The LabSat 4 product range features an external reference input for synchronization to a 10 MHz clock. To use this feature, connect a 10 MHz reference signal with a minimum + 3 dB level to the REF SMA connector and ensure that the External 10MHz reference clock option is ticked in Menu -> Setup -> CLK REF -> External 10 MHz in the Display Menu or in the System Setup menu in the LabSat 4 Web Server.
When you have enabled the External 10MHz option on LabSat 4, you will see the following symbol displayed on the File Selection Screen when you exit the menu:
The circular symbol next to the battery symbol indicates that the External 10MHz reference has been enabled.
