The fire at an electrical substation that shut down London’s Heathrow Airport, Europe’s busiest hub, for 18 hours on March 21 was one of many periodic reminders of the vulnerability of much of our critical infrastructure to a single point of failure (SPOF). A previous one was the CrowdStrike software bug that disrupted hospitals, airlines, banks and scores of other businesses and services around the world on July 19, 2024. Think of the impact on your home or business if the power went out for hours or days, and you did not have a backup generator and/or solar panels.
Our society’s and economy’s enormous reliance on global navigation satellite systems (GNSS) for positioning, navigation and timing (PNT) makes GNSS a huge SPOF. Hence repeated and urgent calls for increasing the resilience of GNSS and for developing complementary and/or alternative sources of PNT (or, to use the mantra of the National Space-Based Positioning, Navigation and Timing Advisory Board in recent years, to “protect, toughen and augment” GNSS).
Yet, at least two existing directives for strengthening PNT have not been implemented: The National Timing Resilience and Security Act of 2018 directed the U.S. Department of Transportation to ensure establishment of at least one terrestrial timing system as a backup for GPS signals, and President Trump’s January 2021 Space Policy Directive 7 ordered the entire U.S. government to “identify and implement … alternative sources of PNT for critical infrastructure, key resources and mission-essential functions.”
Awareness of the key importance and vulnerabilities of GNSS and of the urgent need to develop complementary and/or alternative technologies has reached the U.S. Federal Communications Commission (FCC). It dedicated its March 27 open meeting to hearing recommendations on “promoting the development of PNT technologies and solutions,” which it deems “crucial for national security, public safety and economic stability.”
The Notice of Inquiry (NOI) that the FCC issued in preparation for the meeting is a thorough and very useful compilation of relevant policies, programs, initiatives, reports and policy documents. I highly recommend reading it. Clearly, the commission did its homework — in the footnotes, it cited four GPS World articles among its sources — and demonstrated that it understands the key challenges for GNSS, the options for complementary/alternative systems and the relevant policy history. (See Dana Goward’s March 7 article on this at gpsworld.com/fcc-to-meet-on-gps-alternatives/) The NOI also posed 94 questions to which the FCC seeks answers.
The FCC meeting, available on YouTube, was of great importance to the whole GNSS/PNT community. While the commissioners did not vote to support any existing or proposed PNT system, they engaged in a broad discussion of the issues and heard petitions from NextNav and the National Association of Broadcasters (NAB) related to the provision of nationwide PNT services. NextNav requested spectrum for its project to work with telecom providers. NAB sought to accelerate and mandate implementation of the new ATSC 3.0 television broadcast format, which includes signals for its Broadcast Positioning System.
More than 20 years ago, in these pages, we referred to television broadcast signals as “signals of opportunity” that might be used for positioning, navigation and timing (PNT). Since then, several other signals with a different primary purpose have also been considered as sources of PNT, and some have been used routinely for years now, such as WiFi routers for indoor navigation. On Feb. 26, 2025, the National Association of Broadcasters (NAB) filed a petition for rulemaking with the Federal Communications Commission (FCC) for television to transition to a new standard, ATSC 3.0, that enables what they call Broadcast Positioning System (BPS), as a way to enhance GPS resiliency. I asked NAB’s chief technology officer and executive vice president, Sam Matheny, to answer a few questions about the organization’s proposal. In next month’s issue, we will present a different perspective on it.
Question: Briefly, what is the history of the relevant standards?
Answer: The Advanced Television Systems Committee (ATSC) is an international standards development organization. ATSC developed ATSC 3.0 as the “next-gen” standard, and the International Telecommunications Union (ITU) adopted it as a recommended digital broadcast standard in 2020. Broadcasters in the United States began experimental ATSC 3.0 transmissions in 2016, and there are currently more than 100 transmitters broadcasting in 80 markets. Other nations currently using or considering ATSC 3.0 include Brazil, India, South Korea, Canada, Mexico, Jamaica and Trinidad and Tobago. NAB’s petition to the FCC requests permission to fully transition to ATSC 3.0 by 2030.
Q: Briefly, what is the history of the BPS project/proposal?
A: BPS is a datacast application that uses ATSC 3.0. We at NAB authored a seminal paper on BPS in 2021 and built our first prototype in 2022. We put our second prototype on the air in 2023. We signed a Cooperative Research and Development Agreement (CRADA) with the National Institute of Standards and Technology (NIST) in 2024 and published our first joint paper earlier this year. The paper concludes that “the stability of BPS time transfer is comparable to or better than GNSS, making BPS a viable complementary PNT solution when GNSS is unavailable.”
Our petition to the FCC highlights a transition to ATSC 3.0 that enables the nationwide deployment of BPS.
BPS time is comparable to dual band GPS (L1/L2) time. The data are recorded as 10-minute averages. (Graphic: National Association of Broadcasters)
Q: What is the motivation for broadcasters to implement BPS? What’s in it for them?
A: BPS will further secure television broadcasters’ role in the fabric of U.S. telecommunications. We also witnessed the innovation around GPS, with more than 7 billion GPS receivers being built into myriad devices. We’d like to see BPS experience similar innovation, which will bring new business opportunities. We believe that there is an opportunity for a public-private partnership with the government to deploy BPS for economic and national security.
Q: What have your tests so far shown regarding the timing accuracy of your signals? How much more R&D is required?
A: We’ve completed a wide variety of testing over the years, but probably of most interest is the work done with NIST. They ran common-view experiments using the BPS signal transmitted from KWGN, a TV station in Denver. Receivers were placed at two different facilities equipped with NIST timescale. Their Boulder facility is 30 km away with non-line-of-sight (NLOS) propagation, and their Fort Collins facility is 106 km away with line-of-sight propagation. A 21-day-long test showed that the time deviation (TDEV) statistics were better than 2 ns for all intervals. NIST also tested the stability of the NLOS signal alone at the Boulder facility and found that the TDEV statistics were better than 3 ns.
Q: How can BPS help improve GNSS resilience and integrity?
A: BPS functions completely independent of GNSS, so in the event of an acute GNSS disruption or catastrophic outage, BPS can be a resilient secondary source of timing for critical infrastructure (CI). Integrating BPS into CI applications also makes GPS a less attractive target for intentional disruption. Additionally, being independent means that BPS and GPS can work together in a hybrid mode, where, for example, BPS can help detect jamming and spoofing of GPS.
Time deviation (TDEV) statistics of BPS is less than 3 ns, even for the NLOS test scenario. (Graphic: National Association of Broadcasters))
Q: What are the main benefits of BPS?
A: The key benefits of BPS include:
Existing infrastructure: BPS leverages existing television transmission infrastructure making it low cost and easy to deploy. There are more than 1,700 full power TV stations on the air today. These stations, considered critical infrastructure, are designed to stay on the air on a 24 x 7 x 365 basis, including during emergencies.
Nationwide coverage: Television transmissions are “high-power/high-tower” signals that provide nationwide coverage. Their broadcast power can be up to 1 MW and from towers up to 2,000 feet tall. The signals can be received NLOS, including indoors. The strength of these signals makes them difficult to jam or spoof.
Frequency diversity: Television in the United States operates on 210 MHz of licensed spectrum divided into 35 6-MHz channels. There are multiple stations/channels in each market, which offer geographic diversity along with frequency diversity.
Passive receivers: BPS is a broadcast service, just like GPS, and supports an unlimited number of simultaneous users with no bottlenecks or two-way connectivity dependencies.
Standards-based: BPS is based on ATSC 3.0, an ITU-recommended digital terrestrial broadcast standard with the support of a global community and supply chain.
Independent: BPS operates completely independent of GNSS and is a self-synchronizing network that does not rely on Internet or cellular connectivity.
BPS Installation at WHUT. TV transmission infrastructure is already built out. Only a BPS synchronizer and a reference timing source need to be added. (Graphic: National Association of Broadcasters))
Q: What are the main initial use cases? What are some additional ones that might come later?
A: The initial use case is providing resilient time to CI, which includes the power grid, cellular communications, and financial and data centers. A 2019 NIST study estimated the economic risk of losing GPS at $1 billion a day, and in 2024 a National Security Space Association study said the impact of a disruption or loss would be incalculable, so addressing this CI need is vital. Longer term, we see hybrid applications where BPS and GPS are used together. BPS can be leveraged for GPS health monitoring, which could be especially useful for transportation systems and can help identify and mitigate compromised GPS service. Going further, we see applications for positioning and navigation, plus other data services such as AGPS, GPS validation and RTK.
Q: How will the BPS service be monitored after full deployment?
A: NAB has developed a cloud-based network operations center (NOC) to monitor the health of the BPS-enabled TV stations. As part of our leader-follower construct, TV stations in the BPS mesh network measure each other’s emissions and send the data to the NOC, which can identify any issues.
Q: Which television manufacturers have expressed interest so far?
A: Hisense, LG, Panasonic, Samsung, Sony and TCL are already selling NEXTGEN TV sets. It is important to note that these televisions don’t use BPS. They ignore the BPS data and pay attention to the audio and video payload. The reverse is true for a BPS receiver; it ignores the audio and video and simply uses the BPS data. Both services rely on ATSC 3.0, but they use different parts of the signal.
BPS leader-follower mesh network example. WHUT is configured as a leader tower, and WNUV is set up as a follower tower deriving traceable time from WHUT’s signal. At full deployment, the remaining 12 towers in the DC-Baltimore area can also follow WHUT. (Graphic: National Association of Broadcasters))
Q: Have you talked to any GNSS receiver manufacturers yet?
A: Yes, we have healthy interest from numerous receiver manufacturers. They see BPS as a nice addition to their product lineups. Conversations have focused on performance and integration.
Q: Are there any technical, commercial or legal arguments against BPS? Do you anticipate resistance to your proposal from any quarters?
A: We have not heard any such arguments against BPS. To the contrary, people have been intrigued and supportive of the concept. Recognizing that BPS requires transition to ATSC 3.0, some groups have expressed concerns over the television set upgrade cost for low-income viewers. However, ATSC 3.0 receiver accessories retail for less than $100 today, and prices will drop further with scale.
Q: How does your proposal address backward compatibility?
A: NAB’s petition calls for all television stations to transition to ATSC 3.0 and for all television sets to be equipped to receive ATSC 3.0. As mentioned earlier, millions of NEXTGEN TV sets are already being purchased, so our petition aligns with natural product replacement cycles, including low-cost converters for older TVs.
Q: What is your arrangement and division of labor with NIST?
A: Our CRADA with NIST also includes Nexstar, one of our members. Nexstar operates KWGN where we deployed BPS. NAB provided NIST with BPS receivers and technical support. NIST scientists then performed independent measurements and analysis of BPS using their own techniques and processes. It has been a great experience for us to engage with and learn from the team at NIST. The effort has taught us a great deal about PNT and the capabilities of BPS.
Q: Now that you have submitted your proposal to the FCC, what do you expect to be the timeline for approval, implementation and adoption?
A: The FCC follows a notice-and-comment process for adopting changes to its rules, which can take anywhere from several months to more than a year. The FCC previously convened the Future of Television Initiative to investigate issues associated with the transition, which should give us a bit of a head start. In NAB’s petition, we ask the FCC to establish a timeline that would have the top 55 television markets fully transitioned to ATSC 3.0 by 2028 and the remaining markets by 2030.
Q: How can the GNSS/PNT community help this project?
A: First, it can support the transition to ATSC 3.0 because BPS relies upon it. We need a full transition to recognize its potential. Next, it can continue to collaborate with us. We introduced BPS at the DOT Roundtable in 2022. Since then, we’ve collaborated with the PNT community on research, scientific papers, product design and deployments. We’ve built BPS together, and now we need to deploy it together.
An early 1900s Italian folk song tells of a farmer walking into his fields at dawn to spread wheat seeds with his hand from a small bag.1 Farming has changed quite a bit since then. After remaining essentially unchanged for about 12 millennia, in the past century, it has been transformed by such innovations as tractors, electrification, chemical fertilizers and pesticides. In the 1990s, precision agriculture (PA) emerged. (This magazine produced a few supplements on the subject around 1999. If you still have any of them, please let me know.)
PA reduces inputs of water, fertilizer, seeds, pesticides and fuel and increases harvests by mapping variations in soil characteristics and plant health and then using those maps to adjust the inputs using variable rate technology on sprayers. It also ensures that no part of a field is sprayed twice or missed and greatly reduces overlap in seeding and tilling. Double spraying is costly and wasteful; missing a row when spraying pesticide can cause pests to concentrate there and then spread, nullifying a whole spraying operation.
The data for the maps are gathered from sensors on tractors and other farm machinery in the fields, as well as by aerial platforms — nowadays, mostly UAVs. GNSS receivers are essential in guiding the farm machinery. The required accuracy depends on the crop but is typically at the centimeter to decimeter level.
Increasingly, farm machinery also incorporates a variety of other sensors, both to compensate for GNSS outages and to minimize the risk of collisions, such as when a cow crosses the path of a tractor. To maintain navigation during GNSS outages, inertial navigation is used. For obstacle avoidance lidar, radar and stereo vision cameras are used to measure the distance to the object. (Both challenges — navigation in GNSS-denied areas and obstacle avoidance — and their solutions are very similar to those encountered with autonomous vehicles on roads.)
In-cab displays enable growers to monitor their progress in real time. They often also download the data and maps to a laptop to better identify missed spots or areas with special issues and to plan their next task.
Manufacturers of PA equipment compete in a global market. Some challenges are the same everywhere, while some are specific — such as strong ionospheric scintillations in Brazil or antiquated agricultural practices in Japan’s Furano region. For this year’s cover story on PA, I discussed these challenges and the latest generation of farming hardware, software and services with
■Kirstin Schauble, director of systems engineering, ANELLO Photonics
■ Joey Koebelen, founder and CEO, Deep Sand Technology
■ Chad Huedepohl, PA portfolio manager, autonomy and positioning division, Hexagon
■ Ken MacLeod, director of product management and Gordon Echlin, director of business development, Calian GNSS.
This article contains a few excerpts from those interviews. I also received case studies from AgLeader Technology, ComNav Technology and Harxon Corporation.
ANELLO Photonics makes silicon photonics optical gyroscopes, which enable accurate dead reckoning without GNSS and are targeted mostly at the autonomy market. (Anello means ring in Italian, which reflects the nature of the company’s technology and the Italian-American background of its CEO, Mario Paniccia.) Because ANELLO specializes in high precision in situations with obstructed GNSS signals, orchard cultivation is one of the agricultural practices in which it specializes. “Orchards have high-value crops, such as almonds or walnuts, and you’re driving your tractor between very narrow rows with trees completely covering the sky above you,” Schauble said. “Our job is to replace that GNSS input with our inertial navigation system (INS) input.”
Deep Sand Technology — in partnership with GEODNET, the largest real-time kinematic (RTK) network in the world — sells affordable RTK corrections to farmers. It also maintains and troubleshoots the system, compensated by the network’s cryptocurrency. “We handle the blockchain and use it for maintenance,” said Koebelen. “We have someone that checks every day and makes sure that the bases are up. We do the support on it. Instead of charging for that, we take the tokens; that’s just our part of the program, and they get free RTK.” Koebelen, who is also a peanut farmer, adds: “You can trust anything that we sell because it has been tested and used by a farmer and is supported by a farmer.”
Hexagon, a very large company, makes a wide range of sensors that capture and display data about physical reality. Its latest contributions to PA include the TerraStar-C PRO and the TerraStar-X Corn Belt corrections services, which incorporate improvements in ionospheric resiliency. “Especially in the Brazil market, some growers were often experiencing hours of downtime due to ionospheric scintillation,” said Huedepohl. “With the ionospheric enhancements that we’ve added, that downtime now is down to just a few minutes here and there.” He also cites safety enhancements for the autonomy market, such as dual antenna solutions and geofencing.
Calian GNSS is a global supplier of technical solutions, services and products to the space communications, defense, wired and terrestrial wireless, manufacturing, GNSS, agricultural technology and nuclear industries. The company’s recent entries in the PA market include GNSS antennas with lower elevation gain and extended filtering. “Our GNSS agriculture antennas support centimeter level precision, have best in class lower elevation angle gain enabling L-Band correction reception (at northern and southern latitudes), and have eXtended Filtering (XF), which creates very deep attenuation of nearby out of band radio frequency signals,” said Echlin. “Having a digital signal from the antenna to the smart ag controller simplifies and reduces the cost of the installation,” said MacLeod.
Ag Leader, founded in 1992 and focused exclusively on precision farming technology, offers a complete line of systems that integrate with existing farm machinery. In February, it introduced the RightPath passive implement steering solution to alleviate the problem of trailed implements drifting off the guidance line by up to 10 inches or more, even when farmers utilize auto steer and on flat ground. RightPath keeps implements centered on the guidance line, ensuring precise input placement and increasing operational efficiency throughout the growing season while minimizing crop damage, yield loss and operator challenges, Ag Leader said. To utilize RightPath, both the vehicle and the implement require Ag Leader’s GPS 7500, but only the vehicle needs to be equipped with TerraStar-C, TerraStar-X, or RTK. RightPath will be available in late fall 2025 through a single purchase unlock and without any recurring subscription fee.
ComNav Technology is an original equipment manufacturer (OEM) that develops and manufactures GNSS OEM boards, receivers and solutions for high-precision positioning applications worldwide. Japan’s Furano region is renowned for its vast farmland and abundant agricultural resources. Still, it is challenged by traditional manual driving methods that provide insufficient accuracy, low efficiency, and operator fatigue during prolonged tasks. To address these issues, ComNav introduced the AG502 autosteer system, which integrates satellite reception, positioning, navigation and autonomous driving. It is compatible with a variety of mainstream tractors on the market and is suitable for a wide range of agricultural tasks such as ridging, seeding, spraying and harvesting, ComNav said. In the Furano project, the AG502 demonstrated its versatility through its successful deployment on a transplanting machine.
Harxon Corporation makes GNSS positioning antenna solutions. The company has been collaborating with Brazilian agricultural navigation solutions and systems developer Agres to integrate Harxon’s Smart Antenna into the AgresAutopilot System. This secure and robust agricultural navigation solution has been widely adopted by Brazilian agribusinesses to provide automatic steering on straight or curved parallel lines to assist with such field operations as preparing the soil, planting seeds, cultivating the plantation and harvesting the crops. These systems are suitable for various brands and tractor/vehicle models such as Kuhn, John Deere, Valtra, Massey Ferguson, New Holland, LS, Landini, Jacto and others.
To maximize an operator’s turning accuracy and efficiency, Ag Leader introduced TurnPath, hands-free steering for automatic, repeatable end-of-row turns. (Photo: Ag Leader)
Challenges
The key technical challenges faced by PA systems include minimizing multipath and RF interference and monitoring the positions of implements relative to the tractor. “Agriculture requires positional accuracy, so mounting an antenna on a farm machine is not a trivial matter,” said MacLeod. “On metallic machinery, radio frequency surface currents and reflections (multipath) will degrade the antenna radiation pattern, and RF noise coming from other electronics on the machine can interfere with GNSS.” Additionally, because most GNSS applications now are full band, “the challenge is designing antennas that are small and full band, and which also reduce local multipath on the machine.”
Regarding the position of the implements, MacLeod said: “Many agricultural applications use the moving base technique to estimate a precise heading which can be used to monitor pass to pass overlap. Calian GNSS have smart antennas that support the moving base application.”
Accuracy and Reliability
Nearly all PA practices require RTK, which gives repeatable accuracy of 1 cm to 2 cm. “I have this conversation daily with farmers,” Koebelen said. “All crops or farm practices benefit from RTK, even if you’re just doing hay work — whether you’re planting or harvesting. We can’t control the weather, commodity prices, or fuel prices but we can reduce input costs. So even if you’re just tilling, GEODNET RTK will pay for itself and is better than using traditional autosteer, because you’re eliminating all overlap.”
Additionally, farmers need reliable repeatability, even from one season to the next, to be able to return to the same spot to harvest what they planted. “Peanut farmers may plant with RTX or SF3, but satellite-based corrections, even higher precision ones, didn’t provide them enough repeatability to come back to harvest,” said Koebelen. “So, they still had to adjust their lines or hand-drive them. If the spacing between passes are off by even two to three inches, you’re going to lose peanuts. That’s why peanut farmers — as well as growers of potatoes, cucumbers, and other crops — need RTK.”
Once they enter a GNSS-denied area, such as an orchard, farm machines will need a dead reckoning capability that can keep them within a 20 cm to 30 cm error, said Schauble. “This is typically posed as a cross-track error. Errors in the direction of the distance traveled are slightly less important, because you can tell based on visuals when you exit a row.”
Growers think of reliability, accuracy and repeatability in terms of whether they can count on a system to do what they are asking it to do, Huedepohl explained. “They think about all those things. They do not necessarily focus on one thing versus another.”
Retrofitting
While many agricultural systems are proprietary, there is also a lot of mixing-and-matching and retrofitting going on. More than 90% of new tractors come with factory-installed guidance, but some growers want to retrofit new receivers on their machines, either because they did not have them or to upgrade. On some machines, it is possible to feed better positioning data — for example, integrating GNSS and inertial navigation — into the port that previously took in only GNSS data, using a standard NMEA format.
“It’s a simple plug-and-play to exchange someone’s GNSS receiver with our INS solution. Obviously, they need to do some testing to optimize placement, installation and stuff like that,” said Schauble. “Many companies are retrofitting existing tractors with an autonomy stack. They take commercial off-the-shelf (COTS) systems, such as ours, or a lidar or a camera, and retrofit a tractor. That’s their business model.”
The AG502 autosteer system being tested and calibrated on a transplanter in Japan’s Furano region, which is renowned for its vast farmland. (Photo: ComNav Technology)
Additional Sensors
Among the additional sensors often used are wheel odometers. “Without the wheel speed, you’re relying heavily on accelerometers,” said Schauble. “Growers cannot afford to pay $100,000 for a reference-grade system. The navigation systems for these applications use MEMS accelerometers, as we do. So, wheel speed aiding is extremely important to maintain that distance traveled.”
Integrating GNSS and inertial measurement units (IMUs) has long been standard. Increasingly, this integration is done inside an antenna, called a smart antenna. Calian, among others, does that. “We also have smart antennas that employ the L1-L5 observation pair rather than L1-L2, since the L5 signal is stronger and performs better under cover,” said MacLeod. “L5 uses an enhanced signal architecture with 10x faster chipping rate (10.23 MHz) offering more precise standard localization and improved multipath mitigation for reflections exceeding 29.3 m.”
Corrections
Corrections have also been key to the evolution of PA. A reference base station can provide 1-inch accuracy for up to 21 miles, degrading beyond that distance. It needs a WiFi network to communicate, so farmers often place the base station near their home and connect it to their home network. “We haven’t found an internet connection that isn’t quick enough to handle that,” said Koebelen. “From there, you can use your hotspot with a SIM card on your phone, and it’s like texting, so it will not drop like with voice calls. We haven’t run across rural areas where cell coverage is the limiting factor.”
RTK adoption is growing among farmers. “In the past, many people did not want to use RTK, because it was not very affordable nor easy,” Koebelen said. “However, now that we have these networks [such as GEODNET], you’re going to see a lot more people rely on the precision of RTK and you’re going to see many new products come out. Right now, even John Deere, Trimble and other major brands that are more expensive are trying to make the tier below RTK more affordable or easier to get — for example, RTX, SF3, the satellite-based corrections.” GEODNET’s network is growing rapidly, he said, “because our price for RTK is lower than Trimble’s or John Deere’s basic entries, which use free satellite signals that drift throughout the day.”
Huedepohl agrees that RTK has improved while prices have dropped significantly. “Earlier in my career,” he said, “RTK positioning was very expensive and satellite-based augmentation systems (SBAS) were not as stable. Also, RTK systems and such used a single constellation for the longest time. We started adding in GLONASS and then positioning network (Ntrip) corrections, which gave us a lot more robustness.”
Precise point positioning (PPP) has also improved. It used to have convergence times of up to 45 minutes. “Then, you would drive underneath one tree on the edge of a field, and you had to start all over,” Huedepohl recalls. “That did not sit well with farmers, so PPP corrections struggled to take off. Because of those early experiences, it took a long time for the market to start to accept the newer PPP models that we’ve seen in the past seven or eight years. Now there are farmers who enjoy the reliability of those PPP corrections.” The convergence time for one of Hexagon’s PPP services, TerraStar-C PRO, is often less than five minutes, according to Huedepohl. “We have a fast startup time. So, if the tractor was shut down, already converged and you turn it back on, most people are going to be reconverged in just a minute or two.”
Harxon enables autonomous agricultural applications with GNSS antennas, smart antennas and wireless data radios. (Photo: Harxon)
Division of Labor
The division of labor between manufacturers of PA equipment depends, in part, on whether a system is a retrofit or built from scratch. “If you are, let’s say, John Deere, and you own the entire autonomy stack within this tractor, then you can take our INS solution, add cameras, maybe add a lidar, and you can have your own fusion of those sensors,” said Schauble. “We have our own sensor fusion with IMUs and GPS. The tractor’s autonomy stack can do the sensor fusion with our output and other visual sensors, such as cameras and lidars.”
“Dealerships want their tractors to be known as having the highest tech,” said Schauble. “For a dealership to offer our state of the art, autonomy-enabling technology would be a huge benefit to them.”
Another differentiator is whether a factory-installed system is an OEM or branded. “We’ve been providing NovAtel branded receivers to AGCO for many years, through their channel, both factory-installed and aftermarket. Some of the others, such as CNH, are white labeled, so it would just say ‘Case-IH’ or ‘New Holland’ and have no Hexagon markings.”
Whether OEM or aftermarket, most manufacturers have some type of proprietary integration. “There are products that are just NEMA; they are typically at the lower end and priced much lower,” said Huedepohl. “The higher performing flagship products out of everybody’s portfolio are usually doing a more customized integration.”
Echlin has a similar perspective: “We provide products to OEMs who designed our products into their machinery. There are also system integrators and aftermarket system providers that use our smart antennas.”
According to Harxon, one reason for the success of its smart antenna in the agriculture market, especially for autonomy users, has been its ease of integration and high performance. “GNSS positioning is just one part of an autonomous system, and the autonomous integrators don’t necessarily have resources or expertise to develop an OEM component portfolio. Therefore, it’s a timesaving and cost-effective choice to directly integrate a smart antenna into an autonomous system.”
1 “Di buon mattino il contadino va nei suoi campi a seminare il grano. Ha un sacchettino e ci tuffa la mano.”
An exclusive interview with Joey Koebelen, Founder and CEO at Deep Sand Technology. Read the full story and additional exclusive interviews here.
When and why did you found Deep Sand Technology?
About five years ago. I was looking for an affordable RTK system. I was on a smaller farm and had older equipment. I did peanuts. I needed 7-inch accuracy. I looked around. It was $20,000 a system, plus yearly fees, and they didn’t always work on older tractors. So, I came across the FJDynamics system, and I was the first person in the United States to buy it. I was blown away, because it was a third of the cost of other RTK autosteering systems and great quality. John Deere, Trimble, Outback and Ag Leader asked me what I thought about it and, at the time, the only thing I lacked was some interface changes to make it more user friendly.
They asked me if I wanted to be an engineer for them to make it happen quicker and work directly with the other engineers. So, I did that for about nine months, and then really saw the opportunity of an affordable high precision auto steering system that could really change the world for farmers. For once, the technology was simple enough to be sold remotely. So, I started selling systems across the United States. Once guys tried it, they were blown away. The also realized that I support everything. Who knows how to support a farmer better than a farmer? So, I built my team directly from that.
Then, as we kept growing, we got in partnership with GEODNET because we had to use radio bases, which were nice but were limited and a little hard to troubleshoot remotely sometimes. Once I heard that they were trying to get RTK in rural areas, it was a no brainer, because that’s where our farmers are. It would help farmers. It got more guys into high precision RTK because there are many farmers out there using autosteer, but they never could afford to use true RTK precision. Now that we’re offering that affordable cost, we can help farmers save time and money.
We’re also going to follow the guidelines on some of these environmental practices that are being pushed. Deep Sand Technology will always sell precision agriculture technology. Anything that we sell you can trust because it has been tested and used by a farmer and is supported by a farmer. We always offer a buyback guarantee.
As a peanut farmer, what was your accuracy requirement?
I needed repeatable 1-inch accuracy, which required RTK. Peanut farmers may plant with RTX or SF3, but satellite-based corrections, even higher precision ones, didn’t provide them enough repeatability to come back in to harvest. So, they still had to adjust their lines or hand-drive them. If the spacing between passes are off by even two to three inches, you’re going to lose peanuts. That’s why peanut farmers — as well as growers of potatoes, cucumbers, and other crops — need RTK.
How dense does the network of base stations need to be?
GEODNET is the largest RTK network in the world. They want to expand into rural areas. As we get customers in these rural areas, if they don’t have a base there, we’re able to offer them one. If they keep power and WiFi to it, they get free RTK. That’s going to strengthen our coverage across the United States and the world.
One base can cover up to 21 miles. So, my base covers me and anyone in that area. That’s for 1-inch accuracy but you still have precision accuracy outside of 21 miles.
There are many overlapping circles, each with a 21-mile radius?
Yep. As I said, that is for 1-inch accuracy. There are many things that don’t always need that accuracy. I have guys that will use it up to 40 miles from the base station. There are 10,000 base stations across the world. We enter the location on a map and often, right now, if it’s a rural area and there aren’t a bunch of bases in there, we include one in their package. That way we can keep strengthening the RTK network.
In the past, many people did not want to use RTK, because it was not very affordable nor easy. However, now that we have these networks, you’re going to see a lot more people rely on the precision of RTK and you’re going to see many new products come out.
Besides peanuts, which crops need the highest accuracy? What are the next two or three levels in accuracy requirements?
I have this conversation daily with farmers. All crops or farm practices benefit from RTK, even if you’re just doing hay work — no matter whether you’re planting or harvesting. We can’t control the weather, commodity prices, or fuel prices but we can reduce input costs. So even if you’re just tilling, tem, like RTK, will pay for itself and is better than using traditional autosteer, because you’re eliminating all overlap.
USDA is spending hundreds of millions of dollars to promote farm practices that need RTK. I’m working with the USDA right now to release these programs that express why RTK plays such a factor, because it’s huge. For example, how do you reduce your chemical and fertilizer costs? The simplest way is to not overlap. Also, with accurate repeatability you can take soil samples and map them. So, now guys can adjust their fertilizer or the chemical rate off these samples, but to do that efficiently they need RTK.
The need for WiFi puts farmers are at the mercy of the big telecom companies.
You don’t need WiFi in the field. You need WiFi for the base station to communicate and we haven’t found an Internet connection that isn’t quick enough to handle that. From there, you can use your hotspot with a SIM card on your phone, and it’s like texting, so it will not drop like with voice calls. We haven’t run across rural areas where cell coverage is the limiting factor.
So, there’s enough coverage everywhere for the base station to get online.
A base station normally has a Starlink connection or whatever Internet connection you have at the house. Starlink is pretty popular nowadays.
How is the adoption of RTK going? Is GEODNET the 800-pound gorilla right now?
Yeah, that’s my opinion. Right now, RTK is getting more adopted, because even John Deere, Trimble and other major brands that are more expensive are trying to make the tier below RTK more affordable or easier to get — for example, RTX, SF3, the satellite-based corrections. We’re having a huge trend, because our price for RTK is lower than Trimble’s or John Deere’s basic entries, which use free satellite signals that drift throughout the day.
Drones are becoming a big thing. I’m starting to see in-row cultivators. There are snowplows, a lot of autonomous options. Plus, I see a lot of construction surveying. We’re about to jump off into that. GEODNET is at the front because one their goals, to offer affordable RTK, aligns with farmers and nobody else really has that.
What about the blockchain aspect of GEODNET?
I think it’s a good program. Farmers would rather have the RTK. We handle the blockchain and use it for maintenance. We have someone that checks every day and makes sure that the bases are up. We log people in if they need another log in. We do the support on it. Instead of charging for that, we take the tokens; that’s just our part of the program, and they get free RTK. It’s a good program and it incentivizes other people. Farmers are skeptical when you start talking about blockchain or crypto. We want them to understand why the RTK data is important.
An exclusive interview with Ken MacLeod, Director of Product Management and Gordon Echlin, Director of Business Development at Calian GNSS. Read the full story and additional exclusive interviews here.
What are the main challenges and issues for GNSS antennas in agriculture, as opposed to, say, surveying or construction? How do your products address them?
KM: Many agricultural applications use L-band GNSS corrections, which are broadcast from a geostationary satellite (located above the equator). If you’re close to the equator, the geostationary satellite is roughly above you. However, as you move away from the equator, the look angle gets lower and lower. In Canada and northern Europe for example, the look angle is low, and the signal path is longer than at the equator. Therefore, you need an antenna that has low elevation angle gain. Calian has several antenna products that have great low elevation angle gain.
One of the other differences is antenna mounting. Agriculture requires positional accuracy, so mounting an antenna on a farm machine is not a trivial matter. On metallic machinery, radio frequency surface currents and reflections (multipath) will degrade the antenna radiation pattern, and RF noise coming from other electronics on the machine can interfere with GNSS.
Most GNSS applications now are full band. The challenge is designing antennas that are small and full band, and which also reduce local multipath on the machine.
You mentioned that these antennas are small, but on a tractor, size, weight and power (SWAP) is not a big concern. So, why is size an issue?
KM: As you mentioned, for most large farm machinery, SWAP it’s not a problem. It is, however, for UAVs, which are being used to spray crops with herbicides and pesticides where a small light weight antenna is beneficial.
Do most farm machines now use two antennas for their heading?
KM: Many agricultural applications use the moving base technique to estimate a precise heading which can be used to monitor pass to pass overlap. Calian GNSS have smart antennas that support the moving base application.
You also need to sense obstructions on the ground, but I guess that somebody else deals with integrating other sensors, such as inertial ones, with GNSS.
GE: Calian GNSS smart antennas (GNSS receiver built-in to the antenna) have built in Inertial Measurement Units (IMU). We also have smart antennas that employ the L1-L5 observation pair rather than L1-L2, since the L5 signal is stronger and performs better under cover. L5 uses an enhanced signal architecture with 10x faster chipping rate (10.23MHz) offering more precise standard localization and improved multipath mitigation for reflections exceeding 29.3m
[Shared a screen with eight antenna models.]
What are the key characteristics of your antennas regarding precision agriculture?
GE: Our GNSS agriculture antennas support centimeter level precision, have best in class lower elevation angle gain enabling L-Band correction reception (at northern and southern latitudes), and eXtended Filtering (XF), which creates very deep attenuation of nearby out of band radio frequency signals.
KM: We have deep GNSS antenna knowledge and we know how to integrate receivers into antennas. So, out of the box, you can buy from Calian GNSS a fully functional smart GNSS antenna that outputs a digital signal. Having a digital signal from the antenna to the smart ag controller simplifies and reduces the cost of the installation. Many customers, especially in the autonomy space, know software very well but are not hardware specialists. We remove the problem of integrating an antenna and a receiver into their product, and customers can start solving their PNT application.
GE:There are many startups that don’t understand RF; there are not enough GNSS and RF guys around. Let us take care of the antenna rand receiver integration. Then customers just take the RS-422 or RS-232 signals and read the receiver’s messages or NMEA data and use our ROS2 driver.
Does the installation take place at the factory or at the dealership, or do growers do it themselves?
GE: We provide products to OEMs who designed our products into their machinery. There are also system integrators and aftermarket system providers that use our smart antennas. We offer advice and consulting services to customers who design the products and do the installs and ask us to recommend where they should place the antenna to get the best performance. Let’s say that you have a large metal roof with a patch antenna. The GNSS signal can bounce off the roof or run on top of a metal surface and reach the antenna and interfere with the direct signal. To mitigate these problems, we often provide installation advice.
What are some of the GNSS receivers that you use?
GE: Calian GNSS provides smart antenna products with Septentrio, uBlox or ST-Micro receivers built in. Our ceramic patch antennas typically use a ZED-F9P, which you can use as either a base or a rover. It can take in PPP-RTK corrections through L-band signals. We can also take commercial RTK services, such as those from Point One Navigation or from Swift Navigation. Or, if you have a big farm and many different pieces of equipment that need precise positioning, you could set up your own RTK base, which provide precise positioning for a radius of up to ~20 kilometers from the base station. The point is that we support correction services and are not bound to one service provider.
An exclusive interview with Kirstin Schauble, Director of Systems Engineering at ANELLO Photonics. Read the full story and additional exclusive interviews here.
What crops are we talking about? What positional accuracy do they require? What accuracy can you achieve?
Where ANELLO has been of use in agriculture, typically we’re talking about orchards or dairy farms, because these are the use cases where you have limited open sky view, or, in some cases, no open sky view. For the orchard case, you have high-value crops, such as almonds or walnuts, where you’re driving your tractor in between these very narrow rows with trees completely covering the sky above you. So, in this case, there’s hardly any GPS availability and certainly no RTK-level GPS, which poses a challenge for autonomy in these types of agriculture environments.
Some of the stricter position requirements are on the order of 20 cm to 30 cm, which is approaching RTK-level accuracy. You can’t achieve this with just standard GPS, even under open sky. In those cases, you really need RTK-level GPS and open skies before you enter the orchard’s GNSS-denied area. As you know, RTK gives you 2 cm accuracy.
Then you need to have a dead reckoning capability that can keep you within a 20 cm to 30 cm error. This is typically posed as a cross-track error. Errors in the direction of the distance traveled are slightly less important because you can tell based on visuals when you exit a row. However, while you’re in the row, you don’t want to run into a tree, so that cross-track error is important.
Plus, you can use wheel odometry for the direction of travel.
Yep, exactly. We also found a lot of success in those cases where you have our optical gyro technology plus the wheel speed odometry. Without the wheel speed, you’re relying heavily on accelerometers. Growers need small and cheap systems. They cannot afford to pay $100,000 for a reference-grade system. So, they are probably going to use MEMS accelerometers, which is what we use.
So, wheel speed aiding is extremely important to maintain that distance traveled.
So, the positional accuracy requirement is typically 20 cm to 30 cm and you can achieve that with your system.
Correct.
How much does your application cost? Is it installed at the factory, at the dealership, or by the grower? What’s the learning curve for the grower?
Our main innovation has been in the gyroscope space. Early on in our development of silicon photonics optical gyros, we realized that the main use for them is in navigation for autonomous platforms — such as cars, UAVs, and autonomous boats. Our gyro isn’t something that we can just sell into a market like agriculture on its own. Tractors typically just have a GPS input, then the autosteering system takes care of the rest.
So, our job is to replace that GPS input with our INS input. It uses GPS under perfect open sky. However, when you don’t have those conditions, it integrates the optical gyro and performs high-end dead reckoning, also using the wheel speed odometry, and our advanced sensor fusion engine. We have put years of pretty smart brains towards getting that engine fine-tuned, specifically for the high-end gyro that we have.
It’s very difficult to be an algorithm engineer where you have just a MEMS gyro, MEMS accelerometers, and no real speed data. There’s not much you can do with that. But if you have the high performance of optical gyroscope technology, it enables you, as an algorithm engineer, to dead reckon very accurately without GPS. Then you integrate all that and feed it into the GNSS input on the auto steer system.
Who does that integration?
We do all the inertial measurements internal to our system. We read in the wheel speed. We do all the sensor fusion with GPS. Then, we output the tractor’s position, which is far more accurate than it would be just using GPS. So, we do everything that a typical GPS receiver would do, and we send out a position, velocity and attitude.
Who does the integration depends on whether it is a retrofit or built from scratch. If you are, let’s say, John Deere, and you own the entire autonomy stack within this tractor, then you can take our input, add cameras, maybe add a lidar, and you can have your own fusion of those sensors. We have our own sensor fusion with inertial measurement units and GPS. The tractor’s autonomy stack can do the sensor fusion with our output and other visual sensors, such as cameras and lidars. That’s typically what a full autonomy stack might look like.
However, some farmers just have standard, manually driven tractors but want to know where their workers are and want to document exactly which rows were sprayed, because if you skip a row pests can find their home in those trees and then spread from there. So, if you miss a row, it’s as if you had not sprayed the entire acre or the entire orchard. It’s pretty high stakes.
Also, they often drive at night. It’s a difficult job. They might have to go refuel, then come back and start on the wrong row.
The distance between rows is going to be a lot more than 30 cm, so you don’t need that accuracy to identify a row.
Totally. I’m getting into the autonomy use case, for which you need that 20 cm to 30 cm accuracy.
For the documentation use case — where you just retrofit a tractor with our technology — all this data is saved, then maybe they download the file to their laptop and see exactly which rows were sprayed. Maybe they see that a few rows were missed, so they can go back and spray them the next morning. We found that human error, such as missing a row or double-spraying one, is a big problem. It is true that, for that purpose, you don’t need 20 cm to 30 cm accuracy, but you’d really like to have at least 1 m to 2 m accuracy, which you would not get under heavy canopies without some sort of dead reckoning.
So, you feed the position, speed, and attitude from your integration into the pre-existing input that was made to receive a signal from a GNSS receiver?
Yeah, that’s exactly right.
Is it standard NEMA messages?
Many of these autonomy systems are basically hard coded to accept these messages straight from a GPS source. We put our inertial solution into these messages so that they can be easily ingested by pretty much any autonomy stack that would be using GPS. It’s a simple plug-and-play to exchange someone’s GPS receiver with our INS solution. Obviously, they need to do some testing to optimize placement, installation and stuff like that, but in terms of interfacing, it’s a plug-and-play switch.
You just used the pronoun “they.” So, who is “they”? Do you have privileged relationships with some of the large manufacturers, such as John Deere? Do you sell your box to dealerships, who then sell it to farmers? Or can farmers order it directly from you and plug it in?
Great question. Unfortunately, I can’t give names of customers, but typically the earliest entryway into this market is companies that can easily adopt new technology and who are innovating very heavily in the autonomy and ag space. There are several players in that arena and we’ve found a lot of success there. Many companies are retrofitting existing tractors with an autonomy stack. There are companies that do retrofitting. They take commercial-off-the-shelf (COTS) systems such as ours, or a lidar or a camera, and retrofit a tractor. That’s the business model for some companies.
Others are building, completely from scratch, an autonomous robot that is performing certain tasks, such as spraying or harvesting inside an orchard.
In both of those cases, those who buy your products are integrators who build and sell systems, not dealers or end users.
Yes, they either build systems or retrofit tractors. The dealership is a very good option, because the manufacturers of these tractors have skin in the game for staying ahead on autonomy. They want their tractors to be known as having the highest tech. So, for a dealership to offer our state of the art, autonomy-enabling technology would be a huge benefit to the company.
We have field applications engineers involved — either training dealerships to retrofit or with the integration. So, we might be involved in that integration. So far, however, the earliest market for that has been with companies that are integrators themselves.
When you’re talking about autonomy, are you talking about totally autonomous machines that roam the fields without a driver in the seat or about steering tractors that still have drivers to monitor them and can intervene as needed?
My understanding of how autonomy transforms an agricultural machine is that you start with manual drivers and then move toward autonomy. It is similar to the addition of advanced driver assistance systems (ADAS) to passenger vehicles. Eventually, you have no driver.
I would imagine that farmers who own a tractor and are trying to retrofit — or, maybe, a company like John Deere that sells tractors — might start off with an autonomous tractor that still has a steering wheel and a seat but eventually could just drive itself, once that trust is gained. Trust is the key word. For many of these farmers, it’s hard to go from everything being completely manual and in their control to fully trusting autonomy.
In some cases, that trust can be gained through full testing, over and over again, and continuous improvements. It’s possible for a farmer to go from fully manual to fully autonomous immediately, but I imagine that there’s a transition period during which tractor manufacturers are still adding steering wheels while also integrating more and more autonomy in their tractor systems.
In the agricultural environment, besides INS, which sensors — such as radar, lidar, cameras, and odometers — are most useful? For example, for obstacle detection.
Besides knowing where you are, the most important thing in autonomy is obstacle detection. If a dog runs into the orchard, you want to be able to stop. You can do this with either lidar or radar, which are both depth sensors.
Cameras, plus AI, enable you to identify objects.
You would want a stereo vision camera, so that you can tell the how far the object is. Every company has a different approach to this. Ideally, you have every sensor, but it’s a cost of computation tradeoff. Everyone takes that tradeoff differently, but it’s some combination of cameras, lidars, and radars.
Do you integrate other sensors — such as lidar or cameras — with your inertial systems?
We just do the inertial navigation part and the others integrate.
Every time you acquire the GNSS signals after an occultation, such as under heavy canopy, you re-initialize the INS, correct?
When you start up the system, to know where you are you need to have GPS signals. So, the best scenario would be to start up the system under open sky. However, we’ve found through working with our customers that this isn’t always the case. An autonomous tractor might just stop spraying for the night in the middle of a row and continue its mission the next day. So, they sometimes need to start up under heavy canopy, which means that they wouldn’t be able to acquire GPS signals, at least not accurate enough. In that scenario, we’ve added a functionality to boot up with your last position. What customers often do with this feature is to constantly save their last position and heading from our system; then, as soon as the system boots up, they can decide whether to start from their last known position.
We leave that up to the customer, because there are some cases in which you might boot down the system and then boot it up and it’s somewhere else — for example, often an autonomous tractor will get towed to move it a long distance. If we just always booted it up with its last position that would cause issues in those scenarios.
So, there are always these edge cases. That’s why we have this feature where the system itself will determine whether to boot up with its last known position or with GPS.
Hopefully, that will become standard soon for car navigation, so that when you start driving from a parking space the system already knows which way you are facing and will guide you accordingly — rather than you having a 50/50 chance of starting out in the right direction!
An exclusive interview with Chad Huedepohl, precision agriculture portfolio manager, Autonomy & Positioning division at Hexagon. Read the full story and additional exclusive interviews here.
Precision agriculture has been around for more than 30 years. (GPS World published several issues of a supplement on the subject about 26 years ago.) What have been some of the key turning points? What options do farmers have now that they did not have, say, five years ago? Are the main improvements in accuracy, repeatability, reliability, or cost?
The term precision agriculture started to come into play when yield monitoring was first invented and brought to market. One of the first successful ones was through Ag Leader Technology and their yield monitoring system, which then added positioning through GPS to start mapping where the yields were coming from. This then created the ability to start managing farmland and zones based on productivity. In turn, this very quickly evolved into also mapping soil sampling results and directly tying that type of information to point-specific yield information from a field. Auto-steering systems had been on the market prior, but really started becoming part of the precision agriculture portfolio in the late 90s.
The industry took off in that direction for several years, then started to get into variable rate application of fertilizer, which was another way of more intimately managing the farmland. That then led, in the early 2000s, to the coming to market of auto-swath technology, which made it possible to turn on and off the different implement sections on application equipment — primarily, sprayers and spreaders. This enabled the operator to avoid putting a second application where you had already been, as well as making sure you had full coverage and no skips.
In the mid-2000s, autosteering systems started to become standard on newer equipment and soon became a key product in the aftermarket. Auto-steering had a major impact on farmers because it gave them better efficiency, but also helped provide more hours of productivity per day. It enabled them to focus on other things and not be so physically and mentally drained by the end of the day because of constantly concentrating on where the machine had to go. It allowed them to pay better attention to the equipment and the application that they were set up to do.
So, the combination of swath control and auto guidance is what sent the precision ag world into major acceleration, which eventually led to planter control. The company Precision Planting emerged into the precision ag space at about that time, drawing awareness of the need to utilize precision on row-crop planters. The industry soon started getting into much more finite monitoring and precision ag soon became an integrated featureset into planter equipment, rather than just an add-on.
More recently, we’ve started the trend toward autonomy. It’s not mainstream yet, though. We started putting a lot more focus on live sensors, including camera imagery. There’s been some evolution toward sensors on the implements that make those decisions on the go. It’s catching on somewhat. It still does not have a whole lot of market penetration, yet that’s changing rapidly.
When it comes to GNSS, I think the biggest part has been reliability — on a farmer’s terms. “Can I really count on this system to do what I’m asking it to do?” Farmers view that as reliable in the GNSS world. We then start asking, “What is reliable? Is it accuracy? Is it repeatability? Is it integrity with the actual position?” Growers think about all those things. They do not necessarily focus on one thing versus another.
In terms of the integration, of how they use it in the cab, reliability has had the biggest impact on that, then cost has brought in more people. In the early days, just autosteering cost north of $20,000. Nowadays, a complete systems will cost somewhere around $20,000, so the out-of-pocket cost has not necessarily come down a lot, but what you’re getting for that value has advanced significantly. If you want to do just entry-level autosteering, that can be done relatively inexpensive compared to the early days.
Most growers today are doing far more than just navigation.
I was familiar with this history because I’ve written a dozen articles on precision ag over the past 20 years, but the way you summarized it was great. One thing you didn’t touch on, however, is the vast expansion in options for corrections data.
I’m glad you brought that up. Corrections have been an important part of the evolution of precision agriculture as well. When farmers plant this field or spray that field, they want it to be done reliably. That is where accuracy comes in. Earlier in my career, real-time kinematic (RTK) positioning was very expensive and satellite-based augmentation systems (SBAS) were not as stable.
Also, RTK systems and such used just single constellation for the longest time. We started adding in GLONASS and then positioning correction providers, which gave us a lot more robustness. Some of the early challenges with RTK were having enough common satellites with baselines. I think that really took off in about 2009. Prior to then, it was mostly just SBAS or RTK.
There was also PPP, but the challenges that the industry was facing with PPP was the long convergence time. It used to be common for conversions to take 40 to 50 minutes. Then you would drive underneath one tree on the edge of a field and you had to start all over. When you’re talking about the actual cost of a farming operation, having to sit idle because of something like that did not sit well with farmers. So, PPP corrections struggled to take off. Because of those early experiences, it took a long time for the market to start to accept the newer PPP models that we’ve seen in the last, say, seven or eight years.
Now there are farmers who enjoy the reliability of those PPP corrections, because the redundancy and resiliency between the different providers, such as Hexagon providing TerraStar services, through vegetation and being able to withstand some outages, definitely sits well with customers.
The accuracy and convergence times have also improved significantly. At the end of the day, it’s one fewer thing that can go wrong for them or their dealer to have to deal with. I don’t have to worry about the state-sponsored continuously operating reference station (CORS) network going offline, about software updates or cellular issues, or, season to season, someone having to make sure that their system is all up and operational. A PPP solution is automatic. It either works or it doesn’t. That’s something that farmers like. They don’t like to have to deal with all this other integration technology.
What’s PPP’s convergence time now?
With TerraStar-C PRO, we’re often seeing a convergence time of less than five minutes. We have a fast startup time. So, if the tractor was shut down, already converged and you turn it back on, most people are going to be reconverged in just a minute or two.
That’s a hot start.
Yeah, right.
Precision agriculture involves collecting data (on the ground and from the air), analyzing the data, creating maps, displaying the maps in the cabs of tractors and other machines, and using the maps to guide those machines as they water, spray, plant, and harvest crops. So, it involves hardware, software, data, analyses, and decisions. Besides making GNSS receivers and providing corrections via TerraStar, in which aspects of precision agriculture is Hexagon involved? For example, do you store and/or analyze any of the data that growers collect or create maps for them?
We sell displays and controls that operators use that control equipment and collect the data for the farm. Many of our agriculture OEM and technology customers have their own software solutions that provide their crop growers with the tools they need to manage their farms, and Hexagon provides the hardware that feeds into them. However, Hexagon does have a software portfolio that provides tools for operation planning, monitoring and analysis to large enterprise farming customers like those in the sugarcane, bioenergy and forestry industries. In summary, we sell the control equipment — basically, the display interface — as well as rate control and implement control functionality. We sell the TerraStar PPP corrections as well as RTK corrections through Hexagon’s SmartNet.
Do you have any unit that does a service for the growers of analyzing that data and creating the maps they use for planting, watering, and spraying?
No, Hexagon does not provide any after-the-fact data analysis, certainly not for row crops.
How is the adoption of precision agriculture proceeding in the United States? For example, roughly what percentage of growers currently use autosteer on their tractors?
I don’t have any reports to reference other than those from USDA. Adoption rates across most row crops in the United States are going to typically be north of 70%. On machines built in the last five years, you’re talking about an adoption rate of more than 90%. Acres of crops grown using auto steer are probably 80% in North America. More than 50% of that is using a correction that is more accurate than just simple SBAS.
What is the division of labor between Hexagon and the manufacturers of tractors, combines, sprayers, and other agricultural machines – such as John Deere, AGCO, Case IH, Kubota, Massey Ferguson, etc.? Do you have privileged relations with any of them? Are your guidance systems typically installed at the factory or by dealers?
We go to market in a couple different ways, and we’re involved with most of the leaders in precision agriculture. We’re providing solutions t — whether OEMs, regional OEMs, or after-market solutions. So, we’re involved in most of the leading precision agriculture solutions in the global market.
OEM solutions are factory-installed and the grower doesn’t even see the name Hexagon anywhere, correct?
That is true in many or our partnerships. We are a factory option and some of the leading OEMs do both white label as well as branded. We’ve been providing NovAtel branded receivers to AGCO for many years, through their channel, both factory-installed and aftermarket. Some of the others, such as CNH, are white labeled, so it would just say “Case-IH” or “New Holland” and have no Hexagon markings.
Is the aftermarket phasing out as it becomes standard for these solutions to be factory-installed on new machines?
Yes and no. In some ways, there is more adoption of aftermarket products to pair with the mainline factory systems, but many of the shorter line OEMs and aftermarket solutions are accessing parts of the market that have machines that originally came with factory-installed solutions that are now antiquated, so they want to upgrade to get more out of it.
You also have increasing consolidation — such as AGCO’s joint venture with Trimble and CNH’s acquisition of Hemisphere — so there are fewer GNSS providers for competing brands to utilize in the market.
Does the signal into the autosteer use the NEMA standard, so that you can just replace the old receiver with a new one?
Most of the companies, whether they’re OEMs or aftermarket solutions, have some type of proprietary integration. There are products that are just NEMA; they are typically at the lower end and priced much lower. The higher performing flagship products are usually doing a more customized integration.
Would you like to highlight any recent Hexagon products or services in the precision agriculture area?
Probably the biggest one is bringing more awareness to the TerraStar-C PRO and the TerraStar-X Corn Belt products and a lot of the ionospheric resiliency that we’ve been able to improve with those products. They provide more robustness and reliability in challenging ionospheric scenarios. Especially in the Brazil market, some growers were often experiencing hours of downtime due to ionospheric scintillation. With the ionospheric enhancements that we’ve added that downtime now is down to just a few minutes here and there.
Another one would be enhancements that we’ve been bringing to the autonomy market, such as dual antenna solutions and geofencing, for safety.
Who integrates the other sensors used for safety, such as lidar or radar?
That’s a key area we’re focusing on. We are currently working with specific integrators with our perception system. We have perception systems that primarily utilize cameras, but we can also utilize lidar and other sensors.
We each arrived at our current involvement with the GNSS/PNT industry by a different path. For many, it was through engineering, perhaps initially thinking of focusing on completely different challenges than those posed by extremely weak RF satellite signals, intentional interference, or ionospheric scintillation. For others, it was through surveying, which they might have entered to make a living traipsing through open fields — well, traversing them — while working independently and in nature.
For others still, it was through one of the myriad applications of GNSS — from mapping the geographic distribution of the few remaining Amur leopards to guiding a tractor in the field, from commercial fishing in Alaska to conducting search and rescue missions, to training for military raids. Yet for others, it was through business, perhaps because they were tasked to route delivery trucks more efficiently or to track each vehicle in a rental fleet. Professor Richard Langley started out as an applied physicist and a radio tinkerer, building his first radio at the age of 14. My colleagues at North Coast Media got here via a career in journalism, with the steep subject-matter learning curve following their training in writing and editing.
I got here mostly through my passion for maps, charts and navigation. I first became interested in maps as a child — after twice getting lost. The first time, I was 5 years old and lost track of my mother as she entered a store in Berkeley, California, and I kept walking down the street. The next time, I was 7 and had insisted on walking home alone from school in Milan, Italy. I was determined not to let it happen again. So, when I was 11, I was the only kid I knew who walked around Pisa studying a map and a compass.
Next came the topographic maps I used for hiking. In my 20s, sailing around the Boston Harbor islands and off the coast of Maine, I learned to use nautical charts, sextants, radio direction-finders, sonar, radar, Loran C, and, finally, hand-held GPS receivers. I read my first technical article on GPS in 1985, when I was a graduate student in international security at MIT and Harvard, and the U.S. military was building the system. I studied its technical specifications and dreamt about its many possible future applications.
In 2000, when looking for a career change and a job in journalism, I saw a posting for the position of managing editor of this magazine. I applied and 25 years later I am still in the business.
Throughout, I always have been impressed by the deep expertise of the scientists and engineers who created this fantastic GNSS that billions of people use multiple times a day yet take for granted. Those who discount, belittle or even mock the expertise of people who have spent decades studying complex subjects — from climate change to economics, from foreign policy to epidemiology, from education to urban planning — are profoundly unaware and misguided, when not hypocritical. We need experts.
For our March 2025 issue, Professor Washington Ochieng proposed the following question to members of our editorial advisory board: When we discuss the security of GNSS/PNT systems, we nearly always focus on interference — i.e., meaconing, intrusion, jamming or spoofing. However, GNSS/PNT systems are embedded in systems of systems that also offer many other opportunities for cyberattacks. What should we do about it?
Miguel Armor
“As a GNSS receiver manufacturer and correction service provider, cyber attacks are a risk we must consider seriously that arises from our customers’ integration of our solutions into complex systems. At the receiver level, it is important to make risk assessments to identify vulnerabilities across all components and implement a robust, multi-layered security strategy that includes physical, network and software components. At the core, our strategy incorporates cybersecurity considerations into our product/service development processes. We utilize the ASPICE framework for our engineering processes and we layer into that process the ISO21434 standard to ensure that we take steps all along the development path to consider cybersecurity. We selected this standard from the automotive industry due to the connected car use case, which is now in the front of cybersecurity development. ISO21434 covers the entire development life cycle — from system, to hardware and software, to verification and validation — in a way that many other standards do not. As a correction service provider, we ensure our data streams are secure and reliable, maintaining the highest standards of accuracy and availability. We also use ISO27001 as an IT framework for our correction network infrastructure. Continuous monitoring and iterative improvements are crucial to maintaining a secure and resilient GNSS/PNT infrastructure. It is key also to prioritize redundancy and backup systems to ensure continuity and resilience, to develop a comprehensive incident response plan that allows for rapid action in case of a breach and to conduct regular employee training to promote cybersecurity awareness across all products and platforms.” – Miguel Amor, Hexagon Positioning Intelligence
Alison Brown
“Cyberattacks are a credible threat to all existing GNSS systems and certainly need to be taken into account when considering alternative resilient PNT solutions. In fact, Goal 3 of the recently released U.S. Department of Transportation PNT Strategic Plan identifies PNT cybersecurity as a critical element of PNT resilience. The National Institute of Standards and Technology (NIST) provided a report titled Foundational PNT Profile: Applying the Cybersecurity Framework for the Responsible Use of Positioning, Navigation, and Timing (PNT) Services. This cybersecurity framework was created for both users of PNT services to manage risks when using PNT signals or data, and for operators of alternative PNT services to leverage when providing PNT signals or services. It was created by applying the NIST Cybersecurity Framework (CSF) and provides approaches for cybersecurity for PNT by continuously monitoring for attacks (e.g., denial of service, jamming), false data, and other malicious behavior within the systems and across the PNT services, using data-driven methods and solutions. This Cybersecurity Framework should be routinely adopted by both users and providers of PNT services.” – Alison Brown, NAVSYS Corp.
GPS World is a business-to-business magazine, and most of our readers are engineers, surveyors and other professionals specializing in geospatial technologies. In general, we do not cover consumer applications. Nevertheless, it is important to remember that, while GPS was designed and built, and is managed, by the U.S. military (from 1973 to 2020 by the U.S. Air Force, since then by the U.S. Space Force), more than 99.9% of its users are not members of the U.S. military, nor surveyors, but consumers. They benefit from GPS — and the three other GNSS, namely Russia’s GLONASS, China’s BeiDou and Europe’s Galileo — in many ways and are unaware of most of them, such as the fact that GNSS receivers provide essential timing for radio and television broadcasts, cellphone communications and financial transactions.
The vast majority of consumers access GNSS via their smartphones. We are all familiar with the myriad smartphone applications that rely on GNSS for positioning and navigation — from Google Maps and Apple Maps to Waze and social media platforms such as Instagram. Additionally, weather apps, such as the Apple Weather app, and parking apps utilize GNSS to enhance user experience and functionality. Nearly all smartphones today use at least three of the GNSS constellations — GPS, GLONASS and Galileo — and some use all four. (The use of BeiDou in the United States is a controversial topic that we will explore soon.)
For most people, smartphones have replaced such previously separate electronic devices as calculators, digital cameras and car navigators. (A freestanding GNSS-based car navigation device is still useful, however, when you travel in areas with spotty or nonexistent cell phone coverage, because it relies on maps stored on the device, so it does not require an Internet connection. That is why I still carry a nearly 20-year-old Garmin nüvi in my car.)
For a few years, there were even handheld televisions. (My 1989 Casio TV-400 LCD Pocket Color handheld VHF-UHF TV has a 4 cm x 3 cm LCD screen. It is analog, however, so it stopped working when U.S. television broadcasts switched to digital in 2009.) Now, many people watch news, shows and movies on their phones.
Nevertheless, there are still many freestanding GNSS-based devices. For example:
Handheld receivers for hikers and boaters that display your position and heading on topographic maps or nautical charts, as well as such information as elevation, speed, distance to your destination, number of GNSS satellites in view, tides, and sunset and sunrise times.
Cyclometers that show bicyclists their speed, pace and position on a map.
Fitness trackers and smartwatches that track your exercise, sleep, heart rate and biometric data.
Tracking devices that monitor the movements of people, such as children and Alzheimer’s patients, and help recover stolen vehicles and boats.
Additionally, many digital cameras have GNSS receivers that insert the location of each photo into their metadata.
Since I began working in this industry 25 years ago, I have always detested the term “GPS tracker” because it reinforces the already widely held misperception that a GPS receiver somehow “tracks” its user. As most readers of this magazine know, GPS receivers only display and/or store location data for the user, without sharing it with anyone else, let alone broadcasting it. Tracking something requires coupling a GPS receiver with a way to transmit the location data — typically, using a cellphone connection. Plus, nowadays, the word GPS should in most cases be replaced with GNSS. Therefore, I am always careful to say or write “GNSS-based devices.”
What follows highlights three very different GNSS applications in consumer devices:
Handheld receivers and smartwatches by Garmin for outdoor recreation and fitness.
GNSS-based tracking of vulnerable people.
A smartphone application from Google to monitor jamming and spoofing.
— Matteo Luccio, Editor-in-Chief
A nearly 20-year-old Garmin nüvi still provides the author navigation in areas without cellphone reception. (Photo: Matteo Luccio)
Handheld GNSS Receivers
Garmin, founded in 1989, is the 800-pound gorilla in the consumer GNSS market. The company’s annual revenue of more than $5 billion is comparable to the nearly $4 billion annual revenue of Trimble, founded in 1978, which is the 800-pound gorilla in industrial GNSS markets.
Garmin sells a vast array of handheld receivers, smartwatches and other devices for outdoor recreation and fitness, as well as GNSS receivers for general aviation and marine navigation.
In remote areas with scant or no cellphone reception, Garmin’s GNSS receivers offer users substantially more reliable satellite reception and greater positioning accuracy than smartphones. That is for two reasons. First, because a Garmin receiver can host a larger GNSS antenna than a smartphone, which contains several antennas. Second, because it is mostly dedicated to the positioning and navigation mission — unlike the many missions crammed into a smartphone.
Garmin’s multi-constellation and multi-band GNSS handheld receivers come with preloaded topographical maps optimized for outdoor activities, with terrain contours, summits, coastlines and more.
Garmin’s latest line of handheld GNSS navigators — the Montana 710i and Montana 760i — feature built-in inReach technology, which allows users to stay in touch when venturing beyond cell service using reliable satellite communication. Users can utilize two-way text messaging and location tracking via the global Iridium satellite network. In the event of an emergency, users can send an interactive SOS message to Garmin Response, an international emergency assistance coordination center that is staffed 24/7/365.
These devices are ideal for a variety of outdoor activities, including hiking, mountain biking, off-road riding and more. They are also compatible with multiple mounting options to adapt for use on ATVs, boats, cars, motorcycles, RVs and other vehicles.
Garmin Smartwatches
Garmin smartwatches have established themselves as leaders in the fitness and outdoor adventure market. Whether running, cycling, swimming or golfing, Garmin smartwatches provide users with many activity-specific features and metrics.
These watches feature advanced heart rate monitors and pulse oximeters for health monitoring. The company’s latest line of smartwatches come with a Body Battery feature that continuously analyzes combinations of the user’s heart rate, heart rate variability and movement data. The goal of this analysis is to identify meaningful physiological states and to describe the impact they have on the body’s energy levels. At a high level, this means documenting whether users are awake or asleep and when they are physically active, as well as tracking stress levels during periods of inactivity, according to Garmin.
Garmin smartwatches also feature additional sensors to improve location data. They include an altimeter sensor that helps track elevation changes and an accelerometer that detects movement. The latter is used for such tasks as step counting, sleep tracking and other activity measurements.
Garmin watches use multi-constellation (GPS, GLONASS, BeiDou and Galileo) GNSS receivers that enable accurate distance, pace and route mapping during outdoor activities, even in challenging environments.
— Jesse Khalil, Associate Editor
Tracking Family Members and Pets
The Satellai Collar features a lightweight tracker attached to a padded harness designed to avoid snags, discomfort or mobility restrictions. (Photo: Satellai)
GNSS technology enables consumers to track those most important to them – their family, friends and even their pets.
Companies such as u-blox offer devices that can be worn by the elderly and children to enable their caregivers or parents to track them. The devices help locate individuals through ›GNSS receivers (using all four GNSS constellations); Bluetooth, Wi-Fi and low power wide-area cellular communications; and cloud connectivity.
Families can monitor the movements of their children as they travel to and from school by bus by tracking those buses as they drive along their routes. Families can better time their kids’ departure to the bus stop in the morning and know when the bus has returned in the afternoon — all by viewing a live tracking function, provided by the school district, on their computer or smartphone.
Some of the newest tracking technology was on display at this year’s Consumer Electronics Show (CES) in Las Vegas in January. SATELLAI, a provider of AI-integrated pet solutions, showcased its SATELLAI Tracker and SATELLAI Collar. “The SATELLAI Tracker and the SATELLAI Collar use satellite and AI technologies to accurately relay their positions and status at all times,” said Mark Mao, founder and CEO of SATELLAI.
The lightweight tracker attaches to a padded harness that won’t snag, cause discomfort or hinder a pet’s mobility, according to the company. It features the Qualcomm MDM9205S modem, the 3GPP Rel17 5G IoT-NTN satellite communications system and the Aware platform, allowing it to use both cellular and satellite communication for continuous tracking even in remote areas without terrestrial cellular coverage. Working with the Skylo communications network ensures that the tracker works with more than 680 global networks across more than 180 countries. The SATELLAI Collar leverages a dual antenna and a multi-constellation GNSS receiver to deliver precise tracking, even in areas with low connectivity, the company adds.
Tractive, a global provider of pet GNSS and health tracking, also unveiled its latest dog tracker at CES in Las Vegas. Companies are also offering new ways to keep pets within areas chosen by their owners. According to Tractive, most virtual fences use a collar-mounted GNSS-based tracker in combination with an app or software. Users can create their preferred fence boundaries and receive notifications when pets cross them. Utilizing Mapbox’s advanced mapping platform, the SATELLAI Collar also allows users to manage these virtual boundaries, supporting overlapping and nested fences. The collar supports virtual fencing for areas up to 100,000 acres. Virtual fences are also commonly used with cattle.
— Brian Richesson, Senior Editor-in-Chief
Google Tools for Detecting Jamming & Spoofing
AGC and C/N0 both drop when a phone is held next to a Wi-Fi router (red oval). (Screenshot from Google)
The sharp increase in the past few years of instances of GNSS jamming and spoofing, much discussed in these pages especially with regards to civil aviation, also affects smartphones, smartwatches and other consumer devices. Google — which makes the Pixel phones as well as Android, the most used operating system, which is used by three quarters of the world’s smartphones — has been developing a tool to help detect these attacks.
It is based on the fact that the carrier-to-noise ratio (C/No) of the signal as well as the automatic gain control (AGC) of the GNSS radio in the phone can be good indicators of interference. “The AGC tends to dip when spoofing or jamming is observed,” said Mohammed Khider, Ph.D., manager and senior staff software engineer at Google. However, he pointed out, for jamming events the C/N0 value drops while for spoofing it increases.
Making use of this effect, desktop tools that log data and analyze the AGC and C/No have long made it possible to detect interference. Now, Android users can do the same thing on their phones in real time, using the spoof/jam tab in Google’s GnssLogger app. It creates a graphic of AGC and C/No for each GNSS constellation and band. Moreover, the app cross checks the GNSS signals with other independent sources of information to flag potential jamming and interference. Below the real-time plot of AGC and C/N0 are a series of additional automated jamming and spoofing checks.
This is an experimental feature, and the algorithms behind it will be further improved as research progresses, Khider pointed out. Moreover, it will not catch all jamming or spoofing. However, it will make it much easier to examine data related to these GNSS interference events in real time.
Google launched its GnssLogger app in 2020, and it has been a leading tool for the GNSS community to better understand positioning and navigation on smartphones. “It helped establish a de-facto CSV (.txt) standard for raw measurements and other data for Android devices that has been used in many other tools, including Google’s own Gnss Analysis app,” said Khider.
Last fall, in addition to the new spoof/jam screen discussed above, Google also launched GnssLogger for Wear OS, a new companion app for Android smartwatches that offers several of the key features found in the phone app, and a new measurements screen, which enables users to view GNSS raw measurements in real time.
Federal Communications Commission (FCC) Chair, Brendan Carr announced in a March 5 blog post that the commission would be addressing GPS alternatives along with Next Generation 911 issues at its next meeting.
Pledging that “…public safety and national security will be top priorities for us at the FCC” along with quick action on related issues, Chairman Carr said the commission’s March 2025 open meeting will start “… with an inquiry that explores alternatives to GPS.”
Describing GPS as indispensable but not infallible, Carr’s post showed a substantial appreciation of PNT and GPS alternative issues as well as much of the related policy history.
It also cites President Trump, Senator Cruz, and Senator Markey as advocating action to “… ensure we have a resilient system in place.”
In 2020, President Trump issued Executive Order 13905 on “Strengthening National Resilience Through Responsible Use of Positioning, Navigation, and Timing Services.” Designed to stimulate adoption of open market commercial solutions, it does not seem to have made the nation’s PNT substantially more resilient in the intervening five years. This may be because GPS is free and time and navigation have been provided by the government as free utilities for hundreds of years. Also, many GPS users may be unsure about the need for alternatives since the federal government has not yet acted to protect itself with an alternative system. Potential users are also reluctant to purchase commercial PNT services as they are unsure which commercial services will have the longevity to make the cost and effort of adoption and integration worthwhile.
President Trump also supported the need for GPS alternatives in Space Policy Directive 7, “The United States Space-Based Positioning, Navigation, and Timing Policy.” It called for the government to “…identify and implement, as appropriate, alternative sources of PNT for critical infrastructure, key resources, and mission-essential functions.” This directive was issued shortly before the end of the first Trump administration and, though the directive still stands, this provision has not yet been acted upon.
Carr’s mention of Senators Cruz and Markey undoubtedly refers to their joint sponsorship of the National Timing Resilience and Security Act of 2018. The act called for the Department of Transportation to ensure establishment of at least one terrestrial timing system as a backup for GPS signals. The first Trump administration and the Biden administration never requested funding for such an effort, so the mandate has yet to be implemented.
An FCC meeting on GPS alternatives is also timely as the commission has received two petitions related to provision of nation-wide PNT services. One is from NextNav, seeking spectrum to underwrite its proposal to work with telecom providers. The other is from the National Association of Broadcasters (NAB), asking to mandate and accelerate implementation of the new ATSC 3.0 television broadcast format. NAB says its Broadcast Positioning System signals will be included as part of that format.
While GPS alternatives will be discussed at the upcoming meeting, no decisions on systems is contemplated. Carr says the commission:
“… will vote on an inquiry to explore other Positioning, Navigation, and Timing (PNT) systems that can be complements or alternatives to GPS. Beyond answering technical questions, we hope this effort will engage stakeholders across government and industry to encourage the development of new PNT technologies and solutions.”
Discuss current PNT technologies and efforts, both from governmental and private sector entities, for developing complementary and resilient PNT technologies.
Seek comment on various space-based solutions for resiliency of PNT, such as medium Earth orbit (MEO) satellite systems and low Earth orbit (LEO) satellite systems.
Seek comment on various terrestrial solutions for resiliency of PNT, such as leveraging TV broadcast infrastructure, ground-based transmitters, and/or user equipment positioning.
For all technologies, ask commenters for information on the benefits and challenges of particular PNT technologies or solutions based on factors such as: geographic coverage; availability of existing equipment; use of spectrum resources; the extent to which the technology should be viewed as a complement to or substitute for GPS and other PNT technologies; performance characteristics such as range and precision; durability; international considerations; and the cost and incentives to develop, deploy, and maintain the technology or solution.
Seek comment on additional actions that the Commission could take to facilitate the security of PNT technologies available to consumers.
Seek comment on whether to amend the Commission’s existing rules or adopt new rules to promote adoption of complementary and alternative PNT technologies.
Ask questions about what role public-private partnerships, testbeds, or Innovation Zones may play to test and develop PNT technologies.
The FCC open meeting’s agenda also includes two items about 911 services. One of those is “Strengthening 911 Location Accuracy Rules” especially for the vertical (z) axis. This seems to be a separate and distinct issue from the PNT agenda item with the burden of performance and response placed on telecom providers. That said, some eventual linkage cannot be entirely discounted.
The meeting will take place on March 27 from 10:30 to 12:30 EDT. A formal agenda will be posted approximately a week in advance. The meeting can be live streamed at https://www.fcc.gov/March2025 and a recording will be available on YouTube shortly thereafter.
