[USRP-users] Using REF OUT / REF IN between two X310s

Marcus D. Leech patchvonbraun at gmail.com
Sat Mar 2 23:04:20 EST 2019

On 03/02/2019 04:41 PM, Achilleas Anastasopoulos via USRP-users wrote:
> Hi all,
> In the past I had performed the following successful experiment using 
> two N210's connected with a MIMO cable:
> I transmitted a single sinusoid of 10KHz through on USRP at a carrier 
> of 1GHz and received it on another N210. The latter was configured to 
> use the MIMO cable for clock reference. I was able to verify that the 
> two clocks are indeed synced because I saw a single (noisy) point at 
> the constellation scope (after correcting for the 10KHz on the Rx 
> side) that was very stable (no rotation).
> I wanted to do the same with two X310's and connected them through a 
> cable from the REF OUT of the first to the REF IN of the second.
> I also changed the Rx clock reference:
> Mb0: Clock Source = EXTERNAL
> Mb0: Time source = EXTERNAL
> However this experiment was unsuccessful: I do not see a single point 
> but a circle which indicates that the two clocks at Tx/RX are not synced.
> Can you guide me as to what I am doing wrong.
> thanks
> Achilleas
Based on your description, shouldn't it be mb1 getting the EXTERNAL 
sources, rather than mb0?

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