For users relying on centimeter-level accuracy — such as surveyors, engineers and autonomous systems — ionospheric disturbances can mean system downtime and significant losses. Traditional network real-time kinematic (NRTK) positioning methods assume smooth ionospheric conditions and thus fail during active solar periods.
To meet these challenges, a research team from Wuhan University and Guangzhou Hi-Target Navigation Tech Co. Ltd. developed an NRTK positioning model capable of maintaining centimeter-level accuracy under intense ionospheric disturbances.
This approach could serve as the foundation for next-generation, self-correcting navigation systems that operate reliably under any atmospheric condition.
The study (DOI: 10.1186/s43020-025-00179-4), published in Satellite Navigation on Oct. 6, introduces a dual-optimization framework that integrates real-time ionospheric indices with adaptive functional and stochastic models. By learning from disturbance patterns and automatically recalibrating user-side algorithms, the system dramatically enhances GNSS reliability during the ongoing solar cycle peak — offering a key safeguard for positioning technologies in low-latitude regions most vulnerable to ionospheric turbulence.
The innovation centers on leveraging the rate of the total electron content index (ROTI), a key indicator of ionospheric activity, to dynamically adjust both ionospheric residual estimation and observation weighting. When the system detects disturbances, it automatically reduces the influence of affected satellites and refines error models in real time.
Using data from Hong Kong’s Continuously Operating Reference Station (CORS) network — one of Asia’s most active low-latitude regions — the researchers found that ROTI showed a strong positive correlation (0.91) with ionospheric interpolation errors and a negative correlation (–0.9) with signal-fixing rates.
Compared to conventional NRTK methods, their adaptive “Method B” improved horizontal and vertical positioning accuracy by 37.6% and 41.6%, respectively. Moreover, it achieved a stable 84% average fixing rate, even during equinoctial months when ionospheric scintillation is strongest. The results reveal not just a technical upgrade but a practical solution for real-time navigation across regions frequently affected by solar-induced ionospheric noise.
“Our method essentially teaches GNSS systems to think smarter under stress,” said Xiaodong Ren, senior researcher at Wuhan University and lead author of the study. “By allowing the model to ‘sense’ and adapt to space-weather disturbances in real time, we’ve moved beyond static correction systems toward intelligent positioning. This is crucial not only for maintaining accuracy but also for ensuring resilience as solar activity intensifies.”
He added that this approach could serve as the foundation for next-generation, self-correcting navigation systems that operate reliably under any atmospheric condition.
This adaptive NRTK framework marks a significant leap forward for industries that depend on precise, real-time location data — from autonomous driving and drone surveying to precision agriculture and infrastructure monitoring, Ren said. By integrating live ionospheric monitoring into everyday positioning workflows, it ensures continuous accuracy even when solar storms strike.
Future developments may combine the model with artificial intelligence and multi-constellation GNSS networks to further enhance forecasting and resilience. As Earth moves through one of its most active solar cycles, Ren said, such innovations will be essential to keeping navigation, communication and automation systems firmly on course.
Trimble and PTx Trimble have introduced Trimble IonoGuard, a new technology designed to enhance RTK GNSS signal reliability for precision agriculture applications. The system aims to improve positioning accuracy and reduce signal loss during challenging ionospheric conditions.
IonoGuard is now available for users of the PTx Trimble NAV-900 guidance controller and Trimble base stations equipped with the ProPoint positioning engine. The technology was developed to maintain RTK correction integrity and minimize positioning dropouts during periods of high solar activity.
Solar activity peaks every 11 years, with the next maximum predicted in 2025. This phenomenon can significantly impact GNSS signal stability, potentially affecting precision positioning. Solar Cycle 25, which began in 2024 and is expected to continue through 2026, may present substantial challenges with the possibility of global disruptions.
While solar cycle disturbances often go unnoticed by the public, high-precision RTK GNSS users in equatorial regions frequently experience impacts from solar activity throughout the year, which can lead to costly interruptions in agricultural operations.
IonoGuard is accessible through the latest PTx Trimble Precision-IQ firmware release. When used with compatible GNSS hardware, the system aims to deliver improved RTK performance during both routine operations and periods of solar disturbance.
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.”
