(Invertible Systems)
(Time Variant:)
 
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== Invertible Systems ==
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== Time Invariant Systems ==
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----
  
A system is invertible if distinct inputs yield distinct outputs.
 
 
Invertible System:
 
 
y(t) = <math>\frac{3*x(t) + 8}{1}</math>
 
 
x(t) = <math>\frac{y(t) - 8}{3}</math>
 
 
x(t) -> |Sys 1| -> y(t) -> |Sys 2| -> x(t)
 
 
The two equations are inverses of each other.
 
 
Noninvertible System:
 
 
y(t) = <math>t^4</math>
 
 
   
 
   
  x(t) = <math>t</math>    ->     |Sys|     ->     y(t) = <math>t^4</math>
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  A system is time invariant if for any function x(t), a time shift of the function x(t-t0),
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is commutative with the other effects of the system.
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x(t)  ->   |Sys|   ->   |time delay by t0|  -> a(t)
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x(t)  ->   |time delay by t0|  ->  |Sys|  -> a(t)
 
    
 
    
  x(t) = <math>-t</math>    ->    |Sys|    ->    y(t) = <math>t^4</math>
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  If this resulting function a(t) is the same for both cascades then the system is time invariant.</nowiki>
  
  The System is not invertible because for a given set of inputs you cannot differentiate which of the output will result.
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== Time Variant Systems: ==
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A system is time variant if the results of the cascaded systems are not the same.

Latest revision as of 13:46, 16 September 2008

Time Invariant Systems



A system is time invariant if for any function x(t), a time shift of the function x(t-t0),
is commutative with the other effects of the system.

x(t)   ->   |Sys|   ->   |time delay by t0|   -> a(t)
  
x(t)   ->   |time delay by t0|   ->   |Sys|   -> a(t)
 
If this resulting function a(t) is the same for both cascades then the system is time invariant.</nowiki>

Time Variant Systems:

A system is time variant if the results of the cascaded systems are not the same.

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BSEE 2004, current Ph.D. student researching signal and image processing.

Landis Huffman