RFI mitigation with phase-only adaptive beamforming

TL;DR

This paper proposes a phase-only adaptive beamforming method using evolutionary algorithms to mitigate radio frequency interference in radio interferometers operating in tied-array mode, effectively suppressing RFI while preserving the source signal.

Contribution

It introduces a novel RFI mitigation technique employing phase-only adaptive beamforming optimized by evolutionary programming for radio interferometers.

Findings

Significant RFI suppression demonstrated in simulations

Main array beam remains stable in source direction

Method effective for both 1D and 2D array configurations

Abstract

Connected radio interferometers are sometimes used in the tied-array mode: signals from antenna elements are coherently added and the sum signal applied to a VLBI backend or pulsar processing machine. Usually there is no computer-controlled amplitude weighting in the existing radio interferometer facilities. Radio frequency interference (RFI) mitigation with phase-only adaptive beamforming is proposed for this mode of observation. Small phase perturbations are introduced in each of the antenna's signal. The values of these perturbations are optimized in such a way that the signal from a radio source of interest is preserved and RFI signals suppressed. An evolutionary programming algorithm is used for this task. Computer simulations, made for both one-dimensional and two-dimensional array set-ups, show considerable suppression of RFI and acceptable changes to the main array beam in the radio source direction.