Hi, Jack, I haven’t used the biplex_core block in a while, but I believe the inputs, pol1 and pol2, are two independent complex input signals. The outputs, out1 and out2, first output the frequency channels for input pol1, with the low half of the band being output in bit reversed order on out1 and the high half of the band being output on out2 in bit reversed order. After outputting the channels for pol1, out1 and out2 output the channels for pol2 in a similar order.
For a 16 channel fft, I think out1 will have channels: pol1[0 4 2 6 1 5 3 7] followed by pol2[0 4 2 6 1 5 3 7]. Out2 will have the same output order but 8 (ie N/2) channels higher. I hope that makes sense, but if not I can make a better diagram for you tomorrow. Of course this should be verified with simulation, but I think it’s a good starting point. BTW, this assumes the inputs are presented in natural tone order at both inputs with the t=0 samples of pol1 and pol2 being presented at the respective inputs simultaneously. Dave > On Feb 21, 2018, at 18:04, Jack Hickish <jackhick...@gmail.com> wrote: > > Howdy, > > Partly motivated by a search for RAM savings, and partly for fun, I'm looking > through the innards of the fft_biplex_real_4x block. Can someone tell me, > using short words and/or pictures, what the the relationship between the > inputs (pol1, pol2) and the outputs (out1, out2) on the biplex_core block is. > > I'm in the midst of reverse engineering the block by simulation / staring at > the unscrambler / reading about fft biplex implementations, but surely > someone must(!) know what this block actually does (or claims to do)? > > Yours, optimistically, > > Jack > -- > You received this message because you are subscribed to the Google Groups > "casper@lists.berkeley.edu" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to casper+unsubscr...@lists.berkeley.edu. > To post to this group, send email to casper@lists.berkeley.edu. -- You received this message because you are subscribed to the Google Groups "casper@lists.berkeley.edu" group. To unsubscribe from this group and stop receiving emails from it, send an email to casper+unsubscr...@lists.berkeley.edu. To post to this group, send email to casper@lists.berkeley.edu.
