LIDFT-the DFT linear interpolation method

The method of linear interpolation of the discrete Fourier transform (LIDFT) to estimate parameters of a signal consisting of many sinusoidal oscillations, has been presented in the paper. The LIDFT method combines beneficial properties from known procedures of nonlinear interpolation of a spectrum, obtained as a result of DFT and from parametric methods based on the Prony method. The LIDFT algorithm with beneficial numerical properties has been obtained after formulating the assumptions of the LIDFT method, providing a linear matrix equation and following symbolic transformations of this equation. The basic operations involved are the FFT algorithm and linear matrix equation solving procedure. The parametric, linearizing data window together with the method-developed to choose the window parameter allow for effective application of the LIDFT method depending on the examined signal character.