Abstract: The principle and algorithm of a new approach to the ideal digital filter using harmonic wavelet transforms are introduced, and the characteristics in frequency domain and filtering capability of harmonic wavelets are analyzed. Using the box-like spectrum of harmonic wavelets in frequency domain, a new approach modeling to the ideal digital filter by using har-monic wavelet transforms is established. The bandwidth and central frequency of this approach filter are adjusted with har-monic wavelet transforms. The amplitude-frequency character-istics of the approach filter are close to the ideal digital filter, and have zero-phase characteristic. The fast algorithm of this approach filter is realized by Fourier transform. Examples of application demonstrate that this method presented can effec-tively filter the noise from the signal. This method is also fea-tured by simple algorithm, fast and real time performing in application as well.

Key words: Approach modeling, Digital filter, Filter method, Harmonic wavelets