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5988 Discussions

Help with FFT megacore .mdl design

Altera_Forum
Honored Contributor II
924 Views

Would anybody mind taking a look at my .mdl for me? I'm trying to get the spectrum of a sine wave source block and there seems to be a lot of noise. I'd like to have a solid plot of the spectrum in matlab, so I can continue with the design. Right now I have the imaginary input connected to the real input/source, its set up for a 256 point streaming transform. It's for a school project, none of my professors seem to know that much about simulink. Help would be awesome it's starting to come down to the wire. THANKS

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3 Replies
Altera_Forum
Honored Contributor II
78 Views

**I was inputting negative values into the real input, I think this was one of the problems

Altera_Forum
Honored Contributor II
78 Views

I attached the spectrum of a 64 point streaming arch. transform on a sine wave at 12.5 MHz. I plotted it in MatLab with an FFT shift and without scaling. I wonder if there is an overflow, without the FFT shift the spikes occur at the ends of the spectrum, the data shifts as I change the frequency but for the large part isnt accurate.  

Any body have any ideas with whats going on? :confused:
Altera_Forum
Honored Contributor II
78 Views

-attachment

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