Complex sentence: Digital sampling oscilloscopes operate on the same principle as analog sampling oscilloscopes and, like their analog counterparts, are of great use when analyzing high-frequency signals; that is, repetitive signals whose frequencies are higher than the oscilloscope's sampling rate.
Split into simpler sentences: Digital sampling oscilloscopes operate on the same principle as analog sampling oscilloscopes and, like their analog counterparts, are of great use when analyzing high-frequency signals. That is, repetetive signals whose frequencies are higher than the oscilloscope's sampling rate.