Use of the ac dc function

A general waveform may contain both an AC and DC component the latter will appear as an offset of the AC waveform away from 0 V .When set to DC the oscilloscope displays all of the waveform DC and AC but in the AC setting the DC component is filtered out and only the AC component is displayed. This may be useful for cases where the DC component is significantly larger than the AC component making a measurement of the latter otherwise difficult.