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Chapter 23
SCXI Calibration—Increasing Signal Measurement Precision
SCXI Calibration Methods for Signal Acquisition
There are two ways you can calibrate your SCXI module—through
one-point calibration or two-point calibration. The following illustration
explains why you may need to calibrate your SCXI module.
Binary Reading
Ideal Reading
Actual Reading
Gain Error
Vos
Actual Voltage
in Binary Representation
Binary Offset
This illustration shows the difference between the ideal reading and the
actual reading. This difference is called Vos, or the binary offset, before the
two readings intersect. The difference in slope between the actual and ideal
readings is called the gain error.
One-point calibration removes the Vos (binary offset) by measuring a 0 V
signal and comparing the actual reading to it. Two-point calibration
removes the Vos (binary offset) and corrects gain error by first performing
a one-point calibration. Then you measure a voltage at x volts and compare
it to the actual reading. The x must be as close as possible to the full-scale
range. The following sections explain how to perform a one-point and
two-point calibration.
LabVIEW Data Acquisition Basics Manual
23-4
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