MATLAB: Cant I get the same results IFFT block and HDL Optimized IFFT block.

communications blocksetHDL Coderhdl optimized ifftifft

I'd like to perform OFDM on FPGA's and for that I had to use IFFT block. To perform the IFFT I used the example "OFDM Receiver with 512-Point Streaming I/O FFT". In the example OFDM transmitter part there is an IFFT block and I insert HDL optimized IFFT block and compare them with the spectrum analyzer. However the resultts are different. How can I öconstruct the OFDM transmitter? I put the screen shots of spectrum analyzers and the model.
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Best Answer

The HDL Optimized FFT and IFFT don’t support natural order output in R2014a. The output of the HDL Optimized IFFT in your model is in Bit Reversed order. To be able to compare the output of the HDL Optimized IFFT with IFFT, you need to put the output in natural order. Connect a deserializer and Bit Reverse Order block after your HDL Optimized IFFT and then connect it to spectrum analyzer. You can find these two blocks at the top level of the same example (OFDM Receiver with 512-Point Streaming I/O FFT).
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