The suppression of drift and transient effects for frequency-domain identification

The identification of linear system dynamics from measurements corrupted by low-frequency aperiodic noise is discussed for situations where a periodic excitation can be applied to the system. It is shown that, by considering the low-frequency harmonic content of the disturbing noise, accurate elimination of the disturbance can be achieved for typical linear/nonlinear trend characteristics. The removal of transient effects from the initial response of the system to the excitation is also discussed. This is applicable when the experimental time is limited, as can be the case for systems with long time constants. The removal of the transient effects can be coupled with estimation of the drift parameters, thus allowing the effects of both the transients and the drift to be removed simultaneously