arXiv subjects

Argyris Kriezis

Publications and source records attributed to Argyris Kriezis.

4 recordsLinked to original sources

arXiv2026

Xona Pulsar Compatibility with Spaceborne GNSS Receivers

Low Earth Orbit (LEO) Positioning, Navigation, and Timing (PNT) systems operating in L-band Radionavigation-Satellite Service (RNSS) spectrum are rapidly emerging through both commercial and governmental initiatives. These systems are intended to complement traditional Medium Earth Orbit (MEO) constellations, such as GPS and Galileo, by providing improved satellite geometry, higher received signal power, and greater orbital diversity. As with any new RNSS deployment, ensuring compatibility with existing systems is essential to prevent harmful interference and preserve established services. While compatibility assessments for terrestrial GNSS receivers have been studied extensively, compatibility with spaceborne receivers has received comparatively little attention due to the large separation distances between MEO GNSS constellations and most spacecraft. In contrast, LEO PNT systems operate in close proximity to other satellites in LEO, making spaceborne receiver compatibility an important consideration. This paper extends the established ITU-R compatibility assessment methodology, originally developed for terrestrial receivers, to spaceborne GNSS users. The analysis evaluates the factors affecting carrier-to-noise ratio (C/N0) degradation of legacy GNSS signals in orbital environments. Results show that, although spaceborne receivers may experience higher received power levels from nearby LEO PNT satellites, such as Xona's Pulsar constellation, they can operate compatibly alongside legacy RNSS.

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arXiv2026

GNSS Jamming and Spoofing Monitoring Using Low-Cost COTS Receivers

The Global Navigation Satellite System (GNSS) is increasingly vulnerable to radio frequency interference (RFI), including jamming and spoofing, which threaten the integrity of navigation and timing services. This paper presents a methodology for detecting and classifying RFI events using low-cost commercial off-the-shelf (COTS) GNSS receivers. By combining carrier-to-noise ratio (C/N0) measurements with a calibrated received power metric, a two-dimensional detection space is constructed to identify and distinguish nominal, jammed, spoofed, and blocked signal conditions. The method is validated through both controlled jamming tests in Norway and real-world deployments in Poland, and the Southeast Mediterranean which have experienced such conditions. Results demonstrate that COTS-based detection, when properly calibrated, offers a viable and effective approach for GNSS RFI monitoring.

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arXiv2026

Chasing Lightning: Detecting, Characterizing, and Identifying a Powerful Space-Based GNSS Interference Source

This paper analyzes and identifies a space-based Global Navigation Satellite System (GNSS) interference source that has caused scores of powerful transient wide-area interference events over continental Europe, Greenland, and Canada since 2019. While terrestrial or near-terrestrial sources are primarily responsible for the recent uptick in GNSS interference worldwide, space-based interferers are of special concern given their potential for vast geographic reach and their portent of a qualitative escalation in GNSS interference. Based on data collected between 2019 and 2026 from a network of terrestrial GNSS reference stations, this paper (1) develops a received-power-based detection framework; (2) details the spatial, temporal, and spectral patterns of wide-area interference events caused by the source; (3) presents and analyzes identification techniques that blend received-power and time-difference-of-arrival measurements; and (4) applies these techniques to confidently identify the GNSS interference source as a constellation of Russian early warning satellites in Molniya ("lightning") orbits.

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arXiv2026

Xona Pulsar Compatibility with GNSS

At least ten emerging providers are developing satellite navigation systems for low Earth orbit (LEO). Compatibility with existing GNSS in L-band is critical to their successful deployment and for the larger ecosystem. Xona is deploying Pulsar, a near 260-satellite LEO constellation offering dual L-band navigation services near L1 and L5. Designed for interoperability, Pulsar provides centimeter-level accuracy, resilience, and authentication, while maintaining a format that existing GNSS receivers can support through a firmware update. This study examines Pulsar's compatibility with GPS and Galileo by evaluating C/N0 degradation caused by the introduction of its X1 and X5 signals. Using spectrally compact QPSK modulation, Pulsar minimizes interference despite higher signal power. Theoretical analysis is supported by hardware testing across a range of commercial GNSS receivers in both lab-based simulation and in-orbit live-sky conditions. The study confirms Pulsar causes no adverse interference effects to existing GNSS, supporting coexistence and integration within the global PNT ecosystem.

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