A Graphical Approach to the Intermodulation and Spurious Response Problem

Many computer programs have been developed to help the engineer predict intermodulation components and spurious responses. The purpose of this paper is to show that it is not necessary to use a computer to solve such problems and that the use of graphical techniques can lead to a more intelligent choice of frequencies since a global picture of the problem is presented to the engineer. Equations for two and three signal intermodulation interference cases are derived and put in a form such that graphs can be easily drawn from them. These graphs can be made to fit a specific problem or can be constructed with normalized scales and therefore have a general use. A similar approach can be used for the spurious response problem although, the construction of a simple independent table rather than a graph is much easier to create and utilize.