The article presents the results of approximating of ion current signal of the most appropriate parametrical models in Matlab software. It is shown that in spite of the high accuracy of approximation, parametrical model Gaussian, which chosen early in Matlab, have significant drawbacks. In order to eliminate the identified deficiencies authors was developed parametric model in which the discrete Fourier transform was used to approximate of the ion current signal.
Keywords: ion current, the internal combustion engine, a parametric model, a discrete Fourier transform, the Gaussian model, the approximation of a signal