Synchronization:  Whatever type of weep is used, it must be synchronized with the signal being measured. Synchronization has to be done to obtain a stationary pattern. This requires that the time base be operated at a sub multiple frequency of the signal under measurement (applied to Y plates.) If synchronization is not done the pattern is not stationary, but appears to drift across the screen in a random fashion.

Sources of Synchronizations: there are three usual sources for synchronization which can be selected by synchronizing selector:

(1)            Internal: In this type of synchronization, the trigger is obtained from the signal being measured through the vertical amplifier.

(2)            External: in this method, an external trigger source is also used to trigger or initiate the signal being measured.

Line: In this case, the trigger is obtained from the power supply to the CRO (say 230V, 50 Hz).