Dear Robin,
Thanks for the quick reply. Although the 180-degree ambiguity is already good to know, what we are observing is really some rotation in the IQ plane (not just an ambiguity). Does the LO lock happens fast? Or should I wait for some time after launching my GNURadio script for the PLL to lock? Thanks, François From: Robin Coxe [mailto:[email protected]] Sent: mardi 20 février 2018 15:59 To: Francois Quitin <[email protected]> Subject: Re: [USRP-users] synchronizing two USRP-B205 mini The Analog Devices AD9361 RF integrated transceiver in the B205mini has a divide-by-2 PLL inside when using an external reference input, so there will always be a 180 degree phase ambiguity. See this post from my former colleague (also named Robin) at ADI: <https://ez.analog.com/thread/73543> https://ez.analog.com/thread/73543 -Robin On Tue, Feb 20, 2018 at 8:53 AM, Francois Quitin via USRP-users < <mailto:[email protected]> [email protected]> wrote: Dear all, I’m having a problem synchronizing two USRP-B205 mini. The setup is as follows: I use one USRP as a transmitter, the other as a receiver, and they are connected by cable. The “ref” input of both USRPs is connected to a 10MHz output (also tried with PPS output) of an Octoclock. In GNURadio, the “Clock source” (“Time source” when using PPS) is set to “external”. I then transmit a signal with one USRP (constant source, real sine source, BPSK sequence) with one USRP and receive it with the other USRP. The received signal is rotating in the IQ-plane, as if there were some LO frequency offset remaining. In principle, if both USRPs are connected to the same reference, there should be no frequency offset. Any ideas where this is coming from? Cheers, François _______________________________________________ USRP-users mailing list <mailto:[email protected]> [email protected] <http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
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