Instantaneous frequency estimate for non-stationary signal

Instantaneous frequency (IF) estimate has important physical meaning for non-stationary signal. Traditional IF estimate methods were investigated, their features were compared and each technique had certain weaknesses. On the basis of these, the newly-emerged Hilbert-Huang transform (HHT) method was introduced. The theories and features of HHT were discussed. Its application in IF estimate was presented. It gives accurately the IF estimate for non-stationary signal. The better performance is illustrated by the simulated signal. The results indicate that this method provides an efficient tool for the IF estimation of non-stationary signal.