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Altera_Forum's avatar
Altera_Forum
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16 years ago

FFT output?

This is probably going to be a simple question, but have been unable to find documentation to explain it. I'm running a 512 point 24 bit width data streaming FFT. My output is 24 bits with 6 bits o...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
16 years ago

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The altera documentation states it uses block floating point for the FFT.

so what your saying is, and if my data is x"DEADBE" with an exponent "011100" (28 or -4) than it would shift my value down by 4? and my signal would be x"DEADB.E"

sorry im a little confused, not sure if that makes sense.

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It might actually be floating point then, just with an 6 bit exponent and 17 bit mantissa instead of the standard 8/23. This reduces logic requirements on the chip. It basically sacrifices range and accuracy so that it uses less resources (and possibly clock faster too).