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Altera_Forum's avatar
Altera_Forum
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14 years ago

Strange FFT Output

I've been using SignalTap to create a CSV file of the output from my FFT engine. However, when looking at the output in Matlab, it doesn't look right at all. I know that the ADC's working prop...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
14 years ago

Right, I've identified an error here. As I've mentioned before, the input to my FFT is a 12-bit signed value, and for some reason, when the value is negative, the whole rest of the word is populated with 1s rather than just the MSB. For example, the value 111111111010 is used to represent -6, rather than 100000000010.

I think this is causing the FFT to clip, and give me a really weird output. Any ideas why this would be happening?