Dmitry, The PPS and 10MHz should (at the very least) be generated using the same base clock so they don't drift with respect to one another. Since you are using multiple X310 devices, it is also important that the PPS arrives at each device on the exact same cycle of the 10MHz clock--otherwise you may see your timekeepers in each X310 offset with respect to one another. There are no setup or hold specs for the X310 for PPS relative to 10MHz, but if you use equal length cables for both signals you should achieve a decent level of consistency.
-Daniel On Mon, Jun 18, 2018 at 10:17 AM, Marcus D. Leech via USRP-users < usrp-users@lists.ettus.com> wrote: > On 06/18/2018 10:57 AM, Дмитрий Михайличенко via USRP-users wrote: > > Is it important to have PPS signal aligned with reference 10 MHz signal. > In my case they come from different sources. > > thanks, > Dmitry? > > That shouldn't matter > > > > > пн, 18 июн. 2018 г. в 17:37, Marcus D. Leech via USRP-users < > usrp-users@lists.ettus.com>: > >> On 06/18/2018 10:28 AM, Дмитрий Михайличенко via USRP-users wrote: >> >> The frequency is around 600 MHz. I also tried higher frequencies. The >> offset is visible on picture attached. >> >> thanks, >> Dmitry >> >> If you look here: >> >> https://kb.ettus.com/UBX >> >> You can see that for frequencies below 1GHz, you have to use a 20MHz >> daughterboard clock for UBX to achieve synchronization. >> I don't know if SBX will work correctly with a 20MHz daughterboard >> clock, so you can't have "mixed" UBX + SBX on the same >> X310. >> >> Also, integer-N tuning can help maintain better phase synchronization >> characteristics: >> >> https://files.ettus.com/manual/structuhd_1_1tune__request__t.html >> >> >> пн, 18 июн. 2018 г. в 14:50, Дмитрий Михайличенко <mdm...@gmail.com>: >> >>> Hi, >>> >>> I have a couple of X310 each of them has UBX+SBX cards. The devices are >>> synchronized by external 10MHz + PPS signal. But in my test I see random >>> phase delay between all channels that varies between test runs. The test >>> creates multi usrp device, sets up time and tunes to the same frequency >>> using timed command, then it captures some buffers. The same external >>> signal is supplied to all antenna ports. Is it expected to have random >>> delay between channels? Is there any way to have constant phase delay from >>> run to run? >>> >>> thanks, >>> Dmitry >>> >> >> >> _______________________________________________ >> USRP-users mailing >> listUSRP-users@lists.ettus.comhttp://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 >> > > > _______________________________________________ > USRP-users mailing > listUSRP-users@lists.ettus.comhttp://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 > > -- Daniel Jepson Digital Hardware Engineer National Instruments O: +1.512.683.6163 daniel.jep...@ni.com
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