How to use pretrigger

The pretrigger is used to collect frames before the arrival of a trigger event. The pretrigger frames are saved in the camera buffer before the trigger event and after the event the frames are sent to the measurement computer. When using pretrigger it is impossible to know the delay between the trigger signal and the first frame after the pretrigger frames. This is because the cameras are already measuring and the trigger event can come at any time in reference to the frame rate.

The trigger event can be sent to the camera either with an external trigger or from a dialog in QTM if there is no external trigger.

When using analog boards with pretrigger the connection differs between the boards, chapter Measurement with analog capture while using pretrigger.

The pretrigger settings can be found on the Synchronization page in the Project options dialog, see chapter Pretrigger.