Solving Delta Function Convolution with Sin Wave

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Discussion Overview

The discussion revolves around solving a convolution problem involving a delta function and a sine wave within the context of linear time-invariant systems. Participants explore the integration process, particularly how to handle the delta function in the convolution integral.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant seeks assistance with the convolution integral involving a delta function and a sine wave, expressing confusion about the integration process with the impulse function.
  • Another participant questions the formulation of the delta function as "δ(t).δ(t-2)" and suggests that the convolution integral needs to be correctly set up.
  • A later reply states that the product of two delta functions is zero and implies that the convolution definition provided may be incorrect.
  • One participant introduces the sampling property of the delta function, which states that the integral of a delta function multiplied by another function evaluates to the function at the location of the delta function, provided the limits of integration include that location.
  • Another participant clarifies that the original problem involves the convolution of a sine wave and a sum of two delta functions, suggesting to use the convolution integral and the sampling rule to solve it.

Areas of Agreement / Disagreement

Participants express differing views on the formulation of the delta function and the setup of the convolution integral. There is no consensus on the correct approach to solving the problem, as some participants challenge the initial definitions and assumptions.

Contextual Notes

There are limitations in the clarity of the problem statement, particularly regarding the definition of the delta function and the specifics of the convolution integral. The discussion also reflects uncertainty about the original problem's details.

error 401
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hi

I really need your help ...

for linear time invariant system

f(t) =f1(t) (convolution) f2(t)
f(t) = ∫f1(t).f2 ( t-T)
or f(t) = ∫f1(t-T).f2(t)

where f1(t) = delta function = δ(t).δ(t-2)
and f2(t) = sine wave = sin ( ∏t )

how i can solve this ... my problem is : how can i make this integration with impulse ??


thanks in advance
 
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i forget that ... the limits of integration from (0 ) to (2)
 
error 401 said:
hi

I really need your help ...

for linear time invariant system

f(t) =f1(t) (convolution) f2(t)
f(t) = ∫f1(t).f2 ( t-T)
or f(t) = ∫f1(t-T).f2(t)

where f1(t) = delta function = δ(t).δ(t-2)
and f2(t) = sine wave = sin ( ∏t )

how i can solve this ... my problem is : how can i make this integration with impulse ??


thanks in advance

First, you need to get your convolution integral right.
Then, what do you mean by " f1(t) = delta function = δ(t).δ(t-2) "? It's not an equation I can make sense of ...
 
rude man said:
First, you need to get your convolution integral right.
Then, what do you mean by " f1(t) = delta function = δ(t).δ(t-2) "? It's not an equation I can make sense of ...

i mean how can i solve this integral

∫δ(t).δ(t-2)sin(∏t)
 
[tex]\delta(t)\delta(t-2) = 0[/tex]

And the convolution of a function with zero is zero. Your definition of the convolution integral appears incorrect. I suspect you are not giving us all the details, because the problem makes no sense. What was the original problem? (I know there was one since the limits of integration have already simplified from -inf to inf to 0 to 2)

edit:
I'll go ahead and throw out a property that may be helpful, though what you've given us so far doesn't indicate you will use it. The sampling property states

[tex]\int\limits_{a}^{b}\delta(x-c)f(x)dx=f(c)[/tex]

if b > c > a

This property leads to a very simple result when convolving some function f(t) with an impulse d(t - c).
 
Last edited:
the original problem is : convolution between 2 function ( sine wave and delta function ) but when he sketch delta function ..gives two vertical lines ..one of them at x=0 upward and the other at x=2 downward ...

so how can i solve this ?!

and I really appreciate your assistance :)
 
error 401 said:
the original problem is : convolution between 2 function ( sine wave and delta function ) but when he sketch delta function ..gives two vertical lines ..one of them at x=0 upward and the other at x=2 downward ...

so how can i solve this ?!

and I really appreciate your assistance :)

That is just the sum of two Dirac delta functions.

[tex]f_1(x) = \delta(x) + \delta(x-2)[/tex]

Just write out the convolution integral and use the sampling rule.
 
:D

thank you so much ..
 

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