Revision as of 08:57, 11 September 2008 by Nkgentry (Talk)

TIME INVARIANCE

'''Definition'''
A system is defined as "time-invariant" when its output is not an explicit function of time. In other
words, if one were to shift the input/output put along the time axis, it would not effect the general
form of the function.  

'''Method'''
One of the simplest ways to determine whether or not a system is time-invariant
is to check whether there is a value t outside of the normal x(t) or y(t).  If it does not contain such
a value t (outside of the x(t)), then it is time invariant.  Consider the following systems:

SYSTEMS:
A.) h1(t) = 2x1(3t) + 5
B.) h2(t) = 6t*x2(3t) + 5

System A does not contain a "t" outside of the x1(3t).  Therefore, we can call it time-invariant.
However, system B does contain a "t" outside of the x2(3t).  Thus, system B is not time-invariant.


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