Enabling High‐Fidelity Wave‐Particle Interaction Studies: A Novel Filtering for Isolating Whistlers From Spacecraft Noise

Abstract Resolving the mixture of natural plasma waves and persistent spacecraft interference is a fundamental challenge in space physics, as it obstructs the analysis of wave‐particle interactions and energy transport processes. Traditional signal decomposition methods often fail to adequately separate these components due to their time‐varying frequencies and overlapping spectra. We propose the instantaneous bandwidth Vold‐Kalman Filtering (IB‐VKF), which first defines the component‐specific bandwidth weighting functions , allowing for the independent and precise dynamic tracking of disparate signal features. We demonstrate the algorithm's geophysical utility using data from the CASSIOPE/Swarm‐Echo and CSES missions. The IB‐VKF successfully isolates persistent reaction wheel interference with suppression ratios exceeding 22 dB, and, more critically, separates transient whistler waves from background platform noise, achieving suppression ratios of 9.34 dB for the natural waves. By significantly enhancing the fidelity of space magnetic data, the IB‐VKF provides a powerful new tool for probing wave‐particle coupling and magnetospheric dynamics.