Input frequency requirements for identification through Liapunov methods

A theorem is derived which specifies a sufficient number of input frequencies to guarantee identification of an unknown noise free linear plant. Since all of the referenced work relates to sufficient conditions for nulling of the parameter error vector, it is to be expected that various conditions on the system to be identified will have been imposed. It was found that some of these conditions appear to be necessary while others do not. The main contribution is to provide a theorem which considers the effect of unknown parameters in the state equation upon the frequency requirements.