Ah! You've set the data type of the QT GUI sink to "complex message"; I wasn't aware that this feature had made it to the master branch :)
> The point of moving to C++ was that the flowgraph I /really/ want to > use is just causing me huge problems - most notably that there are > periods of a few seconds every now and again when the USRP drops a > load of packets and then, after a while, the flow just freezes up. I > find it difficult to follow how GNU Radio really works and I thought > it would be a better bet to be directly in control of my samples all > the way. Hm, yeah, I know it's not trivial, but I'm pretty sure this isn't the way to go. What kind of flow graph was giving you so much trouble? Best regards, Marcus On 08/03/2017 11:15 AM, Jack White wrote: > Hi Marcus, > > Thanks for the response. I attach the flowgraph I am using for this > test, and for which I got the "unknown data type of samples" error. > > I wasn't aware that the metadata was included in the PDUs, so that > makes more sense now. > > The point of moving to C++ was that the flowgraph I /really/ want to > use is just causing me huge problems - most notably that there are > periods of a few seconds every now and again when the USRP drops a > load of packets and then, after a while, the flow just freezes up. I > find it difficult to follow how GNU Radio really works and I thought > it would be a better bet to be directly in control of my samples all > the way. > > Jack > > > > On Wed, Aug 2, 2017 at 10:45 PM, Marcus Müller via USRP-users > <usrp-us...@lists.ettus.com <mailto:usrp-us...@lists.ettus.com>> wrote: > > Hi Jack, > > PDUs are not just samples one after the other – they contain > metadata. I can't really imagine what your flow graph looks like, > so I'd be grateful for a screenshot (File->Screen Capture). > > Anyway, there'd be no obvious reason your UDP detour would make > things faster – maybe the intermediate socket buffering might > help, but you'd probably get the same result by extending a UHD > USRP Source's Output Buffer Size. > > So, I'm not sure where we should take this – from a gut feeling, > we should maybe move on to the discuss-gnuradio mailing list and > discuss what part in your GNU Radio application isn't performing > well enough – as I'm currently assuming your approach wasn't born > through an in-depth analysis, but might more be of a trial&error > iteration? > > Best regards, > > Marcus > > > On 02.08.2017 13:10, Jack White via USRP-users wrote: >> Hi, >> >> I've been having some difficulty getting reliable data flow from >> my USRP X310 with a GRC flowgraph, so I'm trying out writing my >> system in C++ with the UHD driver API. My first step has been to >> retrieve samples from the X310, forward them to a UDP port and >> then pick them up with a GRC Socket PDU component and then plot >> them. The C++ programme, so far, follows Ettus's example >> rx_samples_to_udp almost exactly and uses the std::complex<float> >> data type. >> >> When the data enters the running flowgraph from the UDP >> transport, I get this error: >> >> thread[thread-per-block[1]: <block freq_sink_c (1)>]: >> freq_sink_c: unknown data type of samples; must be complex. >> >> Can anyone offer insight into why this should occur? >> >> Many thanks, >> >> -- >> Jack White >> white.n.j...@googlemail.com <mailto:white.n.j...@googlemail.com> >> 07875 813 745 >> >> >> _______________________________________________ >> USRP-users mailing list >> usrp-us...@lists.ettus.com <mailto:usrp-us...@lists.ettus.com> >> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >> <http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com> > _______________________________________________ USRP-users mailing > list usrp-us...@lists.ettus.com > <mailto:usrp-us...@lists.ettus.com> > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > <http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com> > > -- > Jack White white.n.j...@googlemail.com > <mailto:white.n.j...@googlemail.com> 07875 813 745
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