[USRP-users] Multi-PC Sync

Rob Kossler rkossler at nd.edu
Tue Mar 29 15:49:53 EDT 2016


Hi Charlie,
Given that you have 2 X310s working on one PC, I am guessing that you may
have already implemented Marcus' set_command_time suggestion, since this is
necessary even for 1 X310 on a single PC.  I have implemented "multi-PC"
applications for both TX and RX although the TX version has not been well
tested.  It should be able to work in a similar way to a single PC.  The
various PCs must have sync-ed times such that whenever you send a
set_tx_freq command or whenever you start streaming, they all need to
execute the command at the identical time.

Rob


On Tue, Mar 29, 2016 at 3:11 PM, Marcus Müller <usrp-users at lists.ettus.com>
wrote:

> Dear Charlie,
>
> You must use timed commands to tune the RF frontends, so that they are
> phase-synchronous; otherwise, the tuning timing, and hence the phase, will
> be random each time.
>
> Roughly:
> usrp->set_command_time(some_time_in_the_future);
> usrp->set_tx_freq(your_tune_request);
>
> Best regards,
> Marcus
>
>
> On 29.03.2016 21:05, Gorlinski, Charlie @ SSG - PE - IEC via USRP-users
> wrote:
>
> Hi Ettus,
>
>
>
> I am successfully streaming 2 X310s on one Linux PC.   Using a slightly
> modified version of tx_samples_from_file, the carriers of all 4 RF output
> channels are nicely synced together using an Octoclock to distribute 10MHZ
> and 1PPS from a Rubidium clock to each X310.
>
>
>
> I want to sync a 2nd Linux PC with 2 more X310s and sync those 4 RF
> outputs channels to the same Octoclock, so that I wind up with all 8 RF
> carriers synced together from the 2 PCs.  I can successfully instruct the
> modified tx_samples_from_file on PC#2 to start at the same 1PPS as PC#1,
> but the 4 RF carriers from PC#2 are NOT locked to the 4 carriers of PC#1
> even though the X310s in each share the same clock and 1PPS distribution.
>
>
>
> What do you recommend  for RF carrier synchronization between 2 PCs, each
> with their own X310s that share a common 10MHz and 1PPS?
>
>
>
> Thanks,
>
> Charlie
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