The Institute of Navigation (ION) has opened abstract submissions for Joint Navigation Conference (JNC) 2023, which takes place June 12–15 at the Town and Country Hotel in San Diego, California. JNC 2023 is the largest U.S. military positioning, navigation and timing (PNT) conference of the year with joint service and government participation.
Abstract selection for JNC 2023 is expected to be competitive, according to ION. All abstracts must be written for public release with intent to present in a Controlled Unclassified Environment (CUI) U.S. Only environment. Abstracts not meeting the established criteria, received by Feb. 3, will not be considered.
The event will focus on technical advances in PNT with emphasis on joint development, testing and support of affordable PNT systems, logistics and integration. From an operational perspective, the conference will focus on advances in battlefield applications of GPS; critical strengths and weaknesses of field navigation devices; warfighter PNT requirements and solutions; and navigation warfare.
CUI U.S. only conference attendance will be screened by the Joint Navigation Warfare Center and will be restricted to U.S. only. The exhibit hall (June 13-14) will be open to all conference participants, exhibitors, their employees and related organizations. All materials displayed in the exhibit hall must be publicly releasable after review.
Conveners of a session on GNSS applications for water vapor observations are seeking research paper submissions. The session will take place during the Asia Oceania Geosciences Society (AOGS) Conference 2023 taking place July 30 to Aug. 4 in Singapore.
Session AG06 is titled “Assimilation of Space- and Ground-based Water Vapor Observations for Weather Forecasting and GNSS Applications.”
Observation of water vapor is one of the priorities in the Global Climate Observing System. Obtaining and exploiting additional high-quality humidity observations from GNSS and other remote sensing techniques is essential to improve weather forecasting and climate monitoring, the session conveners explained.
Abstract contributions are being sought on the topic, such as:
new algorithms to estimate water vapor from ground-based and space-based techniques, such as ground-based GNSS, space-based RO, InSAR, visible/near-infrared/infrared/microwave sensors and other sensors
retrieval and inter-comparison of water vapor among multiple instruments
assimilation and analysis of water vapor products from ground-based GNSS, space-based RO, InSAR, and various remote sensing/meteorological satellites for nowcasting and weather forecasting
use of numerical weather prediction models for modeling outputs as atmospheric corrections for GNSS, InSAR, VLBI and other geodetic observation techniques
estimation of atmospheric parameters from crowdsourcing equipment
atmospheric products for climate, hydrology, natural disasters and others.
Paris Austin, head of product – New Technology for OxTS, tries out the new backpack at historic Minster Lovell Hall. (Image: OxTS)
More than 400,000 sites in the United Kingdom are on its historical registries. English Heritage site Minster Lovell Hall is located in Oxfordshire, also the home county of inertial navigation company OxTS. The picturesque ruins of Minster Lovell Hall, a 15th-century manor house, include the hall, a tower and a nearby dovecote.
The hall was built in the 1430s by William, Baron of Lovell and Holand — one of the richest men in England. It was later home to Francis, Viscount Lovell, a close ally of Richard III. After changing hands several times, the hall was abandoned and eventually demolished in the 18th century, leaving the extensive remains that stand today.
(Image: OxTS)
The buildings are grouped around a central courtyard in a plan characteristic of a late medieval manor house. For OxTS, the site proved suitable for testing its prototype backpack. The site features dense tree canopies on one side, tight doorways, narrow views of the sky, and plenty of height to test the angled mounting of the survey-focused lidar for when GNSS is denied. Open-sky areas allowed the OxTS team to return to real-time kinematic (RTK) surveying before moving on to another section of the site.
Reconstruction drawing of Minster Lovell Hall as it might have appeared in the 15th century, by artist Alan Sorrell. (Image: English Heritage)
The prototype backpack is based on the OxTS setup for vehicles but was created to enable quick data collection without a car. It is equipped with two Hesai lidar sensors, a new OxTS prototype inertial navigation system and an antenna. The team can connect it to a laptop for configuration and to optimize lever arms and the boresight. Once post-processed with OxTS Georeferencer software, the point cloud below was produced.
OxTS designed the backpack to meet a growing need for localization and georeferencing in both GNSS-denied areas and those that cannot be reached by car, including the construction, environmental, conservation and heritage industries.
It was 2018. Representatives from the European Space Agency were visiting Google headquarters in Mountainview, California.
Under discussion was Europe’s plans to introduce a high accuracy and authentication service to their Galileo satellite navigation system. Galileo would broadcast precise point positioning corrections on the E6-B band and provide users decimeter-level accuracy. They would also be including a navigation authentication message enabling receivers to distinguish genuine messages from deceptive ones sent by spoofers.
Wouldn’t Google like to incorporate these capabilities in future versions of Android phones?
The answer from Google Distinguished Engineer, Frank van Diggelen, was a resounding “yes.”
Technologically Possible
Van Diggelen also had another thought. It should be possible to deliver precise positioning corrections and authentication data via the internet. This could allow phones with an internet connection to access the services as well. With an app, older smartphones would be able to take advantage of the services, and it wouldn’t be necessary to add new hardware to new phone designs.
The next logical step was to establish an internet-based high accuracy and authentication service for the United States’ GPS. Unlike the newer European Galileo and Chinese Beidou systems, GPS satellites don’t have the ability to transmit data to improve accuracy and authenticate signals.
Yet a couple of process challenges in the United States could make establishing such a service difficult and might prevent its creation entirely.
Data collection and use not yet an official program
The first is related to the way in which the U.S. collects and handles real-time tracking data of the Global Navigation Satellite Systems (GNSS) — GPS, GLONASS, Galileo, and BeiDou — to derive corrections needed for a high accuracy service.
NASA’s Jet Propulsion Laboratory (JPL) operates NASA’s Global GNSS Network (GGN) of more than 60 stations around the globe, which provide their tracking data to JPL’s Global Differential GPS (GDGPS) System. The GDGPS System also has access to real-time tracking data from hundreds of additional sites, all of which track GPS and other GNSS. This allows the GDGPS System to generate precise corrections for the navigation messages of GPS and other GNSS. It also enables real time decimeter-level accuracy for positioning applications anywhere in the world. These corrections are provided to some government agencies and commercial entities on a reimbursable basis.
NASA’s GDGPS capabilities are not part of a formal, official government program, though. Rather they have grown organically as part of JPL’s efforts to push boundaries in scientific and engineering applications of GNSS, and its ability to take on work paid for by other agencies. Thus, GDGPS efforts lack a sufficient and established government funding line, formal programmatic tasking, and other structures and procedures needed to ensure its long-term viability as a government-provided service.
NASA and JPL officials recognized this and in 2020 established a working group to advise on how they should go forward. The following year that working group made several recommendations to NASA and the PNTAB. Among them were to establish a consistent level of NASA funding, create a Level-1 capabilities document for GDGPS, and start discussions towards an interagency memorandum of understanding (MOU) for long-term government funding.
At the same time, a PNTAB task force investigated the GDGPS activity and made recommendations to the PNTAB. They included: that NASA/JPL document GDGPS capabilities, including architecture, facilities, functions and products; that a stable government funding line for GDGPS be established; that a security review of GDGPS be undertaken; and to maintain GDGPS entrepreneurial aspects in pursuing multi-agency usage of its services.
Civil GPS rarely needs addressed
The second challenge to establishing high accuracy and authentication service for GPS appears to be the lack of an identified agent or mechanism within the federal government to do so.
Europe’s Galileo is a civilian system established and operated to support economic activity and development. The U.S’s GPS is run by the military.
First created to “put five bombs in the same hole,” it was built and run for years by the U.S. Air Force and is now the responsibility of the U.S. Space Force. Its primary mission is support of military missions and almost all funding comes through the Department of Defense (DOD).
Yet, indisputably, 99% of GPS users are not in the military and the system has become essential to most technologies and nearly every facet of the U.S. economy.
Official government policy has long recognized this, at least at the strategic level. Presidential policies issued in 2004 and in 2021 provided for improvements in functionality for civil users – as long as they were required by and entirely funded by a civil agency.
At a more tactical level, though, attempts to fund civil requirements have always faced great difficulty and rarely succeeded.* Mandates in presidential directives for civil signal monitoring, interference detection and mitigation, increased resilience, alternative PNT, and responsible use have all faced uphill battles and received little funding.
According to former senior government officials, this difficulty stems from civil GPS use being caught in a bureaucratic “Catch-22.”
On the one hand, executive branch policy dictates that funding for GPS capabilities and applications benefiting civil users must flow through the Department of Transportation (DOT). On the other, within government programming and budgeting circles, GPS is seen as an expensive military capability funded through the DOD. Requests for GPS and PNT-related funding through DOT are more difficult to explain and are easier to deny.
Compounding this difficulty is the lack of a clear and empowered national leader to advocate for a comprehensive and national approach to GPS and PNT issues and overcome bureaucratic snags.
As a result, the path forward for adopting the recommendation for a GPS high accuracy and resilience service is, at best, unclear.
Yet many on the President’s advisory board and in government are hopeful. “Establishing a high accuracy and resilience service for GPS is the right thing to do” said one. “We have all the pieces to make this happen. We just need to bring them together.”
And as one of the board members commented at the recent meeting, if the U.S. doesn’t do this “It stinks.”
Image: Slide from the National PNT Advisory Board Meeting in November 2022
*The exception to difficulties funding civil GPS-related capabilities is the Federal Aviation Administration’s Wide Area Augmentation System. It was established as the result of heavy lobbying by the airline industry, which continues to give it strong support.
Another autonomous lawn mower has hit the field. The RoboUp (made by a company of the same name) is offering a no-perimeter-wire real-time kinematic (RTK) artificial intelligence (AI) robot lawn mower.
The mower uses an RTK module built into the charging station and AI real-time recognition support to automatically measure and profile a yard without any perimeter wiring or other installation.
RoboUp’s dynamic exact positioning system integrates RTK, visual simultaneous localization and mapping (SLAM) and an inertial measurement unit (IMU) to offer precise positioning with centimeter-level accuracy. It can also detect boundaries and identify obstacles and will stop cutting when it reaches either.
The robot lawn mower is powered by a maintenance-free brushless motor, which enables it to climb a 45% slope and cut different types of lawns, including over tough terrain. RoboUP is equipped with adjustable cutting heights of 30 mm to 60 mm and 20 cm width and can adjust the height of the cutting disc to match the terrain.
The mower can be controlled with its own app, which identifies the conditions of the user’s yard and generates a recommended cutting schedule. Additionally, it integrates with smart home systems and can be controlled by voice commands.
The earliest article about GPS and agriculture that I found in my collection of this magazine(*) is from the July/August 1992 issue: “Using GPS in Agricultural Remote Sensing,” by Eileen M. Perry of the Remote Sensing Research Laboratory of the USDA Agricultural Research Service. Thirty years later, you cannot buy a tractor from a major manufacturer that does not come equipped with a GNSS-based guidance system, and precision agriculture routinely makes use of remote sensing data and geographic information systems (GIS). The data are collected by Earth observation satellites, manned aircraft, UAVs and sensors on farm machinery. The GIS are used to collect, manage and analyze these data and create maps for the variable-rate machines to follow when seeding, irrigating, spraying fertilizer, herbicide and pesticides, and harvesting.
In this cover story, managers at Trimble, Tallysman Wireless, and ComNav Technology give their perspective on precision agriculture. Additionally, Gavin Schrock explains recently introduced options for tiered precise point positioning (PPP) services, using Trimble’s CenterPoint RTX as an example.
Proponents of precision agriculture and equipment vendors have always claimed that it reduces inputs (water, seeds, fertilizer and pesticide) and environmental impacts while increasing yields and profits. However, I have never been able to find any independent, reliable and comprehensive study of precision agriculture’s return on investment. If you are aware of any, please let me know, at [email protected].
— Matteo Luccio, Editor-in-Chief
Check out these perspectives on precision agriculture:
* I have the entire collection of GPS World’s print edition, except for the first issue, the 10 issues in the second year (1991), and the September through December 1993 issues. I would be thrilled to receive those missing issues, or facsimiles, from anybody who has them.
Correction services enable farmers to pinpoint where to apply fertilizers so as not to waste any. (Image: artiemedvedev/iStock/Getty Images Plus/Getty Images)
Growing among the many options for GNSS corrections open to precision agriculture operators are tiered precise point positioning (PPP) services. Agriculture has had integrated GPS, and now GNSS, for decades. Ranging from individual RTK bases, networks of RTK bases and network RTK (RTN) to dedicated L-band satellite-delivered PPP, operators have been able to receive and apply the appropriate corrections for different crops and applications, from centimeters to meters.
Part of the appeal of such services, particularly for large agricultural concerns with mixed crops and operations, is having the full flexibility of tiered precisions. Additionally, near-global coverage has increased utilization.
“Specialty and high value crops require high accuracy,” said Michael Helling, senior director of strategy for Trimble’s autonomy group. “For instance, when drip tape is laid for fruits and vegetables, you would not want subsequent activities to be off more than an inch or so, to avoid cutting it. This is where RTK was essential, and a base was often set up, or an RTN accessed. But the RTX [Trimble’s PPP delivered by L-band satellites] high-precision option, CenterPoint RTX, easily meets those needs.”
Like some other PPP correction services, Trimble’s RTX also has lower precision subscription options: RangePoint for 15 cm and ViewPoint for 30 cm pass-to-pass accuracy. These services are also utilized outside of agriculture. For example, CenterPoint, delivering centimeter precision, is utilized for certain surveying and construction applications and FieldPoint for asset mapping. Trimble has also developed embedded solutions, based on the same core technology for, among other things, maritime, robotics, autonomous vehicle, and assisted driving applications.
Certainly many agriculture applications can suffice with lower precisions, such as broadacre crops, where there may be no need to maintain row-to-row and year-to-year repeatability. Where some amount of overlap between passes is acceptable, coarse navigation at sub-meter to meter precision may be all that is needed. However, as Helling notes, precision becomes addictive, and as the field equipment becomes more capable of positionally topical functions, many operators are stepping up in levels of precision.
“Farmers are more precisely testing fields with all kinds of sensors and seeing where the field actually differs in soil and nutrient content,” said Helling. “There are different approaches and value propositions. One is saying I need to fertilize this area better so that I can get a better yield. There are also situations where a specific area of the field might only produce to a certain level. Farmers can pinpoint where those areas are to apply fertilizers so as not to waste it and optimize their bottom line.”
For many agriculture applications, the reality is that you have a tractor pulling some other piece of equipment through a field.
“Think about sprayers, forever behind a tractor,” said Helling. “Our equipment can control a lot of things around the rate, precisely targeting specific pieces of a field or row. When you start thinking about sustainability, being able to turn the spray on and off where you’ve already sprayed, you can avoid overspray.”
Sensor integration helps automate the process.
“We just aquired a company in France called Bilberry; their technology is very effective at identifying weeds. You can identify what’s in the field and can decide how you’re going to treat it. The next immediate steps in automation for agriculture might not be full autonomy, but more automation in the equipment that’s being pulled, and sensors that inform what they do.”
Tallysman antennas provide a critical link in the field for autonomous and semi-autonomous farm equipment. (Image: Kinwun/iStock/Getty Images Plus/Getty Images)
How do you define precision agriculture?
Precision agriculture includes all such modern technological advances as precise GNSS, robotics (autonomous vehicles, UAVs), sensors, and GIS that enable improved crop production by soil/field management and minimize the use of energy, seed, herbicides, pesticides and fertilizer.
What have been the key turning points in the development of precision agriculture?
There have been four key precision agriculture developments over the past 25 years. First, field mapping, which enables yield monitoring and the directed application of seed, fertilizer, herbicide and pesticide. Second, precision GNSS, which enables the same plus crop row offset from year to year. This offset, in turn, makes it possible to distribute the plant root system and utilize nutrients in different locations in the field, as well as to minimize soil compaction by ensuring that wheels do not travel over the same row from year to year. Third, autonomy, including UAVs and autonomous vehicles. Fourth, sensors to monitor moisture and water levels, and to identify weeds and plants.
What are the specific requirements and challenges of precision agriculture for GNSS, and how do they differ from those of other kinds of mapping and machine control?
Many precision agriculture applications require L-band corrections, which are typically broadcast from a geostationary satellite 35,800 km above the equator. The distance from the broadcast satellite to the user increases as the user travels either north or south of the equator. At the same time, the elevation angle decreases and at ~70° north or south of the equator the geostationary satellite will be seen at the horizon. As a result, at northern and southern latitudes, the L-band correction signal is seen at a low elevation angle and it is very weak because it has travelled a long distance. Tallysman has designed the VSS6037L antenna to receive L-band signals seen at low elevation angles.
When did Tallysman Wireless begin to focus on precision agriculture and why?
In September 2019, Tallysman Wireless released the VSS6037L agriculture and machine control GNSS antenna. Most GNSS/L-band antennas on the market have significantly lower gain at low elevation angles. Common GNSS antennas will provide good geostationary L-band reception from the equator to approximately 55° north or south latitude. However, as the arrival angle gets lower, a common GNSS antenna will have less gain and it will be challenged to receive the L-band signal at higher latitudes. Tallysman designed the VSS6037L specifically to provide support for all latitudes and specifically low elevation angle L-band signals received by users north or south 55° latitude.
What are your relevant products/product lines?
Tallysman Wireless has several GNSS antennas and smart GNSS antenna product lines that are designed for precision agriculture. The TW3972XF (triple-band plus L-band) and VSS6037L (full-band plus L-band) are ideal precision agriculture antennas. Tallysman has recently released the TW5390, which is a smart GNSS antenna that uses the u-blox F9P chipset and supports its PointPerfect L-band augmentation service.
For farmers, every centimeter counts. ComNav’s AG360 Pro autosteering system controls pass-to-pass accuracy within 2.5 cm. (Image: Daniel Balakov/E+/Getty Images)
How do you define precision agriculture?
Precision agriculture uses new technologies to obtain as much as possible the unique characteristics of a field and input the correct amount of resources at just the right time. It is a system that needs to be implemented throughout the whole process of crop growth, including land preparation, tractor guidance, water management and weather monitoring. Tractors are used at every step, therefore it is critical to make them work consistently throughout the whole process, by using GNSS. ComNav Technology’s autosteering systems can be installed on most types of tractors. This allows farmers to grow the crops in a more autonomous and efficient pattern, which they can then save with high precision and reuse for later steps until harvest, increasing the utilization rate of land and decreasing the use of fuel, water, fertilizer and herbicides.
What have been the key turning points in the development of precision agriculture?
We have been in this sector since 2013. Our current solution is much easier to install and maintain and has higher accuracy and stability. The younger generation of farmers are more receptive to autonomous driving. They would like to try new things and set themselves “free” with technology.
What are the specific requirements and challenges of precision agriculture for GNSS, and how do they differ from those of other kinds of mapping and machine control?
The main challenges for autosteering systems include signal loss and terrain compensation. Most rural areas lack GSM coverages; therefore, in many countries using autosteering requires base stations. However, radio data links between stations far apart could be affected by obstacles, causing frequent correction outages. To compensate for this, ComNav has embedded in its GNSS module its “RTK-Keep” algorithm, which can maintain a relatively high-precision performance for autosteering during corrections outages. The system also must include various terrain compensation algorithms that identify a field’s elevation contours and provide smooth and continuous guidance even in complex terrains.
When did ComNav begin to focus on precision agriculture and why?
In 2013, we introduced our first high precision GNSS board. Initially, our main role was to provide it to integrators with expertise in precision agriculture. Over the years, the market began to boom in China and in 2016 we announced our first generation autosteering system for tractors. The main reason for us to focus on precision agriculture is the increasing demand from the market, which we believe will continue to grow in the foreseeable future due to the increasing demand for food from Earth’s growing population.
What are your relevant products/product lines?
In the past, workers in China drew lines on the land and then planted potatoes roughly along those lines, which was challenging and time consuming. It was hard for the farm owner to hire an experienced driver and guarantee the effectiveness of seeding. Now, however, ComNav Technology’s AG360 Pro autosteering system solves that problem by guiding vehicles according to set routines, including straight lines, curves, automatic turns and headline turns. Importantly, the pass-to-pass accuracy can be controlled to within 2.5 cm. The worker can finish multiple processes within only 24 hours, such as ridging, ditching, sowing, fertilizing and laying drip irrigation under mulch. Furthermore, compared to traditional manual planting, mechanized planting produces a more even sowing rate, which also establishes the foundation for the automated harvesting of potatoes. Potato production has increased by 10% per acre, land use has been reduced by more than 20%, and labor costs have been reduced significantly.
With the aid of Trimble’s correction services, the in-cab GFX-1260 display connects farmers to a wealth of knowledge about their fields and crops. (Photo: Trimble)
How do you define precision agriculture?
Precision agriculture is the use of technology in farming to increase yields through data and precision. Precision ag helps farmers improve yields by collecting data on all aspects of each plant to figure out exactly what it needs, when it needs it and how it will best survive. From planting, growing and cultivating to spreading, spraying and harvesting, precision agriculture allows farmers to monitor, measure and utilize data from beginning to end.
What have been the key turning points in the development of precision agriculture?
Accurate positioning is the enabler for all precision agriculture. RTK was one of the biggest initial developments within positioning as it allowed farmers a higher level of accuracy than had been seen previously. Precise Point Positioning (PPP) was the next big development. Our version of PPP, Trimble RTX, allows farmers the best of both worlds — RTK-level accuracy delivered via satellite, eliminating the need for base stations or sometimes unreliable radio, cell or internet signals. Though precision agriculture started with guidance, it has now made its way to implement-level, variable rate seeding and spraying and section control. ISOBUS has also been a big development in the past few years — allowing machines of all types to interact and communicate with each other, regardless of type, color and shape.
What are the specific requirements and challenges of precision agriculture for GNSS, and how do they differ from those of other kinds of mapping and machine control?
The challenge in GNSS is providing customers with the greatest availability in the field. While most fields are under open sky, obstacles such as trees and gullies make it more challenging. At Trimble, we provide market-leading pass-to-pass value with limited overlap for the customers at different price points. With our latest and most premium correction service, CenterPoint RTX, ease of use is also a key benefit.
When did Trimble begin to focus on precision agriculture?
Trimble unveiled its first agriculture receivers in 1999, signaling the start of the Trimble Agriculture division. In 2000, AgGPS Autopilot and automated steering systems were released for row crop application, further cementing Trimble’s presence in the precision agriculture community.
What are your relevant products/product lines?
Trimble offers technology integration that allows farmers to collect, share, and manage information across their farms, while providing improved operating efficiencies in the agricultural value chain. Trimble solutions include both hardware and software for guidance and steering, flow and application control, water management, harvest solutions, desktop and cloud-based data management, and correction services. Trimble’s CenterPoint RTX satellite-based correction service delivers GNSS positions repeatable to less than an inch. Combined with Trimble’s ProPoint GNSS technology, this service provides greater positioning availability, even in challenging environments such as tree lines, gullies and along contours where much of farming takes place.
For applications where centimeter-level accuracy is not as high of a priority, such as broad acre applications, Trimble RangePoint RTX and ViewPoint RTX give additional correction service options. They hold equipment to 6-inch and 12-inch pass-to-pass accuracy — or about the width of a tire between passing swaths. Trimble also offers Trimble VRS Now, giving farmers instant access to RTK positioning services using a network of permanent, continuously operating reference stations.
The high-accuracy service (HAS) offered by Galileo is now available and provides sub-meter accuracy over most of the globe. It will help enable emerging technologies such as UAVs and autonomous vehicles, which require stringent levels of accuracy for better navigation, safety and efficient traffic management.
Other industries expected to benefit include transportation, agriculture, geodesy and entertainment.
Thierry Breton, European commissioner for Internal Market, announced that the service was now live during the annual European Space Conference in Brussels, Belgium, on Jan. 24.
The European Union Agency for the Space Programme (EUSPA) developed Galileo HAS along with the European Commission and the European Space Agency (ESA). The new service will become a pillar of government programs such as EU sectorial policies and national policies by EU Member States.
“This new service has been made possible thanks to the outstanding cooperation and team commitment of all involved partners,” said Rodrigo da Costa, EUSPA executive director.
“Galileo is not standing still,” said Javier Benedicto, ESA director of navigation. “This new High Accuracy Service offers a new dimension of precision to everyone who needs it, while the Open Service Navigation Message Authentication — already available — allows users to authenticate Galileo signals as they make use of it, to minimize any risk of spoofing. An upgraded integrity message of the signal rolled out last year reduces the time to first fix while enhancing the overall robustness of Galileo.”
Galileo HAS delivers horizontal accuracy down to 20 cm and vertical accuracy of 40 cm in nominal use conditions, according to ESA. The service is transmitted directly via the Galileo signal in space (E6-B) and through the internet.
With HAS, Galileo becomes the first constellation worldwide able to provide a high-accuracy service globally and directly through the signal in space.
The service is freely accessible to all users with a receiver capable of processing the HAS corrections broadcast in the E6-B signal and via the internet. The precise corrections provided by Galileo HAS will allow users to reduce the error associated with the orbit and clocks provided through the Galileo Open Service broadcast navigation messages and the GPS Standard Positioning Service navigation data.
“With the Galileo HAS we are ready to unleash the full potential of new technologies such as drones and bring autonomous driving closer to reality,’’ da Costa said. “At EUSPA, our role is to link space to user needs. With the launch of this new service, we met a clear market demand for accurate, robust, and reliable navigation.”
While single-base real-time kinematics RTK can, under specific conditions, be the best option for certain applications in surveying and construction, corrections services typically eschew this solution in favor of network RTK, PPP, and PPP-RTK. There are, though, some agricultural networks made up of clusters of reference stations delivering RTK corrections. (Images: courtesy of Gavin Schrock and Courtney Townsend Bigmouse108/iStock / Getty Images/Gettu Images)
The boom in the development of corrections services for applications such as autonomy and robotics has brought a whole new slate of market players, and an expansion of services from established corrections providers. This has benefitted high-precision users as well as the new not-so-high-precision applications.
Whereas very high precision — centimeters — is of paramount importance to sectors such as precision agriculture, construction automation, surveying and mapping, new market sectors are less concerned with precision as they are with reliability, availability and resilience. There are many corrections services that can deliver reliable lane-level precision, decimeter precision, sub-meter or whatever the application requires.
Corrections have been around in various forms for nearly 30 years. Whereas traditional high-precision applications would access corrections services or network infrastructure directly, the user of a mass-market application, such as assisted or autonomous driving, receives corrections second or third hand.
A car manufacturer may install an integrated navigation and positioning system (GNSS is typically only one of many technologies in a complete system) from a vendor that receives corrections from one or more corrections services.
A Recap of the Technology
Uncorrected GNSS is limited to precisions in meters. This may be fine for many purposes, such as coarse navigation and local-based apps. However, for high precision uses, external augmentations (commonly referred to as “corrections”) add more and higher accuracy data to help mitigate multiple sources of error that otherwise limit standalone GNSS results. Various augmented data can be delivered via radio, the internet, or communications satellites. Delivery of augmentations by public or commercial generators of this add-on data is broadly referred to as “positioning services.”
Network RTK, implemented as real-time networks (RTN), covers hundreds of localities, states, and entire countries and is a go-to for many applications in surveying, mapping, construction, monitoring and agriculture. One disadvantage, compared to PPP, is reliance on terrestrial IP communications. (Images: courtesy of Gavin Schrock and Courtney Townsend Bigmouse108/iStock / Getty Images/Gettu Images)
There are two fundamental approaches to generating corrections: Observation Space Representation (OSR) and State Space Representation (SSR). OSR uses observations of one or more base receivers to derive correction values representative of local conditions. Examples of OSR include base-rover real-time kinematics (RTK) and network RTK (NRTK). SSR provides “states” of conditions derived from terrestrial tracking networks, to improve clock and orbit “products,” and may also include data from global, regional, or localized ionospheric and tropospheric models. Examples of SSR include precise point positioning (PPP) solutions.
Players in the corrections services sector include vendors who manufacture GNSS hardware, RTK systems, and NRTK software. One example is real-time networks (RTN), which have grown to cover hundreds of localities, states, regions, and even entire countries. Some of these vendors now operate their own wide region RTN. The same large vendors also have developed global PPP services. The most recent decade though has seen rapid growth in new corrections service providers that focus on one or more key markets and develop approaches specifically to serve them. For instance, many agricultural regions of the world have large clusters of RTK stations operated by a vendor or a cooperative. Some newer vendors, focused on the autonomy market, have developed global PPP services, regional NRTK, or hybrids for decimeter to meter precision. One Achilles heel of PPP is its relatively poor vertical precision compared to RTK and NRTK. This partly explains why adoption has been slow for certain high-precision applications, such as surveying.
Where corrections services have become quite interesting, is in amalgams of these approaches. In recent years, the rapid expansion of corrections services for mass-market applications has given rise to what developers call PPP-RTK. Ostensibly, this is to take advantage of the strengths in each approach, however it may be more about trade-offs between precision and the practicalities of serving wide regions in a cost-effective manner. There are many variations on how this hybridization is achieved; for example, PPP- ambiguity resolution (PPP-AR). PPP-RTK can be somewhat of a nebulous term, much in the same way as the term “AI” gets used. Developers of the specific PPP-RTK approaches for the many corrections services keep certain details close to their chests. Clients are less concerned with how it works as they are with the results.
Examples of Vendors
In compiling the following list, we tried to provide examples of all aspects of the corrections service industry — from GNSS network software development to hosting of national and regional networks to providing global PPP. This segment continues to grow; new players continue to develop solutions and enter the market, some with great fanfare, while others seek to stay under the radar. This list does not include the many hundreds of RTN worldwide — local, regional, or national — though the key providers of the NRTK software these networks use are listed.
One advantage of PPP and PPP-RTK over RTK and NRTK is that they can deliver augmentations by satellites, eliminating reliance on terrestrial communications networks. Satellite delivery has a downside: the number of communications satellites broadcasting the augmentations is limited, which can be problematic in sky-view challenged areas. (Image: courtesy of Gavin Schrock and Courtney Townsend Bigmouse108/iStock / Getty Images/Gettu Images)
Note that other vendors are also not listed, such as some that seek to limit their visibility to specific clients and partners. For example, some offer corrections services as an adjunct to inside hardware/software sales, and others work with developers of certain integrated navigation/autonomy systems. In addition, some of the smaller vendors may be working in conjunction with some of the more established developers, often licensing elements of their software, and in many instances piggybacking on their global tracking networks.
In alphabetical order: Atlas. From Hemisphere GNSS. A global PPP service delivered by L-band satellites. It includes tiered precision for different applications, such as surveying, mapping, and asset management. Atlas Basic, Atlas H30, Atlas H10: bit.ly/3V42qxj. CHCNAV. CPS NRTK software: bit.ly/3FI6zlN. It also hosts various RTN and has a global network partner program: bit.ly/3VQugOr. CNH. Advance Farming Software (AFS) RTK+ network delivering corrections mostly via cellular to primarily precision agriculture users: bit.ly/3YiCZur. DigiFarm. DigiFarm VBN. An example of another network that serves primarily agriculture users, however, it now has a spinoff to serve other high precision markets: bit.ly/3hgnYZs. eSurvey. GNSS NET, a VRS management software: bit.ly/3Py0uMp. Fugro. Global PPP corrections services; tiered precision for various applications, mostly maritime and marine construction. StarFix, SeaStar, MarineStar, OceanStar: bit.ly/3W4LkA8. Geo++. One of the first developers of GNSS network and PPP solutions. Its GNSMART software suite provides NRTK and SSR broadcast capabilities: bit.ly/3FhGE2Z. HERE Technologies. HD GNSS, a PPP-RTK solution for mass-market applications: bit.ly/3Fnle4H. Hi-Target. Hi-RTP, a global PPP- RTK service: bit.ly/3hi2xHv. IGS. International GNSS Service, a federation of agencies and research entities with a global tracking network of more than 400 reference stations. The IGS is a vital component of the global geodetic infrastructure. RTS is its real-time PPP service. It is not fast converging like many of the commercial services, but it is free for many applications. It is not broadcast via satellites, only via the internet: igs.org. Leica Geosystems. Part of Hexagon. Provider of NRTK software (Spider), and host of its own RTN covering various regions around the world (SmartNet), and global PPP (SmartLink): bit.ly/3uEwHb9. NovAtel. Part of Hexagon. Includes various tiers of PPP-RTK: RTK Assist, RTK Assist-Pro*, TerraStar-L, Oceanix, TerraStar-C PRO*, and TerraStar-X* (what NovAtel calls“RTK From the Sky”): bit.ly/3HzuqWh. Point One. RTK correction service called Polaris, available also via partners such as Bad Elf: bit.ly/3uPJGqA. Premium Positioning. RTKcorrections service called RTK Premium: bit.ly/3uT0xZi. Rx Networks. A mix of tiered positioning approaches for location- based applications. Truepoint. io (DGNSS, PPP, PPP-RTK): bit.ly/3We1rvT. SBAS (Public). Satellite-based augmentation systems, national or regional services. Like commercial PPP, SBAS corrections are mostly served via satellites. Public safety and civil aviation are the primary drivers for providing such services. For instance, in North America, the Wide Area Augmentation System (WAAS) was chartered by the Federal Aviation Administration (FAA). There are equivalent systems in Europe (EGNOS), India (GAGAN), Japan (MSAS and QZSS), Russia (SDCM), China (SNAS/BDSAS, which is still in development) and Australia and New Zealand (SouthPAN). Other systems are in development in South America and the Caribbean (SACCSA), Korea (KASS) and in Africa and the Indian Ocean (ASECNA). Sino/Comnav. CDC.NET CORS software, RTN software: bit.ly/3W56hvm. Swift Navigation. Skylark RTK and Skylark DGNSS services: bit.ly/3HyWVn5. Tersus GNSS. Tersus Advanced Positioning (TAP), a PPP service: bit.ly/3hoZkWD. Topcon. TopNet and Topnet Live. RTN Software, regional RTN, and PPP services: bit.ly/3FRRcaw. Trimble. RTN software, VRS Now (regional RTN), and tiered PPP services: CenterPoint RTX, RangePoint RTX, ViewPoint RTX, and FieldPoint RTX: bit.ly/3V3bbax. u-blox. PointPerfect regional PPP and PPP-RTK: bit.ly/3FPVmQo. Veripos. Part of Hexagon. Tiered global PPP services, originally focused on maritime applications: Standard, Ultra, APEX: bit.ly/3BBjfsf. Verizon. Telecom infrastructure-based PPP-RTK service called ThingSpace: bit.ly/3Fw1U55. Vodaphone. Currently developing corrections services in conjunction with Topcon: bit.ly/3Pug4s0.
Whatever the application, there are now many options for corrections services. Non-mass-market applications, for traditional high- precision uses, have been tapping such services for (in some cases) decades. The prize of primacy in the autonomy market has been in the sights of many of these vendors for many years, yet there have been relatively few real-world applications to date. That should be changing soon. Early adoptions such as GM’s Super Cruise, which is powered by the same core PPP technology as RTX, have been quite successful. Which will come out on top? That might be a moot question. With the potential of such markets so great, perhaps there is room for all of them, and more.
