We can measure the baseline fluctuations in the electronics. This can only be done when the data is acquired without zero-suppression. If $HARPO_DATA_DIR is set correctly, this can be done with the script:
monitorNoiseRun.sh RUNNO (NEVTS) (S)Where RUNNO is the run number, NEVTS is the number of events to process (optional, default is 10000), and S is the number of events to skip (optional, default is 0).