Triggering on entering of 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 recording starts. The green trace shows when the condition has been met
for a valid trigger. During recording further trigger events are ignored
until the recording 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 and ready to receive triggers. Here the start
occurred when the trigger condition was already fulfilled, so instantly the
card starts to record. The start could be at any point in time as determined
by the user and the application.
Window trigger mode can be combined using in a AND / OR logic arrangement with
other sources, e.g. a software trigger (such as key press), the card's
LVTTL trigger input, or the actual analogue signal you wish to record. The above is just a summary
of the versatile window trigger features. Full details of the trigger operation
can be found in the user manual.
Images courtesy of Spectrum GmbH
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Last modified by DataQuest Solutions Ltd 18.05.18