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Why i do not get a fixed point out from a FFT HDL optimized block in simulink?

I am creating a HDL model on simulink,
using a fixed-point input on FFT HDL Optimized i get a double output, and the block parameters does not have the option of "scaling" or modify the output data type.
I am running a 2015b matlab version


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2 Answers

Answer by Bharath Venkataraman on 19 Jun 2019
Edited by Bharath Venkataraman on 19 Jun 2019
 Accepted Answer

I may need the model to do further debugging. In the meantime, I created a simple FFT model in R2018b which seems to do the right thing in terms of datatypes. One change from your model is that the values are sent in serially to the FFT rather than all at once. I have also attached a model created in 15b.
I defined the input fftIn as:
fftIn = complex(rand(128,1),rand(128,1));


Thank you for sharing the simple model, it worked and i will modify it to meet my objective, i dont know what is wrong with the last one identical FFT block but wathever.
I apreciate your help!.
Great! FWIW, the next few releases have a lot more capabilities for the block, so if you are able to get to a later release like R2018a, you can use these capabilities.
Here are the release notes for DSP System Toolbox.

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Answer by Bharath Venkataraman on 18 Jun 2019

Could you double click on the FFT block and send a snapshot of its parameters?

  1 Comment

Thank's for your reply ,
These are the block properties
Data types
Control ports

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