FFT Nuttall Window Four Spectral Line Interpolation Correction Harmonic Detection Algorithm

When using traditional FT for harmonic signal analysis, it is difficult to strictly achieve synchronous sampling and full period truncation, which inevitably leads to spectral leakage and barrier effects, reducing the accuracy of detection results. In order to improve the accuracy of detection results, based on FFT (Fast Fourier Transformation), Hann window Blackman window Blackmanharis window Nuttall's four line interpolation algorithm was studied, and correction formulas for amplitude, frequency, and phase corresponding to different spinor window four line interpolation were derived through polynomial fitting. And simulation experiments were conducted on different four line interpolation algorithms of the complementary window in Matlab, and compared and analyzed with the corresponding three line interpolation algorithm of the complementary window. The results showed that the four line interpolation algorithm of the fourth-order Nuttall window had higher amplitude accuracy, phase accuracy, and frequency accuracy compared to other algorithms, better sidelobe performance, and can better suppress spectral leakage and barrier effects.