Moku:Lab uses a digitally implemented phase-locked loop architecture to measure the phase, frequency, and amplitude of a signal.
If you are seeing an unexpected and constant drift in your phase measurement, it can be due to frequency settings at the output or the input side. You can adjust Moku:Lab's Phasemeter with the following settings to remove drift.
Output frequency setting:
First disengage "Lock" on output frequency then tap "Reacquire" to restart the measurement.
Input frequency setting:
Manually set the frequency at the Input side then tap "Reacquire" to restart the measurement.