Hi Fabian, Cherif, What is the external PPS device you are using?
-Daniel On Thu, Sep 26, 2019 at 9:18 AM Fabian Schwartau via USRP-users < usrp-users@lists.ettus.com> wrote: > Hi, > I have very similar problem with X310. I am running a C++ application, > so I have a bit more flexibility I guess. After I do the > set_time_unknown_pps to sync to the 1PPS signal, I run the function > get_time_last_pps and it sometimes has an offset of 10ns (it was 5ns for > an old firmware due to a bug, which was fixed a few weeks ago). If that > is the case I just do the sync again until the offset is zero. > I don't know if it is an firmawre problem or if it is because the signal > integrety of the 1PPS signal is not good enough. > Maybe that is also a solution for you. > Best regards, > Fabian > > Am 25.09.2019 um 11:16 schrieb Cherif Diouf via USRP-users: > > Hello, > > I am working with the X310 USRP. I have two identical custom blocks > > feeding the RF frontends. > > > > flowchart > > ----------------- > > HW Block1 -> RF0-TX1 |---< > > HW Block2 -> RF1-TX1 |---< > > > > The system is synchronized to an external PPS reference. The sampling > > rate is 200 MSps and the signal bandwidth is 160 MHz for both channels. > > The two HW blocks start transmitting at the exactly same time. Time > > resolution is 5ns. > > In most cases the two outgoing RF signals present a 1ns time offset. > > Which can be understood as a phase offset. > > > > But From time to time there is a 6ns delay between the channels. I > > assume this 6ns comprises the 1ns delay due to phase offset + 5 ns delay > > due to misalignment of outgoing samples. > > > > What could be the origin of this one sample misalignement? Is it a way > > to fix it? Or working close to the limits of the device should such > > behavior be expected? > > > > Thanks in advance > > > > Best Regards > > Cherif > > > > > > _______________________________________________ > > USRP-users mailing list > > USRP-users@lists.ettus.com > > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > > > > -- > -------------------------------------------------- > M.-Sc. Fabian Schwartau > Technische Universität Braunschweig > Institut für Hochfrequenztechnik > Schleinitzstr. 22 > 38106 Braunschweig > Germany > > Tel.: +49-(0)531-391-2017 > Fax: +49-(0)531-391-2045 > Email: fabian.schwar...@ihf.tu-bs.de > WWW: http://www.tu-braunschweig.de/ihf > -------------------------------------------------- > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > -- Daniel Jepson Digital Hardware Engineer National Instruments O: +1.512.683.6163 daniel.jep...@ni.com
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