Energy and polarization based on-line interference mitigation in radio interferometry

TL;DR

This paper introduces a real-time, energy and polarization-based RFI mitigation method for radio interferometry, optimized for GPU implementation, to improve detection of transient interference in radio astronomy data.

Contribution

It presents a novel online RFI mitigation scheme combining energy and polarization statistics, optimized for real-time processing in modern radio interferometers.

Findings

Effective RFI suppression demonstrated on real data

Suitable for GPU acceleration and real-time deployment

Improves detection of low duty-cycle and transient RFI

Abstract

Radio frequency interference (RFI) is a persistent contaminant in terrestrial radio astronomy. While new radio interferometers are becoming operational, novel sources of RFI are also emerging. In order to strengthen the mitigation of RFI in modern radio interferometers, we propose an on-line RFI mitigation scheme that can be run in the correlator of such interferometers. We combine statistics based on the energy as well as the polarization alignment of the correlated signal to develop an on-line RFI mitigation scheme that can be applied to a data stream produced by the correlator in real-time, especially targeted at low duty-cycle or transient RFI detection. In order to improve the computational efficiency, we explore the use of both single precision and half precision floating point operations in implementing the RFI mitigation algorithm. This ideally suits its deployment in accelerator computing devices such as graphics processing units (GPUs) as used by the LOFAR correlator. We provide results based on real data to demonstrate the efficacy of the proposed method.