W dniu 21.09.2017 o 21:06, Marcus D. Leech via USRP-users pisze: > On 09/21/2017 02:27 PM, Piotr Krysik via USRP-users wrote: >> >> -- >> Piotr Krysik >> >> >> Also take into account that I'm not comparing phase signals observed by >> two different USRPs. What I have shown is for single channel of one USRP >> in which such jumps are observed (I'm comparing phase of digitally >> generated sinusoid with phase of recorded one). Same thing, however, can >> be observed when recording signal with two USRPS in situation where one >> have board mounted GPSDO and another one doesn't (with simple >> unwrap(angle(x1.*conj(x2))) where x1 and x2 are signal vectors). Both >> USRPs synchronized with use of Octoclock-G. >> >> To make the matter simpler to gasp I will check if the same problem can >> be observed on one USRP B210 with board mounted GPSDO - without any >> additional hardware. >> >> > I use B210s for interferometry. Phase coherence is stable basically > "forever" between two B210 RX channels, regardless of the reference > used, since the > LO is shared between the two receive channels. So, absent bugs in > the FPGA digital processing, I'd be very surprised to see phase-hits > within a single > B210. >
Hi, The problem appears only when synchronizing USRPs B210 that have board mounted GPSDO with use of Octoclock-G. This configuration doesn't work correctly. Marcus - I suppose that you haven't seen this problem yet because you didn't try to use B210s in such configuration. I've checked today signal phase on a single USRP B210 with GPSDO, but without connecting external synchronization source. In this situation everything is fine. So what is good is that it is not board mounted GPSDO alone that causes the problem. In short the solution for now is: remove GPSDO from your USRP B210 if you want to synchronize it with use of external PPS and 10MHz ref source. (The solution is not perfect as these GPSDOs have delicate pins at the connector.) Best Regards, Piotr Krysik _______________________________________________ USRP-users mailing list USRP-users@lists.ettus.com http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
