Doppler shift correcting for acoustic signals using resampling technique

To on-line diagnose faults of train bearings, the wayside approach based on acoustic signal analysis is one of the most important development directions in this filed. However, the Doppler Effect due to relative motion between microphone and acoustic source would cause the acoustic signal spectrum distorted, which is not beneficial to accurately reflect health conditions of equipment. Now there is not an appropriate method to correct the Doppler shift although this is a key technique in acoustic fault diagnosis. The paper proposes a signal resampling method based on uniform frequency shift, which can effectively solve the above problem of distorted spectrum for acoustic signals of train bearings caused by the Doppler Effect. Firstly, the curve of frequency shift was figured out with known conditions under measurement; secondly the frequency shift curve was used to divide the acoustic signal to be N local segments by suitable parameter; lastly the resampling technique was conducted in every segment after finding each segment point of resample. The effectiveness of the proposed method is verified by simulation and experiment.