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Unformatted text preview: Diagrams & SignalFlow Graphs ECE382 11 / 31 Definition of Graphs
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e3 e2 A graph G is an ordered pair G = (V , E) consisting of a set V of vertices or nodes and a set E of edges joining pairs of vertices, where V = {v1 , v2 , . . . , vn } and E = {e1 , e2 , . . . , vm }. If the edges of a graph are directional, then it is called digraph. Signal flow graphs are digraphs in which the vertices represent system variables or signals of a system and the edges represent components of the system. The gain of an edge is a transmittance.
C. S. George Lee (Purdue Univ.) Block Diagrams & SignalFlow Graphs ECE382 12 / 31 v3 Signal Flow Graphs  Definitions
Node a node is a point representing a system variable or signal Transmittance is a gain between 2 nodes. Branch a branch is a directed line segment joining 2 nodes. The gain of a branch is a transmittance. Input node is a node that has only outgoing branches. This is independent variable. Output node is a node that has only incoming branches. Path a path is a traversal of connected branches in the direction of the branch arrows.
If no node is crossed more than once, the path is open. If the path ends at the same node from which it began and does not cross any other node more than once, it is closed.
C. S. George Lee (Purdue Univ.) Block Dia...
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 Fall '08
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