Finite-frequency identification of stable plant

A method of frequency identification of a stable plant in the presence of an unknown bounded disturbance filterable by the Fourier filter (FF-filterable), or contiguously FF-filterable (CFF-filterable), is proposed. As distinguished for conventional frequency-domain identification it makes use of the test signal with minimal quantity of the test frequencies. The latter allows on the one hand to replace solution of nonlinearly least squares problem by the linear frequency equations solution and on the other hand to find disturbance class (strong FF (or CFF)-filterable disturbance) for which identification process converges to the true coefficients of plant. These properties of disturbance may be examined by experiment.