Which technician is correct regarding the DC coupling setting on a DSO?

The assertion made by Technician A regarding the DC coupling setting on a Digital Storage Oscilloscope (DSO) is accurate because DC coupling allows both AC and DC signals to be measured without any filtering. This is crucial when analyzing signals that may have a DC offset or when the DC component is important for the analysis, such as in power electronics or when observing battery voltages. DC coupling provides a complete view of the signal, including its steady-state and transient behaviors.

In contrast, if a technician were to rely solely on AC coupling, only the alternating components of the signal would be visible, and any steady-state DC offsets would be blocked. Therefore, using DC coupling when necessary ensures that all aspects of a signal are accurately captured, which is essential for a thorough understanding of the observed phenomena.