A Method for Determining Frequency Response from Step Response Data and Its Accuracy

Abstract

A method for obtaining frequency response from step response data by approximating them with parabolic segments along three sampled data is described and the equations for the calculating error by discrete Fourier transform are introduced. This method (method 2) is compared with a method by means of straight line segments approximation (method 1). In the case of the first order system the method 1 gives slightly better approximation than the method 2, and in the case of the second order oscillatory system the method 2 shows to fit better than the method 1.