An
oscilloscope, previously called an oscillograph, and informally known as a
scope,
CRO (for cathode-ray oscilloscope), or
DSO (for the more modern digital storage oscilloscope), is a type of
electronic test instrument that allows observation of constantly varying signal
voltages, usually as a two-dimensional plot of one or more signals as a function of time. Other signals (such as sound or vibration) can be converted to voltages and displayed.