Separating mixed multi-component signal with an application in mechanical watch movement
Digital Signal Processing
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The acoustic signal of the mechanical watch movement is a distinct multi-component signal containing many frequency components corresponding to the modal frequencies of the escapement parts of the watch. This paper presents a new study on signature analysis of the mechanical watch movement using mono-component signal extraction and analysis. The new method has three main parts: (a) separating the signal into some narrow band signals using Wavelet Packet Analysis (WPA); (b) decomposing each narrow band signal into a number of Intrinsic Mode Functions (IMF) by means of Empirical Mode Decomposition (EMD); and (c) selecting the meaningful mono-component signals to analyse the time-frequency distribution. This method can not only obtain good time-frequency resolution identifying different frequency components at different times, but also highlight the signal components that are informative but have low energy. The effectiveness of the method is demonstrated by means of computer simulation and experiments. The experimental results reveal the insight of the mechanical watch movement, and can be used for fault diagnosis.