Welcome to the Summer 2025 issue of NAVIGATION. As geopolitical events continue to be front and center these days, almost half of the articles in this issue deal with aspects of GNSS integrity. We also have an article on the development and maintenance of the World Geodetic System 1984 – the terrestrial reference frame used by GPS – and its alignment to the International Terrestrial Reference Frame. And we have another article on the use of low Earth orbiting satellites for positioning and navigation. And, as always, a great deal more.
ION promotes the research of journal authors in a variety of ways including video abstracts hosted on the ION website. The latest video abstracts are documented below. You can find the video abstract for any recently published article under the article’s supplemental menu item on the journal’s website. ION also engages with the PNT community, through its webinar series, to highlight current topics of interest to the community. The most recent webinars are also documented below.
VIDEO ABSTRACTS
Video Abstracts allow authors to present their research in their own words. This multimedia format communicates the background and context of authors’ research in a quick and easy way, elevating research from simple print delivery.
Video for “Classification of Authentic and Spoofed GNSS Signals Using a Calibrated Antenna Array”
By Michael C. Esswein and Mark L. Psiaki (https://navi.ion.org/content/72/1/navi.675/tab-supplemental)
Abstract: New optimization-based methods have been developed to use measured direction-of-arrival (DoA) information in order to classify received global navigation satellite system signals into authenticated and spoofed sets and to augment that information with pseudorange information when DoA information alone is insufficient to achieve the needed classification. These methods are designed for a system that is being developed to mitigate spoofing and jamming by using signals from a controlled radiation pattern antenna. These new spoofing classification methods operate on DoA outputs from trackers of various signals. This paper presents a multi-hypothesis test that considers all possible hypotheses regarding the authenticated and spoofed sets of tracked signals. A combinatorial analysis is performed in which all possible authenticated-set/spoofed-set classifications are generated for a given set of tracked signals and the correct authenticated set is determined among the different combinations. Results from Monte Carlo simulations show that using a combined DoA and pseudorange method is suitable for determining the correct combinations.
Article Citation: Esswein, M. C., & Psiaki, M. L. (2025). Classification of authentic and spoofed GNSS signals using a calibrated antenna array. NAVIGATION, 72(1). https://doi.org/10.33012/navi.675
Video for “Performance Analysis of MADOCA-Enhanced Tightly Coupled PPP/IMU”
By Cheng-Wei Wang and Shau-Shiun Jan (https://navi.ion.org/content/72/1/navi.678/tab-supplemental)
Abstract: Precise point positioning (PPP), which is characterized by reliable positioning accuracy and flexibility, has been regarded as a highly promising technique. Precise ephemeris is essential for PPP; however, the conventionally used standard product 3 components have an almost biweekly latency. The multi-global navigation satellite system (GNSS) advanced demonstration tool for orbit and clock analysis (MADOCA), a novel next-generation service, aims to provide real-time correction messages for rapid-convergence PPP in regional areas. Additionally, to ensure seamless navigation during signal-interrupted conditions, an inertial measurement unit (IMU) can be tightly integrated with the motion constraint models. This paper presents a comprehensive analysis of standalone MADOCA-PPP and MADOCA-enhanced tightly coupled PPP/IMU. The approaches were evaluated under multiple scenarios. In suburban regions, the horizontal root mean square error (RMSE) was 0.4 m, with a 95th percentile horizontal error of 0.6 m. In GNSS-challenging environments, the horizontal RMSE was 0.92 m, with a 95th percentile horizontal error of 1.6 m.
Article Citation: Wang, C.-W., & Jan, S.-S. (2025). Performance analysis of MADOCA-enhanced tightly coupled PPP/IMU. NAVIGATION, 72(1). https://doi.org/10.33012/navi.678
Video for “Analysis of IMU Rotation Effects on Inertial Navigation System Errors” By Saeid Mozafari, Hamed Mohammadkarimi, Mahsa Ghasemi, Mohammad Ali Parhizkar, and Mahdi Mobtaker (https://navi.ion.org/content/72/1/navi.680/tab-supplemental)
Abstract: This paper aims to provide navigation system designers with a detailed examination of the impact of inertial measurement unit (IMU) rotation on error reduction or induction in a rotary inertial navigation system (INS). The designer of a rotary INS can select the optimal rotation rate and direction by considering the dynamics of the carrier and the dominant errors based on the findings reported in three concise tables within this paper. This paper presents a comprehensive analytical derivation of error equations for the attitude, velocity, and position of a rotational INS, validated through numerical simulations. Experiments using a rotation platform and actual data from a micro-electromechanical system IMU sensor are also conducted to verify the effectiveness of mitigating errors through IMU rotation. Moreover, a tensor-based modeling technique is employed to facilitate exploring the impact of IMU rotation around an arbitrary axis on accumulated errors. This approach provides a modular platform for further research on rotational navigation systems.
Article Citation: Mohammadkarimi, H., Mozafari, S., Ghasemi, M., Parhizkar, M. A., & Mobtaker, M. (2025). Analysis of IMU rotation effects on inertial navigation system errors. NAVIGATION, 72(1). https://doi.org/10.33012/navi.680
Video for “A Pragmatic Approach to VDES Authentication”
By Gareth Wimpenny, Francisco Lázaro, Jan Šafář, and Ronald Raulefs (https://navi.ion.org/content/72/1/navi.681/tab-supplemental)
Abstract: The very-high-frequency data exchange system (VDES) is an emerging maritime radio communication system that will pave the road for novel e-navigation applications. A key problem in e-navigation is that of data authentication: determining that the data originate from a trusted party and have not undergone changes after transmission. This work considers the authentication requirements in VDES, while considering the constraints typical of the maritime environment, and analyzes several possible solutions. The proposed solution is two-tiered, with the default approach relying on digital signatures in low-traffic areas where available wireless capacity is sufficient. For areas under the control of a shore station for which available wireless capacity is low, we consider a low-overhead authentication scheme using the timed efficient stream loss-tolerant authentication (TESLA) protocol to authenticate all shore-to-ship traffic. TESLA is particularly attractive for future-proof quantum-safe cryptography, offering increased authentication data under the conditions of the low-data-rate VDES.
Article Citation: Wimpenny, G., Lázaro, F., Šafář, J., & Raulefs, R. (2025). A pragmatic approach to VDES authentication. NAVIGATION, 72(1). https://doi.org/10.33012/navi.681
Video for “Performance Analysis and Possible Design of an Optical System for Pulsar Navigation”
By Samuele Larese, Giampiero Naletto, Paolo Zoccarato, Gabriele Zeni, and Luca Zampieri (https://navi.ion.org/content/72/1/navi.682/tab-supplemental)
Abstract: The concept of observing pulsars for space autonomous navigation has already caught the attention of space agencies. Driven by the extremely stable nature of pulsar radiation, many research works and in-orbit demonstrations have been performed, demonstrating the suitability of these sources for navigation. The core concepts of the in-orbit demonstrated X-ray pulsar-based navigation systems and the recently proposed space navigation by optical pulsars (SNOP) systems are based on the capability to accurately define the arrival times of a pulsar signal. Therefore, the performance of a pulsar-based navigation system depends on the timing accuracy of the measured signals, which is a function of the characteristics of the navigation payload onboard the satellite. The aim of this paper is to investigate the impact of the optical parameters of a photometer-based instrument on the timing accuracy of a SNOP system; moreover, a first optical design for the payload is proposed.
Article Citation: Larese, S., Naletto, G., Zoccarato, P., Zeni, G., & Zampieri, L. (2025). Performance analysis and possible design of an optical system for pulsar navigation. NAVIGATION, 72(1). https://doi.org/10.33012/navi.682
Video for “A Robust Approach to Vision-Based Terrain-Aided Localization” By Dan Navon, Ehud Rivlin, and Hector Rotstein (https://navi.ion.org/content/72/1/navi.683/tab-supplemental)
Abstract: Terrain-aided navigation, which combines radar altitude with a digital terrain map (DTM), was developed before the era of the Global Positioning System to prevent error growth resulting from inertial navigation. Recently, cameras and substantial computational power have become ubiquitous in flying platforms, prompting interest in studying whether the radar altimeter can be replaced by a visual sensor. This paper presents a novel approach to vision-based terrain-aided localization by revisiting the correspondence and DTM (C-DTM) problem. We demonstrate that we can simplify the C-DTM problem by dividing it into a structure-from-motion (SFM) problem and then anchoring the solution to the terrain. The SFM problem can be solved using existing techniques such as feature detection, matching, and triangulation wrapped with a bundle adjustment algorithm. Anchoring is achieved by matching the point cloud to the terrain using ray-tracing and a variation of the iterative closest point method. One of the advantages of this two-step approach is that an innovative outlier filtering scheme can be included between the two stages to enhance overall robustness. The resulting algorithm consistently demonstrated high precision and statistical independence in the presence of initial errors across various simulations. The impact of different filtering methods was also studied, showing an improvement of 50% compared with the unfiltered case. The new algorithm has the potential to improve localization in real-world scenarios, making it a suitable candidate for pairing with an inertial navigation system and a Kalman filter to construct a comprehensive navigation system.
Article Citation: Navon, D., Rivlin, E., & Rotstein, H. (2025). A robust approach to vision-based terrain-aided localization. NAVIGATION, 72(1). https://doi.org/10.33012/navi.683
Video for “Fault Detection Algorithm for Gaussian Mixture Noises: An Application in Lidar/IMU Integrated Localization Systems”
By Penggao Yan, Zhengdao Li, Feng Huang, Weisong Wen, and Li-Ta Hsu (https://navi.ion.org/content/72/1/navi.684/tab-supplemental)
Abstract: Fault detection is crucial to ensure the reliability of localization systems. However, conventional fault detection methods usually assume that noises in the system have a Gaussian distribution, limiting their effectiveness in real-world applications. This study proposes a fault detection algorithm for an extended Kalman filter (EKF)-based localization system by modeling non-Gaussian noises as a Gaussian mixture model (GMM). The relationship between GMM-distributed noises and the measurement residual is rigorously established through error propagation, which is utilized to construct the test statistic for a chi-squared test. The proposed method is applied to an EKF-based two-dimensional light detection and ranging/inertial measurement unit integrated localization system. Experimental results in a simulated urban environment show that the proposed method exhibits a 30% improvement in the detection rate and a 17%–23% reduction in the detection delay, compared with the conventional method with Gaussian noise modeling.
Article Citation: Yan, P., Li, Z., Huang, F., Wen, W., and Hsu, L. -T. (2025). Fault detection algorithm for Gaussian mixture noises: An application in lidar/IMU integrated localization systems. NAVIGATION, 72(1). https://doi.org/10.33012/navi.684
Video for “Unveiling Starlink for PNT”
By Sharbel Kozhaya, Joe Saroufim, and Zaher (Zak) M. Kassas (https://navi.ion.org/content/72/1/navi.685/tab-supplemental)
Abstract: This paper provides a comprehensive theoretical and experimental description of how to exploit Starlink low Earth orbit (LEO) satellites for positioning, navigation, and timing (PNT). First, the paper reveals for the first time, the full Starlink orthogonal frequency division multiplexing (OFDM) beacon, which spans the whole time-frequency resource grid. This description of the beacon is achieved through blind beacon estimation, which shows that the Starlink sequences published in the literature only comprise 0.66% of Starlink’s full OFDM. Exploiting this full OFDM beacon is shown to increase the receiver’s process gain by nearly 18 dB compared to only using signals published in the literature. This process gain, in turn, unlocks higher effective SNR at the receiver’s correlator output, enabling reliable acquisition and tracking in low SNR regimes imposed by using low-gain antennas. Second, the paper studies and compares the maximum achievable received carrier-to-noise density ratio (C/N0) for different reception scenarios. Third, the paper shows the first experimental results of navigation observables extracted using OFDM signals transmitted by Starlink satellites, namely the carrier phase, Doppler shift, and code phase. The paper provides the most comprehensive Starlink signal collection from 2021 through 2024 and analyzes the quality of pilot-tone versus OFDM-based observables. Results show that step-like corrections sometimes contaminate all the OFDM-based navigation observables from Starlink satellites, rendering their raw integration a challenge for precise positioning. Fourth, the paper shows how corrections made to the OFDM carrier frequency offset (CFO) can be estimated on-the-fly with a good degree of fidelity within the tracking loop of the software-defined receiver. Unlike the CFO corrections, the estimation of code phase corrections is shown to be intractable, rendering pseudoranges from Starlink signals not suitable for reliable positioning. Moreover, the tracked OFDM carrier phase revealed excessive slips due to the employed communication scheme. Finally, the paper demonstrates the first positioning solution that uses OFDM-based Doppler shift exclusively. Four positioning frameworks are formulated and assessed: (i) pilot tone-based Doppler shift tracking that exhibits no sign of contamination from the OFDM-related corrections, (ii) OFDM-based Doppler shift with uncorrected CFOs, (iii) OFDM-based Doppler shift with corrected CFOs that are estimated on-the-fly, and (iv) OFDM-based Doppler shift with corrected CFOs that are estimated using the knowledge of an assumed cooperative base station. The unprecedented results from these analyses show that, with an average of only three active Starlink satellites, a positioning solution with a 3D position estimation error of two meters can be achieved in only 20 seconds.
Article Citation: Kozhaya, S., Saroufim, J., & Kassas, Z. M. (2025). Unveiling Starlink for PNT. NAVIGATION, 72(1). https://doi.org/10.33012/navi.685
Video for “Analysis of a High Accuracy Service Based on JPL’s Global Differential GPS”
By Nacer Naciri, Yoaz Bar-Sever, Willy Bertiger, Sunil Bisnath, Attila Komjathy, Mark Miller, Larry Romans, Bela Szilagyi, and Michele Vallisneri (https://navi.ion.org/content/72/1/navi.686/tab-supplemental)
Abstract: In the current global navigation satellite system (GNSS) context, with several constellations offering high accuracy services (HAS), we have evaluated a potential HAS for GPS based on JPL’s Global Differential GPS (GDGPS) system. This HAS also provides corrections for Galileo and GLONASS. In this paper, we specifically consider the scenario in which satellite corrections are delivered to users through the internet, similar to one style of access used for Galileo HAS. The GDGPS-based HAS described herein consists primarily of high-quality satellite orbit and clock corrections and currently excludes code and phase biases. Corrections are provided in two parallel variations: one stream supporting GPS and Galileo, and the other supporting GPS and GLONASS. Each variation is provided in two redundant instances for robustness, giving a total of four streams. Our results, including PPP solutions based on these products, attest to the quality of the corrections. PPP results show good performance, comparable to solutions generated based on real-time CNES products and better than solutions generated based on internet-based Galileo HAS products. For example, based on processing over 2,000 independent three-hour data sets, both the GDGPS-based HAS GPS+GAL streams and the CNES stream achieved post-convergence horizontal rms below 20 cm for 97% of data sets and below 10 cm for 80%. In contrast, only 86% of Galileo HAS-based solutions have post-convergence horizontal rms below 20 cm, and only 47% have rms below 10 cm. Overall, these results suggest a promising method of implementing a GDGPS-based HAS that might augment GPS, Galileo, and GLONASS.
Article Citation: Naciri, N., Bar-Sever, Y., Bertiger, W., Bisnath, S., Komjathy, A., Miller, M., Romans, L., Szilagyi, B., & Vallisneri, M. (2025). Analysis of a high accuracy service based on JPL’s global differential GPS. NAVIGATION, 72(1). https://doi.org/10.33012/navi.686
Video for “Adaptive Sea Clutter Suppression for Marine Radar Systems to Enhance Uncrewed Surface Vehicle Autonomy”
By Seongpil Cho, Jae Yong Lee, and Jungwook Han (https://navi.ion.org/content/72/1/navi.687/tab-supplemental)
Abstract: Marine radar is crucial for detecting objects near ships and ensuring safe navigation, and the performance of marine radar relies heavily on gain-tuning. However, the radar sensor lacks sufficient feature information to effectively distinguish desired objects from radar noise or clutter. Selecting an appropriate radar parameter based on environmental conditions is therefore crucial for generating a clutter-minimized radar image for navigation. In this paper, we propose an adaptive decision-making method to select an appropriate sensor parameter value. Through numerous field tests, we determined that the gain value requires frequent adjustment for uncrewed surface vehicle (USV) operation in real-sea environments. To streamline the process of finding the parameter for improved detection performance, we then present an automatic decision-making methodology that determines the appropriate sea clutter adjustment parameter based on the surrounding environmental conditions. We conclude by sharing field test results using this adaptive parameter estimation approach.
Article Citation: Cho, S., Lee, J. Y., & Han, J. (2025). Adaptive sea clutter suppression for marine radar systems to enhance uncrewed surface vehicle autonomy. NAVIGATION, 72(1). https://doi.org/10.33012/navi.687
Video for “Federated Learning of Jamming Classifiers: From Global to Personalized Models”
By Peng Wu, Helena Calatrava, Tales Imbiriba, and Pau Closas (https://navi.ion.org/content/72/1/navi.688/tab-supplemental)
Abstract: Jamming signals can jeopardize and ultimately prevent the effective operation of global navigation satellite system (GNSS) receivers. Given the ubiquity of these signals, jamming mitigation and localization techniques are of crucial importance, and these techniques can be enhanced with accurate jammer classification methods. Although data-driven models have proven useful for detecting jamming signals, training these models using crowdsourced data requires sharing private data and may therefore compromise user privacy. This article explores the use of federated learning to locally train jamming signal classifiers on each device, with model updates aggregated and averaged at a central server. This approach ensures user privacy during model training by removing the need for centralized data storage or access to clients’ local data. The personalized federated learning strategies employed in this study are also tested on non-independent and identically distributed data sets composed of spectrogram images from interfered GNSS signals. In addition, this article discusses the effect of model quantization, which is used to effectively reduce communication costs, as well as a fusion strategy for personalized federated learning schemes in which multiple classifiers are available.
Article Citation: Wu, P., Calatrava, H., Imbiriba, T., & Closas, P. (2025). Federated learning of jamming classifiers: From global to personalized models. NAVIGATION, 72(1). https://doi.org/10.33012/navi.688
Video for “Overbounding of Near Real-Time Estimated Ionospheric Gradient Slope in Low-Latitude Regions”
By Maria Caamano, Jose Miguel Juan, Jaume Sanz, and Sam Pullen (https://navi.ion.org/content/72/1/navi.689/tab-supplemental)
Abstract: This paper addresses the potential threats posed by large ionospheric gradients acting between ground-based augmentation system (GBAS) reference stations and aircraft during approach. Current GBAS stations rely on conservative threat models to mitigate ionospheric gradient threats, limiting system availability and continuity. To solve these issues, previous research has introduced a methodology for real-time detection and estimation of ionospheric gradients using a network of dual-frequency, multi-constellation global navigation satellite system monitoring stations. This paper proposes to expand this approach by including the derivation of an uncertainty model for the estimated gradient slope, allowing the threat model to be substituted with the near real-time estimated and overbounded gradient slope in current GBAS algorithms. Evaluations with simulated and real anomalous gradients produced by equatorial plasma bubbles demonstrate the efficacy of this methodology, indicating its potential to enhance GBASs by dynamically detecting, estimating, and overbounding the estimated anomalous gradients instead of relying solely on worst-case models, thus improving system availability and continuity.
Article Citation: Caamano, M., Juan, J. M., Sanz, J., & Pullen, S. (2025). Overbounding of near real-time estimated ionospheric gradient slope in low-latitude regions. NAVIGATION, 72(1). https://doi.org/10.33012/navi.689
WEBINARS
ION Webinars highlight timely and engaging articles published in NAVIGATION and other topics of interest to the PNT community in an interactive virtual presentation.
May 28, 2025 Webinar: A Robust Approach to Vision-Based Terrain-Aided Localization (https://www.ion.org/publications/webinar-navon.cfm)
By: Dan Navon
Abstract: Terrain-aided navigation, which combines radar altitude with a digital terrain map (DTM), was developed before the era of the Global Positioning System to prevent error growth resulting from inertial navigation. Recently, cameras and substantial computational power have become ubiquitous in flying platforms, prompting interest in studying whether the radar altimeter can be replaced by a visual sensor.
This paper presents a novel approach to vision-based terrain-aided localization by revisiting the correspondence and DTM (C-DTM) problem. We demonstrate that we can simplify the C-DTM problem by dividing it into a structure-from-motion (SFM) problem and then anchoring the solution to the terrain. The SFM problem can be solved using existing techniques such as feature detection, matching, and triangulation wrapped with a bundle adjustment algorithm. Anchoring is achieved by matching the point cloud to the terrain using ray-tracing and a variation of the iterative closest point method. One of the advantages of this two-step approach is that an innovative outlier filtering scheme can be included between the two stages to enhance overall robustness.
The resulting algorithm consistently demonstrated high precision and statistical independence in the presence of initial errors across various simulations. The impact of different filtering methods was also studied, showing an improvement of 50% compared with the unfiltered case.
The new algorithm has the potential to improve localization in real-world scenarios, making it a suitable candidate for pairing with an inertial navigation system and a Kalman filter to construct a comprehensive navigation system.
Article Citation: Navon, D., Rivlin, E., & Rotstein, H. (2025). A robust approach to vision-based terrain-aided localization. NAVIGATION, 72(1). https://doi.org/10.33012/navi.683
April 21, 2025 Webinar: Unveiling Starlink for PNT (https://www.ion.org/publications/webinar-kozhaya.cfm)
By: Sharbel Kozhaya
Abstract: This paper provides a comprehensive theoretical and experimental description of how to exploit Starlink low Earth orbit (LEO) satellites for positioning, navigation, and timing (PNT). First, the paper reveals for the first time, the full Starlink orthogonal frequency division multiplexing (OFDM) beacon, which spans the whole time-frequency resource grid. This description of the beacon is achieved through blind beacon estimation, which shows that the Starlink sequences published in the literature only comprise 0.66% of Starlink’s full OFDM. Exploiting this full OFDM beacon is shown to increase the receiver’s process gain by nearly 18 dB compared to only using signals published in the literature. This process gain, in turn, unlocks higher effective SNR at the receiver’s correlator output, enabling reliable acquisition and tracking in low SNR regimes imposed by using low-gain antennas. Second, the paper studies and compares the maximum achievable received carrier-to-noise density ratio (C/N0) for different reception scenarios. Third, the paper shows the first experimental results of navigation observables extracted using OFDM signals transmitted by Starlink satellites, namely the carrier phase, Doppler shift, and code phase. The paper provides the most comprehensive Starlink signal collection from 2021 through 2024 and analyzes the quality of pilot-tone versus OFDM-based observables. Results show that step-like corrections sometimes contaminate all the OFDM-based navigation observables from Starlink satellites, rendering their raw integration a challenge for precise positioning. Fourth, the paper shows how corrections made to the OFDM carrier frequency offset (CFO) can be estimated on-the-fly with a good degree of fidelity within the tracking loop of the software-defined receiver. Unlike the CFO corrections, the estimation of code phase corrections is shown to be intractable, rendering pseudoranges from Starlink signals not suitable for reliable positioning. Moreover, the tracked OFDM carrier phase revealed excessive slips due to the employed communication scheme. Finally, the paper demonstrates the first positioning solution that uses OFDM-based Doppler shift exclusively. Four positioning frameworks are formulated and assessed: (i) pilot tone-based Doppler shift tracking that exhibits no sign of contamination from the OFDM-related corrections, (ii) OFDM-based Doppler shift with uncorrected CFOs, (iii) OFDM-based Doppler shift with corrected CFOs that are estimated on-the-fly, and (iv) OFDM-based Doppler shift with corrected CFOs that are estimated using the knowledge of an assumed cooperative base station. The unprecedented results from these analyses show that, with an average of only three active Starlink satellites, a positioning solution with a 3D position estimation error of two meters can be achieved in only 20 seconds.
Article Citation: Kozhaya, S., Saroufim, J., & Kassas, Z. M. (2025). Unveiling Starlink for PNT. NAVIGATION, 72(1). https://doi.org/10.33012/navi.685
March 26, 2025 Webinar: Galileo High Accuracy Service: Tests in Different Operational Conditions (https://www.ion.org/publications/webinar-gioia.cfm)
By: Ciro Gioia
Abstract: With corrections transmitted through the E6 signal, the Galileo High Accuracy Service (HAS) provides the information necessary to execute a stand-alone precise point positioning algorithm in real time. Once fully operational, the service aims to deliver an accuracy of 20 cm and 40 cm (at the 95% confidence level) in the horizontal and vertical channels, respectively.
While most of the current literature focuses on analyzing the performance of HAS in static and open-sky signal reception scenarios, this study presents the results of tests conducted in both static and dynamic conditions, including open-sky and urban canyon scenarios. The tests clearly demonstrate that utilizing HAS corrections leads to a significant reduction in positioning error across all tested environments. Furthermore, a specific analysis of HAS message availability in a harsh environment indicates that the corrections obtained from the signal in space are available approximately 95% of the time during dynamic scenario tests.
Article Citation: Cucchi, L., Damy, S., Gioia, C., Motella, B., & Paonni, M. (2024). Galileo high accuracy service: Tests in different operational conditions. NAVIGATION, 71(4). https://doi.org/10.33012/navi.665
HOW TO CITE THIS ARTICLE
Langley, R. B. (2025). Navigator notes: Editorial highlights from the editor-in-chief. NAVIGATION, 72(2). https://doi.org/10.33012/navi.690
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
