High-concentration time-frequency analysis for multi-component nonstationary signals based on combined multi-window Gabor transform

Purpose This study aims to reveal the essential characteristics of nonstationary signals and explore the high-concentration representation in the joint time-frequency (TF) plane. Design/methodology/approach In this paper, the authors consider the effective TF analysis for nonstationary signals consisting of multiple components. Findings To make it, the authors propose the combined multi-window Gabor transform (CMGT) under the scheme of multi-window Gabor transform by introducing the combination operator. The authors establish the completeness utilizing the discrete piecewise Zak transform and provide the perfect-reconstruction conditions with respect to combined TF coefficients. The high-concentration is achieved by optimization. The authors establish the optimization function with considerations of TF concentration and computational complexity. Based on Bergman formulation, the iteration process is further analyzed to obtain the optimal solution. Originality/value With numerical experiments, it is verified that the proposed CMGT performs better in TF analysis for multi-component nonstationary signals.