摘要：The separation of chaos and signal is an important problem of chaos signal processing. In recent years, the time-frequency analysis method is more and more mature. It can extract the time-domain character and frequency-domain character at the meantime. Time-frequency method can mainly carry out the problem of extraction from continuous chaos system background; achieve separation between chaos and signal according to different time-frequency character of chaos signal, noise signal and harmonic signal. So it can get useful signal from chaotic background. This paper first introduced the basic theory of time-frequency methods. Use the wavelet method and empirical mode decomposition method to analyze the extraction performance of harmonic signal from chaos background according to the different noise situation. After compare the wavelet method and empirical mode decomposition method, we summarize a new complementary synthesis method of harmonic signal extraction combine the wavelet threshold and empirical mode decomposition according to the experiments and simulation. Computer simulation verified that the methods have high availability.
