Modified Harmonic Detection Algorithm by Nuttall Window Four-Line Interpolation for FFT
When the traditional Fourier transform is used for harmonic signal analysis,it is difficult to strictly synchronize the sampling and truncate the whole period,which inevitably produces spectrum leak-age and fence effect,and reduces the accuracy of the detection results.To improve the accuracy of detec-tion results based on FFT,four-line interpolation algorithms of Hann window,Blackman window,Black-manharris window,and Nuttall window are studied.The correction formulas of amplitude,frequency and phase corresponding to the four-line interpolation of different corotation windows are derived by polyno-mial fitting.In addition,the simulation experiments of different four-line interpolation algorithms for coro-tating windows and the corresponding three-line interpolation algorithms for corotating windows are com-pared and analyzed in Matlab.The simulation results show that the amplitude accuracy of the four-line interpolation algorithms for four third-order Nuttall windows can reach 10-5～10-9 orders,and the fre-quency accuracy can reach 10-8～10-9 orders.The phase accuracy can reach 10-3～10-7 orders of magni-tude.Compared with other algorithms,the accuracy is higher,the sidelobe performance is better,and the spectrum leakage and fence effect can be better suppressed.
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