This area lists the system reference state. If the analyzer is locked to a signal at the external reference in connector, this area displays the message EXT REF. If the Lock Reference parameter for any hardware has been changed from True to False, this area displays the message UNLOCKED. Otherwise the area displays the message INT REF and the analyzer uses the reference signal generated internally by the reference instrument.

You can double click in this area to open the Reference Frequency dialog box.

If you right click in this area, a menu allows you to open the Reference Frequency or the Reference Details dialog box.