An improved method on reducing measurement noise based on Hilbert-Huang transform

For nonstationary signal in rock bolts detecting, an effective denoise method based on Hilbert-Huang transform (HHT) is presented, cross-correlation for denoise signal is used to estimate the length of rock bolts. At first, by empirical mode decomposition (EMD) algorithm, a sum of intrinsic mode functions (IMF) are got, and then, the IMF coefficients in useful signal dominative layer are proceeded using soft threshold method, those IMF coefficients are reconstructed, at last, cross-correlation is used to estimate the length. Compared with the traditional denoise method, the above method is better to remove measurement noise and estimate the length.