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A specific code
DIGITAL_CODE_LEVEL
ANALOG_LEVEL = ( DIGITAL_CODE_LEVEL / 2^15 ) * ( ACTUAL_ANALOG_RANGE / 2)
2.3 Set analog DC-offset
A user-controlled DC-offset is available. The analog DC-offset is applied to the signal to better adopt to
the signal range of the digitizer. The analog range is by default set symmetrical around zero. If the sig-
nal is unipolar or heavily unsymmetrical, the DC-offset function can adjust the signal to an optimal verti-
cal position for the A/D converter. In this way, the full 10 bits can be used for representing the unipolar
pulse. The DC-offset is set with the command
The DC-offset is set in digital codes
to an analog signal level in the range:
[ –ACTUAL_ANALOG_RANGE / 2: ACTUAL_ANALOG_RANGE / 2 ].
To determine the parameter of
, use:
SET_ANALOG
DC_OFFSET_CODE = round ( DC_OFFSET_ANALOG / ( ACTUAL_ANALOG_RANGE / 2 ) * 2^15 )
Since the digitizer has higher resolution than the intrinsic accuracy of the DC-offset generator, the
actual digital codes read out from the ADQ may differ from the expected level. For accurate baseline
measurements, the Digital Baseline Stabilizer (DBS) offers a digital correction of the baseline to an
accuracy of 22 bits,
Section
2.4 Adjusting the digital gain and offset
The digital gain and offset block is primarily intended for factory calibration but it may also be accessed
by the user, and offers an efficient way of scaling the signal to suit processing in the PC.
The default setting is the calibration parameters
D converter,
ADC_RAW_CODE
DIGITAL_OUTPUT_CODE = ADC_RAW_CODE * CAL_GAIN – CAL_OFFSET
The user can override these settings by using the software command
and
USER_GAIN
USER_OFFSET
to the raw code.
The normal mode of operation is to apply the gain and offset settings relative to the calibrated data as
DIGITAL_OUTPUT_CODE =
ADC_RAW_CODE * CAL_GAIN * USER_GAIN – CAL_OFFSET – USER_OFFSET.
By setting bit 7 in the channels parameter, the calibration data is overridden as:
DIGITAL_OUTPUT_CODE = ADC_RAW_CODE * USER_GAIN – USER_OFFSET
To get the raw code,
ADC_RAW_CODE
19-2302 A
2020-09-16
then represent the analog level as:
SetAdjustableBias
DC_OFFSET_CODE
to get a DC-offset at the voltage level
SetAdjustableBias
3.1.
CAL_GAIN
, is corrected with the calibrated values according to:
can be applied in two ways; relative to the calibrated value or relative
, use
SetGainAndOffset(128+CHANNEL,1024,0)
.
in the range [-2^15: 2^15-1], which correspond
and
. The raw data from the A/
CAL_OFFSET
SetGainAndOffset
ADQ8-4X Manual
19-2302 A 2020-09-16
10(46)
(4)
(5)
DC_OFF-
(6)
(7)
. The parameter
(8)
(9)
.
10(46)
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