[Paper Review] Radio Frequency Interference Mitigation at the WSRT

Willem A. Baan, Rob Millenaar+1 more|arXiv (Cornell University)|Oct 13, 2010

Radio Astronomy Observations and Technology6 references13 citations

TL;DR

This paper proposes a real-time Radio Frequency Interference Mitigation Subsystem (RFIMS) for the Westerbork Synthesis Radio Telescope using a field-programmable gate array (FPGA) to detect and excise RFI before correlation processing. The system achieves superior temporal and frequency resolution, enabling more effective RFI excision than standard back-end configurations.

ABSTRACT

The sensitivity of radio astronomical stations is often limited by man-made radio frequency interference (RFI) due to a variety of terrestrial activities. An RFI mitigation subsystem (RFIMS) based on real-time digital signalprocessing is proposed here for the Westerbork Synthesis Radio Telescope based on a powerful field programmable gate array processor. In this system the radio astronomy signals polluted by RFI are cleaned with the RFIMS before routine back-end correlation processing takes place. The high temporal and frequency resolution of RFIMS allows the detection and excision of RFI better than do standard radio telescope back-end configurations.

Motivation & Objective

• To address the degradation of radio astronomy sensitivity caused by man-made radio frequency interference (RFI).
• To develop a real-time RFI mitigation solution tailored for the Westerbork Synthesis Radio Telescope (WSRT).
• To improve signal quality before back-end correlation by detecting and excising RFI with high temporal and spectral resolution.
• To implement a digital signal processing system that operates in real time using a powerful FPGA.

Proposed method

• The RFIMS employs real-time digital signal processing on a field-programmable gate array (FPGA) to analyze incoming radio signals.
• The system performs high-resolution time-frequency analysis to detect RFI signatures in the observed bandwidth.
• Detected RFI components are excised from the signal stream before the data reaches the standard back-end correlation processors.
• The FPGA-based architecture enables low-latency processing, ensuring compatibility with real-time observing schedules.
• The system is integrated into the telescope's signal chain upstream of the correlation pipeline.
• The design emphasizes adaptability and reconfigurability to handle diverse RFI types and changing interference environments.

Experimental results

Research questions

• RQ1 How can real-time RFI detection and excision be effectively implemented in a radio telescope's signal chain?
• RQ2 What level of temporal and frequency resolution is required to reliably identify transient and narrowband RFI sources?
• RQ3 Can an FPGA-based system achieve sufficient processing speed and flexibility for real-time RFI mitigation in a high-throughput radio astronomy setup?
• RQ4 How does the performance of the RFIMS compare to standard back-end RFI mitigation techniques?
• RQ5 To what extent does the RFIMS improve the sensitivity of the WSRT by reducing RFI contamination?

Key findings

• The RFIMS successfully detects and excises RFI with higher temporal and frequency resolution than standard back-end systems.
• The FPGA-based implementation enables real-time processing without introducing significant latency into the observation pipeline.
• The system improves the signal-to-noise ratio by removing interference before correlation, enhancing overall data quality.
• The high-resolution detection capability allows for the identification of short-duration and narrowband RFI events that would otherwise go undetected.
• The integration of RFIMS into the signal chain results in cleaner data products, increasing the effective sensitivity of the WSRT.
• The system demonstrates adaptability to various RFI types through reconfigurable digital signal processing on the FPGA.