• Support PF! Buy your school textbooks, materials and every day products Here!

Fourier Transform

  • Thread starter FrogPad
  • Start date
  • #1
809
0
I am stumped on this...

Given a discrete function, and transform pair: [tex] x(n) \leftrightarrow \hat x (e^{j\omega}) [/tex]

What is the transform of:
[tex] x_3(n) = (n-1)^2 x(n) [/tex]


I really don't know how to do this. I have a table proprety for [itex] nx(n) [/tex], but nothing with [itex] n^2 x(n) [/itex]. The only thing I can think of is expanding it as: [itex] x_3(n) = (n-1)^2x(n) = n^2x(n) - 2nx(n) +x(n) [/itex]... but I'm stuck on the [itex] n^2 [/itex] part. My intuition says that it has something to do with the differentiation property, but I'm really stuck, and can't figure this out. Any help would be awesome. thanks :)
 

Answers and Replies

  • #2
809
0
Easy. Got it finally.

Just write [tex] x_3(n) = ny(n) [/tex]
where [tex] y(n) = nx(n) [/tex]

and since I have the transform for [itex] nx(n) [/itex], it is cake.
 

Related Threads on Fourier Transform

Replies
7
Views
1K
  • Last Post
Replies
2
Views
554
  • Last Post
Replies
8
Views
979
  • Last Post
Replies
1
Views
995
  • Last Post
Replies
5
Views
1K
  • Last Post
Replies
4
Views
810
  • Last Post
Replies
1
Views
4K
  • Last Post
Replies
1
Views
692
  • Last Post
Replies
3
Views
1K
  • Last Post
Replies
4
Views
832
Top