Use of high frequency signals in identification of certain non-linear systems

By filtering the output of a non-linear element, whose input consists of the normal low frequency input signal with a high frequency (dither) signal added, the equivalent non-linearity of the element can be obtained. Illustrative examples of equivalent non-linearities for several non-linear elements are given. It is shown that the technique of dither injection permits the identification of certain types of open and closed-loop systems. Practical results are included to show the accuracy of the method.