Theory and applications of the pole-zero analog computer

This paper describes an all-electronic analogue of the complex plane in which singularities are positioned by potentiometor settings. Although the basic principle is old, a new method of determining the argument of a function is presented and its implementation discussed. A machine called the Pole-Zero Analogue Computer was constructed to test the method and perform various operations such as the plotting of root loci, Nichols loci and equipotential lines. Other functions which can be performed include the plotting of magnitude, logarithmic-magnitude, phase-slope and phase characteristics of filters or linear systems in general. All of these applications are discussed and test results are presented.