[Discuss-gnuradio] [ USRP configuration with/without MIMO in unshared Ethernet mode ]

[Ashish Raste]

Hi all,

Recently, I tried testing how the data flows from one USRP to another in a 2x2 setup. My configurations went as follows:

2 USRPs were connected via a MIMO. Each USRP was connected to an Ethernet cable and so both of them were in two different subnets. Now when I set one of the USRPs clock source and time source to MIMO, I observed that both of them were synchronized and believe that its acting as a slave for the Master's clock and time source.
What I'm not able to understand is whether the slave is receiving its data via the MIMO (from the Master) or via its own RF input i.e whether . I thought that modulating the RF input to both the USRPs would show some difference on the FFT plot but both were identical. Could any one please tell me how the data flow occurs by suggesting a good test case?

My second question is:
In a 4X4 USRP setup, how can we synchronize all the 4 USRPs without a MIMO connection (between 2 USRPs within a pair), using a 10MHz reference given to each of the USRP and a PPS source?  
Please not that I'm using USRP N210 for my experiments.

Looking forward to your reply.

-- 
Ashish