Robust calibration of radio interferometers in multi-frequency scenario

V Ollier (1, 2) , M. N. El Korso (3) , A Ferrari (4) , Remy Boyer (2, 5) , Pascal Larzabal (1)

1 SATIE - Systèmes et Applications des Technologies de l'Information et de l'Energie
2 L2S - Laboratoire des signaux et systèmes
3 LEME - Laboratoire Energétique Mécanique Electromagnétisme
4 OCA - Observatoire de la Côte d'Azur
5 CRIStAL - Centre de Recherche en Informatique, Signal et Automatique de Lille - UMR 9189

This paper investigates calibration of sensor arrays in the radio astronomy context. Current and future radio telescopes require com-putationally efficient algorithms to overcome the new technical challenges as large collecting area, wide field of view and huge data volume. Specifically, we study the calibration of radio interferometry stations with significant direction dependent distortions. We propose an iterative robust calibration algorithm based on a relaxed maximum likelihood estimator for a specific context: i) observations are affected by the presence of outliers and ii) parameters of interest have a specific structure depending on frequency. Variation of parameters across frequency is addressed through a distributed procedure, which is consistent with the new radio synthesis arrays where the full observing bandwidth is divided into multiple frequency channels. Numerical simulations reveal that the proposed robust distributed calibration estimator outperforms the conventional non-robust algorithm and/or the mono-frequency case.

Keywords: Robust calibration; direction dependent distortions regime; consensus; distributed optimization

Domains: Signal and Image processing; Astrophysics [astro-ph]

V Ollier, M. N. El Korso, A Ferrari, Remy Boyer, Pascal Larzabal. Robust calibration of radio interferometers in multi-frequency scenario. 2018 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), Apr 2018, Calgary, Canada. ⟨10.1109/icassp.2018.8461382⟩. ⟨hal-01851033⟩