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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.

The submission deadline is Feb. 14. Submit abstracts here.

For more information about the session, go here and select AS06 (Atmospheric Sciences AS06).

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.

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.

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.

Technologically, providing corrections for high accuracy and authentication data to users via the internet is entirely possible, according to van Diggelen and other experts serving on the president’s Space-based Positioning, Navigation, and Timing (PNT) Advisory Board (PNTAB).

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.”

*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.

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 mluccio@northcoastmedia.net.

— Matteo Luccio, Editor-in-Chief

Check out these perspectives on precision agriculture:

Trimble

Tallysman Wireless

Comnav Technology

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.”

Answers from Ken MacLeod, Product Manager, Tallysman Wireless

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.

Answers from Simon Peng, Director, Overseas Department, ComNav Technology Ltd.

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.

Answers from Maximilian Hiltmair, Strategic Marketing Manager, Trimble Positioning Services

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.”

All HAS-related documentation and additional information about the Galileo services can be found on the European GNSS Service Centre website.