USRP streaming defaults to internal time and clock source when calling init() even when set as external in yaml files

[SunflowerHaf]

I am trying to use a USRP N321 as the RF frontend for streaming srsRAN (with Open5GS), and using Ubuntu Jammy on my host PC.

I have configured the gnb yaml files to take an external clock and time source (provided by an Octoclock CDA-2990), as well as passing them as arguments into uhd_usrp_probe. I know the hardware doesn't have any issues as all connections have been checked and the 10 MHz and PPS have been tested using an oscilloscope. Tests also show that the N321 is receiving the PPS.

However, when init() is called as part of streaming, the clock and time sources appear to be reset to internal. The log records vary between both, but by observing the N321 output on a spectrum analyser it is clear that the streaming is not aligned with the PPS.

I would be really grateful for any suggestions.