Weighted multipoint interpolated DFT to improve amplitude estimation of multifrequency signal

This paper describes the error reduction of frequency and amplitude estimates of the periodic signals with multipoint interpolated discrete Fourier transform (DFT). The bias removal and noise sensitivity properties of the interpolation algorithms are studied for rectangular and Hanning windows. The correction improves with increasing the number of the interpolation points of the DFT. The use of a suitable interpolation algorithm depends on the effective bits of the A/D conversion, on the position of the frequency component of the signal and on the mutual component interspacing along the frequency axis. Using different algorithms, we change adaptively the apparent window shape for the particular component.