Rotating fourier transform—new mathematical basis for non-stationary impedance analysis

The problems of non-stationary electrochemical impedance spectroscopy are discussed by an analysis of the errors of the classical Fourier transform applied in non-stationary conditions. The essentials of the theory of generalized Fourier transform, called rotating transform, capable of handling non-stationary signals, are described. The application of the rotating transform to impedance analysis of non-stationary electrochemical systems is emphasized.