A FPGA-based Fast Converging Digital Adaptive Filter for Real-time RFI Mitigation on Ground Based Radio Telescopes

TL;DR

This paper presents a real-time FPGA-based digital adaptive filter capable of rapidly canceling diverse RFI signals in radio telescopes, significantly reducing data loss without prior assumptions about the signals.

Contribution

It introduces a novel FPGA implementation of a fast-converging adaptive filter for RFI mitigation in radio astronomy, capable of processing 4096 spectral channels in real-time.

Findings

Achieves convergence in approximately 125-208 microseconds.

Effectively cancels broad and narrowband RFI signals.

Minimizes data loss during interference mitigation.

Abstract

Radio Frequency Interference (RFI) is a growing concern in the radio astronomy community. Single-dish telescopes are particularly susceptible to RFI. Several methods have been developed to cope with RF-polluted environments, based on flagging, excision, and real-time blanking, among others. All these methods produce some degree of data loss or require assumptions to be made on the astronomical signal. We report the development of a real-time, digital adaptive filter implemented on a Field Programmable Gate Array (FPGA) capable of processing 4096 spectral channels in a 1 GHz of instantaneous bandwidth. The filter is able to cancel a broad range of interference signals and quickly adapt to changes on the RFI source, minimizing the data loss without any assumption on the astronomical or interfering signal properties. The speed of convergence (for a decrease to a 1%) was measured to be 208.1 us for a broadband noise-like RFI signal and 125.5 us for a multiple-carrier RFI signal recorded at the FAST radio telescope.