Teledyne LeCroy Conquest User Manual - Users Manual - Manual (Page 117)

Protocol Analysis
107
Pre-Trigger
You can set the amount of data to capture before and after the trigger as a
percentage of pre-trigger, between 1% and 99%, by positioning the pre-trigger
slider. This feature allows evaluation of bus activity leading up to and after the
triggering event. The operation of the pre-trigger in the data memory is
conceptually illustrated in Figure 82.
Capture of the specified percentage of data prior to the triggering event cannot
be guaranteed and may in some cases be 0. This can occur if the triggering
event occurs before the required amount of pre-trigger event data can be
stored. In these cases, the data display shows fewer than the specified data
points prior to the triggering event.
Figure 82 Pre-Trigger Example, 20% Pre-Trigger
If the trigger does not occur prior to a full memory, then new data wraps
around to overwrite the captured memory from the beginning.