Hi John, Are you power cycling the USRPs between tests or just rerunning the GRC flowgraph? Do you have shared 10 MHz and 1 PPS references? What version of UHD is printed in the output?
Thanks, Derek On Mon, Sep 11, 2017 at 1:50 AM, John Shields <sla1nte2...@gmail.com> wrote: > Thanks for the feedback but I am not sure that I understand it. What I was > hoping to do was step through the configurations with increasing levels of > synchronisation and expecting to see same. > > Marcus' comment is correct and I have not, yet, put in the code which > synchronises SBXs. > > I guess my basic point, from looking at previous post from others Marcus L > included, was that UHD would somehow improve the synchronisation between > two USRPs in the same container versus those two separately. > > When I executed the FG shown (separately) with the USRPs individually and > then within a UHD container the results in terms of phase variation was the > same. I had expected that, based on my understanding, the containerised > USRPs would have behaved better. > > So, either my FG does not measure what I thought it should or there is > little UHD-related benefit to having USRPs individually or in the 'domain' > as MarcusL has mentioned previously. From my situation it doesn't hence the > first question in the post: > > > Does my FG not measure what I claim to be wishing to > measure? > > > Kind Regards, > > John > > > > On 11/09/17 01:03, Marcus D. Leech wrote: > > On 09/10/2017 08:58 PM, Dan CaJacob wrote: > > I could be wrong, but I thought the SBX was one of the few daughter cards > that starts with s known phase offset? > > Only if you ask it to do so, and only if it's sharing clock with its > buddies... > > > On Sun, Sep 10, 2017, 2:49 PM Fulcrum Associates <sla1nte2...@gmail.com> > wrote: > >> Dear All, >> >> I have a couple of USRPs connected, through a strong >> attenuator to a signal generator (NWT4001). While the units have a MIMO >> option, I don't have that cable. (Option A) When I run the GRC as >> attached, I see too good a result to the extent that the differential >> Phi seems to range over +/- 5 degrees. >> >> >> What I had hoped to prove to myself that two N200 with SBX >> would have a varying offset without MIMO cable, then I would connect the >> MIMO cable and move the USRPs into a multi-unit and enable GPSD O/B on >> the unit which has the feature and MIMO for one without (Option B) and >> that the phase differential would improve noticeably and be a variable >> constant, but it didn't. >> >> >> If it had, but there still was a fixed phase offset which >> varied each time it was setup (which is what I would expect under B) >> then I would hand-code the SBX stream initialisation code to remove the >> offset. >> >> >> Does my FG not measure what I claim to be wishing to >> measure? >> >> If it does measure it correctly, why do my expectations >> of options A and B leading to a different (though improved) situation >> not eventuate? >> >> >> Kind Regards, >> >> >> John >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> Discuss-gnuradio@gnu.org >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> > -- > Very Respectfully, > > Dan CaJacob > > > _______________________________________________ > Discuss-gnuradio mailing > listDiscuss-gnuradio@gnu.orghttps://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > > > > _______________________________________________ > Discuss-gnuradio mailing > listDiscuss-gnuradio@gnu.orghttps://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > >
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