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
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