Understanding Convolution Sum: Solving a Signal Equation

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Discussion Overview

The discussion revolves around the evaluation of a signal defined by the equation x[n] = 2u[n+2] - 3u[n-2] + u[n-4]. Participants are examining specific values of the signal and the correctness of their evaluations, as well as the application of convolution sums in understanding the signal's behavior.

Discussion Character

  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant claims that the values x[-2]=2, x[2]=-1, and x[4]=0 are false based on their calculations involving the unit step function u[n].
  • The same participant provides specific calculations for u at different n values, suggesting that the method used to evaluate the signal may be incorrect.
  • Another participant asserts that all values are true and suggests that drawing the signal x[n] is necessary before applying the given equation.
  • A later reply mentions the use of convolution sums and the drawing of graphs with u[n], indicating an attempt to visualize the signal for better understanding.

Areas of Agreement / Disagreement

Participants express disagreement regarding the correctness of the signal values and the method of evaluation. There is no consensus on the validity of the claims made by the initial poster.

Contextual Notes

Some participants reference the need to draw the signal and apply convolution sums, but the discussion does not resolve the mathematical steps or assumptions involved in evaluating the signal.

Who May Find This Useful

This discussion may be useful for individuals interested in signal processing, particularly those studying convolution sums and the evaluation of piecewise functions involving unit step functions.

Angello90
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Hi there,

This is a different question I tried.

The signal is given as x[n] = 2u[n+2] - 3u[n-2] +u[n-4], and it has values x[-2]=2, x[2]=-1 and x[4]=0. True or false?

I think it's false cause If I plug in all the x in each case ie, -2, 2 and 4, into the signal, than I get 3 different values for u.

For x[-2]; u = 1/3
For x[ 2]; u = -1/6
For x[ 4]; u = 0

Is that correct way to do this question?
Help guys!

Thanks
 
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This is not homework!
 
Angello90 said:
This is not homework!

The Homework Help forums are the right place for this type of question, since it is schoolwork. Please see this thread for a discussion about the PF Rules on schoolwork:

https://www.physicsforums.com/showthread.php?t=373889

.
 
you have to draw x(n) first. Then apply what they gave you. All are true
 
Ok so today I did something called Convolution Sum, and my lecture showed me how to draw graphs with u[n], and for the question above I was able to come up with a graph.

Is this correct?

attachment.php?attachmentid=29447&d=1288203219.jpg
 

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