[USRP-users] 2 B210 synchronous problem
hideyuki.matsunaga at gmail.com
Wed Oct 25 02:59:39 EDT 2017
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 126.96.36.199 |
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
- 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
start_time = uhd.time_spec(5.0)
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.
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