Denoise for propeller acoustic signals based on the improved wavelet thresholding algorithm of CEEMDAN

Figures & data

Figure 1. Plot of the hard and soft threshold and the improvement threshold.

Figure 2. Flow chart of the noise reduction algorithm.

Figure 3. Model configuration. (a) Computing domain and (b) cavitation numerical results.

Figure 4. Simulation signal time-domain diagram.

Figure 5. EMD-CWT noise reduction diagram.

Figure 6. EMD-BWT noise reduction diagram.

Figure 7. CEEMDAN-BWT noise reduction diagram.

Table 1. SNR and RMSE of the different noise reduction algorithms.

Algorithm	EMD-CWT	EMD-BWT	CEEMDAN-BWT
SNR(dB)	11.7874	12.4146	14.2200
RMSE	0.3645	0.3020	0.2752

Figure 8. Time domain diagram of different rotational speeds.

Figure 9. Spiral noise signal.

Figure 10. EMD-CWT of noise reduction effect diagram.

Figure 11. EMD-BWT of noise reduction effect diagram.

Figure 12. CEEMDAN-BWT of noise reduction effect diagram.

Figure 13. IMF component plot.