Frequency measurement algorithm of two spectral phases difference based on Flat-top window

Taking Flat-top window for a example,this paper analyzed its spectral characteristics of sidelobes and made a double-line phase based on the weighted harmonic correction algorithm to obtain the frequency offset.Firstly,it sampled N point signal,then extracted N/2 odd and N/2 even point signal to run FFT,which could get the phase of the maximum line and sub-maximum line spectra respectively.Lastly,it obtained frequency of harmonic with the phase-weighted difference.The simulation results show that the algorithm can effectively reduce estimation error in phasor parameters and improve detection accuracy of the harmonic.