Hi Chenwei, I'm not sure about the qdr corner turn block, but the qdr transpose is fairly simple. It has two parameters, "input block size", and "output block size". The first is the number of channels in the fft input stream, the second is the number of spectra you want to buffer and transpose. I.e. the number of consecutive samples of each channel you want the block to output. For the million channel spectrometer, I expect you'd want something like:
2**11 point (real) fft (2**10 channels output) -> Qdr transpose, input size = output size = 10. -> 2**10 point complex fft. On roach 2, the inputs and outputs of the qdr transpose data streams are 72 bits wide. As with the other Casper blocks, there's also the usual boolean sync pulse which should be input the clock before the first sample in a transpose is input, and will be output the clock before this sample arrives on the data output port. Hope that helps, Jack On Thu, 26 Mar 2015 7:38 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 > >
