Re: [Discuss-gnuradio] OFDM IFFT calculate
Ah, forgot to actually cite one thing: On 30.05.2016 14:49, Marcus Müller wrote: > >> I can't find its' implementation in anywhere so that I can't >> understand what happen in this function. > A DFT is performed, by calling the fftwf_execute function of the FFTw > library, which really, just executes a fast DFT. And because "DFT" is not totally unambiguous (because there are different normalization conventions out there), if you care for the actual formula, it's on http://www.fftw.org/doc/The-1d-Discrete-Fourier-Transform-_0028DFT_0029.html#The-1d-Discrete-Fourier-Transform-_0028DFT_0029 i.e. the backwards (inverse) n-point FFT is really just plain, old, boring, textbook No normalization. Best regards, Marcus ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] OFDM IFFT calculate
Hi SangHyuk On 30.05.2016 14:25, SangHyuk Kim wrote: > Hi all, > > The file, /gr-fft/lib/fft_vcc_fftw.cc(http://goo.gl/X8WNPh), No need to use URL shorteners in Emails. Why are you using a revision of that file from 2012? That is not what you should do. Select "branch: Master" from the drop-down menu; you should be looking at http://gnuradio.org/redmine/projects/gnuradio/repository/entry/gr-fft/lib/fft_vcc_fftw.cc?rev=master . Reading versions of code that no-one uses anymore doesn't help you ! > I can understand how get inputs to 'd_fft', but I don't know about d_fft->execute() that compute the fft. So, here's how you approach something like this: Find out what "d_fft" is. For that, you often need to look in the .h file to your .cc. There you'll find out which class type d_fft has. Find that type's definition. Or, you could just go to and search for "execute" in the search box. That'll tell you the classes that have a method called "execute", and you can access the documentation to these. > I can't find its' implementation in anywhere so that I can't > understand what happen in this function. A DFT is performed, by calling the fftwf_execute function of the FFTw library, which really, just executes a fast DFT. Best regards, Marcus ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] OFDM IFFT calculate
Hi all, The file, /gr-fft/lib/fft_vcc_fftw.cc(http://goo.gl/X8WNPh), changes domain from frequency to time using IFFT(Inverse-Fast-Fourier-Transform). It takes parallel subcarriers in frequency-domain (it is defined 'in' in the file) and converts it into time-domain(it is defined 'out'). I can understand how get inputs to 'd_fft', but I don't know about d_fft->execute() that compute the fft. I can't find its' implementation in anywhere so that I can't understand what happen in this function. Could anyone tell me how compute the fft in the function ? Thanks. ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
