Digital frequency analysis enhancement with the aid of the complex spectrum smoothing

The performance of the digital spectral analysis of periodic and quasi-periodic signals can be substantially enhanced by the complex spectrum smoothing with the aid of a window. The window width is chosen in accordance with the double distance between the side lobes of the analyzing window frequency characteristic. As a result of this type smoothing, the amplitude spectrum for a harmonic wave simplifies due to the suppression of spectrum ripples caused by the finite length of the analyzing window. The spectral envelop remains the same as the harmonic wave frequency changes.