Spectral Kurtosis Based RFI Mitigation for CHIME

TL;DR

This paper introduces a spectral kurtosis-based RFI detection system for the CHIME instrument and its pathfinder, demonstrating improved interference detection in compact multi-receiver arrays through on-sky data and simulations.

Contribution

It extends spectral kurtosis RFI detection to compact arrays by combining samples from multiple receivers, enhancing detection confidence and scalability.

Findings

Spectral kurtosis properties are unchanged by cross-array integration.

The implementation effectively discriminates RFI in compact arrays.

The system is scalable for high-cadence RFI detection.

Abstract

We present the implementation of a spectral kurtosis based Radio Frequency Interference detection system on the CHIME instrument and its reduced-scale pathfinder. Our implementation extends single-receiver formulations to the case of a compact array, combining samples from multiple receivers to improve the confidence with which RFI is detected. Through comparison between on-sky data and simulations, we show that the statistical properties of the canonical spectral kurtosis estimator are functionally unchanged by cross-array integration. Moreover, by comparison of simultaneous data from CHIME and the Pathfinder, we evaluate our implementation's capacity for interference discrimination for compact arrays of various size. We conclude that a spectral kurtosis based implementation provides a scalable, high cadence RFI discriminator for compact multi-receiver arrays.