In the current context of the Russian invasion of Ukraine, the issue of GNSS jamming and/or possible spoofing has intensified in geographical areas surrounding the conflict zone and other areas, according to the European Union Aviation Safety Agency (EASA). The agency issued a safety information bulletin on March 17 warning of a GNSS outage leading to navigation / surveillance degradation. According to the bulletin, which was directed at national aviation authorities and airlines, reports analyzed by EASA indicate that since February 24 GNSS spoofing and/or jamming has intensified in four key geographical areas:
the Kaliningrad region, surrounding Baltic Sea and neighboring states
Eastern Finland
the Black Sea and
the Eastern Mediterranean area near Cyprus, Turkey, Lebanon, Syria and Israel, as well as Northern Iraq.
“The effects of GNSS jamming and/or possible spoofing,” the bulletin stated, “were observed by aircraft in various phases of their flights, in certain cases leading to re-routing or even to change the destination due to the inability to perform a safe landing procedure.” It pointed out that in the present conditions it is not possible to predict these outages and their effects. Potential issues include:
loss of ability to use GNSS for waypoint navigation
loss of area navigation (RNAV) approach capability
inability to conduct or maintain various operations
triggering of terrain warnings, possibly with pull-up command and
inconsistent aircraft position on the navigation display
loss of automatic dependent surveillance-broadcast (ADS-B), wind shear, terrain and surface functionalities
failure or degradation of ATM/ANS/CNS and aircraft systems that use GNSS as a time reference and
airspace infringements and/or route deviations due to GNSS degradation.
The bulletin also offers several recommendations to airlines for mitigating these issues.
Hexagon AB, a provider of digital reality solutions combining sensor, software and autonomous technologies, has acquired ETQ, a provider of SaaS-based quality management system (QMS), environment, health and safety (EHS) and compliance management software.
Customers have long relied on ETQ’s QMS solution, ETQ Reliance, which provides the data backbone for automating the collection and delivery of manufacturing quality control data, non-conformance reports, customer feedback and more, providing an enterprise view of quality management across a product’s lifecycle. Its portfolio of applications comes with out-of-the-box functionality and no-code configurability, enabling customers to tailor the solution to their needs and optimize business processes to achieve their quality, safety and environmental goals.
ETQ’s data management capabilities, driven by machine learning and artificial intelligence, make quality data fully actionable and available further upstream. In addition to reducing defects, scrap, rework, and recalls, it enables an autonomous feedback loop, digital information trail and virtuous cycle of continuous improvement.
Founded in 1992 and with a staff of 185, ETQ is headquartered in Massachusetts with additional offices in Arizona and Dublin, Ireland. It operates in industries including the life sciences, healthcare, heavy manufacturing, electronics, food and beverage, heavy process, and automotive. ETQ will operate as part of Hexagon’s Manufacturing Intelligence division. Completion of the transaction is subject to regulatory approvals and other customary conditions, which are expected to be fully completed by early in the second quarter 2022.
The U.S. Marine Corps has selected Northrop Grumman Corp. to provide it with the Next Generation Handheld Targeting System (NGHTS), a compact device that provides high precision targeting and can operate in GPS-denied environments.
The laser-based device will give Marines an enhanced capability to identify and designate targets from extended ranges, enabling them to identify ground targets under a wide range of conditions.
NGHTS can perform rapid target acquisition, laser terminal guidance operation and laser spot imaging functions. Its high-definition infrared sensors provide accuracy and grid capability over extended ranges.
Additional features include a high-definition color display and day/night celestial compasses.
The Mayflower Autonomous Ship (MAS) is set to re-embark on its three-week trans-Atlantic journey in April 2022 equipped with two of Silicon Sensing’s AMU30 inertial measurement units (IMUs). These devices send highly precise motion data to the new ‘AI captain’ that guides the vessel. They also assist in measuring sea surface height as part of detailed scientific analysis of ocean topography.
AMU30 is a micro electro-mechanical system (MEMS) unit with excellent inertial performance, including very good bias stability and low noise characteristics, plus an embedded Kalman Filter-based AHRS (attitude and heading reference system) algorithm. It delivers precise 3-axis outputs of angular rate and acceleration, plus roll, pitch and heading angles, altitude and pressure, and temperature, at 200 Hz — all critical to precise maritime navigation.
“The two AMU30 are used to make real-time, precision measurements of the movement of the Mayflower Autonomous Ship in 6 degrees of freedom (DOF) so that the AI Captain may make minute manoeuvring adjustments to optimise vessel performance in a complex wavefield, while also providing redundant general navigation capability at sea,” said Brett Phaneuf, co-director of the project. “Furthermore, when coupled with optical and RTK (real time kinematics) GPS data, the AMU30 assists the ship in making highly accurate measurements of sea surface height, which are important for studying ocean tides, circulation and the amount of heat the ocean holds.”
The MAS journey across the Atlantic will celebrate the voyage of the original Mayflower some 400 years ago. It is just one element of an extensive scientific data gathering and research programme the vessel will complete in the coming years. The ship is guided by its new AI Captain, built using IBM cloud, artificial intelligence (AI) and edge computing technologies, and uses a hybrid engine that draws on solar power. Working with scientists and other autonomous vessels it provides a flexible platform for deepening understanding of issues such as climate change, ocean plastic pollution and marine mammal conservation. In parallel, the development of marine autonomous systems such as this will transform ocean-related industries such as shipping, oil & gas, telecommunications, security & defence, fishing & aquaculture.
In recent years, the architecture, engineering and construction (AEC) industry has benefited greatly from growing GNSS accuracy, smaller laser scanners, UAVs, and more efficient management, collaboration and visualization software. We asked five companies operating in this space to address three questions:
What are the key challenges of surveying for the AEC industry today, compared with traditional boundary surveying and other types of surveying?
Which of your products are particularly relevant for this kind of surveying?
What was a recent AEC surveying success story?
In the following articles, five companies briefly describe their experience with the AEC industry:
In this issue’s cover, a man with a backpack lidar unit, a GNSS receiver and a tablet computer is surveying in a complex and challenging urban setting. That same lidar unit also can be mounted on a UAV. One of the contributors to this month’s cover story describes the role of aerial photogrammetry in the architecture, engineering and construction (AEC) industry. Satellite navigation, remote sensing, mapping software, a great variety of platforms, and ever more powerful handheld computers — those are the key ingredients in today’s ecosystem of geospatial technologies. The current generation of surveying equipment has more than halved fieldwork in the past two decades while greatly improving the quality of the data collected.
The AEC industry relies on surveyors to be “a bridge between the existing landscape and the design landscape,” said another contributor to our cover story. Unlike traditional boundary surveying, he explained, surveying for AEC requires consideration of a detailed 3D world. It also involves many more stakeholders and much greater liability.
The tight integration of GNSS, inertial systems, lidar sensors and 360° spherical imagery into mobile mapping systems makes 3D modeling possible and traditional GNSS or optical measurement instruments obsolete. However, while inertial systems are invaluable to bridge brief gaps in the availability and reliability of GNSS signals, they are far from the panacea they are sometimes claimed to be, as Brad Parkinson reminds us in an interview with Dana Goward, also in this issue.
Surveying for AEC requires at least centimeter accuracy. The challenges of surveying in urban settings include urban canyons that occult signals and create multipath, traffic and multiple layers of underground, ground-level and above-ground infrastructure.
Beyond the construction phase, 3D survey data is increasingly used to create digital twins of buildings, which facilitate their operation and maintenance throughout their life cycle and help lower their carbon footprint. Once they have completed an initial survey, surveyors often set control to be used for machine control — the theme of our cover story in next month’s issue.
In this issue we also:
• Inaugurate a “letters to the editor” section to make more room for debate in the GNSS/PNT community on the critical issues it faces.
• Report on a Jet Propulsion Laboratory study of the impact on the ionosphere of the enormous volcanic eruption in Tonga and the beginnings of a GNSS-based early warning system for natural hazards.
• Continue our series of articles on GNSS constellations, with an update from Japan’s QZSS constellation.
• Feature three studies: one on real-time simulator testing using an NMEA data stream, one on the first transmission of L1C/B signals by QZSS, and one on self-driving cars in major metropolitan areas.
All these advances, however, are threatened when GPS is threatened. Earlier in the month, three members of our editorial advisory board comment on the recent threat to GPS satellites by the Russian government.
On Jan. 15, Hunga-Tonga-Hunga-Ha’apai, an uninhabited volcanic island on the Tongan archipelago in the South Pacific Ocean, erupted with spectacular force, churning ocean waters halfway across the globe.
GNSS engineers also detected its effects hundreds of miles above, in the ionosphere. The GNSS community is now moving from such after-the-fact detection to real-time monitoring using NASA’s Global Differential GPS (GDGPS) system, according to a team with the Tracking Systems and Application Section at NASA’s Jet Propulsion Laboratory (JPL) in Southern California.
“We monitored, in real time, four GNSS satellite constellations from numerous stations around the world using the GDGPS network. In particular, the three stations closest to the volcano, in Samoa, Fiji and Tahiti,” said postdoctoral associate Leo Martire. “We could see extremely high and strong signals in the ionosphere, which is very unusual. As a function of radial distance from the eruption, the first detected ionospheric perturbation likely originated directly from the explosion. Then we see patterns propagating at increasing distances at different radial propagation speeds.”
Monitoring such events adds information to the catalog of signals from natural hazards, pointed out Siddharth Krishnamoorthy, a research technologist who manages JPL’s GUARDIAN near-real-time tsunami warning system, currently under development. “That is useful because, in the future, if you want to be able to spot natural hazards and issue alerts, you need to know what the signal looks like. There have been reports of a tsunami in Tonga due to this event, so we will look at potential tsunami-induced signatures in the ionosphere. We are trying to get to a place where we pick up a signal like this and we are able to say, ‘This is a tsunami propagating at this speed and in this direction.’”
Chart: Jet Propulsion Laboratory
Before being detected in the ionosphere, signals from natural hazards must travel all the way from the surface. For tsunamis, this usually takes more than 10 to 20 minutes, but the volcanic eruption only took a couple of minutes to reach the ionosphere because it shot straight up. “We do not know yet, based on observations, how exactly different events on the surface caused by natural hazards couple with the atmosphere,” said research technologist Panagiotis Vergados. “Every event is unique in its spectral properties.”
The event did not affect the quality of GDGPS’s GNSS positions or orbits, because dual-frequency measurements remove significant ionospheric effects. “Instead of looking at the direct effects on the position of our available reference stations, which is what our traditional real-time monitoring does and which was basically negligible, imagine the links from each of those stations to a dozen or more satellites,” said Larry Romans, GDGPS chief technologist. “Every time one of those many links pierces the ionosphere, we can monitor that signal for ripples as waves go by. So, this is an incredibly powerful method for seeing disturbances, just in terms of the density of data. It is very complementary to position-based natural-hazards monitoring because the data is much richer.”
In addition to volcanoes and tsunamis, several other natural events, such as earthquakes and very large thunderstorms, also produce these effects. “These natural forcings cause large-scale, low-frequency pressure perturbations that tend to travel up and be visible in the ionosphere,” Krishnamoorthy said. “There are also perturbations of the ionosphere due to events from outside the Earth, such as solar flares or bolide impacts.”
Many of these perturbations start from the troposphere, which ranges between 10 km and 15 km in altitude — including hurricanes, which overshoot gravity waves all the way to the ionosphere, and thermal tides that have been observed to go all the way up to 600 km, said Vergados. “There are also geomagnetic storms and sub-storms that, during electron precipitation, can change the ionization of the ionosphere. So, the coupling can happen from either below or above or simultaneously, and then the effect can be dramatically enhanced.”
Most of the perturbations that come from below are of a pressure nature — that is, they start out as mechanical waves — while most of those that come from above are electromagnetic. “Aside from nuclear explosions, very large chemical ones, such as the 2020 Beirut explosion, also cause a signature on the ionosphere because they create very large pressure waves,” Krishnamoorthy said.
Photo: Tonga Meteorological Services, Government of Tonga
Precision agriculture — which promises to reduce inputs of water, fertilizers and pesticides by matching them to variations in soil conditions, thereby reducing environmental impacts, while increasing yields and productivity and reducing fuel consumption —has been around for a long time. This magazine published a few issues of a special supplement on the subject more than 20 years ago. In recent years, the convergence of enabling technologies — including improved satellite-based sensors, unmanned aerial vehicles, ground-based sensors, and GNSS corrections services — and greater demand has made agriculture one of the largest users of GNSS.
Compared to autonomous vehicles on public roads, autonomous tractors, sprayers, combines, and other farming equipment pose much lower safety concerns, because they need not deal with the vagaries of traffic, accidents and construction. They also are not subject to the kind of signal occultation and multipath that is the bane of GNSS navigation in urban canyons and, at least for now, they are not at significant risk of jamming or spoofing. However, they face other challenges, including severe roll and pitch due to bumpy terrain, some multipath from silos and other tall structures, occasional signal interference, occasional dense tree canopies, the requirement to maintain exact heading at very low speeds, the need to receive corrections over very large areas, complicated weather conditions (including rain, fog and dust clouds) and, like every other sector, cost constraints.
Despite this, guidance for farm vehicles must be consistently accurate at the decimeter-level, lest the machines damage the valuable crops that they are designed to service.
In the following articles, seven companies briefly describe their advancements in precision agriculture:
Although GNSS has been applied in agriculture for many years, farmers still encounter challenges caused by GNSS. No matter the farm task — planting, spraying, harvesting or specialized applications such as robotic grass mowing — position accuracy matters.
Here are the most common issues farmers have and how Unicore’s products help.
Under canopy. They are unable to get a fix under heavy foliage canopy because the real-time correction signal is interrupted or “shaded out” by the canopy. Unicore is launching two new modules that will help mitigate this problem.
Loss of lock. At times, the receivers lose lock or get large position errors when the ionosphere’s effects are severe. Driven by a full-constellation and full-frequency RTK engine, Unicore’s RTK algorithm takes advantage of triple and quad frequency observables, effectively mitigating ionospheric residuals.
Loss of 4G signals. RTK can provide real-time centimeter-level high-precision positioning, which requires real-time base station data. In practical applications, radio or wireless network communication is often interrupted. During the interruption of the base station data, RTK’s positioning accuracy decreases quickly. Unicore’s RTK KEEP technology can maintain the centimeter-level positioning accuracy for more than 10 minutes after the interruption.
Lack of CORS stations. It is challenging to provide a stable high accuracy position for an ultra-long baseline. With the mitigation of ionospheric and tropospheric delays, Unicore products’ RTK baseline can be extended to up to 50 kilometers.
The UM980 is Unicore’s new-generation high-precision RTK positioning module, supporting full constellation and full-frequency. Relying on the strengths of high reliability, precise positioning accuracy and low latency, UM980 is not only well suited for high-precision surveying and mapping, but also a good choice for rover or base station receivers in agriculture.
The UM982 is a dual-antenna high-precision positioning and heading module. Since its master and slave antennas can simultaneously track all the frequencies of all the GNSS systems, the UM982 performs fast on-chip RTK positioning and dual-antenna heading solutions without the need to initialize the IMU. Featuring great positioning performance and stability, the UM982 is a perfect choice for high-precision agriculture applications, such as drones, autonomous tractors and autonomous lawnmowers.
Controlling weeds is a natural challenge in agriculture. The cost of controlling these unwanted plants is also one of the most expensive line items in a farmer’s budget. For third-generation Brazilian farmer Ivan Bedin, trying to rid his 8,620-hectare soybean and corn farm of hearty weeds has been a costly challenge.
“Typically, we’ve had to blanket spray weed-killing chemicals throughout the entire farm,” Bedin said. “Even if only 15% or 20% of the area was weed-infested, we had to spray the total area. We were spending more than $145,000 a year on chemicals, and it wasn’t good for the environment.”
The Bedin family then acquired Trimble’s WeedSeeker 2 technology. This intelligent spot-spray system senses whether a weed is present and signals a spray nozzle to deliver a precise amount of chemical, spraying only the weed. By targeting resistant weeds individually, WeedSeeker 2 can reduce the amount of herbicides used by up to 90%, promoting sustainability and cost savings on the farm.
While driving 18–20 km/hr, the sprayer’s operator focuses on the WeedSeeker application while the AutoPilot system guides the sprayer. As he drives between crop rows, optical sensors distinguish the green of the crop from the green weed and release herbicide just on the weed. From inside the cab, the operator can monitor the spray system and adjust any application parameters in real time. With the reliability of the steering technology and the efficiency of WeedSeeker, Bedin has been able to reduce refueling time and cover his entire field 30% faster than with his conventional system.
Most importantly, the technology has significantly slashed his weed-chemical expense. “WeedSeeker 2 has yielded us nearly 90% savings in herbicide costs,” said Bedin. “Now we only need to spray between 10% to 30% of the farm — where the weeds actually grow — which equals a savings of about $70,000 for each 1,000 hectares sprayed. Additionally, because we use less herbicide, we impact the environment less.”
Because the spot-spray system logs and maps every weed sprayed, Bedin can also see in real time where there are weed infestations and review the detailed maps before the next spray. With the “seek and destroy” premise of WeedSeeker 2, Bedin’s formidable weeds may have finally met their match.
On a French vineyard in the Loire Valley, a tractor is driving between the grape vines with no one behind the wheel. Meet TREKTOR, the autonomous hybrid robot that works tirelessly to weed the organic vineyard producing some of the finest Gamay wine, called Anjou Gamay Village.
After TREKTOR worked the land for a month, its developer, a company called Sitia, reviewed the quality of their autonomous robot’s work. They counted grape vines damaged during operation — two in one month — and approached the farmer to reconcile the liability. To Sitia’s surprise, he responded, “When I use my manual tractor to get the same job done, I damage at least two vines a day! How did your tractor manage to be so careful?” Sitia’s developers thought for a while and then replied, “It’s thanks to the high quality and accuracy of the components that are inside.”
“Despite the strong magnetic field emitted by the generator on the TREKTOR, the AsteRx SB ProDirect receiver did not have any issues,” said Clément Aubry-Tardif, Sitia’s R&D manager. “The spectrum analyzer in its web interface showed other small radio interferences aboard the robot, but everything was still working fine.”
Integrated into the TREKTOR is an AsteRx SB ProDirect dual-antenna receiver, which provides the reliable high-accuracy positioning and heading needed for autonomous operation. Sitia chose the receiver for the following reasons.
It has centimeter-level accuracy with RTK, which reduces crop damage and increases yields.
Its heading helps point implements in the right direction. Unlike inertial systems, it’s reliable and accurate even in static or slow-moving applications.
Built-in advanced interference mitigation (AIM+) technology makes it resistant to radio interference, while its LOCK+ technology ensures robust satellite tracking even under intense vibrations or shocks.
It includes an intuitive web interface for fast prototyping and easy real-time testing.
Sitia is a French company specializing in autonomous robots. Its TREKTOR helps compensate for the current farmer shortage, which is especially felt on organic farms, where weeding is seven times more labor intensive due to the use of few (if any) herbicides. TREKTOR is a flexible solution that can adjust its height and width on the fly, adapting to various working environments. It can also change implements to perform various functions. Depending on TREKTOR’s dimensions and implements, the distance from the crop to the robot changes, making high-accuracy positioning crucial to minimize damage to any of the crops.
Farmers rely on their GNSS receivers to keep their machines on track, their maps accurate, and their rows straight in demanding environments. GNSS receivers on agricultural equipment need to continue to perform at a high level when faced with extreme weather, temperature and vibration while navigating varying terrain. In addition, farmers rely on the correction services that provide them with the high accuracy needed to keep them operating. Still, they face challenges with outages and interruptions from obstacles blocking satellite signals.
Hexagon | NovAtel’s SMART7 GNSS receiver and TerraStar Correction Services together create an accurate, robust and reliable solution for farmers. These products undergo extensive testing to ensure a high-performing and dependable solution. The SMART7 accesses all four GNSS constellations (GPS, GLONASS, BeiDou and Galileo), providing the best availability in variable terrain and environmental conditions. To compensate for the pitch and roll in the field, the receiver includes terrain compensation — keeping farmers at centimeter-level accuracy when using TerraStar-C PRO, TerraStar-X or RTK corrections.
Photo: Hexagon | Novatel
TerraStar Correction Services are based on a global network of advanced and proprietary GNSS control centers to ensure 99.999% signal availability to farmers. By delivering quality satellite corrections without the need for base stations, farmers can get the accuracy needed for their operations in a scalable format that moves with their equipment.
Jacob Van Den Borne is a potato farmer in the southern region of the Netherlands. He has been working with precision farming for more than 10 years and recently switched his Fendt tractor to NovAtel’s SMART7. Throughout his last season, Jacob noticed a substantial improvement in signal reception while passing along the edges of his heavily treed field. Previously, his GNSS equipment would lose reception, causing his rows to wander. After using a SMART7 for one season and experiencing its high precision and reliability, Van Den Borne plans to switch all receivers on his farm to the SMART7.
Evolving advanced driver-assistance systems (ADAS) and developing safe perception and positioning systems in the agriculture industry are top priorities for NovAtel. With the challenges faced by farmers, finding new ways to support a sustainable increase in their production and productivity will help ease the pressures of a growing population.
Hexagon AB, a provider of digital reality solutions combining sensor, software and autonomous technologies, has acquired ETQ, a provider of SaaS-based quality management system (QMS), environment, health and safety (EHS) and compliance management software.
