Re: How to perform FFT shift after FFT?

[Ron Economos]

Just look at the code for the FFT block.

https://github.com/gnuradio/gnuradio/blob/main/gr-fft/lib/fft_v_fftw.cc#L81

Ron

On 8/22/22 03:37, Bartłomiej Sójka wrote:
> Hi,
> I'm trying to write a block that would compute FFT on the received samples, but 
> I'm having trouble with finding how to perform FFT shift after the computation. 
> Any help with that?
> So far I'm using
>
> d_fft = std::make_unique<fft::fft_complex_fwd>(d_fftsize);
>
> memcpy(d_fft->get_inbuf(), d_fft_processed.data(), 
> d_fftsize*sizeof(gr_complex)); //get samples from input and store them in input 
> buffer
> d_fft->execute(); // compute the fft
> memcpy(d_fft_processed.data(), d_fft->get_outbuf(), 
> d_fftsize*sizeof(gr_complex)); //get processed samples from output buffer and 
> storing them in d_fft_processed
>
> I'll appreciate any help
> Bartek