Abstract <p>The article focuses on parametric identification of a single-input, single-output linear dynamic object in the conditions of incomplete a priori information based on the least squares method. At the stage of generating a system of equations with respect to unknown parameters, a special type of forming function is used, which allows replacing the operations of numerical differentiation of the measured input and output signals of the identified object with the operation of integration by parts. The dependence of the frequency properties of the forming function and its derivatives on the corrective parameters of this function are obtained in the analytical form. The presented results illustrate the almost total coincidence of frequencies obtained experimentally and analytically.</p>