(6A)
(6B)
 
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== 6A ==
 
== 6A ==
<math>\,y(t)=(a+1)^2x(t-a)}\,</math>
+
<math>\,x(t-k) \to System \to y(t)=(k+1)^{2}x(t-k-1)\,</math>
  
  
 
'''Proof:'''
 
'''Proof:'''
  
<math>x(t) \to System \to y(t)=e^{x(t)} \to Time Shift(t0) \to z(t)=y(t-t0)</math>
+
<math>x(t-k) \to System \to y(t)=(k+1)^{2}x(t-k-1) \to Time Shift(t0) \to z(t)=y(t-t0)</math>
  
<math>\,                                                            =e^{x(t-t0)}\,</math>
+
<math>\,                                                            =(k+1)^{2}x(t-t0-k-1)\,</math>
  
  
  
<math>x(t) \to Time Shift(t0) \to y(t)=x(t-t0) \to System \to z(t)=e^{y(t)}</math>
+
<math>x(t-k) \to Time Shift(t0) \to y(t)=x(t-t0-k) \to System \to z(t)=(k1+1)^{2}y(t-k1-1)</math>
  
<math>\,                                                            =e^{x(t-t0)}\,</math>
+
<math>\,                                                            =(t0+k+1)^{2}x(t-t0-k-1)\,</math>
  
 +
It is not time invariant.
  
Both cascades yielded the same outputs, thus <math>\,y(t)=e^{x(t)}\,</math> is time invariant.
+
 
 +
== 6B ==
 +
If superposition works, integrating input will yield integration of output,
 +
integration of <math> u[n-1] </math> is <math>\delta[n-1]</math>, thus u[n] as an input will yield the desired output.

Latest revision as of 18:33, 12 September 2008

6A

$ \,x(t-k) \to System \to y(t)=(k+1)^{2}x(t-k-1)\, $


Proof:

$ x(t-k) \to System \to y(t)=(k+1)^{2}x(t-k-1) \to Time Shift(t0) \to z(t)=y(t-t0) $

$ \, =(k+1)^{2}x(t-t0-k-1)\, $


$ x(t-k) \to Time Shift(t0) \to y(t)=x(t-t0-k) \to System \to z(t)=(k1+1)^{2}y(t-k1-1) $

$ \, =(t0+k+1)^{2}x(t-t0-k-1)\, $

It is not time invariant.


6B

If superposition works, integrating input will yield integration of output, integration of $ u[n-1] $ is $ \delta[n-1] $, thus u[n] as an input will yield the desired output.

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Mu Qiao