Digital computation of frequency response

Abstract

This paper describes three algorithms for the digital computation of the frequency response of linear sys tems and discusses their advantages and disadvantages.

The third method presented is a novel one which applies the standard polynominal quadratic synthetic division algorithm in a unique way to the problem. The method allows the forward and feedback-path transfer functions to be inputted in any form; it computes the open-loop and closed-loop frequency responses in one pass; and, most importantly, it does not require numerical factoring at any point. The method is easy to use and appears to run effi ciently, particularly for high-order systems. The paper concludes with FORTRAN and BASIC programs which implement the algorithm of Method Three.