Thank you for your answer Marcus. Do you know when support for fragmentation of big vectors will arrive in RFNoC, are we talking more than a year or just a couple of months/weeks?
Best regards Simon On Thu, Mar 3, 2016 at 5:20 PM, Marcus Müller <[email protected]> wrote: > Dear Simon, > > it's actually really just a constraint of how RFNoC packages data for > transport. It doesn't support fragmenting big vectors (yet), so your vector > has to fit one packet. Since the maximum size a packet can carry is 9000B, > and a sc16 complex is 8B long, you only get 9000/8-long FFT output, or > shorter. > > > Ok thanks, so it's a limit in the RFNoC software and not related to > Ettus FPGA hardware or something like that? > Now, whether our FPGA code having that limitation is a software or an FPGA > hardware problem is up for discussion, in my opinion :) > > A possible workaround would be writing your own wrapper for the Xilinx IP > core used to actually do the FFT, which would be able to fragment. But then > again, the question is what you want to do with the output afterwards. > > Best regards, > Marcus > > > On 03/03/2016 05:10 PM, Simon Olvhammar wrote: > > Ok thanks, so it's a limit in the RFNoC software and not related to Ettus > FPGA hardware or something like that? > I dont see that limit in regular GNURadio and 8192 channels works fine, > isnt the packet size also max 9000 there? > Simon > > On Thu, Mar 3, 2016 at 3:45 PM, Marcus D. Leech < <[email protected]> > [email protected]> wrote: > >> On 03/03/2016 05:21 AM, Simon Olvhammar wrote: >> >>> Hi, >>> >>> I'm wondering what it would take to modify the current FFT RFNoC block >>> to be able to compute a 8192 channel FFT. Someone that can guide me in the >>> right direction? I'm a quite experienced programmer, however not in HDL. >>> >>> Best regards >>> Simon >>> >>> >>> The main current stumbling block to large FFTs in RFNOC is that the FFT >> output has to be able to fit into a single transport packet, and >> that is limited to 9000 bytes, which pretty-much limits you to 2048-bin >> FFTs. There will be work in the future to allow FFT outputs in >> RFNOC to span multiple packets. >> >> >> >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> [email protected] >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> > > > > _______________________________________________ > Discuss-gnuradio mailing > [email protected]https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > >
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