Nonstationary signals analysis by Teager-Huang Transform (THT)

In this paper a new method called Teager-Huang Transform (THT) for analysis of nonstationary signals is introduced. The THT estimates the Instantaneous frequency (IF) and the Instantaneous amplitude (IA) of a signal. The method is based on the Empirical mode decomposition (EMD) algorithm of Huang et al. [1] and the Teager energy operator (TEO) [2]. Both EMD and TEO deal with non-stationary signals [1],[3]. The signal is first band pass filtered using the EMD into zero-mean AM-FM components called Intrinsic mode functions (IMFs) with well defined IF. Then TEO tracks the modulation energy of each IMF and estimates the corresponding IF and IA. The final presentation of the IF and the IA results is an energy Time frequency representation (TFR) of the signal. Based on the EMD, the THT is flexible enough to analyze any data (linear or nonlinear) and stationary or nonstationary signals. Furthermore, the THT is free of interferences. To show the effectiveness of the THT, TFRs of five synthetic signals are presented and results compared to those of the Hilbert-Huang transform (HHT) [1], the spectrogram, the Smoothed pseudo Wigner-Ville distribution (SPWVD), the scalogram and the Choi-Williams distribution (CWD).