An Introduction to Signal-Flow Graph Theory

Abstract

In this chapter, we show how signal-flow graphs can be used to graphically represent linear systems and in particular the sets of equations describing them. It is shown that the usefulness of signal-flow graphs stems from the fact that, once a system or network has been reduced to a signal-flow graph (SFG), well-defined rules allow network transfer functions, as well as other characterizing quantities, to be evaluated by inspection. This goes for systems in general and, for our purposes, for analog, sampled-data, and digital systems and networks. [The basic rules of SFGs are sometimes referred to as “Mason’s rules” after Samuel Jefferson Mason (1921–1974), who first formulated them. Mason was an American electronics engineer and MIT professor from 1949 till 1974.]