[USRP-users] UBX coherence between TX and RX

Michael R. Freedman mfreedman at ll.mit.edu
Sat Mar 23 17:06:23 EDT 2019


I have an issue where I tune both the TX and RX side of a UBX40 card in 
an X310 to the same frequency and find that the transmitted signal and 
what is received are not coherent.  I am using an external 10MHz 
reference and have tried the documented suggestions.

at 150MHz it is coherent.

at 155MHz it is NOT coherent.

I have tried setting the dboard_clock_rate to 20MHz.  This made the 
problem appear at 150MHz as well.  I've tried integer_n tuning.

I have verified that the ref_lock and lo_lock are both true.

Any suggestions?


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