The Institute of Navigation

Reminder: Join us on Monday, April 21 at 2 PM EDT for a complimentary webinar with Sharbel Kozhaya, Ph.D. candidate at The Ohio State University, as he discusses his research on "Unveiling Starlink for PNT." Register now at info.ion.org/webinar This paper can be downloaded for free on our open access website at https://lnkd.in/e2s-zSMD 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...

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. Read the full technical paper, "Analysis of a High Accuracy Service based on JPL’s Global Differential GPS," on our open access website: https://lnkd.in/easfRXua

📢 JNC 2025 Early Bird Deadline – May 2 JNC is the largest U.S. military Positioning, Navigation and Timing (PNT) conference of the year with joint service and government participation. The JNC’s DTS conference ID is N20150610734. The event will focus on technical advances in PNT with emphasis on joint development, testing, and support of resilient PNT systems, logistics and integration. From an operational perspective, the conference will focus on advances in military applications of GPS; critical strengths and weaknesses of field navigation devices; warfighter PNT requirements and solutions; and navigation warfare. Register now: info.ion.org/jnc

Congrats to my #wvurobotics graduate students for their full papers being accepted for presentation at IEEE/The Institute of Navigation Position, Location and Navigation Symposium (PLANS) taking place April 28- May 1 in Salt Lake City, UT. A Pointcloud Registration Framework for Relocalization in Subterranean Environments David Akhihiero and Jason Gross https://lnkd.in/ezyg3UFK Analysis of the Unscented Transform for Cooperative Localization with only Inter-vehicle Ranging Information Uthman Olawoye Cagri Kilic and Jason Gross https://lnkd.in/etqaEKr9 Experimental Analysis of Quadcopter Drone Hover Constraints for Localization Improvements Uthman Olawoye David Akhihiero and Jason Gross https://lnkd.in/eg22aKVA

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. Read the full paper, "Fault Detection Algorithm for Gaussian Mixture Noises: An Application in Lidar/IMU Integrated Localization Systems" on our open-access website: https://lnkd.in/eBwPSeFF

Join us for a complimentary webinar with Sharbel Kozhaya, Ph.D. candidate in the Department of Electrical and Computer Engineering at The Ohio State University. On Monday, April 21 at 2 PM EDT, we’ll explore "Unveiling Starlink for PNT", featured in the Spring 2025 issue of NAVIGATION. Kozhaya is a member of the Autonomous Systems Perception, Intelligence, and Navigation (ASPIN) Laboratory, with research interests in opportunistic navigation, low Earth orbit satellites, cognitive software-defined radio, and 5G. He is also the recipient of the 2023 IEEE/ION Position, Location, and Navigation Symposium (PLANS) Best Student Paper Award. Register now: info.ion.org/webinar

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. Read the full technical paper, "Performance Analysis of MADOCA-Enhanced Tightly Coupled PPP/IMU" on our open-access website: https://lnkd.in/eQv8Sj8i

This week, Dr. Ciro Gioia of the European Commission’s JRC presented his research, "Galileo High Accuracy Service: Tests in Different Operational Conditions," in one of ION's most highly attended webinars, with nearly 300 global viewers! Thank you, Dr. Gioia, for your excellent presentation and to our audience for the great participation! Watch the full recording on YouTube channel: https://lnkd.in/eaCYi5BN

The IEEE/ION PLANS 2025 Early Bird deadline is this Friday, March 28. Register now to save $200: info.ion.org/plans This biennial conference features researchers and engineers from around the world who will present their latest work in the field of PNT. The presentations range from fundamental research and applications to field test results, with a particular emphasis on inertial navigation. Technical sessions cover a range of subjects for both beginners and seasoned professionals. IEEE/ION PLANS 2025 Technical Tracks: ➡️Pre-conference Tutorials ➡️Track A: Inertial Sensing and Technology ➡️Track B: Global Navigation Satellite Systems (GNSS) ➡️Track C: Integrated and Opportunistic Navigation ➡️Track D: Applications of Localization Technologies

Reminder: Join us this Wednesday, March 26 for a complimentary webinar featuring, "Galileo High Accuracy Service: Tests in Different Operational Conditions." This webinar is based on a paper published in the Winter 2024 issue of NAVIGATION and will be presented by one of the paper's authors, Dr. Ciro Gioia - European Commission, Joint Research Centre. Register today: info.ion.org/webinar