Coherent Line Removal: Filtering out harmonically related line interference from experimental data, with application to gravitational wave detectors

TL;DR

This paper introduces a new technique for removing harmonic interference from gravitational wave data, improving detector sensitivity by reducing non-Gaussian noise and cleaning the spectrum.

Contribution

The paper presents a novel method for filtering out coherent harmonic interference in gravitational wave data, effective even with frequency variations.

Findings

Successfully removed wide lines from the Glasgow interferometer data

Reduced non-Gaussian noise, enhancing detector sensitivity

Improved the quality of the gravitational wave spectrum

Abstract

We describe a new technique for removing troublesome interference from external coherent signals present in the gravitational wave spectrum. The method works when the interference is present in many harmonics, as long as they remain coherent with one another. The method can remove interference even when the frequency changes. We apply the method to the data produced by the Glasgow laser interferometer in 1996 and the entire series of wide lines corresponding to the electricity supply frequency and its harmonics are removed, leaving the spectrum clean enough to detect possible signals previously masked by them. We also study the effects of the line removal on the statistics of the noise in the time domain. We find that this technique seems to reduce the level of non-Gaussian noise present in the interferometer and therefore, it can raise the sensitivity and duty cycle of the detectors.