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346 Views
Registered: ‎07-04-2018

What does type(fix12_11) mean? and how to set input in FFT

Hi, everyone!
I have serached for so long but I sill can't fingure out what does "fit12_11" mean in the FFT IP.
1.png
Does it mean there is only 11 bit of integer part and 1 bit of fractional part?
 
Also, my maximum of input data is 525. Should I adjust all my input data to xx*2 if I set SCALE_SCH to 2("10 00 00 00 00") ?
 
What would happen if I set the SCALE_SCH to "00 00 00 00 00"? I think outputs are also near to the correct ones, but why it seems totally different from the matlab results?
 
Thanks very much!
 

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263 Views
Registered: ‎08-16-2018

Re: What does type(fix12_11) mean? and how to set input in FFT

@liutianyang_sari 

"fix12_11" is the fixed point number of with 11 bits as "fractional bit". 

SCALE_SCH is a part of "s_axis_config_tdata" format. You need to set it accordingly. 

Please see page 16 of PG109 for more details.

 


/ 7\7     Meher Krishna Patel, PhD
\ \        Senior Product Application Engineer, Xilinx
/ /        
\_\/\7   It is not so much that you are within the cosmos as that the cosmos is within you...
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244 Views
Registered: ‎07-04-2018

Re: What does type(fix12_11) mean? and how to set input in FFT

Thanks a lot!

But R U sure that fix12_11 means there is 11 bits as fractional bit? So all the input data have to be range [-1,1]?

 

Look forward to your reply!

 

Thanks!

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Moderator
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Registered: ‎08-16-2018

Re: What does type(fix12_11) mean? and how to set input in FFT

All the values will be represented as 12 bits with range [-1, 1].

Can you please elaborate your last question? I did not understand your issue with range [-1, 1]?


/ 7\7     Meher Krishna Patel, PhD
\ \        Senior Product Application Engineer, Xilinx
/ /        
\_\/\7   It is not so much that you are within the cosmos as that the cosmos is within you...
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