A New Variable-Band Filter Design Method for the Discrete Wavelet Transform

In this study, a new design method for Variable-Band Filters (VBFs) corresponding to the Real-signal Mother Wavelet (RMW), which is constructed from a real signal, is proposed. In order to detect and extract unsteady abnormal signals, the designed VBFs are used in the discrete wavelet transform (DWT) instead of traditional wavelets. The DWT that uses the VBFs is called the Variable-Band Filter Discrete Wavelet Transform (VBF-DWT). The VFB-DWT is applied to remove the pulse noise in the ion current waveform, which is measured in a spark-ignition engine and extracts the knocking components. The obtained results show that the VFB-DWT is effective in the detection and extraction of abnormal signals.