Multiple AD9371 Phase Difference


I read all the topics in the forum that related to the AD9371 Sync. 

the wiki shows only AD9361 (i assume that it's the same method in the AD9371). As we understand, in multiple chips the sync of the chips is related only for the data and the RF sync (phase ) will be achieved in case we will connect all chips with same LO or if we will use switching to one RX in order to sample the signal and evaluate the phase difference.

we would like to know if it's possible to say that even if the chips has difference phase, the phase difference will be the same (in  this case Teta1-Teta2 will always give Delta Teta12).

In this case we can calibrate the Phase difference in the factory:

Our agenda is to calibrate all TX Outputs and RX inputs so there will be no phase difference. In order to do that we connected all AD9371 TX path to the ORX with coupler (every TX to his own ORX port). Our assumption was that the difference between the phases (even between two different chips) will be the same even if we will restart the system (we don’t care if the system is not sync as long as the difference will be the same all the time). In this case what we planned to do is to calibrate the TX phase in the factory and after that to transmit from all TX channels at the same time and then sample the signal from the ORX and calibrate the ORX path.

Then, in the field because we know what is the phase difference for every chip + Phase difference for every path it will be easy to sample the TX and correct the phase.

We would like to know if our assumption is correct. If it’s the case, we would like to have an explanation why the phase difference will be the same.