Research on features of time-frequency of underwater target by underwater explosion

The experiment data of a underwater target subjected to underwater explosion was analyzed in time and frequency domain by means of short time Fourier transform and wavelet packet transform. By using these signals, the time-frequency distributions and the energy distributions of blasting frequency bands were obtained. The analyzed results from short time Fourier transform with fixed window function and single resolving power could only reflect how the signal energy varied with time approximately and results from wavelet packet transform had better features of time-frequency, which can obtain the shock wave signal, the afterflow signal and the second pressure pulse to analyze its energy and frequency component, and the respective influence of the signal in different period on the target could be assessed.