Application of the improved generalized demodulation time–frequency analysis method to multi-component signal decomposition

The generalized demodulation time–frequency analysis approach is a novel signal processing method, which is suitable for processing non-stationary signals, especially for processing amplitude-modulated and frequency-modulated (AM–FM) signals. The novelty of this method is that the signal whose time–frequency distributions are curved paths can be transformed into that whose time–frequency distributions are linear paths paralleling time axis by using generalized demodulation. Furthermore, the generalized demodulated signal can be decomposed into a number of mono-component signals whose instantaneous frequencies have physical meaning through the use of the maximal overlap discrete wavelet packet transform (MODWPT). Therefore, the complete time–frequency distributions of the original signal can be obtained. However, the generalized demodulation time–frequency analysis method fails to provide the time domain waveform of each mono-component signal. In this paper, aiming at the multi-component AM–FM signal, each mono-component signal of which only has single-sided spectra, the improvement to the generalized demodulation time–frequency analysis approach has been made and the improved method is introduced into certain multi-component AM–FM signal decomposition. The analysis results demonstrate that the validity of the proposed approach. In addition, the estimation of the phase function that is key step in the generalized demodulation time–frequency analysis approach is also discussed.