Acqiris U5309A User Manual page 15

If comparing the initial trigger time T0 measured using the same waveform either used
as channel input trigger or as an external trigger, the T0 position can be slightly different
(especially if the waveform used as trigger has a slow edge).
First, the analog bandwidth can be different for the channel trigger input and the
external trigger input, resulting in a different slope and so a different T0.
Secondly, compared with the channel trigger, the external trigger threshold is not
calibrated. The input channel trigger calibration allows a T0 adjustment both in
threshold and in timing, resulting in a more accurate T0. However, when using the
external trigger, the measured T0 is still precise and theT0 position difference stays
stable.
Using a signal with faster edge as external trigger can reduce this effect.
Pre- and Post-Trigger Delay
To increase trigger flexibility, a pre- or post-trigger delay can be applied to the trigger position.
The amount of pre-trigger delay can be adjusted between 0 and 100% of the acquisition time window (i.e.
sampling interval x number of samples), whereas the post-trigger delay can be adjusted within the time
interval:
32
from 0 to (2
where block_size is 16 .
Pre- or post-trigger delays are just different aspects of the same trigger positioning parameter:
U5309A User's Manual
– 1) * block_size (samples)
Pre- and Post-Trigger Delay
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