Data Translation MACH Series, User Manual

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Principles of Operation
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Reference
The reference is the maximum voltage (after offset and gain have
been applied) that you want to digitize. Reference is defined as
follows:
reference = gain (V
max
+ offset)
The DT3152-LS board digitizes the signal between 0. 0V and the
reference voltage. All data above the reference voltage is digitized as
white pixels.
The DT3152-LS Device Driver supports a minimum reference of 0 V
and a maximum reference of 1.28
V, in 256 steps of 5 mV. Note,
however, that the hardware uses 64 steps of 19 mV.
For area-scan operations, the default reference is 660 mV for 60 Hz
and 700 mV for 50 Hz. For line-scan operations, the default reference
is 700 mV.
Note: For proper operation, once offset and gain are applied, the
difference between the adjusted minimum voltage (0 V) and the
reference voltage should not be less than 500 mV.
Table 1: Gain Values
If.. Use a Gain of..
V
max
+ offset > 1.28 V 0.5
0.64 V < V
max
+ offset
≤
1.28 V 1
0.32 V < V
max
+ offset
≤
0.64 V 2
V
max
+ offset
≤
0.32 V 4