Hi, @Pinut, it’s possible that Pothos drivers do not expose the ADF4002 phase modulator. In that case, you need to switch the clock reference source before running your application.
Another participant @cswiger found us a solution for switching to an external clock reference, using a small C program. See here.
The script performs the action you’d execute In the LimeSuiteGUI. You enable use of an external reference clock by connecting to the board, and choosing **Modules -> ADF4002 **
You then enter the frequency of your external clock source in Fref, MHz, and click Calculate R, N & Upload.
Assuming your external clock is connected (via onboard uFL connector J14), you should see a fourth LED on the board light up green.