cancel
Showing results for 
Show  only  | Search instead for 
Did you mean: 
Anonymous
Not applicable
718 Views

FFT(9.0) output magnitude threshold

Hello!

 

I am trying to implement a FFT magnitude estimation system. I am using a DDS compiler which outputs a sine wave into the FFT block. After the FFT the regular formula : Mag= sqrt( Re^2 + Im^2) is added. Basically what I want to achieve is to detect is if the output of the FFT is over a certain magnitude. I don't really understand the FFT output or what I am doing wrong.


 Should I not be getting a single spike where the inputted sine wave of 10MHz is added?

 

tb_Res.png

 

syst.png

 

What am I missing here?

 

Thank you in advance!

 

 

0 Kudos
2 Replies
Anonymous
Not applicable
715 Views

Pictures in higher res:
tb_Res.png

 

 

 

syst.png

0 Kudos
bwiec
Xilinx Employee
Xilinx Employee
662 Views
Registered: ‎08-02-2011

I would start by validating FFT output data to make sure your core configuration/interfacing is correct and then debug your custom logic.

So can you split fft_data_out into real and imaginary parts and plot it to make sure it looks reasonable?
www.xilinx.com
0 Kudos