Tektronix 4000 Series, User Manual

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Trigger Setup
The part of the record that occurs before the trigger is the pretrigger portion. The part that occurs after the trigger is the posttrigger
portion. Pretrigger data can help you troubleshoot. For example, to
fi nd the cause of an unwanted glitch in your test circuit, you can
trigger on the glitch and make the pretrigger period large enough to capture data before the glitch. By analyzing what happens
before the glitch, you may uncover information that helps you
fi nd the source of the glitch. Alternatively, to see what is happening in
your system as a result of the trigger event, make the posttrigger period large enough to capture data after the trigger.
Slope and Level
The slope control determines whether the
instrument
fi nds the trigger point on the rising
or the falling edge of a signal.
The level control determines where on that
edge the trigger point occurs.
The oscilloscope provides a long horizontal bar
or bars across the graticule to temporarily show
the trigger level.
122 Tektronix 4000 Series Oscilloscopes User Manual