Graphing fequence of the signal

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    Graphing Signal
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Discussion Overview

The discussion revolves around the graphing of the Fourier transform of a discrete signal defined as x(n) = n for 0 <= n < 4 and 0 otherwise, as well as a continuous signal x(t) = t over the same interval. Participants explore how to represent these transforms graphically.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant presents the discrete signal and its Fourier transform, X(W), and asks how to graph F(W).
  • Another participant points out that F(W) has not been defined and suggests that the provided expression seems to be a Fourier series expansion.
  • It is noted that the expression does not appear to depend on W but rather on w, raising questions about the definitions used.
  • For the continuous signal, a participant provides the integral for X(W) but reiterates the lack of clarity regarding F(W) and its relationship to x or X.
  • A later reply clarifies that the intended notation might be X(F), but this is also questioned by another participant.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the definitions of F(W) and X(F), indicating that there is no consensus on how these terms relate to the signals discussed. The discussion remains unresolved regarding the graphing of these transforms.

Contextual Notes

There are missing definitions for F(W) and X(F), and the relationship between these terms and the original signals is unclear. Participants have not reached a conclusion on how to graph the transforms.

cutesteph
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Say x(n) = n for 0 <= n < 4 and 0 o.w.

So X(W) = Sum n=-∞ to ∞ x(n) exp(-inw) = sum from n=0 to 3 nexp(-inw)
= 0 + exp(-iw) + 2exp(-j2w) + 3 exp(-j3w)

How would I graph F(W)?


Also if the signal was continuous x(t) = t for the same interval

X(W)= integral 0 to 4 texp(-iwt) dy = (4exp(-i4w)/ -iw) - (exp(-iw4) -1)/w^2

How would I graph F(W) for this?
 
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cutesteph said:
Say x(n) = n for 0 <= n < 4 and 0 o.w.

So X(W) = Sum n=-∞ to ∞ x(n) exp(-inw) = sum from n=0 to 3 nexp(-inw)
= 0 + exp(-iw) + 2exp(-j2w) + 3 exp(-j3w)

How would I graph F(W)?
You wouldn't - no F(W) has been given.
You have an X(W) - which seems to be the fourier-series expansion of x(w) or something.
As it is written, it does not seem to depend on W though - but on w.
It helps if you say what things are.

Anyway - if your problem is to graph a sum of complex exponentials - you'd either plot the real and imaginary parts separately or plot the trajectory in the complex plane.

Also if the signal was continuous x(t) = t for the same interval

X(W)= integral 0 to 4 texp(-iwt) dy = (4exp(-i4w)/ -iw) - (exp(-iw4) -1)/w^2

How would I graph F(W) for this?
Again - no F(W) or any indication how it may be related to x or X. Same advise I guess.
 
I mean X(F).
 
I don't see any X(F) either.
What are these things supposed to represent?
 

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