Measurement Computing USB-1208FS User Manual page 22

USB-1208FS User's Guide Functional Details
The accuracy plots in are drawn for clarity and are not drawn to scale.
Figure 13
Figure 13. ADC Transfer function with gain error
For example, the USB-1208FS exhibits a typical calibrated gain error of ±0.2% on all ranges. For the ±10 V
range, this would yield 10 V × ±0.002 = ±20 mV. This means that at full scale, neglecting the effect of offset for
the moment, the measurement would be within 20 mV of the actual value. Note that gain error is expressed as a
ratio. Values near ±FS are more affected from an absolute voltage standpoint than are values near mid-scale,
which see little or no voltage error.
Combining these two error sources in Figure 14, we have a plot of the error band of the USB-1208FS for the
±10 V range. This is a graphical version of the typical accuracy specification of the product.
The accuracy plots in Figure 14 are drawn for clarity and are not drawn to scale.
Figure 14. Error band plot
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