Aspects of change detection in vibrational processes based on time-frequency transforms

The main goal of the work is to present some aspects in using time-frequency transforms, applied to the vibration signals and for change detection purposes, from signal processing point of view. The processed object is the time-frequency image (TFI), as result of the time-frequency transform. Two distributions are considered: Wigner-Ville and Choi-Williams, each with specific properties and matched to particular structures of the analyzed signals. The detection of the region of interest inside of TFI, and the estimation of relevant parameters of such regions, is considered as a problem of feature extraction and representation. The parameters, as the coordinates of the energy concentration area and the size of the region, are considered in the first stage. At the next stage, extensions of the parameters in the (t, f) plane is considered.