IF Estimation of Multicomponent Nonstationary Signals Based on AFSST

The instantaneous frequency (IF) provides important characteristic information for analyzing signals. To improve the accuracy of IF estimation, time–frequency (TF) analysis with high resolution and high aggregation is necessary. A new IF estimation method is proposed in this paper, which is referred to as ridge path regrouping based on an adaptive short-time Fourier high-order synchrosqueezing transform (AFSST). In the TF analysis of the non-stationary signal, we optimize the window function of the short-time Fourier transform to be adaptive to signal characteristics, and then perform the high-order synchrosqueezing transform. Based on the high-resolution time–frequency distribution (TFD), the frequency ridge of the signal is extracted, and the ridge of the modal aliasing at the intersection is discarded and reorganized according to the fundamentals. Experiments on multicomponent nonstationary signals were performed, and the results show that AFSST has satisfactory TF aggregation and TF resolution. IF estimation experiment based on AFSST, the results indicate that the proposed method can estimate the IF accurately even under a low signal-to-noise ratio (SNR).