Increasing Pulsar SNR by Using Spectral Kurtosis as a Radio Frequency Mitigation Technique

We apply the Spectral Kurtosis (SK) estimator as a radio frequency interference (RFI) mitigation technique. The technique is applied to MeerKAT pulsar data whilst operated in beamformer mode. According to the central limit theorem, the unique probability distributions of all radio sources in the sky would add to a Gaussian distribution. The SK estimate of a Gaussian signal is 1. Therefore, any signal that deviates from 1, above or below a specific threshold, can be accounted for as RFI and eliminated. This forms the basis of the SK RFI mitigation technique. However, care should be taken when the astronomical signal contains non-Gaussian components, which is the case for pulsar astronomy. Initially, the statistics and methodology of the estimator are investigated. Afterward, we look at the effects of data clipping, RFI duty cycle, and SNR on the SK estimator. We provide details on the implementation and how to obtain the thresholds used for RFI mitigation. Signal-to-noise ratio (SNR) optimization studies are conducted for two pulsars, J0835-4510 and J0437-4715, where a 116% and 125% improvement in SNR is obtained, respectively.