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ptc-50085241-Visitor
1-Visitor
March 13, 2013
Question

OFDM Signal Reconstruction via DFT

  • March 13, 2013
  • 1 reply
  • 4236 views

I'm having trouble reconstructing an OFDM QAM signal using its amplitude and phase spectra obtained by using the DFT. The QAM signal is given in the image below.

qam+.PNG

I have tried to do it so far using the below equation.

lab6-1.PNG

This is the closest I have reconstructed it to the original. What am I missing?

I am using Mathcad 13.

1 reply

W
Werner_E25-Diamond I
25-Diamond I
March 13, 2013

You sure would get a better respones if you attach a worksheet. From the pic alone probably nobody would be able to determine what the problem ould be.

Would the following link be of any help?

http://www.comlab.hut.fi/users/tko/geta07/GETA fall 07- OFDM with MathCAD.ppt

P
ptc-50085241-VisitorAuthor
1-Visitor
March 13, 2013

No sorry that doesn't help. I was browsing through that just last night actually. I have attached my worksheet.

W
Werner_E25-Diamond I
25-Diamond I
March 13, 2013

Jonathan Mayers wrote:

No sorry that doesn't help. I was browsing through that just last night actually. I have attached my worksheet.

Was just a try.

So hopefully someone with better technical background could jump in.

BTW,

  • are you sure about the absolute value of X0 in the definition of sDFT(t)?
  • could it be that you used the wrong vector X in the last definition? You redefined X in the Spectral Analyisis section.
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