An Aliasing Compensation Method for Wavelet Packet Transform

Wavelet packet transform is very useful in signal processing, especially in some applications where the information in each part of the frequency band is concerned. The measurement of harmonic current and voltage in supply power can use wavelet packet transform to evaluate the harmonic groups. However, the frequency aliasing caused by the filter banks would divide some frequency component into wrong frequency bands. This made it impossible to measure harmonic groups accurately. This paper introduces a new method to solve the problem of frequency aliasing when measuring harmonic groups using wavelet packet transform. Compensation methods is made by combination of an improved a'trous algorithm and wavelet packet transform. This method was proved to be effective by simulation.