Fundamental wave extraction and frequency measurement based on IIR wavelet filter banks

A wavelet function with good frequency response was adopted and the optimal decomposition level of wavelet transform was studied in order to improve the accuracy of fundamental wave extraction and frequency measurement in signal processing. In frequency measurements, an evaluating method was proposed to determine right maximal value points, and the fundamental frequency of signal was estimated by the least squares method, which could reduce the influence of low frequency noises. An interpolation method in parabola form was used to eliminate the error of the non-integral period sampling. A digital signal processing system was developed with a digital signal processor (DSP) to realise the wavelet filter and frequency measurement algorithms in real time. The testing results show that both the methods and system proposed by this paper are effective.