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Altera_Forum
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13 years ago

FFT Megafunction problem - strange spikes

Hi, I use FFT IP Core (Quartus 9.1 SP2 / Quartus 11.1 SP2). I send sine-signal to sink pins and get fft-signal from source pins of core. Then I plot ABS, real and imag of my fft-signal in Matlab. ...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
13 years ago

I do not use a real signal (from ADC). I use "ideal" sine generated at Matlab:

signal 1:

for i=1:128;

ss(i) = Amp*sin(pi/100+pi*i/4);

end

signal 2:

for i=1:128;

ss(i) = Amp*sin(pi/10+pi*i/4);

end.

I put this signal (ram_in.hex) to In-System Memory Content Editor and then send to FFT core. Then I get signal from FFT core and save to ram. Then I get ram_out.hex from In-System Memory Content Editor and put to Matlab.