Applying the continuous wavelet transform to the analysis of diesel engine conditions

The continuous wavelet transform (CWT) is applied to analyse the acoustic signals obtained from a diesel engine. First a brief review in the analysis of engine acoustic signals is given. To obtain condition-indicating information, the characteristics and implementation of the CWT are addressed. Its capability of time-frequency localisation is demonstrated using a numerical example. The CWT representation of the acoustic signals exhibits a clear picture of the combustion process. The feature is then quantified using a local energy index. The results show that the method is able to discriminate a number of abnormal injection faults.