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JWall40's avatar
JWall40
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6 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...
CheepinC_altera's avatar
CheepinC_altera
Icon for Regular Contributor rankRegular Contributor
6 years ago

Hi,

As I understand it, you have some inquiries regarding to the data format for the FFT. For your information, by default, the data format configuration in the FFT = Fixed Point. With Fixed Point, the FFT will treat the input and output data as normal binary data without sign. Note that after the FFT, there will be bit grow. So, you will ensure you have sufficient output width.

Please let me know if there is any concern. Thank you.

Best regards,

Chee Pin

JWall40's avatar
JWall40
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6 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