Teledyne SP Devices ADQ8-8C, Руководство пользователя

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17-2000 C
2020-09-17
26(50)
ADQ8-8C Manual
17-2000 C 2020-09-17
26(50)
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 (10)
The
ACTUAL_ANALOG_RANGE
is the analog full scale range. If a DC-offset is used at the input, add the
DC_OFFSET_CODE
from (6) .
Note that the trigger level is given in 16 bits MSB aligned format and that the range is from
–2
15
to 2
15
-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
into DBS. The level trigger is set relative to the analog baseline as:
ANALOG_STEP = ANALOG_TRIGGER_LEVEL - ANALOG_BASELINE (11)
LEVEL_CODE = DB ANALOG_STEP / ( ACTUAL_ANALOG_RANGE / 2 ) * 2^15 (12)
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,
Figure 18 . After
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.
# DESCRIPTION USER COMMAND REF
a When the signal passes the trigger level, a trigger event is generated and
the first record is captured. SetupLevelTrigger 4.10.1
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. SetupLevelTrigger 4.10.3
Figure 17: Level trigger introduction.
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