|NI-SCOPE (English | Japanese)|
On many digitizers, you can configure the input channels to be DC-coupled, AC-coupled, or GND coupled. DC coupling allows DC and low-frequency components of a signal to pass through without attenuation. In contrast, AC coupling removes DC offsets and attenuates low frequency components of a signal. This feature can be exploited to zoom in on AC signals with large DC offsets, such as switching noise on a 12 V power supply. GND coupling disconnects the input and internally connects the channel to ground to provide a ground, zero-voltage reference.
Refer to the specifications for your specific digitizer for input limits that must be observed regardless of coupling.