Whistler analysis in the time‐frequency plane using chirplets

Abstract

This paper shows the benefits of using chirplet analysis of multipath magnetospheric whistlers. Higher resolution can be achieved than with the customary dynamic spectra (Gabor diagram), in which the cells characterizing resolution in time and frequency are the same over the whole diagram. Here we not only allow the aspect ratio of a resolution cell to vary within the one diagram but also introduce oblique cells corresponding to a new kind of elementary signal not discovered by Gabor. Chirplet analysis is also applicable to arbitrary signals and is most striking where certain kinds of finely detailed structure are present. We also describe a user interactive system that allows regions of interest to be selected in the time‐frequency plane and enhanced by selecting chirplets appropriate to the local structure.