arXiv subjects

Federico Di Vruno

Publications and source records attributed to Federico Di Vruno.

6 recordsLinked to original sources

arXiv2026

A measurement-based approach to EPFD calculation, to quantify the impact of satellite mega-constellations on low-frequency radio astronomy

Context: Satellite mega-constellations generate Unintended Electro-Magnetic Radiation (UEMR) impacting low frequency radio astronomy. The Radio Regulations of the International Telecommunications Union Radiocommunication Sector (ITU-R) contain the basis for addressing UEMR, but enforcement mechanisms are absent. Aims: To adapt compatibility study methods based on satellite constellation simulations, in particular the Equivalent Power Flux-Density (EPFD) framework, to radio telescope measurements. Methods: We adapt the ITU-R EPFD calculation framework to measurement data obtained from all-sky interferometric imaging. We address the conceptual differences between forward-model EPFD calculations and measurement-based approaches. In particular, we consider low frequency systems, which are typically wide field-of-view and interferometric instruments. Results: For the first time, we demonstrate that all-sky interferometric observations enable a direct adaptation of the EPFD formalism to measurement data. We thus confirm previous estimations (Di Vruno et al. 2023) that the resulting measurement-based EPFD distributions exceed the radio astronomy interference threshold levels defined in Recommendation ITU-R RA.769-2 in 50-70% of samples. These exceedance fractions are well above the 2% single-system data-loss criterion in Recommendation ITU-R RA.1513-2. Expressed using the conventional 2% compatibility margin, the corresponding margins are negative, ranging from -18.6 to -16.3 dB, equivalent to a required uniform attenuation of 16.3-18.6 dB. Conclusions: Measurement-based implementations provide a practical pathway toward verification and long-term monitoring at low radio frequencies, which could form an important component of enforceability. We suggest instrumentation approaches to support measurement.

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arXiv2026

Towards Genuine Coexistence: Per-Satellite Emission and Radiation Limits to Protect Radio Astronomy and Geodetic VLBI at 1-14 GHz from Satellite Constellations

Geodetic very long baseline interferometry (VLBI) is a vulnerable application of the radio astronomy service (RAS): it provides the fundamental link between the celestial and terrestrial reference frames, and is the only technique that uniquely determines UT1-UTC. The next-generation geodetic VLBI Global Observing System (VGOS) achieves millimetre accuracy by synthesising group delay across 3-14 GHz using 32x32 MHz channels, most of which lie outside RAS primary allocations. The SNIFFLES-I survey (Indermuehle et al 2026) measured intended emissions, unwanted emissions (spurious emissions, notably harmonics), and unintended electromagnetic radiation (UEMR) of NGSO systems from 1-26 GHz. On this basis we model the equivalent power flux density (EPFD) of current and future constellations and compare against protection criteria of ITU-R RA.769. The analysis extends to frequencies without radio astronomy allocations where SNIFFLES-I made detections. For geodetic VLBI, we run a Monte-Carlo EPFD model at the AuScope VGOS stations and scale the aggregate from the present catalogued fleet (~12000 satellites) to the hundreds of thousands on file with a validated method. Inverting the EPFD analysis against the interpolated RA.769 thresholds yields maximum tolerable per-satellite levels for spurious emissions and for UEMR, expressed as a field-strength limit in dB(uV/m) at 10 m for standard-setting bodies. We treat proposed orbital-data-centres in Sun-synchronous orbit as a distinctively UEMR-dominated case. We find that already today the single-dish protection criteria are exceeded in two primary RAS bands. For geodetic VLBI, the dominant threat is spurious emission from the 2620 MHz Direct-to-device (DTD) downlink, whose second harmonic at 5240 MHz already causes at least 59% data loss today. (Abstract modified for arxiv limits)

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arXiv2025

Modelling steerable beams of satellite constellations for radio astronomy impact studies

Modelling is essential for studies that quantify the impact from satellite downlinks on radio astronomy sites. To estimate this impact it is necessary to know not only the position and velocity of satellites but also their behaviour in the radio spectrum domain. As many large satellite constellations are using steerable beam antennas, deterministically predicting the transmitted power towards a defined direction (in this case where a radio telescope points) becomes an almost impossible task and therefore another approach has to be used. This work presents a method to simulate and estimate the percentiles of the radiation pattern of satellites with steerable beam patterns based on simulations and a comparison with measurements of Starlink satellites using the Onsala Twin Telescopes in Sweden.

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arXiv2025

Call to Protect the Dark and Quiet Sky from Harmful Interference by Satellite Constellations

The growing number of satellite constellations in low Earth orbit (LEO) enhances global communications and Earth observation, and support of space commerce is a high priority of many governments. At the same time, the proliferation of satellites in LEO has negative effects on astronomical observations and research, and the preservation of the dark and quiet sky. These satellite constellations reflect sunlight onto optical telescopes, and their radio emission impacts radio observatories, jeopardising our access to essential scientific discoveries through astronomy. The changing visual appearance of the sky also impacts our cultural heritage and environment. Both ground-based observatories and space-based telescopes in LEO are affected, and there are no places on Earth that can escape the effects of satellite constellations given their global nature. The minimally disturbed dark and radio-quiet sky is crucial for conducting fundamental research in astronomy and important public services such as planetary defence, technology development, and high-precision geolocation. Some aspects of satellite deployment and operation are regulated by States and intergovernmental organisations. While regulatory agencies in some States have started to require operators to coordinate with their national astronomy agencies over impacts, mitigation of the impact of space objects on astronomical activities is not sufficiently regulated. To address this issue, the CPS urges States and the international community to take steps to protect the dark and quiet sky as specified in this paper.

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arXiv2023

Preserving your skies since 1988 -- Committee on Radio Astronomy Frequencies (CRAF) -- Periodic Review 2011-2021

The Committee on Radio Astronomy Frequencies (CRAF) is an Expert Committee of the European Science Foundation. It aims to provide a cost-effective single voice on frequency protection issues for European radio astronomy observatories and research institutes, achieving a significantly greater impact than that achievable by individual national institutions. By working together, European observatories and institutes can profit from synergy effects, cover many more topics, and learn from each other. CRAF was founded in 1988 and has since then been engaged with the International Telecommunication Union (ITU), in particular its Radiocommunication Sector (ITU-R), and the European Conference of Postal and Telecommunications Administrations (CEPT) and its European Communications Committee (ECC). This is the self-evaluation report prepared by CRAF for its periodic review of the years 2011-2021.

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arXiv2023

Large Satellite Constellations and Their Potential Impact on VGOS Operations

Large LEO satellite constellations (or so-called Mega-constellations) will significantly change the view of the sky in some radio frequency bands. For VGOS telescopes it is important to understand the potential impact these constellations will have in their operations, what is the risk of its receivers going into non-linear behaviour and how much additional power would a telescope receive if observing in the same frequencies where satellites are transmitting. This work describes three of these new constellations (as they would look fully deployed) and summarizes the results of a particular study considering two VGOS telescopes (Onsala and Wettzell).

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