Disabling GPSDO on N310 to reduce phase noise when using external reference

[Christopher Flood]

Hi all,

I am using the N310 to transmit a signal. An issue I ran into is that the phase noise of the generated signal gets worse when using an external reference. I read in the documentation (listed below) that the GPSDO can have an effect on the phase noise of the external reference. I tried following the steps provided to turn off the GPSDO (create configuration file on the device in the folder path /etc/uhd/mpm.conf and add enable_gps=False), but the signal quality did not change. Is there any way to query the device to confirm that the GPSDO is indeed turned off? Has anyone else run into this issue?

https://files.ettus.com/manual/page_usrp_n3xx.html#n3xx_synchronization_external

Thanks!

-Chris