GPS World Editor-in-Chief, Matteo Luccio, met with UHU Technologies President, Jeffery Sanders, to discuss the company’s new four channel system, seven channel system, their applications and more from the ION GNSS+ 2023 show floor.
Author: Matteo Luccio
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Surveying on a busy runway
Image: NV5 Geospatial NV5 Geospatial, a large geospatial data company, provides services for airport projects across the United States and U.S. territories — mainly supporting airport planning and engineering firms that must meet FAA survey and mapping requirements for data collection at airports. “We generally are a sub-consultant to them, helping them achieve those survey standards for collecting the data and submitting it to the FAA,” said David Grigg, the company’s Aviation Program Director. Typically, this is around planning projects such as airport layout plans and master plans, but also engineering projects such as runway extensions and runway reconstructions.
As an example, Grigg cited the extension of a runway, which requires new flight procedures to be established. “Two survey missions are required for runway extensions. The primary mission is to establish control for the aerial imagery. Using the imagery, control and design data, we check for obstacles photogrammetrically. That data is sent to the FAA and procedures are developed. After construction is complete, we go back to the airport to survey the changed runway and navigational aids (NAVAIDS) to verify that what was designed was ultimately built.”
Another way in which NV5 Geospatial supports airport clients is by conducting obstruction studies around them for vegetation management. “That’s generally where we pull in the lidar surveys,” said Grigg. The FAA’s standards for relative and absolute positioning accuracy for trees are “rather generous” by surveying standards, he said. “We’re talking two to three feet vertically and twenty feet horizontally. It’s not like a typical mapping job where you’re guaranteeing it to one foot or better horizontally and half foot or better vertically.”
The FAA, he points out, has published guidance on how lidar may be used. “We mostly use aerial photogrammetry to support projects in the FAA’s airports GIS program. When we collect lidar at an airport, we do it to generate contours and to identify individual tree canopies. Our lidar-derived data is most often developed to benefit airports for tree mitigation not for FAA airports GIS survey projects.”
Image: NV5 Geospatial On the other hand, the FAA has strict requirements regarding metadata to document when, where, and how each control point is collected. “At the time of the survey, photographs are taken of the GPS units from different angles and cardinal directions,” Grigg said. “This is visual documentation for NGS that the surveyed point is at the location described. ”
Another challenge for surveyors working at airports is that they are required to pull back for incoming aircraft. “Obviously, you will have some logistical issues at busy airports,” said Grigg. Surveyors are required to have special lights and markings on any vehicles that enter the airport property to ensure ground and air visibility. Aircraft movement also impacts surveyors as they must move away from the runway safety area (RSA) for take-offs and landings. Busier airports are surveyed at night, when air traffic is reduced or runways are closed.
Image: NV5 Geospatial A typical project for a small airport takes about nine months, while for bigger airports — such as Chicago O’Hare, Dallas-Fort Worth, or Hartsfield-Jackson Atlanta — they can take up to twice as long. “The large hubs update their master plan on a more reoccurring basis, such as every three to five years,” said Doug Fuller, NV5 Geospatial’s Airport Solutions Specialist. “As the airports get smaller, you start stretching out that timeframe.”
Airport survey requirements
[The following was written by NV5 Geospatial and only lightly edited by GPS World.]
Airports have surveys conducted for many different reasons. However, all survey types require the collection, classification and reporting of accurate data about the project. The methodology selected to gather the information is up to the professional surveyor’s judgment. Some features require observation through ground field methods, while others lend themselves to collection via remote sensing technologies.
All surveys start with a search for existing airport control, which are called Primary Airport Control Points (PACS) and Secondary Airport Control Points (SACS). These are points on the airport that have been adjusted by the National Geodetic Survey (NGS). This ensures that the survey is done on the National Spatial Reference System (NSRS).
A typical survey includes surveying the runway, the end points, any displaced thresholds, and a profile along the centerline of the runway. If the centerline marker is not in the correct location or if it is not there at all, the surveyor will make the necessary measurements to establish the proper location and set a new marker. Next the surveyor must locate all NAVAIDS and survey them at the proper location as described in FAA Advisory Circular 150/5300-18B.
After the NAVAIDS are located, the photo control survey will be done. This still requires the PACS and SACS to be the points of origin of the survey. The base requirement as described in FAA Advisory Circular 150/5300-16C is to survey ten photo control points and five check points. The check points are sent to NGS’s Online Positioning User Service (OPUS). This is used to check that the survey was done on the NSRS and that the compilation meets FAA standards.
The standards the surveyor must meet vary depending on the equipment type or photo control point. Examples of the accuracy requirements for the NAVAIDS are as follows:
Point Horizontal Vertical Distance measuring equipment +/- 1 ft +/- 1 ft Glideslope +/- 1 ft +/- 0.25 ft Inner marker +/- 10 ft +/- 20 ft Localizer +/- 1 ft +/- 0.25 ft Runway end point +/- 1 f ft +/- 0.25 ft Runway profile points +/- 1 f ft +/- 0.25 ft Photo control +/- 1 ft +/- 1 ft PACS and SACS
X Y Z Ellip. Inverse from PACS to SACS surveyed relative to published
0.09 ft 0.09 ft 0.15 ft 0.13 ft When surveying on airport property, the largest challenge is always accessing the runway safety area to locate the runway ends and profiles. At small airports Surveyors must work when the runway is not busy; at airports with FAA control towers when the runway is closed. Frequently this is done overnight. Other challenges include access to the FAA NAVAIDS. Some of them must be turned off to be surveyed and others require survey points on which it is not possible to set an instrument. When we are not able to occupy a point, we collect it by surveying multiple equidistant locations around the NAVAID and averaging them.
Image: NV5 Geospatial NV5 Geospatial surveyors use a combination of real-time (R/T) and post-processing techniques. We also use OPUS with the PACS and SACS and the five check points. Once the PACS and SACS have been determined to be stable, the proper coordinates are applied to them and the R/T points are adjusted using Trimble Business Center (TBC). NV5 Geospatial uses Trimble TRM-R8s and we recently added TRM-R12i receivers to our equipment. We use ground control points to orient the photography and to calibrate the lidar.
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ION GNSS+ 2023: Safran Navigation & Timing
GPS World Editor-in-Chief, Matteo Luccio, met with John Fischer, resilient PNT and wireless systems, Safran Navigation & Timing, at their booth at ION GNSS+ 2023. Fischer, a GPS World Editorial Advisory Board member, discussed the Minerva Academic Program, the goal of the program and more in this exclusive interview.
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EAB Q&A: Is the GNSS community failing to exploit the potential of CSAC?
“Is the GNSS community failing to exploit the potential of chip-scale atomic clocks (CSAC)?”
John Fischer “Yes! And there are several CSAC suppliers, each with varying accuracies, power consumptions, and price points. These atomic clocks are no longer exotic scientific instruments but rather commercialized, proven devices that can be mounted on a circuit card at a reasonable cost. They offer extended holdover time in the absence of GNSS and help with spoofing detection by verifying the incoming signal. They provide exact frequency recovery on power-up (re-trace) for power saving modes. Defense, telecom, financial transactions, and autonomous navigation for cars and drones are all applications that can be made more resilient by these clocks.”
— John Fischer
Safran Navigation & Timing
Jean-Marie Sleewaegen “Atomic clocks, including CSAC, are frequently used in GNSS timing applications, for example to keep accurate time during GNSS outages or to assist in identifying spoofing attacks targeting the time component. On the other hand, the long-term stability of atomic clocks is not particularly relevant in navigation applications where time is not the main output, and the additional cost, power consumption and size of CSAC are not justified.”
— Jean-Marie Sleewaegen
Septentrio
Ismael Colomina “Indeed. After the DARPA-NIST initiative and subsequent commercialization, affordable, accurate and stable chip-scale oscillators can be easily integrated into circuit boards providing additional measurements to PNT systems to improve positional vertical accuracy, as well as reliability and integrity. For example, in high-end mobile mapping systems operating in complex urban scenarios, their use helps detect GNSS outliers at a relatively negligible additional cost.”
— Ismael Colomina
GeoNumerics -
ION GNSS+ 2023: Microchip Technology
GPS World Editor-in-Chief, Matteo Luccio, met with Will Krzewick, Principal Engineer Product Marketing, Microchip Technology, to discuss remote sensing, new atomic clocks, and more products featured at their booth at ION GNSS+ 2023.
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ION GNSS+ 2023: Spirent Communications
GPS World Editor-in-Chief, Matteo Luccio, met for an exclusive interview about Spirent Communications collaboration with Xona Space System‘s PULSAR, new releases, and more with Adam Price, Vice President – PNT Simulation, Spirent Communications.
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ION GNSS+ 2023: ANELLO Photonics
GPS World Editor-in-Chief, Matteo Luccio, met with Kirstin Schauble, Senior Systems Engineer at ANELLO Photonics, to discuss the company’s new silicon photonic optical gyroscope, SIPHOG, and more company updates at ION GNSS+ 2023.
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ION GNSS+ 2023: Day two recap
ION GNSS+ 2023 is underway at the Hyatt Regency Denver at Colorado Convention Center. On the second day, industry leaders and show attendees gathered for the 63rd meeting of the Civil GPS Service Interface Committee. During a break, a cake was wheeled out to celebrate 50 years of GPS. GPS World staff wanted to highlight some key parts of the event.
(From left to right) Rick Hamilton, GPS Info Analysis Team Lead, U.S. Coast Guard; Harold “Stormy” Martin, Director, National Coordination Office for Space-Based Positioning, Navigation, and Timing; Dr. Bradford Parkinson, Edward Wells Professor, Emeritus, Aeronautics and Astronautics (Recalled), Co-Director, Center for Position, Navigation and Time, Stanford University; Capt. Scott Calhoun, Commanding Officer, U.S. Coast Guard Navigation Center (NAVCEN) and Karen Van Dyke Director, PNT and Spectrum Management, U.S. Department of Transportation, gathered around a cake to celebrate the 50th anniversary of GPS.
Image: Matteo Luccio 
Image: Matteo Luccio A closer look at the 50 years of GPS cake. Learn more about the history of GPS here.
Image: Matteo Luccio Lt. Colonel Robert Wray, Commander, Second Space Operations Squadron, U.S. Space Force (second from left), who was featured on the May cover of GPS World. Click here to read our May cover story, featuring an exclusive interview with Lt. Colonel Wray about the training and duties of his team, the challenges they face, and more.
Image: Matteo Luccio Dr. Bradford Parkinson (left) and Dr. Robert Hampshire, Deputy Assistant Secretary of Research and Technology and Chief Science Officer, U.S. Department of Transportation (right). Click here to learn more about Dr. Bradford Parkinson, who is nicknamed “The father of GPS.”
Image: Matteo Luccio Col. Andy Menshner, GPS Space and Ground (SML), Space Systems Command, U.S. Space Force, speaking about GPS acquisitions and development updates during the Civil GPS Service Interface Committee.
Image: Matteo Luccio (Second from left) Karen Van Dyke, Director, PNT and Spectrum Manager, U.S. Department of Transportation Deputy Chair, serves as chair of the 63rd Civil GPS Service Interface Committee. Read more from the Department of Transportation here.
Image: Matteo Luccio Attendees gathered to hear speakers from the U.S. Department of Transportation, the U.S. Space Force, and other departments and agencies.
Click here to stay up to date with our show coverage!
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New Receivers for More Signals
JAVAD GNSS’ Triump-1M Plus receiver has 874 channels for acquiring all available GNSS satellites and patented mobile antenna technology for robust UHF and cellular communications. (Image: JAVAD) As most readers of this magazine know, GPS, like the other three GNSS, consists of three segments: the space segment — i.e., the satellites; the control segment — i.e., the monitoring and control stations on the ground around the world; and the user segment — i.e., the receivers. The first two are developed, operated and maintained by the U.S. Space Force, while the third one, for civilians, is totally in the hands of the private sector.
Most of the progress in receivers is evolutionary, with rare dramatic changes. To provide a snapshot of the current state of GNSS receivers, I asked several manufacturers three questions. What follows are short, etre dited excerpts of their answers that showcase the applications of GNSS receivers in a wide range of industries.
The participants in this cover story are:
- Eos Positioning Systems Inc. — Sarah Alban, Director of Marketing
- JAVAD GNSS — Simon Baksh, VP Product Development
- Hexagon’s autonomy & positioning division — Stephen Ching, Core Segment Manager
- Trimble — Karl Bradshaw, Market Manager, Mobile Mapping
- u-blox — Oreste Concepito, Head of Product Strategy Positioning
- Septentrio — François Freulon, Head of Product Management
- Hemisphere — Miles Ware, VP of Marketing
- Geneq — René Parisé, President
What is one of the most recent end-user applications for your receivers? What challenges does it pose and how do your receivers address them?
Sarah Alban (SA): Eos Positioning Systems is lucky to have innovative customers who span a variety of industries. In just these past few weeks, we’ve connected to customers who are using Arrow Series GNSS receivers to meet myriad business needs. Here are just a few examples: On the Caribbean island of Martinique, Odyssi uses an Arrow 100+ with RTK to get accurate water utility locations in a challenging environment. In Texas, midstream pipeline operator Kinetik and its GIS Manager Papillon Romero equip their field workers with an Arrow Gold to update the locations of previously unreliable legacy as-builts. In the Galápagos Islands, a researcher has been using the Arrow Gold+ and Galileo High Accuracy Service (HAS) to georeference drone imagery. In Colorado, GIS specialist Jim Casey uses an Arrow Gold to bring to life a Japanese internment camp in augmented reality.
Simon Baksh (SB): One of our customers is a leading construction contractor who uses our DELTA GNSS receiver for monitoring during deep crack grouting deformation to ensure that the natural state of the ground remains undisturbed during remedial work.
Stephen Ching (SC): One of the most exciting projects happening within Hexagon’s Autonomy & Positioning division is the automated road train platooning application within the mining industry. Transporting raw materials, iron ore in this case, has posed a huge challenge in terms of drivers’ safety, labor shortages and rising fuel costs. Our division is currently developing an autonomous hauling system that solves this challenge by integrating drive-by-wire, perception, positioning and path planning technologies. Our positioning system utilizes a PwrPak7D-E2 plus TerraStar-C PRO solution from Hexagon | NovAtel, which incorporates GNSS+INS technology and real-time kinematic (RTK) From the Sky technology.
Mobile mapping systems such as the Trimble MX50 allow survey companies to safely and accurately gather point cloud and immersive imagery of roads without the need to put a surveyor in the field. (Image: Trimble) Karl Bradshaw (KB): Traditional survey methods or tripod-based scanning on highways can be time-consuming and dangerous. Survey companies do not want to put surveyors in danger of traffic while traversing along a road. Mobile mapping allows them to safely, accurately and productively gather detailed point cloud and immersive imagery of highways without needing to put a surveyor in the field.
Oreste Concepito (OC): At u-blox, we have seen an increasing demand for GNSS receivers to be used for advanced driver-assistance systems (ADAS) applications and for mobile robotics (such as robotic lawnmowers). GNSS technology is adopted when an accurate, trustworthy position with high availability is required. In the autonomous operations domain, customers are constantly pushing u-blox to improve dependability while maintaining or ideally improving position accuracy, even in challenging environments.
François Freulon (FF): One of our most recent end-user applications is related to resilient timing for mission-critical infrastructure, including finance, data centers, energy and telecommunications. The relevant Septentrio product is the mosaic-T. The recent addition of the AtomiChron timing service further enhances its timing precision, GNSS resilience and anti-spoofing by offering navigation message authentication (NMA) on all for GNSS constellations. The first customer integrating this technology is Meinberg.
Miles Ware (MW): The Galileo High Accuracy Service (HAS) has created new interest in a traditional GNSS market, GIS and mapping, in which the availability of global 20 cm accuracy is turning many heads. While there are many technologies to improve accuracy for this market, few are appropriate. Often the work takes place in remote areas where cellular connectivity is not available for delivering corrections. They may also be in regions of the world where satellite-based augmentation systems (SBAS) are not available or able to meet performance expectations. Galileo HAS resolves both of these concerns. We now support it in our Phantom and Vega receivers.
In the past few years, we have seen the completion of two new GNSS constellations and a large increase in the options for corrections services. How has this impacted the design and/or features of your receivers?
SB: Our 874 channel TRIUMPH ASIC design has capacity for all constellations and signals to utilize current and future GNSS technologies. Additionally, our J-Star PPP Service using geostationary satellite broadcast for global delivery and cm level positioning extends operations to remote areas where networks are absent or where a base station setup and operation is not feasible.
SC: With BeiDou and Galileo in addition to GPS and GLONASS, there can be upward of 40 satellites in view — compared to 20 years ago when having 10 or 12 satellites in view was considered good availability. This gives much more choice as to which measurements contribute to a position solution, provided that the receiver can make measurements to all the satellites in view. Hexagon | NovAtel’s OEM7 was designed to support all GNSS constellations and frequencies, which required supporting many channels as well. The benefits of more satellites in the sky come under challenging conditions with many obstructions and strengthened positioning geometry in unobstructed conditions. In addition to more satellites, BeiDou and Galileo also introduced a new frequency at E6/B3, in addition to L1/L2/L5, which is particularly useful in global PPP solutions, such as RTK From the Sky and TerraStar C-PRO Correction Services.
KB: We have onboarded these constellations into our mobile mapping portfolio in the same way as all other Trimble GNSS portfolios, through rigorous, tried and tested methodologies.
FF: Septentrio receivers already support all GNSS constellations for high precision and resilient positioning. We have added Galileo E6 support and OSNMA, BeiDou phase III satellites (PRN>37) and other new signals (B3I, B2b) to our products through our latest firmware releases. We are also contributing to the large increase of corrections services by providing the backend core technology through our base station receivers or reference receivers. For example, the PolaRx5 reference receivers are used worldwide in many correction network infrastructures. With the support of all in view constellations and signals, Septentrio products are becoming part of critical infrastructure. Therefore, it is essential they have reliable continuous operation as well as security to protect them from potential jamming or spoofing attacks. Additionally, Septentrio has recently launched the Agnostic Corrections Partner Program to help customers find their way in the growing maze of correction offerings and to facilitate the integration of the right service into their system.
Geneq Inc. employee Alex Arsenault operating an SXblue Platinum receiver in Anjou, Montreal. (Image: Nikita Sapeguine / Geneq) OC: Our customers are increasingly operating in a global market. To respond to that need, u-blox receivers support both the global and the regional constellations, such as Japan’s Quasi-Zenith Satellite System (QZSS) and India’s Indian Regional Navigation Satellite System (IRNSS, aka NavIC). The offer for correction services has also evolved to be able to serve the global market, moving toward uni-directional streams, possibly distributed via L-band. We support a complete portfolio of correction services, responding to all commercial and performance requirements, from the soon available, free-of-charge, lower accuracy correction services, up to the dm-level functional safety-certified correction services for autonomous driving.
MW: Since 2019, our core receiver technology has been intrinsically both multi-GNSS and multi-frequency by design. This allows our engineering team members to rapidly adapt to new and emerging solutions, and for Hemisphere to meet user and market demands. Hemisphere has also worked with our integrators to recognize the need to simplify the decision process around selecting receivers. While it is possible to configure our receivers to track specific constellations only, Phantom and Vega are being offered with multi-GNSS as standard. Similarly, clients can choose L1-only, or all-frequencies. This is why many integrators will quickly be able to take advantage of Galileo HAS.
RP: We have upgraded our SXblueGPS receivers with new GPS chips and with firmware updates to keep up with the new constellations available. Regarding the new correction services, the SXblueGPS have used and use by default the SBAS correction service and its associated networks throughout the planet to improve their precision. Where correction services via internet or SBAS do not exist, they use L-band correction services to have global coverage. In some cases, for topography base and mobile solutions, UHF links provide a customized correction service.
Are jamming and spoofing significant challenges in your key markets? If so, how do you address them?
SB: Yes, and AJ/AS expands on existing RAIM for assured position quality. Patented anti-jamming and anti-spoofing techniques identify and suppress GNSS interference, while maintaining navigation from good signals. Updated firmware for Navigation Message Authentication extends AJ/AS protection further.
SC: GNSS interference such as jamming and spoofing do present significant positioning challenges in many of our markets, especially defense, marine and autonomy applications in which safety and 24-7 operation are paramount. How often GNSS interference happens (and is detected) and how seriously it affects the application depends on the market. It is a threat that can be mitigated by well-designed user equipment. Hexagon | NovAtel has developed a comprehensive GNSS resiliency portfolio to assure that our users’ position is protected with our interference mitigation technology, starting from the GAJT antennas all the way down to the receiver level. NovAtel’s OEM7 receivers include our GNSS Resilience and Integrity Technology (GRIT) firmware options, which provides spoofing detection, interference detection, and mitigation with digital filters, as well as time-tagged digitized samples for advanced situational awareness.
KB: As it applies to mobile mapping with the Trimble MX50, jamming and spoofing are not significant challenges.
OC: A team of engineers is constantly improving our anti-jamming and anti-spoofing technology. U-blox customers are today more mindful of the risks associated with GNSS interference, both intentional and unintentional. GNSS is adopted in critical infrastructures and autonomous vehicles, where jamming and spoofing could lead to severe consequences. While no system can be safe in absolute terms, increasing the sources of information can greatly improve the resilience against jamming and spoofing attacks. Multi-constellation GNSS receivers, multi-band constellations, inertial sensors and accelerometers, can all be individually used as additional safety layers contributing to a more robust solution. Additional measurements are implemented at the positioning engine level, as part of our functional safety program. The availability of authenticated signals, being introduced by Galileo’s Open Service – Navigation Message Authentication (OS-NMA), will also contribute to increasing the GNSS robustness against interference.
Hemisphere GNSS’ GradeMetrix is a machine guidance solution for GNSS-based machine control and guidance applications. (Image: Hemisphere) FF: Definitely, and we are seeing a large increase in demand for resilience in many applications and for assured positioning, navigation and timing (PNT). Providing trustworthy information is critical now for many markets, such as machine control, robotics, timing, infrastructure and assured PNT. Our multi-frequency multi-constellation GNSS technology not only maximizes accuracy and availability in areas where the sky is partially obstructed, but also provides extra resilience against jamming and spoofing. All our GNSS receivers are resilient to jamming and spoofing thanks to the built-in Advanced Interference Mitigation (AIM+) technology, which suppresses the widest variety of interferers, from simple continuous narrow-band signals to the most complex wideband and pulsed transmissions.
MW: Fortunately, jamming and spoofing are not common occurrences in most of our markets. However, their nature is such that they can appear at any time, in any place, without warning. This can cause otherwise routine plans for users to suddenly grind to a halt. Hemisphere’s Cygnus interference solution provides protection against up to 60 dB of jamming and is built into our current generation products by default. Having Cygnus available can make the difference between working normally and searching for alternate solutions. A welcome tool offered through Galileo satellites is OS-NMA signal verification, which provides excellent protection against spoofing attacks. Firmware updates provide our current product platforms access to OS-NMA spoofing protection. As our standard products are already activated for multi-constellation operation, it simplifies integration for our users.
RP: Interference is inevitable given the enormous number of signals from telephone and electrical networks, among others, as well as buildings, trees and, of course, the weather. To mitigate this, we use multi-frequency and multi-GNSS antennas that allow us to obtain the best reception in areas of interference. Additionally, we have state-of-the-art GPS chips that block and purify signals that generate distortion. On the other hand, there is interference by intentional GNSS falsifications or by radio amateurs who transmit radio signals for drones and other devices that cause GPS signal loss, which are mitigated by the latest technology algorithms of our SXblueGPS.
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First Fix: 50 years since “Lonely Halls”
Matteo Luccio In 1973, on March 1, Xerox launched the Alto, the first computer designed from its inception to support an operating system based on a graphical user interface; on April 3, Martin Cooper of Motorola made the first cellphone call, from 6th Avenue in New York City; and TCP, Ethernet, and fiber optics were created.
That same year, over Labor Day weekend, a dozen people in a small conference room on the top floor of a nearly deserted Pentagon, at a meeting called and chaired by Brad Parkinson that became known as “Lonely Halls,” made the key design choices for the Global Positioning System. None of those fundamentals have changed in the intervening half century, during which GPS was developed, launched, and modernized and became a worldwide utility underpinning many critical economic sectors — including precision agriculture, financial services, location-based services, mining, surveying and telecommunications.
At the time, Parkinson — a United States Air Force colonel with a Ph.D. in astronautical engineering from Stanford University, three years of experience in inertial guidance, and 26 combat missions in AC-130 gunships — was the first director of the GPS Joint Program Office in Los Angeles. As he and his co-authors recalled in a detailed two-part history of GPS (see the May and June 2010 issues of GPS World), the aspects of GPS that were defined at Lonely Halls included:
- Simultaneous passive ranging to four satellites in inclined orbits, ensuring user equipment would not require a synchronized atomic clock.
- A signal structure using CDMA modulation, including both a precision military code and a clear acquisition one that would be freely available to civil users worldwide.
- Two GPS broadcast frequencies in the L band.
- A family of user equipment prototypes, including a low-cost set that would demonstrate civilian use.
I recently asked Parkinson how GPS today differs from the design that came out of the Lonely Halls meeting. “The fundamental answer is that it’s identical,” he said, “in terms of design, the atomic clock, the CDMA signal, and four satellites to eliminate the need for a user clock. What has been evolving, of course, is that we’ve added another frequency and several new signals, including those for the military and L1C.”
From the very beginning, Parkinson encouraged civilians to use the system, correctly predicting that “they would apply their research and design talents to drive the size, weight and power requirements of the receivers down and the family of applications up,” he said. “That’s exactly what happened, in my opinion.”
Which applications surprised him the most? “Our revolution has been enabled by the advent of integrated circuits in terms of size and cost,” he said. For example, RTK has now given dynamic users access to centimeter accuracies.
“We were driven by visions of the many beneficial applications of GPS; visions that were not yet shared by the Air Force. GPS is a testimony to my team’s engineering competency, their tenacity, and their resourcefulness. I, and the whole world, owe them a large debt for the benevolent revolution they created.”
Matteo Luccio | Editor-in-Chief
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EAB Q&A: Should countries build their own GNSS constellations?
“When Galileo was just an idea, its EU proponents used the argument of “political, economic, social and technological sovereignty.” Should countries such as Brazil build their own GNSS constellations?”
Ismael Colomina “When, almost 20 years ago, I was in Brazil giving talks about the future of Galileo and promoting its combined use with GPS, I was often asked the logical question as the EU Galileo sovereignty arguments were known. It is not for us Europeans to answer that question for other countries or oppose their plans. However, while being aware of the defense aspects of GNSS, we may ask ourselves whether an international cooperative approach could avoid a somewhat unjustified future proliferation of GNSS constellations.”
— Ismael Colomina
GeoNumerics
Jules McNeff “GPS enables continuous access, free of fees and political encumbrances. A decision by any nation to bear the cost of creating a separate GNSS should be justified by realistic requirements for security or coverage that cannot be satisfied by GPS. Japan, South Korea and India are models for additional GNSS services driven by regional needs. For any new system, compatibility with other GNSS, as well as life-cycle costs, are the primary factors to consider.”
— Jules McNeff
Overlook Systems Technologies
John Fischer “When Galileo was just an idea, the U.S. military’s GPS was the only viable global constellation. GLONASS was a rusting cold-war relic and BeiDou was in an embryonic stage. The U.S. military’s official policy was that any civilian use was not guaranteed and could be interrupted anytime. Therefore, no nation outside of the United States could depend on GPS and maintain its independent interests. However, today, any country could reasonably maintain its sovereignty by ensuring interoperability with all four — betting that at least one of those constellations would always be available to them. They don’t need their own system.”
— John Fischer
Orolia
F. Michael Swiek “Those are always nice-sounding words when trying to justify a monumentally huge expense. However, is there an actual need to justify that expense? Can the expense and burden of perpetual system operation and maintenance, along with technological innovation to keep pace with other systems and user requirements, be guaranteed over the long term? For the users, GPS can be seen as the gift that keeps on giving, whereas to the operators it is the gift that keeps on costing. So, do Brazil, or other nations, have the commercial or social need, technological foundation, economic resources and political will to initiate a new system and sustain it over the long term? Providing a GNSS constellation is not for the faint of heart or those of short-term vision.
— Michael Swiek
GPS Alliance -
Faux signals for real results: Spirent Communications / Spirent Federal Systems
An exclusive interview with Mark Holbrow, VP of Product Development, Spirent Communications and Roger Hart, Sr. Director of Engineering, Spirent Federal Systems. For more exclusive interviews from this cover story, click here.
What are your roles?
MH: Our business is based in the UK. I am responsible for the vision and direction of the Technology portfolio required by Spirent’s Positioning Technology business unit.
RH: I am responsible for the U.S. add-on components to the simulator, the restricted signals, and support for the U.S. government labs and contractors.
How have the need for simulation or the requirements for it changed in the past five years, with the completion of the BeiDou and Galileo GNSS constellations, the rise in jamming and spoofing threats, the sharp increase in corrections services, and the advent of new LEO-based PNT services?
MH: I would say that the need for thorough and comprehensive testing has never been greater. That need is being driven on multiple fronts due to the understandable pressure on PNT systems needing to deliver enhanced accuracy, reliability and resilience, in the presence of emerging threat vectors and an expanding application space that’s utilizing ever more complex combinations of new and enhanced signals and sensors of opportunity. Underpinning Spirent’s leadership in ensuring the test needs for this evolving, challenging and increasingly diverse market are its team, its technology and its partners. That team is well-established, dedicated and highly experienced — their sole focus is designing, manufacturing and supporting PNT test solutions. The technology focuses around our pioneering dedicated SDR hardware platform and software simulation engine, which allied provide performance, scalability and flexibility, within an open accessible architecture. In addition, close collaboration with our selected partners ensures the opportunity to support and integrate new and emerging PNT technologies through their tools, applications and hardware.
You mention the advent of LEO. A key reason why Spirent was first to market and successfully supported an early LEO + GNSS receiver test-bed (through close and collaboration with Xona and NovAtel) was driven by team, technology and partners.
Two other important areas that have definitely continued to grow and evolve in importance and priority have to be increased realism and test automation. Both are areas in which Spirent continues to prioritize and invest R&D dollars.
Spirent’s integrated, software-defined wavefront simulation system for a 5-element controlled reception pattern antenna (CRPA). Spirent solutions support 16+ antenna elements. (Image: Spirent) With all these additional signals, is it still a single simulator or do you have to somehow split it up into different modules?
MH: Good point. Again, a key element with the Spirent solution is that it is very scaleabale and flexible. Spirent has a generic SDR that can be re-purposed to simulate whatever signals are required. That way, we can compile different signals from either one radio or multiple radios coming from the same system. Together with being able to bring in multiple chassis to gradually grow the simulation solution, while also maintaining for each of those signals the fidelity, channel count, and accuracy that customers demand.
Including every signal currently available?
MH: Absolutely, sir. In fact, signals that are still on the drawing board as well. We can enable the user with effectively an arbitrary waveform simulator or ‘sandbox’ to experiment with different modulation schemes, different chipping rates, codes, bandwidths and navigation data content. So, in addition to using that architecture to generate the signals, we allow customers to experiment with it themselves. That’s certainly accelerated over these last five years, and there’s no sign of it stopping. We’re currently working with customers and partners all over the globe who are developing both brand new and emerging PNT systems, whilst also providing all the vital simulation tools to aid the R&D of existing and planned SIS evolutions.
RH: The increasing number of signals that we can support multiplies the permutations and combinations of test cases that users can do. There is a lot of emphasis also on the user interface side of things, so that from one interface you can also easily control all these interfaces with third-party tools, because proliferation of signals produces a huge possible test volume.
What are the specific challenges in realistically simulating new LEO-based signals and any new services being developed for which you don’t have any live sky signals to record yet, only ICDs and other documents?
MH: Again, great question. The key reason Spirent excels in this arena is that the core simulation engine and SDR are agnostic of the constellation and signal type that’s being generated. So, the underlying principles of accuracy, range rate, pseudo-range control, and delay, together with the RF fidelity from Spirent’s SDR+ Sim engine, can be readily manipulated to simulate the wealth of emerging signals, including LEO.
The other area that becomes very important is that if we do not have sight of the ICD, we can enable customers to use our tools to readily populate elements of that ICD themselves. That way, the best of both worlds is achieved, i.e. a turnkey SIS solution, or we can just enable the customer to do it themselves.
Are accuracy requirements or any other requirements for simulation increasing to enable emerging applications?
MH: They are. Both current and emerging test needs are continuing to drive the need for enhanced simulation realism. Always a tough nut to crack, but our hard-won experience and expertise, allied with continuing adoption of latest-generation technology, is allowing us to take some significant strides forward. Real-world testing has an incredibly important role to play and that’s why at Spirent we continue to invest in and develop the GSS6450 Record & Playback System (RPS). However, we are also on that quest for the ‘Holy Grail’ that has all the well understood and necessary advantages of lab-based testing but with the simulation environment being as true to the real world as possible.
A German Armed Forces test center, WTD-61, recently used Spirent’s new Field Simulator to conclusively demonstrate the susceptibility of some UAS to spoofing. (Image: Spirent) A further area where both current and emerging test needs are demanding more and more from the test environment is resilience testing. Spirent now supports a multitude of vulnerability and corresponding mitigation/prevention test cases. Those test cases become increasingly complex as multiple combinations of the threat/mitigation surface evolve — including jamming, spoofing, cyber-attack and CRPA.
Many of these test cases are driving the state of the art and, especially in the case of CRPA testing, Spirent’s purpose-designed SDR comes into its own. Technology bakeoffs and corresponding customer adoption have shown that only through the use of that dedicated purpose-built technology, the simulator test bed can deliver the necessary carrier and code phase stability, very low levels of uncorrelated noise across antenna elements and high J/S that is demanded.
Again, with respect to flexibility, we also support ways to let customers generate their own IQ data. That data can be streamed into the Spirent simulator and combined sympathetically and coherently with the signals generated inside the platform. So, you can layer new signals on existing ones, or introduce a completely new dedicated IQ stream.Finally, hardware-in-the -loop (HIL) testing requirements continue to be a crucial aspect in test coverage. Whether that application is automotive, projectiles or autonomous vehicles, the need for lower latency and higher 6DOF sampling to capture as many trajectory nuances as possible continues to grow. Spirent’s 2KHz system achieves very high iteration rates (SIR) and <2msec latency.
What are the key differences between your simulators for use in the lab and those for use in the field? I assume that the latter are lighter, smaller, and less power hungry. Do they use modules so that users can pick the ones they need for a particular test?
MH: We do support in-the-field test use cases. Spirent has record-and-replay (RPS) systems to take soundings in a wide-band RF environment, record them, then bring them back into the lab for replay. They are sized to fit into a backpack, battery-powered, accessible, and easy to use.
Recently, we have also taken some of our signal generator IP and been able to create a smaller form factor portable simulator for outside use. Its footprint is considerably smaller than that of one of our lab-based simulators. It’s primarily a mechanism for testing the resilience in the field of devices under test. Armed with a Spirent simulator and the appropriate transmit licenses, a customer can put their DUT through an array of vulnerability test cases in a live real-world environment.
You mentioned licenses. As far as jamming, specifically, and maybe spoofing, I presume that you’ll need a license for a specific time and place and that you will have to be far away from, say, an airport.
Absolutely. Right. The details will vary depending on the jurisdiction, but you will need a license to transmit. And, as you rightly say, often those places will be very remote so as not to interfere with the public. We’ve had instances where we’ll work with a customer who has those appropriate licenses and then we can provide this equipment for them to be able to put it through a battery of tests.
You generate the spoofing in your simulator, of course. Do you also generate the jamming inside the same box or from a separate jammer nearby?
It could be either. We can use our simulators to generate internally wide range of interference signals supporting a wide bandwidth, high max o/p power and large dynamic range. This is especially important in instances of CRPA testing, in which it is vital to accurately reproducing a jamming wavefront commensurate with the arrival angle and delay incident at each antenna element. Correspondingly, we support turn-key solutions to connect, control and integrate 3rd party external signal generators into the test scenario.
Are you at liberty to describe any recent success stories?
We have a Xona simulator. So, this is back on the topic of LEO. We’ve recently released that in partnership with Xona. We are also working closely with Hexagon. All those things I mentioned earlier about enabling the customer to use the flexible features that we have, that is where it came into its own. That’s certainly a significant recent success.
We’re continuing to add many realism-related capabilities, including simulating the vibration and temperature effects of inertial systems. Working with a Swiss partner called Space PNT, we’ve recently introduced another LEO-based product, called SimORBIT. That tool enables us to generate incredibly representative and accurate LEO orbits that also include gravitational effects based upon the SV size. We recently introduced a new software tool to support “GNSS Assurance” requirements.
We have a newly patented cloud-based software application called GNSS Foresight that enables users to understand the GNSS coverage they would expect during a particular time, date location and trajectory inclusive of the 3D environment they would be experiencing. We continue to evolve the tool to support real-time operation to enable it to deliver aiding content to appropriately equipped systems.
We continue to be able to support more and more automation. Automation has always been important, but with ever increasing demands of test asset utilization and in a post-pandemic world of remote working, it’s more important than ever right now. The number of test cases and corner cases required and the amount of equipment, coverage, and efficiency required, which was being demanded by using our kit means that automation is vital. So, we’ve introduced several new automation tools to build up on top of our current SimREMOTE interface.
Spirent has also developed a simulation test solution for the Galileo Open Service Navigation Message Authentication (OSNMA) mechanism. SimOSNMA is designed to work with Spirent’s GNSS simulation platforms to test OSNMA signal conformance, which will bring new levels of robustness for both civilian and commercial GNSS uses. SimOSNMA provides developers with vital new simulation tools to test for OSNMA, the security protocol that enables GNSS receivers to verify the authenticity of signals distributed from the Galileo satellite constellation. Designed to combat spoofing, OSNMA ensures that the data received is authentic and has not been modified in any way. It is currently completing the test phase before its formal launch, and SimOSNMA enables developers to simulate and test OSNMA signals and features, allowing GNSS receiver manufacturers and application developers to accelerate and assure development programs.