ComNav’s high-accuracy PileMaster sped construction of the Aarah Resort in the Maldives. Photo: LANKA Foundation and Piling Services Pvt. Ltd.
The construction of the Aarah Resort in the Maldives involved building 64 luxury water villas and 12 beach buildings on a shallow-water area with about 1,400 piles. LANKA Foundation and Piling Services Pvt. Ltd. was able to complete the piling project in only 32 days by using a high-accuracy piling solution from ComNav Technology Ltd.
The traditional piling approach requires many surveyors to stake out the positions of the piles underwater in advance. Not only is this process labor-intensive, it also creates a real-time problem: even if the coordinates are measured accurately by lofting, the primary coordinate markers are soon out of position due to the movement of the piling machines. The stakeout’s accuracy is also threatened by strong waves, ocean currents and coral reefs. Furthermore, in the subsequent piling process, the piling accuracy is reduced due to artificial aiming. During the whole process, surveyors must work in the water and fix the piles at short range, which is dangerous. For these reasons, the traditional piling approach is a low-efficiency, high-cost and high-risk operation.
Photo: Google Earth
ComNav’s professional positioning solution for high-accuracy piling provides a 9-inch high-resolution tablet with an integrated GNSS receiver, a T300 GNSS receiver as the base station, and two AT340 antennas with magnetic mounts combined with PileMaster software. Its integrated GNSS receiver tracks GPS, GLONASS and BeiDou signals, enabling the system to work even in challenging environments. The system can acquire real-time kinematic (RTK) corrections via an internal UHF transceiver from the T300 receiver or connect to a local continuously operating reference station (CORS). Moreover, PileMaster is designed with an intuitive interface with clear element-management capability, supporting import of up to 10,000 points from Excel, TXT and CAD formats to meet the specific demands of a high-accuracy piling project.
Compared to the traditional piling method, ComNav’s intelligent control system for piling is an all-weather, high-accuracy solution with the additional advantages of being widely compatible and easy to manage. Through software system control and real-time processing and display, it can greatly reduce the number of surveyors required on-site. The system can guide users to the location, shorten the construction period, save construction costs, and enable intelligent visualization and monitoring to ensure high-precision construction work.
After a first successful application in 2017, Foresight Surveyors Pvt. Ltd, ComNav’s local partner in the Maldives, used the solution in many projects, including construction of the Kunaavashi Resort & Spa in 2018 and the Kuda Villingili, Dhigufaru Island and Maniya Faru resorts in 2019.
A mining road-train loaded with ore passes through an outback town. A Hexagon system will guide autonomous movement of similar heavy vehicles. Photo: BeyondImages/iStock/Getty Images Plus/Getty Images
Hexagon’s Autonomy & Positioning and Mining divisions recently partnered with Mineral Resources Limited (MRL), a mining services company, to develop an automated road-train solution for deployment on MRL’s haulage fleet over the next two years. The solution integrates drive-by-wire technology with an autonomous management system to orchestrate vehicle movement in road-train haulage to improve safety, productivity and sustainability. We asked Lee Baldwin, the director of Hexagon’s Autonomy & Positioning division, a few questions about the system.
What does an automated road-train do?
It is for haulage on roads hundreds of kilometers long. It first will be used to move ore from a mine processing facility in the Pilbara region of Western Australia, about 1,200 kilometers north of Perth, to Port Hedland, where it is loaded on ships bound for Asia for use in steel mills. Typically, this is done using either rail or a road train, which is a highway truck pulling multiple trailers. Today, a person drives a road train.
What motivated this project?
Mines have difficulty finding drivers for mining trucks and road trains because the mines are very far away from the nearest city, Perth, so they must fly workers in and out, which is very costly. Many of them are on 10-day shifts. Also, there are safety concerns.
How does an automated road-train work?
It requires three typical subsystems that you would have on any autonomous vehicle. The first one is positioning, including redundant GNSS receivers with our TerraStar correction services. The second is a perception system for collision avoidance, using our HxGN MineProtect Collision Avoidance System. The third one is route planning. We will start by platooning, with a driver in the first truck, which will be followed by three unmanned ones, each towing multiple trailers. Each truck will have the positioning, perception and route-planning systems. Later, we will achieve full autonomy by removing the driver from the lead vehicle.
How will the transfer at the mine work?
At a mine site, the road train will be commissioned in a sequestered area, then sent to a loading area where it will be loaded with ore, either automatically or by a manned wheel loader. Next, it will travel 200 kilometers to the port, where it will dump the ore. Finally, it will be decommissioned and queued up for the return journey.
Which parts are already in place and which ones are still being developed?
At Hexagon, we are already putting technology in manned mines. For example, we already have the collision-avoidance system, a fleet management system, and some sitewide planning systems. However, the trucks that the customers are choosing will have to be converted to be drive-by-wire to accommodate our autonomy system. They will use two PwrPak7 GNSS receivers and the TerraStar correction service.
On a project on the Butterfield Landfill — about 45 miles south of Phoenix, Arizona — Buesing Corp. needed to excavate and haul 1,850,000 cubic yards of dirt from a landfill more than 60 feet deep while grading the slope, basin and stockpile; inserting storm drains; and making an operations layer.
Buesing, founded in 1965, specializes in modeling and building complex underground systems in challenging conditions. It had four months to complete the initial mass grading, with another month for shaping the stockpile and a final month for the operations layer and piping. The mass grading of the site required an accuracy of plus or minus one tenth of a foot in a landfill with 4:1 slopes and a slope length of 300 linear feet, and the operations layer had to be two feet thick. The project also required installing storm drain inlets, flow lines, and outlets to grade.
To remain on schedule, the project required moving large quantities of soil quickly and efficiently, as well as adjusting grading models to incorporate design updates and changes while in production. “We used DTMs and orthophotos collected with our UAV to track progress quantities and adjust the stockpile model to minimize haul distances and slope rework as well as maintain proper drainage and control of stormwater,” said Rio Byman, Buesing’s GPS manager, who is responsible for building 3D models and managing the maintenance, calibration and updates for the company’s machine control (MC) solutions.
A caterpillar CAT14M3 motorgrader is guided by Trimble’s dual-mast Earthworks system. (Photo: Trimble)
For this project, the company used heavy equipment both with and without MC, including blades, excavators and dozers with MC, along with GNSS-based grade checkers to control the earthmoving operations. Specifically, Buesing, which started converting its equipment to Trimble around 2018, used the Trimble Earthworks Grade Control Platform and the Trimble GCS900 Grade Control System on the site and Trimble Business Center at its office.
Buesing works in a variety of market segments for public and private entities in seven states, though it performs most of its work in the Phoenix metropolitan area. Key to its success has been an emphasis on skilled crews, continuous training and technology. In fact, Buesing was one of the early adopters of machine control in 2006. “A decade ago, the technology was pretty rudimentary, which limited adoption,” Byman said. “That’s changed a lot in recent years, particularly in the ease of use and flexibility. Today, grade control is an integral part of the company’s ability to build ever-more-complex solutions in even more challenging site and soil conditions.”
The company started with the Trimble GCS900 on single-mast and dual-mast blades, excavators and dozers. It has since moved to the Trimble Earthworks Grade Control Platform along with Trimble Business Center for managing 3D models. Working closely with SITECH Southwest, Buesing has gone from six machines with grade control to more than 20 in just five years. The company relies on grade-control solutions on its excavators, dozers, motor graders and scrapers, and has used them on projects of every scope and scale, though their value is most evident on urban high-rise excavation.
“It takes time for operators to gain faith in the data, and know that the machine will excavate efficiently and accurately, whether building pads or cutting basements,” Byman said. He believes that improved productivity in the field comes with trust in the technology.
Using Trimble Earthworks’ Autos mode, the software controls the implements while the operator controls the machine’s direction and speed for consistent, high-accuracy finished grade in much less time than it would take without automation. “On any jobsite, the operators have to be aware of everything around them, as well as what’s going on with the blades or scrapers,” Byman said.
“With Autos, they’re able to focus on what’s going on around the job and plan for watering and other environmental conditions with confidence that the machine is digging to grade. This makes our jobsites more productive, safer and more efficient. We have happier operators who are excited to come to work with newer equipment.”
Lidar sensors that used to cost tens of thousands of dollars now cost only hundreds of dollars. With prices significantly decreasing, 3D sensors are more accessible than ever before. Now, what was once a niche technology exclusively for autonomous vehicles is being deployed globally to make places safer and smarter. Additionally, the industry is continuing to grow: market analysis firm Yolé estimates that the lidar industry will be worth nearly $4 billion by 2025, a 19% CAGR between 2020 and 2025.
While decreasing sensor prices are a critical factor in the proliferation of lidar, an arguably more significant development is the development of robust perception software that can track, identify and monitor with far greater accuracy and efficiency than ever before.
Effective 3D sensors, from lidar to radar and 3D cameras, require both hardware and software components. The hardware is critical to capturing data with high resolution and accuracy, while the software processes and comprehends the data, making them actionable. Essentially, software is the “brain” of sensors. Lidar, without equally strong perception software, is like an iPhone without iOS — inoperable and just a piece of machinery.
Today, at the confluence of these factors, we are beginning to see a proliferation of 3D perception applications beyond autonomous driving. Cities, security and retail are a few key sectors where I predict we will continue to see advancements over the next few years.
Making Cities Smarter
The steep drop in the cost of lidar sensors has made 3D sensors more accessible than ever. (Image: Seoul Robotics)
Today’s cities have a variety of challenges to address, from decreasing traffic collisions to reducing congestion, and we are witnessing municipalities leveraging lidar to collect critical insights into city safety and efficiency.
However, why are they turning to 3D solutions, specifically? Because they can capture the data necessary to make actionable changes. 3D sensors were developed to quickly track and analyze city surroundings for autonomous vehicles, so they are an effective way to ensure that vehicles are not veering into opposing lanes or traversing crosswalks already occupied by pedestrians.
Cities also adopt 3D applications because they can often address multiple challenges with one system. For example, a city may install a lidar system on an intersection to detect traffic violations, but the system can also capture data about pedestrian safety and traffic flow. These multi-benefit solutions are ultimately more cost-effective for cities because they eliminate the need to install multiple different solutions to solve these problems.
Creating Safer Spaces
Companies are turning to 3D data to create safer and more secure environments. (Image: Seoul Robotics)
From airports to museums, from stadiums to music venues, the market for 3D-based security solutions is vast. While each of these environments is unique in how it operates, they all rely on technology to ensure that areas are secure, visitors do not enter prohibited areas, and crowds are seamlessly moving through the space.
3D perception helps address these challenges by creating “zones” that can alert security systems if someone enters. Additionally, because 3D sensors can detect and track various objects, including humans, they are increasingly becoming a popular solution for crowd control. They can help venues monitor and address foot traffic, such as with security lines, and they can be valuable in the event of an emergency to ensure that an area is clear.
Beyond the tangible benefits 3D sensors bring to different venues, companies are turning to 3D data to create safer and more secure environments because they are more accurate and anonymous. Unlike traditional camera-based systems such as CCTV, which are often prone to false positives, 3D data are incredibly accurate and precise, so they are less likely to set off alarms unnecessarily. Additionally, 3D data do not include biometric information, so they address privacy concerns while still ensuring that areas are secure.
Building 3D Retail Environments
By implementing 3D-based solutions into a physical retail environment, companies can better understand how shoppers are moving through and spending their time in stores. They can glean insights into key metrics, such as:
How long are people in line?
What areas of the store are receiving the most traffic?
With what products are people engaging most frequently?
As one example, Mercedes-Benz has integrated 3D sensors into its showrooms in Korea, gaining fascinating insights into customer behavior. For example, they’ve discovered that nearly 60% of customers spend their time looking at the trunk space of SUVs, and that red is the most popular color.
As these solutions continue to become more sophisticated and accessible, we should expect to see them in more areas of our everyday lives. The future of 3D perception is exciting, and it will ensure safer, smarter and more efficient spaces — improving the quality of life.
HanBin Lee is CEO of Seoul Robotics, a 3D perception company specializing in lidar.
Currently, 37 Global Positioning System satellites are on-orbit, with 29 of them set healthy. The system continues to provide an average 48-centimeter position accuracy. Despite this achievement, the U.S. government — specifically, the Space Force — continues to modernize GPS’s space, control and military user equipment segments.
Modernization of the space segment is centered on the GPS III satellites, which provide up to eight times better anti-jam capability and a new L1C signal to improve user connectivity. GPS IIIF satellites, scheduled for delivery starting in early 2026, will add a search-and-rescue payload, a fully digital navigation payload, and greatly enhanced anti-jam capability for military operations.
Modernization of the control segment is focused on the next-generation Operational Control System (OCX), scheduled to become operational early next year. OCX will sport an updated architecture to provide enhanced command-and-control capabilities and enhanced cybersecurity. Despite the pandemic, all 17 global OCX monitoring station installations were completed last summer, and most of the remaining equipment was fielded by the end of 2021.
Twenty-four GPS satellites are broadcasting the military code (M-code). The Modernized GPS User Equipment (MGUE) program is developing military GPS receivers able to take advantage of these signals to improve defenses against spoofing and jamming while allowing navigation warfare operations.
On the civil side, GPS modernization will play a key role in the development of the Next Generation Air Transportation System and intelligent transportation systems. The Department of Defense coordinates its GPS activities with the Department of Transportation (DOT), the Federal Aviation Administration (FAA) and many other federal departments and agencies via the National Executive Committee for Space-Based PNT. The term “space-based PNT” refers to GPS, GPS augmentations and other GNSS.
However, this government-wide coordination and cooperation is contradicted by the stand of the Federal Communications Commission (FCC) on the matter of Ligado Networks’ applications to modify its license for terrestrial service, which it approved in 2020. The FCC’s decision is opposed by the executive branch, represented by the National Telecommunications and Information Administration (NTIA), and by 14 federal agencies and departments individually (including the departments of Defense, Transportation, State, Treasury, Justice, Interior, Agriculture, Commerce, Energy and Homeland Security), as well as by the National PNT Advisory Board and by most GNSS receiver manufacturers and aviation organizations. NTIA took the unprecedented step of filing a still-pending petition for reconsideration with the FCC. The concern is that Ligado’s proposed transmission power exceeds the thresholds established by the DOT’s April 2018 GPS Adjacent Band Compatibility study to protect GPS users from harmful interference.
So, the list of threats to GPS now includes solar flares, spoofing, jamming, “legal jamming” by Ligado, and the Russian government’s recent threat to destroy GPS satellites. Modernizing GPS must proceed hand-in-hand with protecting it.
ByBradford W. Parkinson Aeronautics and Astronautics Professor Emeritus (recalled) Stanford University
Brad Parkinson
We, of the PNT universe, have been hearing a rather continual message of doom from the media regarding the fragility of the GPS (or GNSS) signals. In a way, they are right. The received GPS signal is 1/10th of 1 millionth of 1 billionth of a Watt. It can be susceptible to jamming and spoofing.
In response, the U.S. government has sponsored major studies and some competitive tests of techniques to augment or possibly replace GPS. I applaud such queries, but also would strongly advocate more balance in efforts to increase robustness of positioning, navigation and timing (PNT).
Specifically, I argue for increased emphasis on well-known techniques that can greatly toughen GNSS receivers to both jamming and spoofing. Some of these techniques are deliberately denied to civil users by government policy.
Background
The PNT Advisory Board (PNTAB) is a panel of national experts who report to the PNT ExCom. The ExCom is comprised of the deputy heads of the nine U.S. government departments with the largest stakes in PNT. The PNTAB has a starkly simple and well-stated goal:
To meet its overarching goal, the PNTAB has developed a three-legged strategic framework, known as “PTA”: “We must protect, toughen and augment GPS to ensure that it continues to provide economic and societal benefits to the nation.”
Most current U.S. government efforts have been focused on the third of the PNTAB strategic legs: augmenting the GPS system. These system augmentations include: modernized Loran (eLoran), fiber-optic distribution of time, and ranging to low-Earth-orbit (LEO) satellites (particularly the swarms of communications satellites). In general, these system augmentations offer no hope of being equivalent to GPS in terms of availability and accuracy.
However, augmentations have the advantage of either being less vulnerable to interference, or highly proliferated in case of satellite outages. As supplements, or in an emergency, they can perform a very valuable role, but with nowhere near the equivalent performance of normally operating GNSS, which can routinely provide worldwide, 24/7 precisions better than decimeters in the dynamic real-time kinematic (RTK) mode. In the United States, GPS also offers continuous, real-time integrity assessments courtesy of the FAA1. Europe has a similar, compatible integrity system called EGNOS, and there are other regional system augmentations.
In summary, the current PNTAB assessment regarding these substitutes is:
“No current or foreseeable alternative to GNSS (primarily GPS) can deliver the equivalent accuracy (static down to millimeters) and worldwide, 24/7 availability.”
Toughening User Equipment
Toughening, the second leg of our assurance strategy, includes all aspects of GPS enterprise vulnerability — satellites, ground control and user equipment. For this article, I am focused on toughening the user equipment. I would argue that we have largely under-emphasized, or been prohibited by national policy from using, well-known and widely available user equipment toughening technology.
The main vulnerabilities of GPS receivers are jamming and spoofing of the received signals. Familiar anti-jam (A/J) methods can substantially overcome the inherent weakness of GPS signals to defeat deliberate jamming and spoofing. As I outline here, such measures can reduce a jammer’s effective radius by a factor of more than 100 and reduce the effective jammer area by a factor of 10,000 compared to the unprotected receiver.2
Thus, these methods are also deterrents, because they can render ineffective such hostile (or possibly inadvertent) acts. Further, the technology that provides this significant toughening is available now or will be within a few years, rather than the many years required by some alternative, system-level augmentations.
Toughening techniques (A/J improvements) are traditionally calibrated as the improvement in the amount of jamming that can be tolerated, measured by the jamming-to-signal power ratio (J/S) expressed as decibels (dB). However, for this discussion, I will also use a different, more intuitive, measure. This metric is the Denial Radius Reduction Ratio (DRRR):
DRRR = (radius of jammer denial after J/S measure applied)/(jammer radius without improvements)
For example, a 15-dB improvement in J/S would lead to a DRRR of 0.178.3 In other words, the 15-dB improvement has reduced the denial radius to about 18% of the line-of-sight radius that would be denied to an untoughened receiver. Note that the simultaneous use of techniques is generally multiplicative. For example, simultaneously applying technique #1 with a DRRR1 of 0.5 and technique #2 with a DRRR2 of 0.3, would result in a DRRR1&2 of 0.3 *0.5, or an overall DRRR of 0.15. This is the advantage of using this metric to describe the A/J improvements. 4
Baseline Case
For our basis for comparison, we will consider the L1 C/A signal in full accuracy (State 5) tracking mode and a 1-kW noise jammer.5,6 For this situation, the line-of-sight jammer could deny GPS to a radius of about 560 kilometers. A discussion of the lower accuracy State 3 tracking is included below.
It is useful to consider toughening techniques in four major categories.
Toughening Category 1: Signal Processing. With L1 C/A, GPS receivers can improve jamming resistance, albeit with loss of ranging (tracking) accuracy, by using code tracking mode – State 3. This reduces a line-of-sight jammer’s denial radius (DRRR) to about 0.29 (a 10.7 dB improvement).
Toughening Category 2: Inertial Components and Very Stable User Clocks. This includes miniature micro-electromechanical (MEMS) components up to high-grade inertial measurement units (IMUs) and quartz to chip-scale atomic clocks (CSACs). These techniques enable narrower tracking filters and longer averaging, as well as allowing navigation through regions when GPS is denied. The range of DRRRs is 0.40 down to 0.10. We will use a nominal value of 0.18 (a 15-dB improvement).
Toughening Category 3: CRPAs. Controlled reception pattern antennas (CRPAS) are digital, multi-element, phase-steered antennas. They represent well-understood and available technology; they have been used in large surface-search radar systems for many decades.7 They can be used in null-steering or beam-steering modes.8 The number of antenna elements could range up to dozens. Potentially, they could produce DRRRs down to .01 — that is, a 99% reduction of jammer radius to 1% of the unprotected GPS receiver value.
Unfortunately, the U.S. government does not allow more than three-element CRPAs to be manufactured or sold for civil use. 9 This is due to some very old International Traffic in Arms Regulations (ITAR). For our nominal example, we will assume the restriction has been relaxed and use a CRPA of about 20 elements, which should produce a DRRR of 0.06 (a 25-dB improvement).
Toughening Category 4: Signal Alternatives. This category includes alternative modulations at 1575 MHz (L1C, Galileo or other GNSS) and alternative frequencies (L5, L2, Galileo). Note that the modern signals generally offer significantly improved signal-processing toughening as well as increased power.
Using L1C in State 3 compared to L1 C/A in State 5 would yield a DRRR of 0.10. (a 20.3-dB improvement). The L1C international signal should be operational on GPS by mid-decade. The L5 signal, at 1176 MHz, is clearly the most capable of the civil GPS signals in terms of jam resistance. L5 also should be declared operational by mid-decade. As the use of LEO communication satellites matures, their use may also fit this category.
Summary of Receiver Toughening Options. Quantification of the selected, nominal receiver augmentations are summarized in FIGURE 1 for both full accuracy (State 5, centimeter-level accuracy in RTK) and for less accurate code tracking (State 3, meter-level accuracy). These results are shown with a logarithmic scale to accommodate the wide range of denial radii.
Figure 1. Effect of receiver augmentations on accuracy for both State 5 and State 3. (Image: Brad Parkinson)
The example shows that a 1-kW hostile jammer’s denial radius10 can be reduced by a factor of about 100, using the conservative example augmentations of inertial and CRPAs. Because area is proportional to radius squared, the effective denial area of an augmented receiver would be 1/10,000th of the unaugmented receiver, using the example values.
Reverting to code-only (State 3) tracking, it enables operating through higher levels of jamming, albeit with less ranging precision. All these receiver augmentations and tracking techniques would also offer a significant defense against any attempt to spoof (deceive) the position measurement. Again, none of these techniques are new; we demonstrated the capabilities at the original GPS Joint Program Office in 1978, more than 40 years ago. Today, many competent manufacturers are offering toughened GPS receivers with combinations and variations of these techniques.
GPS jamming tests at White Sands have caused aircraft interference, which could be largely avoided with toughened receivers. Here, M-code is tested on Joint Light Tactical Vehicle platforms in 2020. (Photo: Joe Bullinger/U.S. Navy)
Meeting Increasing Threats
Threats of both jamming and spoofing seem to have accelerated. Devices to perform these illegal acts are freely advertised on the internet. In fact, we read of incidents both in the United States and abroad.11 Near White Sands Missile Range in New Mexico, there have been GPS air traffic control outages due to authorized military operational jamming exercises. Such interruptions could be largely avoided if more robust (toughened) GPS receivers, with the enhanced jam resistance techniques outlined here, were in use.
News reports also highlight the spoofing issue. Hardening against this threat is also a task for toughening. A serious spoofing sequence usually starts with a strong jamming signal to cause the user’s receiver to break lock, followed by a strong false GNSS signal that causes false lock by the receiver. Using the false signal leads to a false position, of course. The first line of defense is to avoid the break-lock threat. Failing this, numerous self-check and authentication schemes can be used to avoid false positions.
A conclusion is that avoiding the break-lock jamming is a first line of defense against a spoofing attack. Of course, the toughening techniques to avoid this are the main subject of this paper. One well-known expert has stated that, for a well-designed receiver, a spoofing attack might deny the measurement of position, but should never cause false PNT. I will leave further discussion of spoofing to other authors.
Returning to disruptions of service in general, some have suggested many interference occurrences have gone unreported, because the typical user would not know where to make such a report. To remind the reader, the official reporting center is online at www.navcen.uscg.gov/?pageName=gpsUserInput.
In addition, the U.S. Federal Communications Commission (FCC) has repurposed a portion of the spectrum adjacent to the main GNSS L1 frequency (1575 MHz). The agency is converting the license holder’s original authorization to transmit a weak space-transmitted signal into a much stronger terrestrial system, potentially with thousands of transmitters. Extensive testing of civil GPS receivers by the U.S. Department of Transportation demonstrated that the planned repurposing will interfere with many existing receivers. Some observers call this disruption “legal jamming.”
Such a new spectrum use could have grave impacts on those existing receivers, notably aviation (especially helicopters and UAVs) and first providers. On the other hand, installing toughened replacement receivers would make the users virtually immune to this threat.
So, this begs the question: If the receiver toughening techniques are so effective, why are they not more prevalent?
Barriers to Adoption
Let’s examine the potential resistance to more extensive use of receiver augmentations.
Knowledge. This involves underestimating the threat to PNT and not understanding that toughening techniques are available. As mentioned above, threats to the fragile GNSS signals are growing.
There seems to be little interest in the U.S. government to monitor and suppress interference in the United States. Internationally, the reported incidents continue to increase.12 It is also reported that certain European aircraft manufacturers have installed advanced, deeply integrated inertial systems with civil GNSS receivers to defeat or “flywheel” through radio-frequency threats (particularly in the Middle East).
As this threat trend continues, GPS manufacturers and users must realize that many of these solutions will take time to authorize, implement and install. It appears that the media are not aware that not only are the toughening techniques outlined here feasible, but many manufacturers have product offerings that address these threats. Having off-the-shelf solutions will give the PNT user the opportunity to retrofit and defeat such threats.
Cost. The cost for a receiver to revert from State 5 to State 3 is zero, and all receivers that use Code 5 (for example, RTK) would naturally have this built in. Regarding use of other frequencies (such as L5) and modulations (L1C) rather than the original L1 C/A, there is some small cost associated, including the additional antenna for L5. Note that all modern cellphone chips, such as Qualcomm’s, have this capability — including integrated carrier-phase measurements — in a chip that is estimated to cost about $5. A potential barrier is that the L5 and L1C signals are not yet declared operational, but these newer GPS signals should be operational within about five years.
The costs of many inertial components (accelerometers and gyros) have plummeted in the last few decades with the proliferation of MEMS devices, particularly into cellphones and automobiles. Their power consumption has also decreased while their performance has steadily improved. Full IMUs are much more expensive, but are already installed on many commercial aircraft. Robust toughening with inertial sensors can be achieved, but requires deep integration and careful engineering.
Depending on their complexity, CRPA antennas can be a costly receiver augmentation. Very high-speed (330 MHz is available), 16-bit, A-to-D converters are at the heart of most of these phased-array devices. Some are priced at about $150 each. Applications with a high premium for PNT availability in the face of interference — such as commercial aircraft and cargo ships — should find them affordable. Aircraft manufacturers have resisted retrofitting existing aircraft with larger diameter CRPA antennas because of costs. For some of these applications, integration costs can be more than the costs of the receiver itself, particularly if not included in the original manufacture.
As the yearly sales of fully toughened receivers increase, the economies of scale should significantly reduce unit costs. Each application will make its own determination of affordability, based on risk.
Government restrictions. Civil use of CRPAs with four or more elements is restricted by ITAR. These are well-meaning restrictions on technologies that could be used against the United States by hostile military forces. Unfortunately, the phased-array antenna techniques are not only well understood and tested, but relatively inexpensive components are widely available on the open world market. In particular, the restriction on the number of CRPA elements for civil use should be completely removed. All potential enemies are well aware of the beam-steering method and have ready access to the parts to build them. Thus, the restriction is only harming civil users without affording any apparent improvement in general military posture.
Certified aviation receivers need approval for deep integration of inertial systems and multi-element CRPAs. (Photo: JasonDoiy/iStock/Getty Images Plus/Getty Images)
Gaining permission: FAA flight certifications. To be used in commercial aircraft operations, navigation equipment must be certified by the U.S. Federal Aviation Administration (FAA). Current, certified GPS aviation receivers have rudimentary toughening techniques, but gaining approval for deep integration of inertial systems and multi-element CRPAs must be completed. It is gratifying to hear that work is underway to do this.
Any civil solution for the United States must expand integrity monitoring beyond GPS to include all GNSS, and must be operationally included in the FAA’s integrity monitoring with WAAS.
Recommendation
In describing resistance to interference, I have introduced the idea of DRRR – Denial Radius Reduction Ratio. Also, I have used a 1-kW white-noise jammer as a standard threat for calculating the denial radius of various GPS receiver configurations. My recommendation is that equipment manufacturers specify their receiver offerings by stating their equipment’s denial radius against a “standardized” 1-kW EIRP white-noise jammer.
Summary
Media reports of interference to GPS may be accurate, but they generally do not recognize that available toughening techniques can largely defeat those interference threats. While exploring systems-level replacements or augmentations (such as LEO ranging or Loran) is worthwhile, GPS (or GNSS) still offers the greatest capability in combined terms of accuracy, integrity and coverage.
The goal of all PNT providers — GPS operators, certifiers and manufacturers — should be assured PNT, with the expected accuracy and availability. The described toughening techniques to do that have been known for decades, but have not been generally adopted by many critical civil users. Many manufacturers do offer civil products under existing government constraints.
The purpose of this article was to describe and advocate the solutions available to increase the robustness and toughening of civil GPS receivers. For example, readily available toughening augmentations for civil receivers can reduce the denial radius of interference by 99% or more. This implies that any denied area would be squeezed down to 1/10,000th of that experienced by an unaugmented receiver.
The payoff is high, and should be affordable to many high-end, safety-of-life users. Therefore, a renewed focus on toughening of GPS receivers is overdue. We discussed barriers to rapid adoption but, more than the specifics, it is crucial to fully and urgently embrace the goal of toughening receivers, particularly removing the ITAR restriction on antennas.
Opinions expressed in this article are those of the writer and should not be construed as the official position of the PNTAB or any U.S. government organization.
Notes
1. While not a part of the U.S. Department of Defense’s GPS operation, the FAA’s integrity signal (WAAS) is a GPS-type signal directly available and being used by almost all modern GPS receivers, including cellphones.
2. This is the ration of Denial Radius between, for example, unaugmented L1 C/A in State 5 and augmented L1C in State 3. Please see later footnote and graph.
3. Calculated as 10 (–15/20)
4. Of course, the more traditional dB measure of jammer resistance can (in most cases) be simply summed to estimate the total effectiveness. The use of DRRR gives a more intuitive calibration, particularly for non-technical persons who may not be at all familiar with dBs.
5. State 5 is the tracking mode that provides full accuracy; it requires tracking both the PRN code and the reconstructed carrier. It is required for RTK positioning, which is usually used for automatic control of machines or vehicles. It is most vulnerable to interference. Less vulnerable is State 3 tracking, which only provides code tracking, with precisions of perhaps a few meters.
6. Deliberate jamming using “matched spectrum” GPS-like modulations have also been employed in the Middle East. The toughening techniques described are also generally applicable, with appropriate rescaling. The matched spectrum is fundamentally used to improve the jammer spectrum efficiency.
7. See Michael Jones, “Anti-jam systems: Which one works for you?”, posted on gpsworld.com on June 14, 2017, for a survey of manufacturer offerings at that time. Named companies generally continue to offer improved, jam-resistant products.
8. Phased-array antennas, by their nature, distort phase and would probably have to be calibrated for precise operations such as RTK. Fortunately, we understand that this problem has been reportedly addressed and largely solved by the U.S. Navy’s JPALs program.
10. The denial radius results shown can be easily scaled for weaker or more powerful jammers. The scaling goes as simply the square root of the power ratio of a different size jammer to the 1-kW example. A 10-watt jammer is 1/100th the power of the example. The denial radius would then be one tenth of the example, which is the square root of 1/100.
11. “Ships have reported an increasing number of cases of significant GPS interference and jamming in recent months. The geographic areas with more than one reported incident include the eastern and central Mediterranean Sea, the Persian Gulf, and multiple Chinese ports.” (Source: www.gard.no/web/updates/content/30454065/gps-interference-and-jamming-on-the-increase).
“North Korea is using radio waves to jam GPS navigation systems near the border regions, South Korean officials said. The broadcasts have reportedly affected 110 planes and ships and can cause mobile phones to malfunction.” (Source: www.bbc.com/news/world-asia-35940542).
12. “Reports of GPS outages submitted by pilots from the cockpits of commercial flights show that disruptions to the navigation system, which was created and is maintained by the U.S. government, are now standard occurrence on the flight routes between North America and Europe and the Middle East, according to data from the European Organization for the Safety of Air Navigation, known as Eurocontrol.” Fortune Magazine, Nov. 1, 2020.
Innovation is the watchword in Washington this year. Amidst an ongoing supply-chain crisis and rising global trade tensions, policymakers have put renewed emphasis on U.S. leadership in such industries as semiconductors, wireless broadband and artificial intelligence — areas rightly seen as the “enabling technologies” of the 21st century.
Alongside chips and supercomputers is another innovation underpinning everything from our communications networks to financial transactions and air transportation: GPS technology. 2022 will see a flurry of activity to accelerate U.S. competitiveness for the modern economy and accelerating the modernization of our GPS constellation must place high on this list.
It’s no surprise that allies and adversaries alike have taken notice of GPS. While for decades U.S.-led GPS was the “only game in town” for global navigation satellite systems (GNSS) services, the current global picture is much changed. Russia, China, the European Union, Japan, India and other nations have explored, tested and deployed satellites to build out their own global or regional positioning, navigation and timing (PNT) networks and capabilities. The more recently deployed GNSS — including China’s BeiDou, which was completed in 2020 — represent a competitive threat by our international adversaries in spite of U.S. GPS technology advancements in performance and resilience. The potential loss of global leadership poses a dramatic challenge for U.S. interests.
Although our current GPS constellation continues to enable critical services that touch nearly every aspect of daily life, the oldest satellites were launched in the late 1990s. As new, more advanced GPS satellites go up in the sky, we can take several policy steps here on the ground to ensure that GPS remains the global standard — undermining attempts to create an information ecosystem independent of the United States and reliant on our international competitors.
Enter the United States’ GPS modernization program. Allocating the resources necessary to accelerate the launch of new GPS satellites will pave the way to keeping GPS globally competitive — both in defense and civil applications. Take accuracy, for starters. New GPS satellites will bring three times better accuracy than existing systems and up to eight times improved anti-jamming capabilities, both of which will keep us competitive and add critical security against domestic spoofers and foreign adversaries.
While U.S. firms should continue to create multi-constellation receivers that are interoperable with global PNT signals, U.S. policy should promote American technological leadership by accelerating modernization of the GPS space and control segments. Importantly, a necessary element of this technological leadership is development of a systematic roadmap to spur adoption of these new modernized features in civil applications. Establishing this clear pathway for civilian applications of a modernized GPS constellation is critical to ensuring that the potentially more than $1 billion of economic benefits added every day by the U.S. civil GPS sector are fully realized.
As Congress continues to focus on innovation and global competition, the GPS Innovation Alliance is committed to working with policymakers to promote the critical security, economic and diplomatic benefits to the United States of investing in next-generation GPS infrastructure.
Originally a product of the Sputnik era, GPS has demonstrated the very best features of competitive U.S. government investment. As the United States prepares for a renewed era of global competition, the promise today of invigorated support for GPS remains the same.
The United States must continue to lead by modernizing GPS and establishing a clear pathway for civilian applications of the improved constellation. (Image: matejmo/iStock/Getty Images Plus/Getty Images)
Given that space is increasingly a congested and contested arena, should the U.S. government establish a new office to manage both space-based and terrestrial-based PNT systems?
John Fischer
“The U.S. government already has the National Executive Committee for Space-Based PNT (see gps.gov), which coordinates policy among all the branches of government. There is also a PNT Advisory Board, which includes some international members to inform the committee, and a National Coordination Office to execute the policies. This is in addition to the new U.S. military’s Space Command under which GPS operates. So, space-based issues are being addressed, but maybe more could be done to coordinate terrestrial-based PNT systems with space-based ones.” — John Fischer
Ellen Hall
“As new technology advances, government, along with its policies and laws, struggles to keep pace. This was certainly true of the internet and cybercrime. This is also true of terrestrial-based PNT, where new technology emerges in areas not currently covered. Policy gaps and overlapping technologies need to be addressed and coordinated. It certainly seems that this would be one of those areas that could benefit from oversight. Space-based PNT is currently addressed by the National Executive Committee for Space-Based PNT, among others.” — Ellen Hall
Bernard Gruber
“The threat to U.S. space-borne assets and the signals they generate is very real. Both commercial and military users of GPS continue to seek independent alternatives to current PNT systems that are diverse and robust. The National Coordination Office supports the National Executive Committee (NEC) for Space-Based PNT. I believe the role of the NEC should be broadened to include terrestrial and alternative PNT as a first step to charter/secure a new or expanded program office.” — Bernard Gruber
Editorial Advisory Board
Tony Agresta, Nearmap
Miguel Amor, Hexagon Positioning Intelligence
Thibault Bonnevie, SBG Systems
Alison Brown, NAVSYS Corporation
Ismael Colomina, GeoNumerics
Clem Driscoll, C.J. Driscoll & Associates
John Fischer, Orolia
Bernard Gruber, Northrop Grumman
Ellen Hall, Spirent Federal Systems
Jules McNeff, Overlook Systems Technologies
Terry Moore, University of Nottingham
Mitch Narins, Consultant
Bradford W. Parkinson, Stanford Center for Position, Navigation and Time
Artist’s impression of the Lunar Pathfinder satellite built by Surrey Satellite Technology Ltd. (SSTL) that will provide communications and navigation services for the Moon.
NASA and its international partners are planning a return to our natural satellite. The following three papers — presented at the Institute of Navigation (ION) GNSS+ conference Sept. 20–24, 2021 — discuss the role of GNSS in lunar exploration. The full papers are available at www.ion.org/publications/browse.cfm.
Using GPS for Time Transfer
NASA and the European Space Agency have conceptualized the initial framework for a GPS-like constellation for the Moon, which will ensure uninterrupted navigation and communication services for future lunar missions. The authors designed a smallsat-based Lunar Navigation Satellite System (LNSS) with time-transfer from Earth-GPS to alleviate the size, weight and power (SWaP) and timing stability requirements of the onboard clocks. A timing filter corrects the lower grade clock when Earth-GPS signals are available and propagates these clock estimates forward in time when no Earth-GPS signals are available. The authors analyzed their proposed time-transfer technique using high-fidelity simulations of an LNSS satellite with an onboard chip-scale atomic clock for three cases of elliptical lunar frozen orbits.
Bhamidipati, Sriramya, Mina, Tara, Gao, Grace, “Design Considerations of a Lunar Navigation Satellite System with Time-Transfer from Earth-GPS,” https://doi.org/10.33012/2021.18021
GNSS Nav for Moon Missions
The authors show the potential of autonomous GNSS signal-based navigation for a set of Moon scenarios. This technology could be a game changer for the future of lunar exploration, representing an extremely low cost and effective alternative for Moon navigation. Results show that not only autonomous GNSS navigation for lunar orbiters is possible, but it also delivers good navigation performance. In fact, navigation with root-mean-square (RMS) errors on the order of 50–100 meters were obtained for scenarios of high interest, such as for the planned Lunar Pathfinder and near-rectilinear halo orbit of the Lunar Gateway space station around the Moon.
Mangialardo, Marco, Jurado, María Manzano, Hagan, David, Giordano, Pietro, Ventura-Traveset, Javier, “The full Potential of an Autonomous GNSS Signalbased Navigation System for Moon Missions,” https://doi.org/10.33012/2021.18040
Finding the best lunar orbit
A continuous and reliable lunar positioning and timing system, such as a GNSS-like constellation, is considered essential infrastructure for lunar exploration. The authors focus on halo orbits with the aim of defining an optimal halo constellation for supporting and delivering a navigation service on the Moon. This paper shows the performance of a GNSS-like constellation deployed in Halo orbits around Earth-Moon L1 and L2 collinear libration points. Different phases have been considered, from a minimum number of satellites able to provide a local PNT service on the South Pole (Initial Operational Capability), to a final, extended constellation able to cover the whole lunar surface (Final Operational Capability).
Musacchio, Daniele, Iess, Luciano, Carosi, Mattia, Capolicchio, Jacopo, Eleuteri, Massimo, Stallo, Cosimo, Di Lauro, Carmine, “Design of Earth Moon Halo Orbits for a Global Lunar PNT Service,” https://doi.org/10.33012/2021.18020
A roundup of recent products in the GNSS and inertial positioning industry from the March 2022 issue of GPS World magazine.
OEM
Correction Service
Achieves RTK-level accuracy
Photo: Hexagon
“RTK From the Sky” technology has been integrated into the core of the TerraStar-C PRO corrections service. As a result, TerraStar-C PRO provides centimeter-level accuracy, not just in open-sky environments but also across challenging conditions created by buildings and foliage. TerraStar-C PRO now converges in less than three minutes by utilizing quad-band receiver and antenna technology to leverage modernized BeiDou 3, GPS III and Galileo E6 signals. The resulting process generates state-of-the-art corrections for all GNSS frequencies. The service improvements are accessible through the 7.08.10 firmware release for users of OEM7700, OEM719 and OEM729 cards and their associated enclosures for land and air applications.
A north orientation mark is being added to the TW3000 family of Accutenna precision antennas and the TW5000 family of smart antennas. The new feature allows customers to align their antennas, standardize radiation patterns, and increase the synchronicity of their azimuth gain readings across multiple devices. The new north mark design has been thoroughly tested to ensure it conforms to or exceeds customer expectations and maintains each antenna’s stringent IP69K rating.
OtoSphere is a small, add-on module to the ViaLite GPS RF over fiber link and any GNSS-based system, providing GNSS protection against GPS jamming attacks, making any receiver more resilient. It ensures continuity of timing and navigation capability and enables normal operation during a jamming attack. According to ViaLite, no other solution that offers such protection is as small, light, affordable, or easy to install. The Otosphere protection module adds resilience to critical GPS timing services.Using OtoSphere, GPS receivers are up to 50 times more resilient to jamming attacks on positioning, navigation and timing (PNT) systems compared with having no protection. The GPS receiver can continue working normally throughout the attack. Timing-critical infrastructures in areas such as defense and cybersecurity can now be protected from these attacks. The Otosphere has a unique interference filtering algorithm that combines patterns from two external omnidirectional antennas that pinpoints the direction of the attack, then directs a null toward the unwanted signal to reject and reduce disruptions.
Infrastructure system for autonomous transportation
Photo: Seoul Robotics
The Level 5 Control Tower (LV5 CTRL TWR)) is a mesh network of sensors and computers on infrastructure that guides vehicles autonomously without requiring that sensors be placed on individual vehicles. The technology is automating last-mile fleet logistics at BMW’s manufacturing facility in Munich. The system has the potential to transform operations for a wide range of business applications, from vehicle distribution centers to car rental companies and trucking logistics.
Savvy Navvy provides essential marine information, allowing boaters to cross-check their traditional navigation plans. It integrates plotting charts, weather and tide data, marina details and passage planning into one app. The app reduces the risk of human error as well as the stress of voyage preparation. It is used by boaters in more than 100 countries around the world, with more than 43 million miles plotted. It works on phones or tablets using Android, IOS, PC or Mac.
The Pix4D viDoc RTK handheld rover attaches to iOS devices to bring RTK accuracy to terrestrial scanning on iPhones and iPads. When paired with the PIX4Dcatch mobile app, the viDoc rover can replace survey tools such as RTK GNSS rovers and terrestrial scanners, the company said. The two products create a workflow that turns iPhones or iPads into an accurate terrestrial scanning device, with centimeter-accurate RTK positioning from an existing NTRIP network. The tools can be used to 3D model small areas or structures.
Bad Elf now provides an integrated laser-offset workflow for acquiring high-accuracy field data in GNSS-challenged environments using Esri ArcGIS Field Maps for Android, as well as iOS. The workflow integrates Bad Elf and Laser Tech (LTI) hardware in collaboration with ArcGIS technology from Esri. The Bad Elf Flex connects to any LTI TruPulse rangefinder over a wired or Bluetooth connection to deliver high-accuracy location data to Esri ArcGIS Field Maps. Mobile workers can efficiently complete position and height data collection in access-limited situations, saving time, money and effort.
A free global map created from processed satellite imagery is available. To create the world image, satellite imagery was processed to remove clouds and balance shades and tones, and then carefully stitched together to create a seamless map layer with beautiful colors. The input data is recent, from 2020 and 2021, and rendered as one tiled file with 13 zoom levels 0-13 for use in web applications. It is a viable, up-to-date alternative to Google maps for software developers, without privacy issues.
The MetaGeo geographic information system (GIS) platform enables organizations of all sizes to host, analyze, find and share 3D map datasets among any internet-capable devices. The platform processes location-based map or sensor data from the real world, combines it into a single 3D virtual environment, and streams it to any device or mapping platform. The affordable and easy-to-use platform can load data from multiple sources: satellites, drones, mobile devices, public and crowdsourced repositories, internet of things (IoT) sensor data, 3D models and topographic maps. The data is then processed by the MetaGeo platform into a 3D world and streamed to any internet-connected device, enabling live collaboration between the office and field via mobile or augmented reality device. A plug-in software development kit (SDK) allows for third-party tools to scale and fit user needs.
Trimble has launched the Trimble AP+ Land GNSS-inertial OEM platform for accurate and robust position and orientation for georeferencing sensors and positioning vehicles in land mobile-mapping applications. The platform enables users to accurately and efficiently track and monitor fleets and produce high-definition (HD) maps and 3D models. It can also serve as a reference solution for advanced driver-assistance systems (ADAS) testing, even in challenging GNSS environments. The comprehensive Trimble AP+ Land is small enough to integrate into compact mobile-mapping systems. It is compatible with virtually any type of mapping sensor, including single- or multi-lidar systems, video cameras, photogrammetric and panoramic cameras, and similar sensors.
Ronin 4D, a professional cinema camera from DJI, incorporates the full-frame Zenmuse X9 gimbal camera, active four-axis stabilization, lidar focusing, and wireless transmission. Firmware available at launch will allow the remote monitor to view and control the main monitor, interface with mirror control mode, and allow a clean video stream over HDMI and SDI ports on the Remote Monitor Expansion Plate with no overlaid information. It will also support automatic calibration for some third-party auto lenses to realize Lidar Focusing System functions.
Parallel Hybrid Electric Multirotor (PHEM) drone technology improves flight time with a heavy payload, yielding increased efficiency and eliminating the large battery used in other hybrids. It has the potential to extend a UAV’s flight time from 15 minutes to well over an hour and drastically increase range. In the search-and-rescue field, a heavy-lift drone can enhance first responder capabilities by allowing for substantially quicker response times to remote locations. Other applications include military platforms, fighting wildfires, and medical and logistics missions.
An off-the-shelf PC provides the computing power for complex GNSS driving simulations. (Photo: Racelogic)
By Julian Thomas Managing Director, Racelogic
Driving simulators are commonly used by vehicle manufacturers to expedite the test and development process of their many electronic systems. This not only saves the considerable time and expense of using a real car on a test track, but it is, of course, significantly more environmentally friendly.
LabSat simulators are used by many leading technology companies and car manufacturers to develop and verify the performance of their new products containing GNSS receivers. These tests are performed using either a pre-recorded or an artificially generated RF signal. This RF signal contains the combination of multiple satellite signals, which are decoded by the GNSS engine, tracking the artificial satellites as though they were real. Static or moving scenarios can be generated, and the user can select parameters to suit their own application, such as time, date and available constellations.
Julian Thomas Managing Director Racelogic
Recently, an automotive LabSat customer had a specific requirement to synchronize a GNSS receiver with the real-time trajectory data generated by one of their driving simulators. This was for a hardware-in-the-loop test rig where a human driver would navigate a route around a virtual test track, while the normal electronic systems reacted as if the vehicle were being driven around a real environment.
The challenge in this customer’s application was that the time delay between the trajectory coming from the simulator and the generation of the corresponding GNSS signals had to be less than 100 ms. This low latency was necessary to achieve realistic synchronization between the driver’s inputs and the resulting output from the GNSS-based device under test.
Traditionally, low-latency real-time simulators use bulky expensive hardware that relies on power-hungry field programmable gate arrays (FPGAs) to create the necessary satellite signals. However, due to the inevitable tick of Moore’s Law, and with some clever optimizations, your entry-level desktop PC now packs more than enough punch to simulate multiple constellations and signals with very low latency.
Using a standard PC to do the heavy lifting means that the hardware required to output the simulated signal is much easier to obtain, can be a lot simpler, and is considerably more cost effective. For example, an 8-core, 3-Ghz Intel i7 processor can generate the signals from 20 satellites in real-time, which normally is sufficient to simulate all but the most complex scenarios.
Our LabSat SatGen software has been continuously developed and optimized during the past 15 years, so it did not take us long to enable the reception of an NMEA trajectory stream with a latency of less than 100 ms. We then streamed this simulated data via USB to our LabSat Real-Time, which generated a corresponding RF signal that can be connected directly to the RF input of any modern GNSS engine.
Using a PC to generate the signals does not mean a loss of fidelity, with the resulting output achieving a repeatable position of less than 10 cm, while the trajectory data can be received at up to 100 Hz.
The resulting solution can take trajectory data from any kind of simulator that has an API to obtain real-time data, such as many popular off-the-shelf driving and flight software simulators, and use this to provide a real-time signal that can be utilized by the GNSS device under test.
Our future development roadmap includes synthesizing external signals, such as CAN-based sensors or inertial measurement units, and then synchronizing these signals with the incoming trajectory. With the amazing power of a modern PC, we are finding that this kind of complex simulation is now much more cost effective and easier to achieve.
Surveyors used ComNav equipment to construct a hospital in Burkina Faso. (Photo: ComNav)
Line of sight to GNSS satellites is sometimes obscured by buildings and trees, which also cause multipath, as does nearby water. These conditions require an RTK receiver with multipath mitigation. Often, surveying must occur on property corners or on uneven ground, where it is hard to place surveying equipment. For these reasons, reliability and accuracy are essential, especially in harsh environments. Ground control points require 1-2mm accuracy and topo surveys 1-2cm accuracy. Surveying for AEC also requires software that processes digital files.
ComNav has focused on GNSS core technology innovation and applications for 10 years. The Quantum III technology includes algorithms to suppress multipath and supports all GNSS constellations, allowing the users to acquire and keep RTK centimeter accuracy even in harsh environments. The built-in tilt IMU will help where the exact location to be surveyed is hard to reach. For example, the T300 Plus and N Series GNSS receivers support a maximum pole tilt of 60° and keep the compensation accuracy within 2.5cm, making the field work more efficient, convenient and reliable.
With the Survey Master software’s stake-out points, users can import DXF or DWG files directly and the software can stake out the point, line and surface in CAD.
In April 2021, the government of Burkina Faso used ComNav GNSS T300Plus to provide ground control points survey for the construction of a hospital.
The land security and topographic surveying were completed within only six days, less than half the time that had been scheduled for those tasks. This greatly expedited the construction of the hospital and helped with the fight against infectious diseases, including COVID-19.
