2025-02-12 ブラウン大学
＜関連情報＞
- https://www.brown.edu/news/2025-02-12/pinpointing-unwanted-signals
- https://www.cambridge.org/core/journals/publications-of-the-astronomical-society-of-australia/article/altitude-estimation-of-radio-frequency-interference-sources-via-interferometric-nearfield-corrections/FFBE40FB0C2AB27485F41AA90C7705FA
干渉ニアフィールド補正による無線周波数干渉源の高度推定 Altitude estimation of radio frequency interference sources via interferometric near-field corrections
Jade M. Ducharme and Jonathan C. Pober
Publications of the Astronomical Society of Australia Published:12 February 2025
DOI:https://doi.org/10.1017/pasa.2024.123
Abstract
Radio-frequency interference (RFI) presents a significant obstacle to current radio interferometry experiments aimed at the Epoch of Reionization. RFI contamination is often several orders of magnitude brighter than the astrophysical signals of interest, necessitating highly precise identification and flagging. Although existing RFI flagging tools have achieved some success, the pervasive nature of this contamination leads to the rejection of excessive data volumes. In this work, we present a way to estimate an RFI emitter’s altitude using near-field corrections. Being able to obtain the precise location of such an emitter could shift the strategy from merely flagging to subtracting or peeling the RFI, allowing us to preserve a higher fraction of usable data. We conduct a preliminary study using a two-minute observation from the Murchison-Widefield Array (MWA) in which an unknown object briefly crosses the field of view, reflecting RFI signals into the array. By applying near-field corrections that bring the object into focus, we are able to estimate its approximate altitude and speed to be 11.7km and 792 km/h, respectively. This allows us to confidently conclude that the object in question is in fact an airplane. We further validate our technique through the analysis of two additional RFI-containing MWA observations, where we are consistently able to identify airplanes as the source of the interference.
