A modern digital oscilloscope, manufactured by Lecroy, a diagnostic instrument comprising a cathode ray tube (CRT - left), a time base and amplifiers. The instrument is used for displaying voltage waveforms. In an oscilloscope the time base signal is a waveform that increases to a maximum and then rapidly returns to its reference (base) level before commencing a successive sweep. The time base signal draws the spot horizontally across the tube in order to display a particular waveform. A waveform is defined as the graphical representation of the variation of amplitude with time for a particular wave.