Eliminating Speckle Noises for Laser Doppler Vibrometer Based on Empirical Wavelet Transform

Abstract

This paper presents a novel approach for eliminating speckle noises in Laser Doppler Vibrometer signals based on empirical wavelet transform (EWT). The moving root-mean-square thresholds are utilized to cut off signal drop-outs and produce noise discontinuity that EWT can identify. The extremum ratio behaves as the criterion to reject or accept the EWT decomposed components. While processing simulated signals, the EWT-based approach outperforms others and presents de-speckle robustness. In experiments, EWT reveals the actual vibration despite low signal-to-noise ratios, which indicates de-speckle efficiency.