hi chenwei, i don't know of anyone who has developed a megachannel spectrometer for roach2, so i hope you can share your design with the casper community.
here are three designs that you might find useful: 1) south africa develeped a mega channel spectrometer for roach1 : perhaps you can adapt their design ? 2) we developed a 128 million channel spectrometer for the bee2. info at https://casper.berkeley.edu/wiki/SETI_Spectrometer this 128 million channel spectrometer uses 3 steps a) course channelization (PFB) b) corner turn c) fine channelization on each course channel (FFT) 3) the old serendip3 and serendip4 spectrometers implemented a large FFT by implementing small FFT's on rows and columns, after putting the time domain vector into a 2D matrix, and applying these six signal processing steps: a) permute (either bit reverse or transpose) b) FFT each row c) permute (either bit reverse or transpose) d) apply complex twiddle factors to each element in matrix e) FFT each row f) permute (either bit reverse or transpose) best wishes, dan On Thu, Mar 26, 2015 at 12:38 PM, Chenwei Cai <caichenwei1...@gmail.com> wrote: > Dear CASPER, > > My name is Chenwei Cai, and I am constructing the Mega-Channel > Spectrometer with ROACH II. To achieve that, two corner turners are > required before we implement FFTs, which means I may use qdr_transpose or > qdr_ct blocks. Since I cannot find any explanations on these blocks > anywhere, could you provide me some details about the functions of these > two blocks and what kind of data do those ports receive/export? > > Look forward to hearing from you! > > -- > Best Regards > Chenwei CAI > > Mobile: +86-152-0147-9411 > Email: caichenwei1...@pku.edu.cn > >
