[Discuss-gnuradio] Synchronisation

[Fulcrum Associates]

Dear All,

             I have a couple of USRPs connected, through  a strong 
attenuator to a signal generator (NWT4001). While the units have a MIMO 
option, I don't have that cable. (Option A) When I run the GRC as 
attached, I see too good a result to the extent that the differential 
Phi seems to range over +/- 5 degrees.


             What I had hoped to prove to myself that two N200 with SBX 
would have a varying offset without MIMO cable, then I would connect the 
MIMO cable and move the USRPs into a multi-unit and enable GPSD O/B on 
the unit which has the feature and MIMO for one without (Option B) and 
that the phase differential would improve noticeably and be a variable 
constant, but it didn't.


              If it had, but there still was a fixed phase offset which 
varied each time it was setup (which is what I would expect under B) 
then I would hand-code the SBX stream initialisation code to remove the 
offset.


              Does my FG not measure what I claim to be wishing to 
measure?

              If it does measure it correctly, why do my expectations 
of options A and B leading to a different (though improved) situation 
not eventuate?


              Kind Regards,


                             John

usrp_ind_no_MIMO.png
Description: PNG image