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Homework Help: Fourier transform limit of finite signal

  1. Dec 21, 2011 #1
    So this is a very simple question that I am having some trouble figuring out:

    Let s(t) be a finite energy signal with Fourier Transform S(w).
    Show that [tex]\lim_{w \to \infty } S(w) = 0[/tex]

    We know by defintion that the FT of this signal is [itex]\int[/itex]s(t)e[itex]^{-jwt}[/itex]dt and also that ∫|s(t)|2dt < ∞.

    I'm a little lost on how I can start proving this. I thought about something using Parseval's theorem but I have no idea. Or maybe I can use the FT in it's ∫s(t)cos(wt)dt - j∫s(t)sin(wt)dt form? I have no idea. I'm sure the solution is much simpler than I think it is.
    Last edited: Dec 21, 2011
  2. jcsd
  3. Dec 22, 2011 #2
    Nobody has any clue? I'm still stuck. I'm studying for an Electronics Math exam and this question (from a past exam) is really stumbling me.
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