[USRP-users] MIMO synchronization performance

Marcus Müller marcus.mueller at ettus.com
Fri Jul 3 10:26:24 EDT 2015

Hi Iftah,

temporal Synchronization is mainly a motherboard issue. The trick is
that the MIMO cable guarantees that the time on both N210 motherboards
is the same, so commands that say "at 12 o'clock sharp, start giving me
samples" are synchronous down to 1/master clock rate; the latter is
fixed a 100MHz for the N210, plus the time the synchronization signals
take to pass the MIMO cable. The timing offset between the two
motherboards should be quite constant.

Now, this does not imply phase alignedness: Your daughterboard does not
have a tuner that allows for tuning with a guaranteed phase, so the
phase relation between your two receivers (or transmitters, or your one
receiver and one transmitter) is going to be random after every tuning.

If you want that feature, I'd recommend going for SBX daughterboards, or
UBX, or with some constraints, WBX.
For more information on the synchronization features, I'd like to point
you to

Note that the XCVR is one of the very few, very dated daughterboards
that don't support full duplex operation -- building something that
synchronously changes between RX and TX modes might get relatively
complicated, if your application requires that.

Best regards,

On 07/03/2015 11:18 AM, iftah giladi via USRP-users wrote:
> i am using 2 N210, with XCRV  with MIMO cable, what synchronization
> performance should i expect?
> better then 1ns, 10ns, 100ns or more?

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