Re: [USRP-users] 2 B210 synchronous problem
Hi Hideyuki, For the solution look at the end of "Is it possible to time synchronize multiple USRPs B210?" thread. I attached there a working example for two USRPs B210. -- Best Regards, Piotr Krysik ___ USRP-users mailing list USRP-users@lists.ettus.com http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
Re: [USRP-users] 2 B210 synchronous problem
dniu 23.01.2018 o 19:11, Martin Braun via USRP-users pisze: > On Thu, Jan 18, 2018 at 10:34:14AM +0100, Piotr Krysik via USRP-users wrote: >> Hi Hideyuki, >> >> Our students were working (with my help) on synchronizing two USRPs B210 >> with use of Octoclock-G. >> To make your code work without any race-conditions I would add a loop >> that waits for pps edge before your adjustment code, like this: >> ``` >> time_last_pps = self.uhd_usrp_source_0.get_time_last_pps() >> while(self.uhd_usrp_source_0.get_time_last_pps() == time_last_pps): >> time.sleep(0.01) >> ``` > This is good advice. You can go to multi_usrp.cpp and take a look at > set_time_unknown_pps() for a reference on how to do that. > Hi Martin, The problem is that even when I replicated exactly the set_time_unknown_pps() function in Python it doesn't work with USRPs B210. It works perfectly well with X310s but somehow with B210s there is some time offset (few hundreds us) that changes from one program execution to another. I still have to check on different B210s and different Octoclocks but it requires some time and in the end I don't expect a surprise (probably I will just be more sure that it is fault of the B210). So even to get information from someone like: "I checked and it works for me" would help me and others a lot. -- Best Regards, Piotr Krysik ___ USRP-users mailing list USRP-users@lists.ettus.com http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
[USRP-users] 2 B210 synchronous problem
Hi I bought 2 B210s for testing direction of arrival estimation, like below. === Configuration = Ch0 <--> | USRP0 Rx 0 | || <-- USB3.0 --> | PC| Ch1 <--> | USRP0 Rx 1 || Ubuntu 14.04| | GNU Radio Companion 3.7.11.1| Ch2 <--> | USRP1 Rx 0 || UHD_003.010.001.001-79-g7ac01c7f| || <-- USB3.0 --> | | Ch3 <--> | USRP1 Rx 1 | - External 10MHz reference CLK & 1PPS are provided by function generator(Tektronix AFG1012) to each B210 - center freq 2.4GHz - samping rate 4MHz In GRC - 2 separate USRP Source for each B210, settings are below - Sync option unknown pps - Clock Source External - Time Source External - Num Channels 2 I generated python code by GRC and then I added custom timing adjustment code. ``` self.uhd_usrp_source_0.set_time_next_pps(uhd.time_spec(0)) self.uhd_usrp_source_1.set_time_next_pps(uhd.time_spec(0)) time.sleep(1.0) start_time = uhd.time_spec(5.0) self.uhd_usrp_source_0.set_start_time(start_time) self.uhd_usrp_source_1.set_start_time(start_time) ``` === I believe that I am following all the instructions what I found in web. but, when I tried to check that sampling timing is exactly matched or not by dumping all the samples(connect File Sink), I found sampling gaps between 2 B210. While testing, I confirmed that - there are no overflow, - start timing would be exactly the same(using Tag Debug to confirm) I observed that - gaps looks fixed size during running - gaps are slightly different every time Please let me know what I am missing. Thanks, Matsu ___ USRP-users mailing list USRP-users@lists.ettus.com http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
