GNSS researchers presented hundreds of papers at the 2022 Institute of Navigation (ION) GNSS+ conference, which took place Sept. 19–23 in Denver, Colorado, and virtually. The following five papers focused on atmospheric effects on GNSS signals. The papers are available at www.ion.org/publications/browse.cfm. 

Addressing Scintillation Error

Mitigating the scintillation effect at low latitude is a complex matter: several kinds of experimental data must be collected, realistic models must be developed, and, most importantly, useful real-time indices and alerts must be made available.

The authors introduce a prototype based on a patent owned by SpacEarth Technology to address scintillation error detection and mitigation, supporting precision GNSS-based services at low latitudes in any season and space weather conditions. The patent relates to a method of total electron content (TEC) and scintillation empirical forecasting, in particular short-term forecasting (seconds to minutes). The output of the method is necessary to feed mitigation algorithms aiming at improving accuracy on GNSS precise positioning techniques (RTK, NRTK, and PPP) under ionospheric harsh conditions.

The prototype is designed with a Central Elaborating Facility, which collects the data provided by a network of GNSS monitoring stations detecting scintillation events, and broadcasts foreseen scintillation parameters. Users with a rover mitigation device can apply the parameters from the central facility for scintillation error mitigation. 

Vincenzo Romano, INGV and SpacEarth Technology; Claudio Cesaroni, INGV; Luca Spogli, Alessandro Fiorini, INGV and SpacEarth Technology; Marco Fermi, Gter; Lorenzo Benvenuto, Gter and University of Genoa; Tiziano Cosso, Gter; Marcin Grzesiak, SRC/PAS; Joao Francisco Galera Monico, Italo Tsuchiya, UNESP; Gabriel Oliveira, Marcos Guandalini; “Ionospheric Scintillation Mitigation at Low Latitude to Improve Navigation Quality.”

Ring of Fire GUARDIAN 

Commonly, natural hazards release energy into the Earth’s atmosphere in the form of acoustic-gravity waves, which propagate up to the ionosphere. The resulting traveling ionospheric disturbances (TIDs) can be detected using GNSS signals, through the computation of the integrated total electron content (TEC) along the lines of sight between GNSS receivers and satellites. The global distribution of ground-based GNSS receivers constantly tracking multiple GNSS constellations (GPS, Galileo, GLONASS, BeiDou, and others) provides excellent spatio-temporal coverage around the world, including in areas of limited coverage by existing warning systems.

The authors present the operational GNSS-based Upper Atmospheric Real-time Disaster Information and Alert Network (GUARDIAN). Based on dual-frequency GNSS data from the Global Differential GPS (GDGPS) network of the Jet Propulsion Laboratory, the GUARDIAN architecture computes slant TEC time series in near real time.

As part of the GDGPS network, 78 stations around the Pacific ring of fire monitor the four GNSS constellations: GPS, Galileo, GLONASS and BeiDou. Cycle slips are corrected and the time series are filtered, both in real time. The resulting data stream is output live to a user-friendly public website, benefitting the general public and the scientific community. 

The current GUARDIAN focuses on the Pacific region. However, the architecture can readily be extended to a worldwide coverage.

Léo Martire, S. Krishnamoorthy, L. J. Romans, B. Szilágyi, P. Vergados, A. W. Moore, A. Komjáthy, Y. E. Bar-Sever, A. B. Craddock, NASA Jet Propulsion Laboratory, California Institute of Technology; “GUARDIAN: A Near Real-Time Ionospheric Monitoring System for Natural Hazards Early Warnings.”

Civil Aviation Interference

The authors provide a survey on GNSS receiver architectures with emphasis on new carrier-tracking techniques for mitigating the adverse effect of ionospheric scintillation within the context of civil aviation. The survey is complemented by results gathered from simulations on the impact of ionospheric scintillation in conventional receiver architectures. A review on scintillation mitigation techniques is carried out, covering several “technique families,” highlighting their potential for performance improvement, as well as their shortcomings and challenges in implementation.

A semi-analytical simulation campaign is carried out for different modulations: L1, L5 for GPS, and E1, E5a for Galileo. Here, the performance of a standard receiver tracking a set of GPS and Galileo satellites affected by ionospheric scintillation is analyzed to pinpoint existing vulnerabilities to this effect.

The simulation results show that ionospheric scintillations are responsible for large variations in carrier-to-noise ratio, which in turn can be responsible for losses of lock and large phase variations, increasing phase RMSE and in some cases leading to cycle slips of the phase estimation. Thus, the adopted solution must be robust to signal power fluctuations and the occurrence of cycle slips and able to maintain phase lock.

António Negrinho, GMV-PT Pedro Boto, GMV-PT Marta Cueto, GMV-ES Mikael Mabilleau, EUSPA Claudia Paparini, EUSPA Ettore Canestri, EUSPA; “Survey on Signal Processing Techniques for GNSS Ionospheric Scintillation Mitigation.”

Tonga Eruption Data Analyzed

Extreme natural disasters, such as volcanic eruptions, can create visible pressure waves in the atmosphere and trigger observable ionospheric wave responses that can travel hundreds of kilometers in the ionosphere. The acoustic and gravity waves generated can cause ionospheric TEC perturbations and variations. The TEC determines the GNSS ionospheric delay and can cause significant positioning errors, which may affect the performance of GNSS-based applications.

The researchers processed GNSS data collected from the Hong Kong Satellite Positioning Reference Station Network to analyze the ionospheric activity and positioning performance responding to the Tonga volcanic eruption on Jan. 15, 2022. To detect and repair cycle-slip jumps, the researchers applied theTEC rate and Melbourne Wubbena Wide Lane (MWWL) linear combinations. A Savitzky-Golay low-pass filter with a 30s window was used to improve the TEC accuracy.

The team investigated the changes in TEC, Rate of TEC index (ROTI) and positioning errors in the eastward, northward and upward directions after the anomalous ionospheric propagation to Hong Kong between 11:30 and 14:30. The team found the ionospheric anomaly could generate large changes in the three parameters, with peaks up to three times the calm period. Their prompt research contributes to a better understanding of the coupling of extreme ionospheric activities and dynamics caused by volcanic eruptions. 

Xiaojia Chang, Kai Guo, Zhipeng Wang, Kun Fang, Hongxia Wang, Beihang University; Hailong Chen, China Academy of Aerospace Electronics Technology; “Ionospheric Anomaly and GNSS Positioning Responses to the January 2022 Tonga Volcanic Eruption.” 

Toolbox for Monitor Network

The MONITORtoolbox is a set of Python-coded software tools to perform automatized large-scale processing of data from the Monitor network of the European Space Agency (ESA). The Monitor network aims to continuously monitor ionospheric scintillation events from multiple ground stations strategically located around the globe. It accommodates a repository with a large number of GNSS measurements containing scintillation events for users to analyze scintillation data or for research purposes.

This paper shows the potential of the MONITORtoolbox for providing access to a large amount of data that otherwise, without a systematic processing, becomes practically useless. The software developed implements the means to collect data and store it in a local database for quick offline access. It detects the presence of scintillation events based on certain conditions and criteria defined by the user and identifies its properties in terms of duration, time of occurrence, intensity and satellite location. It implements the tools to compute relevant statistics, providing insights on ionospheric scintillation phenomena.

Sergi Locubiche-Serra, Alejandro Pérez-Conesa, Diego Fraile-Parra, Gonzalo Seco-Granados, José A. López-Salcedo, Universitat Autònoma de Barcelona, IEEC-CERES; Juan M. Parro-Jiménez, Raúl Orús-Pérez, ESTEC, European Space Agency; “MONITORtoolbox — Software Tool for the Analysis of Ionospheric Scintillation Data from the ESA Monitor Network.” 

Achieving PNT resilience for critical infrastructure applications

GNSS are magic. They are. One dictionary defines magic as “a power that allows people (such as witches and wizards) to do impossible things by saying special words or performing special actions.” By this definition, we have all become witches and wizards, doing what previous generations would have deemed impossible.

This magic, however, can be affected by external forces that render it useless at best and, at worst, dangerous. Warnings about GNSS positioning, navigation and timing (PNT) service vulnerabilities have been raised for 25+ years. Numerous organizations have warned of the potential safety, security and economic impacts of GNSS interference. Still, like modern-day Cassandras, their warnings have been ignored, and sole use of PNT services that rely on space-based signals continues to expand.

“Magic services” are addictive and cannot be ignored. Yet, it is well past the time to merely admire the problem of GNSS interference — benefitting from magical GNSS services while ignoring existing and emerging threats and challenges. It is time to draw a line and implement resilient, complementary PNT solutions to support all critical infrastructure sectors and applications in the event of any GNSS disruption, due to jamming or spoofing or systemic causes. “Magic” is magical when it works. When it does not, first and foremost, it should “do no harm.” 

Threats, Challenges and Needs 

Presidential Policy Directive (PPD) 21, Critical Infrastructure Security and Resilience, issued in 2013, defines resilience as “the ability to prepare for and adapt to changing conditions and withstand and recover rapidly from disruptions.” It also notes that “resilience includes the ability to withstand and recover from deliberate attacks, accidents, or naturally occurring threats or incidents.”

In 2016, the UK Department of International Development noted that “Resilience covers both ‘physical and societal systems” through four “R” principles: robustness, redundancy, resourcefulness and rapidity (see Figure 1).

More recently, Andy Proctor (RethinkPNT) pointed out that “A resilient PNT system protects its critical capabilities (assets) from harm by using protective resilience techniques to passively resist or actively detect threats, respond to them, and recover from the harm they cause.” 

Policies, processes, financial arrangements and incentives are also crucial to achieving resilience — and that has been, and remains, the problem. Lacking the emergence of strong leadership from our institutions, the ability to achieve actual resilience will continue to falter and admiration of the problem will continue.

Developing a resilient PNT system is always a balance of technical complexity and non-technical aspects, for example, costs. The key consideration for users must be the required performance metrics they need for their use-case(s) to ensure their resilience — including accuracy, availability, integrity, continuity and coverage. The one least understood and many times omitted is integrity — the level of trust a user/use-case needs to safely and securely use the PNT services. The ability to trust PNT services must always be a consideration for critical infrastructure applications.

Unfortunately, many users of critical infrastructure PNT do not know some of the PNT metrics they need to ensure safety and security. More troubling, there is no guidance as to what constitutes “significant economic impact” (see PPD 21) or acceptable economic loss — and over what period or range of use cases. This understanding will require analysis of their design, development and operational experiences, and working with PNT systems engineers to first derive these metrics and then drive the continuous improvements (see Figure 2) needed to achieve and retain truly complementary PNT capabilities. Without clear metrics and guidance, one cannot claim that any solution will meet any “required level of resilience.”

Supporting PNT Users

As with all systems engineering (SE) activities, PNT system resilience begins with identifying and documenting user needs based on their specific user stories/use cases. Figure 3 depicts different aspects of resilience that can be sought, depending on the unique use-case “demands.”

While the resilience needs of different use cases will differ, for any specific use case, a given “PNT solution” will either achieve the required/threshold level of resilience (based on the operational environment) or it will not. Some use cases may also require fail-safe or fail-soft capability and the ability to recover to known, trusted and usable states. Shouldn’t many, if not all critical sector use cases require this?

Equally important is the identification of risks and threats, as they are critical to understanding the challenges that the system must face while continuing to provide the necessary P, N and/or T service performance. It is also key to understand and document the system architecture and environment in which it must perform. With knowledge of a user’s needs, the threats, hazards and challenges they face, and the system architecture, the SE process can develop an understanding of the “gaps” that exist and of the levels of risk they impose on a critical infrastructure system’s functional, physical and operational performance. Understanding this, essential use-appropriate mitigations can be identified, or if need be, developed, and a resilient, solution-agnostic PNT requirement document created.

The Way Forward

The Critical Infrastructure Resilience Institute (CIRI), a U.S. Department of Homeland Security Center of Excellence, notes that “critical infrastructure systems are facing a myriad of challenges. Solutions must address the cyber, physical and human dimensions.” They keyed into four areas where critical infrastructure resilience activities should be directed: building the business case, information policy and regulation, developing new tools and technologies, fostering and educating the workforce.

These include the recognition that “policy and regulation have a powerful impact on market forces.” While the fact that “most U.S. infrastructure is owned and operated by the private sector” is a challenge, it should not be an excuse.

We must start immediately to re-establish strong SE practices, policies, and principles to help critical users understand their needs and determine the metrics required to ensure safety and “preclude significant economic impact.” Only then can we understand from a national perspective, the needed safety and security metrics and what constitutes significant economic impact, and then establish categories of solution-agnostic requirements. Lacking these clear resilience targets, detailed planning, and required resource commitments, the growing threats of PNT vulnerability will continue only to be admired, rather than be mitigated. Hope is not a strategy, but this systems engineer hopes that it does not take a truly catastrophic event to finally prompt much needed and long overdue actions. 

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Mitch Narins is the principal consultant/owner of Strategic Synergies LLC, a consultancy he formed following more than 40 years of U.S. government service. He is a Fellow of the Royal Institute of Navigation, a aenior member of the Institute of Electrical and Electronic Engineers, a member of the Institute of Navigation and head of its Washington, D.C., section, and a member of RTCA, RTCM, IEEE and SAE Standards Committees.

Multinational technology firm GMV has signed an agreement with Lockheed Martin Corporation to develop the processing and control centers for the Southern Positioning Augmentation Network system (SouthPAN).

The project is a joint initiative of the Australian and New Zealand governments to provide a satellite-based augmentation system (SBAS) for navigation and precise point positioning (PPP) services. GMV will also be responsible for monitoring both of these services in the region and for ensuring compliance with the committed performance levels.

SBAS and PPP systems have applications in industries as diverse as agriculture and road, air, maritime and rail transportation, as well as in the field of geomatics. SouthPAN is expected to accelerate development of applications in these areas.

SouthPAN is also the first system with these characteristics available in the Southern Hemisphere. With this new program, Australia and New Zealand will be contributing to improved global coverage and interoperability for services of this type, joining the list of countries and regions that already have their own SBAS system: the United States (WAAS), Europe (EGNOS), India (GAGAN) and Japan (MSAS).

On Sept. 26, two weeks after the agreement was signed, the first services were provided by activating transmission of the system’s first signals. This was a significant milestone, because SouthPAN is the first project where an industry consortium provides an SBAS as a service, rather than as a turnkey system.

GMV’s role

GMV will be responsible for developing two key subsystems for SouthPAN: the Corrections Processing Facility and the Ground Control Center. The company will also be responsible for monitoring the system and ensuring it complies with the committed performance levels.

GMV also will provide support for the system’s operation and maintenance.

Corrections Processing Facility. The facility generates correction messages for signals transmitted by GPS and Galileo, improving precision for users by improving accuracy to as little as 10 centimeters.

The facility also detects malfunctions in the satellites and generates warnings for users. This will allow use of SouthPAN by civilian aircraft as a navigation system during various flight operations, including precision approaches to runways for landing.

Safety-of-life services such as these will be available in 2028.

Ground Control Center. The control center remains in operation 24 hours a day seven days a week, and will perform all the functions needed to monitor and control the system. It will also provide information to users about the system’s operation and availability of services.

In Australia, SouthPAN development, entry into service and operation are being supervised by Geoscience Australia in collaboration with Toitū Te Whenua Land Information New Zealand.

In 2020, the two agencies signed the Australia New Zealand Science, Research and Innovation Cooperation Agreement (ANZSRICA). Over the next 20 years, the Australian government will be contributing 1.4 billion Australian dollars to the SouthPAN project.

Innovative chip offers multiple ultra-low power connectivity options and low-power processing for internet of things (IoT) market

Sony Semiconductor Israel has launched the ALT1350 for the global market. The ALT1350 is a cellular LTE-M/NB-IoT chipset designed to enable additional low-power wide-area (LPWA) communication protocols, as well as GNSS, in a single chipset.

The ALT1350 incorporates a sensor hub to collect data from the sensors while maintaining ultra-low power consumption. It also provides cellular and Wi-Fi-based positioning and is tightly integrated to provide power-optimized concurrent LTE and GNSS to accommodate various tracking applications, which can be demanding with a single chip.

“The market demand for this multiprotocol, ultra-low power IoT chipset is intensifying, and Sony’s ALT1350 chipset meets that demand,” said Nohik Semel, CEO at Sony Semiconductor Israel. “This is the game changer we’ve been waiting for, which will enable IoT deployments, utilizing universal connectivity on edge processing and multiple location technologies.”

The ALT1350 is an advanced cellular IoT solution, with architecture that resolves IoT service provider’s power-consumption concerns. Its optimized standby mode (eDRX) reduces power consumption by 80% when compared to the current generation and by 85% when using it to send short messages.

Overall improvements in the system’s power consumption will enable four times longer battery life for a typical device, enabling additional functionalities and use cases with smaller batteries.

The ALT1350’s sub-GHz and 2.4 GHz integrated transceiver enables hybrid connectivity for smart meters, smart cities, trackers and other devices. This enhances coverage, reduces costs and further decreases power consumption using IEEE 802.15.4-based protocols such as Wi-Sun, U-Bus Air and wM-Bus, in additional point-to-point and mesh technologies.

The chipset is designed to support the wide-ranging market needs of utilities, vehicle, tracking devices, smart cities, connected health and other verticals. Device manufacturers across all verticals can take advantage of its low power consumption, long-lasting battery life, mature Release 15 LTE-M/NB-IoT software stack, and future compatibility with 3GPP release 17.

All these guarantee longevity and ensure the ALT1350 will operate with 5G networks. It contains an additional LPWA radio transceiver with targeting operation in <1 GHz and 2.4 ISM bands for universal connectivity options.

The chipset provides advanced on-the-edge low power processing capabilities, ranging from data collection, low power AI/ML processing of the data, and MCU to enable IOT applications on the chip.

The device is now sampling to lead customers and will become commercially available in 2023. The ALT1350 also includes a secure element for application usage and integrated SIM designed for PP-0117 to meet GSMA requirements.

The IMU-FI-200C FOG IMUs are a fully integrated inertial measurement solution that combines the latest closed-loop FOG and MEMS sensors technologies

Inertial Labs has released the IMU-FI-200C high-performance fiber-optic gyroscope (FOG) inertial measurement unit (IMU), a compact, self-contained strapdown, advanced tactical-grade IMU that measures linear accelerations and angular rates with three-axis tactical-grade, closed-loop FOG and three-axis high-precision MEMS accelerometers in motionless and high-dynamic applications.

The IMU-FI-200C FOG IMUs are a fully integrated inertial measurement solution that combines the latest closed-loop FOG and MEMS sensors technologies. It is designed for a wide range of higher order integrated system applications, such as

• antenna and line-of-sight stabilization systems
• passenger train acceleration/deceleration and jerking systems
• motion reference units
• motion control sensors
• gimbals
• electro optical components/infrared
• platform orientation and stabilization.

Fully calibrated, temperature-compensated and mathematically aligned to an orthogonal coordinate system, the IMU contains gyroscopes with an accuracy of up to 0.5 deg/hr and accelerometers with a bias repeatability of less than 2-mg over their operational range, very low noise and high reliability.

The IMU-FI-200C FOG IMUs have been thoroughly tested to perform in significant variations in temperature, high vibration and shock, and is designed to be used in air, marine and land environments.

“New technology creates new opportunities, and the new IMU-FI-200C represents the innovative approach we take every day at Inertial Labs,” said Jamie Marraccini, president & CEO of Inertial Labs. “The high performance and flexibility to integrate into different systems and applications is what we have striven to provide to our customers with this new release.”

Registration is now open for the jointly sponsored Position Location and Navigation Symposium (PLANS) taking place April 24-27. PLANS is a biennial technical conference that occurs in the spring of odd-numbered years to provide an international forum to share the latest advances in navigation technology. The conference is sponsored by the IEEE’s Aerospace and Electronics Systems Society (AESS) and the Institute of Navigation (ION).

The PLANS conference takes place over four days, with the first day for hosting tutorials and three days dedicated to technical sessions.

The tutorials aim to provide attendees with the opportunity to learn about navigation technology from industry experts. A variety of tutorials are offered to serve the needs of both newcomers and those well versed in the field of navigation. This year’s tutorials will include a range of navigation subjects from core navigation fundamentals to in-depth classes about the latest technologies.

Technical sessions are offered over a three-day period, with four sessions running simultaneously each morning and afternoon. At the technical sessions scientists, researchers, and engineers from around the world present their latest work in the field of PNT. Technical session topics will include inertial sensing and technology; GNSS; integrated, collaborative and opportunistic navigation; and applications to automated, semi-autonomous and fully-autonomous systems.

To view the PLANS 2023 technical program and register for the event, visit ion.org/plans.

A new partnership between all-in-one navigation app and Waterway Guide gives U.S. boaters an enhanced user experience, integrating comprehensive marina details and user reviews into the navigation app.

The savvy navvy app, described as “Google Maps for boaters”, has grown by 132% this year in the United States.

Waterway Guide is a resource for cruising boaters. Its data on more than 4,000 marinas and thousands of anchorages are now integrated into the savvy navvy app for all the users to access.

“One of the most significant factors in deciding where to go with your boat is reviews from other boaters,” said Jelte Liebrand, CEO and founder of savvy navvy. “With a wealth of information on all marinas and anchorages and honest reviews, it’s an amazing addition to our offering for our growing American customer base.”

Liebrand, a former Google software engineer and avid sailor based in the UK, developed and launched savvy navvy, bringing an all-in-one navigation solution to the market. This season alone savvy navvy users have plotted more than 40 million nautical miles of routes. Earlier this year, the navigation app launched a freemium plan and functionalities for paddleboarders, kayakers and jet skiers.

Waterway Guide is continuously updated by a network of on-the-water contributors, marina partners, NOAA data, the Waterway Guide team, and crowd-sourced information.

Data from the Waterway Guide is live in the savvy navvy app for users to see now when pressing the blue POI icons across the United States and Canada, giving users  information on services and facilities alongside marina reviews.

Linx Technologies, now part of TE Connectivity, has expanded on its Splatch antenna series with the release of the ANT-GNL1-nSP, a surface-mount embedded GNSS antenna supporting GPS, Galileo, GLONASS, Beidou and QZSS in the L1/E1/B1 bands.

“The new linear GNSS antenna from Linx expands upon our already robust embedded PCB antenna portfolio of customer favorites like the uSP410, SP610 and the nSP250, by adding a GNSS solution,” said Rick Stuby, vice president of product management. “The antenna displays high performance in a compact surface-mount package, making it especially well-suited for small devices in the growing internet of things market.”

The ANT-GNL1-nSP antenna exhibits notable performance in a compact size (10 mm x 8 mm x 1 mm) and features linear polarization and an omnidirectional radiation pattern. The antenna is available in tape and reel packaging and is designed for reflow-solder mounting directly to a printed circuit board for high-volume applications.

The new GNSS antennas are available now via Linx Technologies’ distributor and manufacturer representative networks. For larger quotes, email Linx Technologies at contact@linxtechnologies.com.

The recommendation is based on demonstrations at Yuma Proving Ground, Arizona

EnforceAir, a solution that counters small unmanned aerial systems (sUAS), has been recommended by the U.S. Department of Defense’s (DoD) Joint Counter-sUAS Office (JCO).

Developed by D-Fend Solutions, EnforceAir was recommended as a subcomponent integrated within SAIC’s Valkyrie C2 system.

EnforceAir was recognized for its RF detection and mitigation, its demonstrated impressive effectors and its ability to force land certain drones. D-Fend Solutions’ EnforceAir was the only RF cyber takeover technology named.

EnforceAir automatically executes cyber drone detection and takeover mitigation of rogue drones for safe landings and outcomes, empowering security agencies and professionals with control while preserving operational continuity.

The JCO recommendation is the result of a formal U.S. government evaluation event held at Yuma Proving Ground in April 2022.

“It’s an honor to be recognized by the U.S. DoD Joint C-sUAS Office, following a rigorous demonstration and evaluation” said Zohar Halachmi, Chairman and CEO of D-Fend Solutions. “We’re excited to provide continued support for the counter-drone mission, within a layered defense, integrated in the most advanced C-UAS systems for the nation’s defense.”

EnforceAir is D-Fend’s flagship offering. With hundreds of deployments worldwide, EnforceAir focuses on the most dangerous drone threats in the military, public safety, airport, prison, major event and critical infrastructure environments.