Can I Ignore Offset Error While Calculating Accuracy for AC Coupled Signal?

Updated Jun 27, 2019

Reported In

Hardware

  • NI-9234

Issue Details

I have a microphone sensor and am trying to measure it with a C series module (NI 9234). The absolute accuracy I calculated is much higher than the voltage reading I am expecting to get. From the white paper on calculating absolute accuracy of dynamic signal acquisition devices- I noticed the equation: Absolute Accuracy = Gain Error + Offset Error + Flatness.

Since my microphone signal is AC, can I ignore the offset error in my calculation?

Solution

If you signal is purely AC and you are able to characterize it at a null level, it is okay to ignore the offset error when it is AC coupled since the offset would be a DC value. Otherwise, it is better to include the offset error in your calculation.