Nonlinear squeezing transform for weak signal detection

We introduce a novel algorithm, called nonlinear squeezing transform, to characterize the time-frequency pattern of nonstationary multi-component signals, especially for weak component detection. As a generally known, conventional time-frequency analysis (TFA) methods can characterize the time-frequency pattern of nonstationary signal. However, it is difficult to detect the weak component hidden in complex signals because the time-frequency information is influenced by the amplitude of the signal. Inspired by the calculation procedure of instantaneous frequency in the synchro-squeezing transform, nonlinear squeezing transform is presented, which is only relevant to the phase but is independent of the signal amplitude. The experiment on real signal shows that the method can effectively detect the weak component in complex signals, and the comparison study with some TFA methods also shows the advantages in weak signal detection.