(TIME INVARIANCE)
(TIME INVARIANCE)
Line 11: Line 11:
 
'''METHOD'''
 
'''METHOD'''
  
One of the simplest ways to determine whether or not a system is time-invariant
+
To check if a system is time-invariant, we can shift the function by a given value of T.  Then, we send the
is to check whether there is a value t outside of the normal x(t) or y(t)If it does not contain such
+
function through the system and obtain an outputNow, take the same input function and put it into the system
a value t (outside of the x(t)), then it is time invariant. Consider the following systems:
+
without shifting it first.  Then take the output of the system and shift it the value of T used previously.  If
 
+
these two processes yield the same results, then the system is called "time invariant."
  
 
'''SYSTEMS'''
 
'''SYSTEMS'''
Line 21: Line 21:
  
 
B.) h2(t) = 6t*x2(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 time-variant.
 

Revision as of 14:28, 11 September 2008

TIME INVARIANCE

DEFINITION

A system is defined as "time-invariant" when its output is not explicitly dependent on time (t). In other words, if one were to shift the input/output along the time axis, it would not effect the general form of the function.


METHOD

To check if a system is time-invariant, we can shift the function by a given value of T. Then, we send the function through the system and obtain an output. Now, take the same input function and put it into the system without shifting it first. Then take the output of the system and shift it the value of T used previously. If these two processes yield the same results, then the system is called "time invariant."

SYSTEMS

A.) h1(t) = 2x1(3t) + 5

B.) h2(t) = 6t*x2(3t) + 5

Alumni Liaison

Basic linear algebra uncovers and clarifies very important geometry and algebra.

Dr. Paul Garrett