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Honored Contributor I
1,012 Views

FFT MegaCore simulation

Hi, 

 

I'm working with Altera streaming 1024 points FFT core (fft v13). I want to get spectrum but i'm enable to extract frequency information from outputs. 

 

Anybody can help me please! Thanks 

 

Regards,
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Honored Contributor I
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I attached the response that I get. My input is a sin. In the axis of the spectrum i have time samlpes but i want to have frequence. 

 

PS: Sorry for my poor english 

 

Regards,
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Honored Contributor I
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You're not very clear on what you're doing. My guess is you're using DSP Builder and the FFT Megacore as that screenshot looks like a Simulink scope. If you want useful answers you need to give much more information so that people don't have to guess. 

 

You've connected your input data and output data to a scope, which always shows a signal plotted against time. To get a graph of the frequency you need to save that data to a variable using a "To Workspace" block. Then you can use the MATLAB command "plot" the points against any values you like. 

 

You may be able to do it directly using the vector scope block as well.
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Honored Contributor I
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Hi dabuk,  

 

Thank you for your reply. I will do it. 

Sorry, I am a beginner in DSP. I will be more clear.  

 

I have to implement an algorithm in fpga which allows me to make the time-frequency analysis. 

 

I'm obliged to extract input signal frequency??
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Honored Contributor I
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I'm no expert either. 

 

I guess you will have to create a component that reads in the values of the FFT and then finds the maximum magnitude. You can then multiply the time-step of the maximum value by the frequency per bin and you will have the frequency of the largest component. 

 

To do this you will have to write some HDL or use a tool like DSP Builder.
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Honored Contributor I
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I'm using DSP Builder. I will try it and i'll tell you the result. 

 

Regards,
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