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LSBs
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–2.0
–4.0
–6.0
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a. Dither Disabled; No Averaging
LSBs
6.0
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–2.0
–4.0
–6.0
0
100
c. Dither Enabled; No Averaging
Multichannel Scanning Considerations
© National Instruments Corporation
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Dither cannot be disabled on devices with 16-bit ADCs.
E Series devices can scan multiple channels at high rates and digitize the
signals accurately. However, you should consider several issues when
designing your measurement system to ensure the high accuracy of your
measurements.
In multichannel scanning applications, accuracy is affected by settling
time. When your E Series device switches from one AI channel to another
AI channel, the device configures the NI-PGIA with the input range of the
new channel. The NI-PGIA then amplifies the input signal with the gain
and polarity for the new input range. Settling time refers to the time it takes
the NI-PGIA to amplify the input signal to the desired accuracy before it is
sampled by the ADC. The specification document for your DAQ device
shows its settling time.
LSBs
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–4.0
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b. Dither Disabled; Average of 50 Acquisitions
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–6.0
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d. Dither Enabled; Average of 50 Acquisitions
Figure 2-3. Dither
2-9
Chapter 2
Analog Input
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E Series User Manual
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