Influence of the spectral image component on the amplitude and phase estimators provided by the interpolated DFT method

In this paper the contribution of the spectral image of a sine-wave fundamental component on the amplitude and phase estimators provided by the Interpolated Discrete Fourier Transform (IpDFT) method based on the Maximum Sidelobe Decay (MSD) windows is analyzed. In particular, accurate analytical expressions for the amplitude and phase estimation errors are proposed. Leveraging on these expressions, amplitude and phase estimators that compensate the above detrimental contribution are proposed. The accuracies of the derived expressions are verified through computer simulations. Simulations are then used also to compare the accuracies of the uncompensated and compensated amplitude and phase estimators.