Abstract
In recent years, the rapid development of marine science has put forward higher and higher requirements for the processing of ship-radiated noise signal. Ship-radiated noise is the noise signal generated by the vibration of various mechanical equipment or the movement of the hull and radiated into the sea when the ship is traveling. Ship-radiated noise signal contains a large number of time-varying, nonlinear and non-stationary components. The denoising processing of ship-radiated noise is the most critical part of underwater acoustic signal processing. In order to more effective reduce the noise of the ship-radiated noise signal, a new denoising method for underwater acoustic signal based on mutual information variational mode decomposition (MIVMD), multivariate multiscale dispersion entropy (mvMDE), and lift wavelet threshold (LWTD) and Savitzky Golay filter (S-G filter), named MIVMD-mvMDE-LWTD-SG, is proposed. Firstly, MIVMD is used to decompose the original signal into $n$ sub-signals. Secondly, the mvMDE value of each sub-signal is calculated, and the $n$ sub-signals are divided into high-frequency components and low-frequency components according to the threshold. Then, S-G filter and LWTD method are used to reduce the noise of low-frequency components and high-frequency components respectively. Finally, the low-frequency components and high-frequency components after the denoising processing are reconstructed to obtain the denoising signal. In order to verify the effectiveness of the proposed method, the proposed method is used to reduce the noise of chaotic signal under different signal-to-noise ratios (SNR), and compared with the EMD-mvMDE-LWTD and MIVMD-mvMDE-LWTD method. The results show that the proposed method can effective remove the noise in the chaotic signal, better distinguish the adjacent trajectories in the phase space, approximate the real chaotic attractor trajectory, and better retain the useful information in the chaotic signal. The proposed method is further applied to the actual ship-radiated noise signal, and the experimental analysis shows its effectiveness, which lays a solid foundation for further prediction and detection.
Highlights
With the rapid development of marine technology, the processing of underwater acoustic signal has become more and more important
In order to reduce the noise of ship-radiated noise more effectively, this paper proposes a new denoising method for underwater acoustic signal based on mutual information variational mode decomposition (MIVMD), multivariate multiscale dispersion entropy (mvMDE), lift wavelet threshold (LWTD) and S-G filter, named MIVMD-mvMDE-LWTDSG
In order to show the effect of noise reduction intuitively, the waveform comparison diagram before and after noise reduction using empirical mode decomposition (EMD)-mvMDE-LWTD, MIVMD-mvMDELWTD and the proposed method are given
Summary
With the rapid development of marine technology, the processing of underwater acoustic signal has become more and more important. According to the characteristics of different sub-signals, we adopt different methods to reduce the noise of highfrequency and low-frequency components respectively. In order to reduce the noise of ship-radiated noise more effectively, this paper proposes a new denoising method for underwater acoustic signal based on MIVMD, mvMDE, LWTD and S-G filter, named MIVMD-mvMDE-LWTDSG. Step 3: Use the S-G filtering method for low-frequency components to reduce noise, and use the lifting wavelet soft threshold method for high-frequency components to reduce noise. Step 4: Reconstruct the low-frequency and highfrequency components after the noise reduction process to obtain the final noise reduction signal. When the maximum Lyapunov exponent is negative, it indicates that the system is in a stable state
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