I can tell you the answer to #3 off the top of my head: the two streams will be sample-aligned, and if you use timed start commands, they will be time-aligned.
The other two are probably best answered by trying it out. Maybe someone from Ettus can chime in. Nick On Fri, Mar 22, 2019 at 7:09 AM Rob Kossler via USRP-users < usrp-users@lists.ettus.com> wrote: > Any suggestions? > > On Wed, Mar 20, 2019 at 9:49 PM Rob Kossler <rkoss...@nd.edu> wrote: > >> Yes, the example was for illustration only. You can throw a couple of >> DDCs in between the radio and add/sub block to slow the rate down. But, >> the questions are still the same. >> >> On Wed, Mar 20, 2019 at 7:49 PM Nick Foster <bistrom...@gmail.com> wrote: >> >>> First things first. The flow graph you're describing don't work because >>> the two radio blocks will saturate the bus going into the addsub block. You >>> will need to decimate the streams going into the addsub block. >>> >>> I don't have a ready answer to your question about the streamers, but >>> I'd suggest using timed commands to align the two radio streams, if UHD >>> isn't smart enough to recognize the two radios and propagate the stream >>> command accordingly. >>> >>> Nick >>> >>> On Thu, Mar 21, 2019, 6:46 AM Rob Kossler via USRP-users < >>> usrp-users@lists.ettus.com> wrote: >>> >>>> Hi, >>>> I am starting to develop more complicated RFNoC graphs and several >>>> questions occurred to me. I am using my own C++ application with the UHD >>>> RFNoC-enabled library. >>>> >>>> Consider a receive-only RFNoC graph with 2 radio blocks feeding a >>>> 2-input, 2-output Add/Sub block. Also, assume there are two rx_streamers >>>> connected to the 2 output ports of the Add/Sub block. Note that these >>>> streams are no longer independent or one-to-one matched with the radio >>>> channels. >>>> >>>> 1) How does an "issue_stream_cmd()" to one of the Add/Sub block ports >>>> propagate back to the radio block? Actually, it would need to propagate >>>> back to both Radio blocks no matter which rx_streamer I used since they are >>>> no longer independent streams. Does this make sense? >>>> 2) What happens if I only call "issue_stream_cmd()" for one of the >>>> rx_streamers instead of both? Perhaps since the other streamer isn't >>>> running, it backpressures the streaming such that it eventually quits and >>>> thus quits for the other port as well? >>>> 3) Do I have to do anything in the Add/Sub block to sync up the streams >>>> or can I rely on the first sample from Radio 0 being time-aligned with the >>>> first sample from Radio 1 (assuming I issued timed start commands)? >>>> >>>> Rob >>>> _______________________________________________ >>>> USRP-users mailing list >>>> USRP-users@lists.ettus.com >>>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >>>> >>> _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >
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