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DESCRIPTION
a
When the signal passes the trigger level, a trigger event is generated and
the first record is captured.
b
During the record, incoming triggers are ignored.
c
When the signal passes the trigger level, a trigger event is generated and
the second record is captured. Re-triggering is also controlled by a
hysteresis function.
Figure 16: Level trigger introduction.
4.10.1 Setting the level trigger level
The level is given in digital codes:
LEVEL_CODE = ANALOG_TRIGGER_LEVEL / ( ACTUAL_ANALOG_RANGE / 2 ) * 2^15
The
ACTUAL_ANALOG_RANGE
from (6).
DC_OFFSET_CODE
Note that the trigger level is given in 16 bits MSB aligned format and that the range is from
15
15
–2
to 2
-1.
4.10.2 Level trigger and DBS
The Digital Baseline Stabilizer, DBS, compensates for fluctuations in the baseline. The DC level is then
set by a parameter
DBS_CODE
ANALOG_STEP = ANALOG_TRIGGER_LEVEL - ANALOG_BASELINE
LEVEL_CODE = DBS_CODE + ANALOG_STEP / ( ACTUAL_ANALOG_RANGE / 2 ) * 2^15
4.10.3 Controlling noise sensitivity
The level trigger is sensitive to noise since it can detect a step as small as one digital code. This can
cause unwanted triggering. The noise sensitivity is controlled by a hysteresis function,
triggering, the signal has to cross a reset level before it can trigger again.
Setting the reset level far from the trigger level will give a robust trigger.
Setting the reset level close to the trigger level will give a sensitive trigger.
19-2302 A
2020-09-16
+ ,
is the analog full scale range. If a DC-offset is used at the input, add the
into DBS. The level trigger is set relative to the analog baseline as:
+-,
+
,
USER COMMAND
SetupLevelTrigger
SetupLevelTrigger
ADQ8-4X Manual
19-2302 A 2020-09-16
25(46)
REF
4.10.1
4.10.3
(10)
(11)
(12)
Figure
17. After
25(46)
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