Spectral Kurtosis-Based RFI Mitigation for CHIME

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 sizes. We conclude that a spectral kurtosis-based implementation provides a scalable, high cadence RFI discriminator for compact multi-receiver arrays.