Robust distributed calibration of radio interferometers with direction dependent distortions

TL;DR

This paper introduces a robust, distributed multi-frequency calibration algorithm for radio interferometers that effectively estimates receiver gains and ionospheric distortions, outperforming traditional methods especially in the presence of data outliers.

Contribution

It presents a novel iterative robust calibration method using consensus optimization, specifically designed for multi-frequency radio interferometry with direction-dependent distortions.

Findings

Outperforms conventional non-robust calibration methods

Effective in the presence of outliers and direction-dependent distortions

Enhances calibration accuracy for next-generation radio telescopes

Abstract

In radio astronomy, accurate calibration is of crucial importance for the new generation of radio interferometers. More specifically, because of the potential presence of outliers which affect the measured data, robustness needs to be ensured. On the other hand, calibration is improved by taking advantage of these new instruments and exploiting the known structure of parameters of interest across frequency. Therefore, we propose in this paper an iterative robust multi-frequency calibration algorithm based on a distributed and consensus optimization scheme which aims to estimate the complex gains of the receivers and the directional perturbations caused by the ionosphere. Numerical simulations reveal that the proposed distributed calibration technique outperforms the conventional non-robust algorithm and per-channel calibration.