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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.

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

Yes because after the first K components, all others are zero and do not affect the calculation. The DC value is positive for me so I'm not sure what you mean. However, I changed the equation up a bit and instead I put my DC value to be negative and the two signals overlay exactly. For anyone who may be in a similar situation, find attached the mathcad 13 worksheet.

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