Time-frequency-based Non-Harmonic Analysis to Reduce Line-Noise Impact for LIGO Observation System

Gravitational waves (GWs) are the subjects of a new type of space observation that is expected to reveal new information on the early universe, neutron stars, and black holes. To reduce the impact of the widely used notch filter on GW observations, we propose the use of non-harmonic analysis (NHA) for the high-accuracy visualization of GWs. A simulated signal is used to compare the results obtained using short-time Fourier transform, Hilbert spectrum analysis, Hilbert–Huang transformation, and NHA. We demonstrate that NHA exhibits superior performance. In addition, we verify the analytical precision of NHA using actual data measured by the Laser Interferometer Gravitational-Wave Observatory (LIGO). We found that the high time–frequency resolution of NHA and the small influence that the analysis window has on this technique facilitate effective quantitative analysis, even for LIGO signals containing mixing noise. In addition, we achieve GW visualization up to the noise limit without using a notch filter.