C28x Fixed Point DSP Library RFFT32_brev problem

Hi Vladimir,

Im not sure I understand your question fully when you say you run the restoration of the output data. If you bit reverse the input and then run the fft you will get the output in the correct order, you dont have to reorder the output.

Did i misunderstand your question?

Hi,

The input is NOT bit reverse, opp. output is bit reverse. I restore the output order, but the output is not the spectrum, there is a sine wave.

Very strange, as you explain this?

What is the input wave(frequency, complex or real etc) and what spectrum do you get. can you post graphs of both of them .

Also, which library are you using and what is the size of the FFT you are running?

Hi Vishal!

Input data is real (because the algorithm is RealFastFourier - RFFT_brev - bit reversion(output)). 64 point signed long integer on a input 64pointFFT. Later uploaded signals graphic, there is no possibility.

Vladimir,

Im assuming you are using the Fixed Point library in controlSUITE. There is an example of an RFFT in there although it bit reverses the input befor running the FFT. Can you modify that example with your input data and verify he spectrum?

Hi Vishal!

 Thank you very much for your help!

The question is answered.