Triggering on entering or leaving a defined window
|The analogue trigger input is continuously sampled at the selected
sample rate. If its signal leaves a user programmed window, defined by a higher
and lower threshold level, then a valid trigger is seen and acted upon so
that signal replay (waveform generation) starts. The green trace shows when
the condition has been met for a valid trigger. During replay further
trigger events are ignored until the replay period has completed. Programmed
window levels are simply made in the appropriate code register of the driver
software. The level is defined in millivolts allowing for fine adjustment.
|Alternatively the window trigger also works for situations where the
incoming trigger signal enters the defined window, this choice is also
made by the programmer in the appropriate register.
|Note that in both diagrams above the "Start" indicates the point
at which the card was armed ready to receive triggers, here the start occurred
when the trigger condition was already fulfilled, so instantly the card starts
to replay. The start could be at any point in time as determined by the user
and his application.
Window trigger mode can be combined in a AND / OR logic arrangement with
other sources, e.g. a software trigger (such as key press), or the card's
LVTTL trigger input. The above is just a summary of the pulsewidth features.
Full details of the window triggering operation can be found in the user manual.
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Last modified by DataQuest Solutions Ltd 09.03.17