Identification of a system in the presence of low-frequency drift

A technique is described, by which the elimination of error terms, due to low-frequency-drift disturbances, in the determination of the impulse-response function of a time-invariant system is achieved. The method uses a chain code as the perturbating input. It is shown that, by advancing the output rather than delaying the input, the errors that arise in the estimation of the impulse-response function are completely determined.