1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Simple Fourier transform problem

  1. Mar 2, 2015 #1
    1. The problem statement, all variables and given/known data
    Given x[n] with transform X(ejw), find the fourier transform in terms of X(ejw).

    x1[n]=[0.9ncos(0.6*pi*n)] * x[n-2]

    2. Relevant equations
    time shift: x[n-k] -> e-jwkX(ejw)
    convolution: x[n] * h[n] -> X(w)H(w)
    freq. shift: x[n]ejwcn -> X(ew-wc)

    3. The attempt at a solution
    I think that this problem has no solution because 0.9n has no Fourier transform (not summable). 0.9nu[n] on the other hand does but not the same case here. am i doing this right?
     
    Last edited: Mar 2, 2015
  2. jcsd
  3. Mar 2, 2015 #2

    Svein

    User Avatar
    Science Advisor

    I am at a loss to understand the problem. It seems to me as if the problem is to calculate the Fourier transform of a constant - or a sequence of constants. Is that correct?
     
  4. Mar 2, 2015 #3
    yeah, I guess i didn't word it correctly. what it reads exactly is 'given a sequence x[n] with Fourier transform Xejw, determine the Fourier transform of the sequences in terms of Xejw.
     
  5. Mar 3, 2015 #4

    Svein

    User Avatar
    Science Advisor

    Still does not make any sense to me...
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted