Feature extraction of ship-radiated noise using higher-order spectrum

The features of the ship noises are analyzed by using the higher-order spectrum (HOS) after studying their distribution. The results show that the different ship noise has different ranges of the main frequency. The main frequencies of the first class ships are less than 120 Hz, while the second class ships drop in 130 Hz - 320 Hz. The different relationship between (omega1) and(omega2) corresponds to different bispectrum graph. There are the same results in the trispectrum. The feature vector is consist of the (omega1s) which correspond to the maximum bispectrum B(omega1,omega1) and the maximum trispectrum B(omega1,omega1,omega1) respectively, the (omega1,omega2) which correspond to the maximum bispectrum B (omega1,omega2).