On 01/09/2019 08:54 PM, Yang Liu wrote:
Hi Marcus,
Thanks!
I feel a little confused about the term 'frequency synchronization'.
if the two LOs on the two daughterboads are using the same frequency
reference, does it mean that after tuning, they will produce
identical CFOs to the same receiver (one receiving channel) or we can
say that the difference in CFOs are almost negligible? (lets for now
ignore other factors that can contribute to CFO)
I read through 'align LOs in the front-end' in the link
https://files.ettus.com/manual/page_sync.html. timed command makes
sure that different daughterboads can be tuned at the same time, so
that it can only help to mitigate the phase offset, but it doesn't say
anything about the potential frequency offset between the two
daughterboards.
Best,
Yang
There will be no frequency offset between the two cards--they're
programmed identically, and use the same reference clock. So other than
phase-noise and phase-offset, they will be, for all intents, "identical".
On Wed, Jan 9, 2019 at 3:17 PM Marcus D Leech <patchvonbr...@gmail.com
<mailto:patchvonbr...@gmail.com>> wrote:
Yes they’ll use the same reference clock provided by the motherboard.
There’ll be a residual phase offset which can be mitigated using
timed tuning.
Sent from my iPhone
> On Jan 9, 2019, at 3:01 PM, Yang Liu via USRP-users
<usrp-users@lists.ettus.com <mailto:usrp-users@lists.ettus.com>>
wrote:
>
> Dear all,
>
> I have a usrp x310 with two UBXs installed. And I want to use it
as a MIMO transmitter (two outgoing channels streaming at the same
frequency).
>
> When we need to build a MIMO system by connecting different
usrps, I know that we need to have either MIMO cable or external
time and frequency reference. In the one usrp x310 case, since two
daughterboards seems to be independent, do we need to synchronize
them? or they are already synchronized by default (for example,
two local oscillators are synchronized, and will be tuned to
exactly same frequency?)?
>
> Thanks,
> Yang
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