A new approach of recognizing the propeller blade numbers based on harmonic distortions

The rotation speed as well as the propeller blade numbers of marine ships are frequently used in underwater targets recognition. Based on the harmonic distortions, a new approach was presented in this paper to get the right number of the blades when the background noise is strong of the DEMON spectrum. The results find that, the recognizing approach given by this paper has a good correspondence with the real recording marine ship samples. And the sampling time suggested to be more than 30s in getting the DEMON spectrum of the recording samples investigated by this paper.