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JWall40's avatar
JWall40
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5 years ago

FFT IP Core - Input and output number format?

I am unsure what data format I should use for the FFT IP core input and what data format it will output I can only find a few references to this topic in the user guide: “Imaginary input data, whic...
JWall40's avatar
JWall40
Icon for New Contributor rankNew Contributor
5 years ago

So using fixed point number format means that the FFT cannot deal with negative numbers and will treat all values as unsigned fixed point with no scale factor. So just whole, positive numbers?

So to see a correct display of my output values in signal tap, I should set the bus display format to unsigned decimal?

Many thanks

Jack

CheepinC_altera's avatar
CheepinC_altera
Icon for Regular Contributor rankRegular Contributor
5 years ago
Hi Jack, Yes, you are right. When you are using fixed point number format, the FFT will treat the number as if positive binary number. You can use unsigned decimal for bus display in signaltap to view. Alternatively, you can also use single floating point if you would like to the FFT to process decimal and signed/unsigned number. Please let me know if there is any concern. Thank you. Best regards, Chee Pin