A Combined Denoising Method for Microseismic Signals from Coal Seam Hydraulic Fracturing: Multithreshold Wavelet Packet Transform and Improved Hilbert-Huang Transform

Table 1

Quantitative comparison of four denoising methods.

Method	SNR	RMSE (%)	ER (%)
HHT	12.72	1.88	79.42
WT	30.00	3.45	84.47
WPT	24.71	2.26	93.54
MWPT-IHHT	31.53	0.40	92.20