Keysight DSOX3012T, User Manual

Page: 212 / 530

212 Keysight InfiniiVision 3000T X-Series Oscilloscopes User's Guide
12
Trigger Mode/Coupling
To set the trigger holdoff
Trigger holdoff sets the amount of time the oscilloscope waits after a trigger
before re-arming the trigger circuitry.
Use the holdoff to trigger on repetitive waveforms that have multiple edges (or
other events) between waveform repetitions. You can also use holdoff to trigger on
the first edge of a burst when you know the minimum time between bursts.
For example, to get a stable trigger on the repetitive pulse burst shown below, set
the holdoff time to be >200 ns but <600 ns.
To set the trigger holdoff:
1 Press the [Mode/Coupling] key.
2 In the Trigger Mode and Coupling Menu, press Holdoff .
3 In the Trigger Holdoff Menu, press the Random softkey to enable or disable the
random trigger holdoff mode.
The random trigger holdoff mode ensures that the oscilloscope re-arms after
each acquisition in a manner that minimizes or eliminates the likelihood of
triggering at the beginning of a DDR burst. Randomizing the holdoff time
increases the likelihood that the oscilloscope will trigger on different data
phases of a multi-phase (8 data transfer) burst. This mode mixes up the traffic
pattern the oscilloscope triggers on and is very effective when used on
repeating patterns.
4 If random trigger holdoff is disabled, use the Holdoff softkey to enter the trigger
holdoff time.
If random trigger holdoff is enabled, use the Min and Max softkeys to enter the
minimum and maximum trigger holdoff times.
Trigger Holdoff
Operating Hints
The correct holdoff setting is typically slightly less than one repetition of the
waveform. Set the holdoff to this time to generate a unique trigger point for a
repetitive waveform.
200 ns
Oscilloscope triggers here
Holdoff
600 ns