laboratories, including key algorithms to synchronize satellite timing and determine orbits, as well as test versions of a GNSS receiver and emergency beacon.
Two independent families of satellites, totaling 12 G2 satellites, are being procured by Thales Alenia Space in Italy and Airbus Defence & Space in Germany. With their first launches due in the middle of this decade, G2 satellites will be much larger than existing Galileo satellites, and they represent a major technical step forward.
Backwards-compatible with the current constellation, the G2 satellites will incorporate numerous technology upgrades, developed through EU and ESA research and development programs. They will employ electric propulsion for the first time and host an enhanced navigation antenna. Their fully digital payloads are being designed to be easily reconfigured in orbit, enabling them to actively respond to the evolving needs of users with novel signals and services.
The GNSS antenna farm on the ESTEC roof for live signal reception. (Photo: ESA)
Algorithms at the heart of G2
At the heart of satellite navigation is the ability of the satellites to determine where they are in space and the precise time down to a few billionths of a second as they transmit their navigation signals. The greater the precision of these factors, the greater the accuracy of the positioning for users, because Galileo receivers take the time between the signals being transmitted and received and turn it into a measurement of distance. Signals from four or more satellites are used to pinpoint the receiver’s location.
The Advanced Orbit Determination and Time Synchronisation (ODTS) Algorithms Test Platform evaluates the advanced software that will perform these calculations for G2. Developed by Thales Alenia Space through an EU Horizon 2020 project coordinated by ESA, the platform is now installed and running in ESA’s Navigation Laboratory. The laboratory is based at ESA’s technical heart, the ESTEC establishment in the Netherlands, where it is helping simulate how the G2 satellites will operate in practice.
“This platform represents a dynamic, highly-performing environment for algorithm experimentation in both real-time and post-processing modes, using either real or simulated data,” said Francisco González, the project’s technical officer. “It contains the algorithmic core of Navigation for Earth Orbit Determination and Identification Segment, NEODIS, which is the suite of algorithms developed by Thales Alenia Space for precise orbit determination of the satellite constellation. These algorithms allow the real-time estimation of orbits and clocks, as well as the generation of Galileo navigation messages, with an estimated accuracy in the tens of centimeters.”
“Important evolutions aimed at improving the estimation of clocks and orbits are being incorporated,” said Gustavo Lopez-Risueno, head of ESA’s Galileo G2 System Engineering Unit. These improvements include:
integration of composite clock algorithms for a stable and robust reference timescale
the dynamic modeling of satellite and station clocks based on their known behavior
the processing of auxiliary measurements such as laser range measurements, in which lasers are reflected off of satellites to measure their orbital position, delivering a ranging accuracy down to under a centimeter —significantly better than the half-meter or so available from radio ranging
intersatellite links.
The first G2 receiver prototype “breadboard” is now running in ESTEC’s Navigation Lab. (Photo: ESA)
First G2 receiver up and running
Another outcome of ESA-led H2020 research is also up and running in the lab: the first G2 receiver prototype “breadboard,” developed by GMV.
“Its development has been key to supporting the fine-tuning and assessment of some signal design options we are considering,” said Jose A. Garcia-Molina, who leads the G2 signal-in-space design at ESA. “Representative mass-market receiver processing architectures and techniques have been considered to assess the final benefits a user would receive.”
“This first G2 receiver breadboard allows us to better understand the performance G2 can achieve in different user conditions, such as the urban environments in which many Galileo users are based today,” said Miguel Manteiga Bautista, who leads ESA’s G2 Programme.
Meanwhile, two parallel activities have been started for development of the G2 test user receiver. The receiver will be taken outside the lab for various test activities ahead of the first G2 launches, and then again for in-orbit testing and validation.
Arctic Mass Rescue Operation in 2021 tested the rescue of 200 cruise-ship passengers using Galileo SAR. (Photo: EUSPA)
Search-and-rescue system also being updated
Nearby, in ESTEC’s Telecommunications Lab, is the G2 search and rescue test beacon simulator, now operational following site acceptance testing.
Like their first-generation predecessors, the G2 satellites will pick up emergency signals from beacons on Earth and relay them to a ground station, which will forward them to local emergency services. This contributes to emergency response saving more than 2,000 lives annually.
Emergency position-indicating radio beacon (EPIRB). (Photo: ESA)
The new simulator to model the performance of these emergency beacons was developed over three years by Thales Alenia Space, under ESA leadership through a G2G System Engineering Technical Assistance Activity.
“Equipped with state-of-the-art signal generation and processing capabilities, coupled with a 200 W amplifier, this new simulator offers several enhanced functionalities over first-generation simulators, including the transmission of the new G2 beacons developed by the Cospas-SARSAT organization and the simulation of complex operational scenarios of up to 15 parallel distress beacons,” said Eric Bouton, ESA’s Galileo search and rescue engineer.
“Its development is really a crucial step to gaining a better understanding of the in-orbit behavior of Galileo’s First and Second Generation search-and-rescue payloads with the new waveforms of the G2 beacons and with the growing beacon population and associated alert traffic,” Bouton said. “It will be used for an initial test campaign already in preparation, and in the future to support the commissioning of all new Galileo search-and-rescue systems.”
Galileo Control Centre in Oberpfaffenhofen, Germany. (Photo: ESA)
News from the European Space Agency (ESA)
Europe’s Galileo satellite navigation system continues to evolve. For the first time, end-to-end testing of the Galileo system demonstrated signal acquisition of an improved version of the Public Regulated Service (PRS), the most secure and robust class of Galileo services.
The system test extended from the Galileo Security Monitoring Centre in Spain and the Galileo Control Centre in Germany to a Galileo satellite at ESA’s ESTEC technical heart in the Netherlands, which then broadcast in turn to a user receiver.
Galileo’s PRS is an encrypted navigation and timing service for governmental authorized users and sensitive applications intended to remain available even in scenarios where other Galileo services might be degraded or jammed.
An initial version of the PRS signal has been broadcast by the satellites up to now, but as of next year the signals will evolve into an enhanced version known as Full Operational Capability Public Regulated Service (FOC PRS), which has been defined in close collaboration with the European Commission, the European Union Agency for the Space Programme (EUSPA) and the EU Member States.
The system’s FOC PRS capability is being enabled by an expansion of the Galileo ground mission segment — important upgrades of the Galileo Security Monitoring Centres (GSMCs) in St. Germain-en-Laye, France, and Madrid, Spain. These two sites oversee PRS provision and monitor its performance.
This coming version of the security monitoring centers, set for the following year, is being developed by an industrial consortium led by Thales Alenia Space in France.
Meanwhile the progressive deployment of remote system infrastructure is taking place over the course of this year, readying Galileo sensor stations to receive the upgraded PRS signals.
Upgrade of Galileo Sensor Station on Norway’s remote Jan Mayen Island in the Arctic Ocean. (Photo: ESA)
“To qualify, the FOC PRS Signal in Space required a major Galileo end-to-end test, demonstrating the compatibility of the space segment with the ground and user segments, called the System Compatibility Test Campaign (SCTC),” explained Federico Di Marco, ESA SCTC test director. “This test involved all Galileo key players spread across Europe, requiring close cooperation between the teams and months of preparation.”
The SCTC was led by an ESA engineering team from the agency’s ESTEC technical center in Noordwijk, the Netherlands supported by the System Engineering Technical Assistance industrial team led by Thales Alenia Space in Italy and in close collaboration with the operations team supervised by EUSPA.
“The testing involved three centers across Europe: the GSMC in Madrid, the Galileo Control Centre in Oberpfaffenhofen, and ESTEC hosting an actual Galileo satellite plus FOC PRS user receivers,” added Edward Breeuwer, who is in charge of Galileo system qualification at ESA.
FOC PRS test receiver developed by Antwerp Space under ESA contract. (Photo: ESA)
The FOC PRS signal was generated at the GSMC, sent to the German control center, then uplinked to the Galileo satellite at ESTEC, where the satellites are tested for space in advance of launch. The Galileo satellite then broadcast the FOC PRS signal in turn, to be picked up by a pair of receivers also on site: one developed by Antwerp Space under ESA contract and the other developed by Leonardo as part of a national development undertaken by Italy’s Competent PRS Authority, charged with overseeing the country’s PRS use.
“This marks the first time we have integrated such a nationally developed receiver within a system test activity,” said Fabio Covello, who oversees system security for ESA. “Having achieved this for PRS makes us very proud. We are confident that this experience can pave the way for future fruitful collaborations between the Galileo Programme and EU Member States, in the frame of specific tests to guarantee compatibility between the ESA-developed system and nationally developed PRS receivers.”
This successful outcome sets the scene for the PRS qualification at ground segment and system level, followed by operational validation planned in coming months, culminating in the first FOC PRS Signal In Space operational broadcast, in the course of next year.
FOC PRS test receiver developed by Leonardo as part of a national development undertaken by Italy’s Competent PRS Authority, charged with overseeing the country’s PRS use. (Photo: ESA)
The National Academies of Sciences, Engineering and Medicine (NASEM) has issued a report discussing whether a terrestrial wireless network proposed by Ligado Networks — and approved by the Federal Communications Commission (FCC) in April 2020 —will cause widespread interference to millions of GPS receivers.
The 77-page report reviews order FCC 20-48, which authorized Ligado Networks LLC to operate a low-power terrestrial radio network adjacent to the GPS frequency band. It considers how best to evaluate harmful interference to civilian and defense users of GPS, the potential for harmful interference to GPS users and DOD activities, and the effectiveness and feasibility of the mitigation measures proposed in the FCC order.
Section 1663 of the Fiscal Year 2021 National Defense Authorization Act called on the Department of Defense (DOD) to enter into an agreement with the NASEM to carry out “an independent technical review of the order and authorization [of FCC 20-48] to the extent that such Order and Authorization affects the devices, operations or activities of the Department of Defense.”
The committee formed in response met weekly from September 2021 to April 2022 to plan the study; receive briefings from experts and stakeholders; and review relevant reports, technical literature, and written submissions to the committee. In addition, a cleared subset of the committee received a set of classified briefings.
Most receivers in the clear,
high-precision and Iridium vulnerable
The committee found that most commercial and certified aviation GPS receivers will not experience significant harmful interference from Ligado emissions as authorized by the FCC.
However, high-precision receivers are vulnerable. That said, the committee claims current technology enables building a receiver robust to Ligado signals for any GPS applications.
“All GPS receiver manufacturers could field new designs that could coexist with the authorized Ligado signals and achieve good performance even if their existing designs cannot,” the report states.
For Iridium, the report states, “Iridium terminals will experience harmful interference on their downlink caused by Ligado user terminals operating in the UL1 band while those Iridium terminals are within a significant range of a Ligado emitter — up to 732 meters.”
For defense devices, operations and activities, the committee acknowledged that proposed mitigation procedures may be effective, but “may be impractical without the extensive dialog among the affected parties,” and mitigation “may not be practical at operationally relevant time scales or at reasonable cost. ”
This report concludes, “Spectrum real estate is a living asset and approaches must allow not only for a degree of confidence that a deployed system will not be compromised by future, unforeseen entrants, for a period of time, but also must recognize that capabilities will evolve.
“Some form of more definitive receiver standards and establishment of set time periods where adherence to those receiver standards will ensure successful operation for a frequency band’s incumbents and new entrants seem to be important tools in this regard.”
Responses to the Report
Ligado Networks
“Ligado’s licensed and authorized operations can co-exist with GPS. As the report concludes, the technology to enable compatibility has been in use for over a decade, and most consumer equipment, commercial general navigation, timing, cellular and aviation receivers will not experience harmful interference from Ligado’s operations.
“The NAS found what the nation’s experts at the FCC already determined: A small percentage of very old and poorly designed GPS devices may require upgrading. Ligado, in tandem with the FCC, established a program two years ago to upgrade or replace federal equipment, and we remain ready to help any agency that comes forward with outdated devices. So far, none have.
“Now that the review is completed, it is our sincere hope the DOD and the NTIA will stop blocking Ligado’s license authority and focus instead on working with Ligado to resolve potential impacts relating to all DOD systems, including but not limited to GPS. We will continue working with all involved stakeholders to determine a mutually beneficial way forward.”
U.S. Department of Defense
“National security missions that our service men and women execute every day are of the utmost importance and require a solution that ensures continued operations of critical systems.
“The NASEM study confirms that Ligado’s system will interfere with DOD GPS receivers, which include high-precision GPS receivers. The study also confirms that Iridium satellite communications will experience harmful interference caused by Ligado user terminals. Further, the study notes that when DoD’s testing approach, which is based on signal-to-noise ratio, is correctly applied, it is the more comprehensive and informative approach to assessing interference. The study also concludes that the Federal Communication Commission’s (FCC) proposed mitigation and replacement measures are impractical, cost prohibitive, and possibly ineffective.
“These conclusions are consistent with DoD’s longstanding view that Ligado’s system will interfere with critical GPS receivers and that it is impractical to mitigate the impact of that interference.
“DoD looks forward to continuing to work with the National Telecommunications and Information Administration, FCC and Ligado on this complex and important issue.”
GPS Innovation Alliance
Acting Executive Director of the GPS Innovation Alliance (GPSIA), Alex Damato, issued the following statement on the release of the National Academies of Sciences, Engineering, and Medicine study on reviewing the FCC’s Ligado Order:
“GPSIA and the GPS industry applaud the National Academies of Sciences, Engineering, and Medicine’s reaffirmation that Ligado’s terrestrial operations would have a harmful, real-world impact on the millions of federal and commercial users that rely on GPS, satellite communications, and weather forecasting services every single day. The report’s evaluation of the materials, developed over years of extensive and technically rigorous testing, demonstrates that Ligado would pose an unacceptable risk to services critical to safety-of-life operations, our national security, and our economy. It also builds on the broad consensus, including within fourteen federal agencies and departments, that Ligado’s proposed deployment would result in widespread interference to a substantial number of GPS receivers.
“Following the release of this study, GPSIA urges government action to address the imminent, but preventable, harm that would result from Ligado’s deployment.”
**Consistent with the terms of their litigation settlements with Ligado, GPSIA members Deere & Company and Garmin International, Inc. do not affirmatively endorse or oppose the deployment of Ligado’s proposed communications network.**
Keep GPS Working Coalition
The Keep GPS Working Coalition was formed in response to the FCC order. Spokesperson Dale Leibach issued the following statement.
“The NAS report, which follows the analysis of an immense amount of technical information and review by experts from a broad range of disciplines, highlights the fundamental flaws in the FCC’s Ligado decision. The order must therefore be vacated in its entirety, so that millions of GPS devices are protected from harmful interference caused by Ligado’s planned network.
“It is important to note that the potential for interference arises because Ligado proposed, and the FCC approved, a fundamental change in the use of the spectrum adjacent to the band used by GPS. With this approval, the FCC essentially authorized terrestrial operations in a satellite band without adequately considering the impact Ligado’s proposed operations would have on countless consumers, farmers, ranchers, pilots, boat owners, surveyors, construction companies and others.
“Furthermore, the FCC’s decision failed to take into account that there are more than a billion GPS receivers in use in the United States. The NAS report notes, and the Keep GPS Working Coalition acknowledges, that the majority of GPS receivers will not be harmed by Ligado’s operations. However, the massive GPS user base means that tens of millions of devices will suffer harmful interference if Ligado deploys its network. And, as stated in the report, the risk of interference is greatest for high precision receivers used in some of the most significant sectors of the U.S. economy.
“Lastly, the NAS report describes in detail the fundamental flaws in the safeguards the FCC adopted to address harmful interference where it occurs. It is simply not feasible, nor reasonable, to force first responders, farmers, boat owners, and the many other owners of equipment and machines that rely on GPS to police interference and bear the costs of addressing it. The best approach is to avoid interference altogether by rescinding Ligado’s authorization to conduct terrestrial operations under its satellite license.
“While Ligado may seek to cherry pick details to fit its misleading narrative, the truth is that this report validates the concerns raised by virtually everyone who has taken a position on this matter other than the FCC and Ligado itself. In particular, the report highlights significant national security concerns raised by the U.S. Department of Defense, which has said the FCC Ligado order will put missions and troops at risk. Likewise, the National Telecommunications and Information Administration, the Departments of Homeland Security, Transportation, Interior and Justice, the Federal Aviation Administration and other expert agencies all opposed the FCC order because of the substantial harm it would cause to critical civilian industries and users.”
Iridium
“The findings from NAS are consistent with the opposition from 14 federal agencies, more than 80 stakeholders, and Iridium’s concerns that Ligado’s proposed operations will cause harmful interference. The NAS study clearly demonstrates what the rest of the industry has known for years: the prior FCC order failed to fully consider the risk of harmful interference posed to mission-critical satellite systems. Iridium urges the FCC to take swift action to reverse the order before Ligado starts its technical demonstrations this fall.”
Satellite Safety Alliance
“The Satellite Safety Alliance applauds NAS for its comprehensive review of the record and findings that Ligado’s plan threatens vital GPS and satellite communications services. These findings align with the concerns across the vast federal and commercial user base of GPS, satellite communications, and weather forecasting services.
“This study is a reminder to our nation’s leaders and the Federal Communications Commission that Ligado’s harmful interference will disrupt day-to-day operations and cost billions of dollars to the consumers of these mission-critical services. The FCC must stay or reverse the Ligado order to address the imminent — but preventable — harm from the company’s proposed terrestrial network that it intends to deploy a test network this fall.”
National Telecommunications and Information Administration, U.S. Department of Commerce
“The Report from the National Academies indicates that Ligado’s terrestrial operations would cause harmful interference to GPS devices and that a number of the FCC’s mitigations would be practically unworkable. NTIA will review this detailed report more carefully, but we believe this offers the commission an important opportunity to reconsider Ligado’s authorization.”
