Oscilloscope

An oscilloscope is a piece of electronic test equipment, used for observing the voltage of an incoming signal as a function of time; it can be used to observe the behaviour of both analog and digital circuits. It allows the observer to see the waveforms present in the circuit as it operates; it is also used for debugging equipment which has developed a fault. They are actually very old devices, preceding by some decades the first computers; before them, they were used on analog equipment (such as radars).

The first generations were built around a CRT; it displayed a point, formed by a single electron beam. Analog circuitry repetitively swept the beam across the face of the tube horizontally, and amplifiers used the input signal to deflect the beam vertically.

Devices with the functionality of an oscilloscope (i.e. they display the waveform of an incoming signal) still exist, but they are mostly completely different internally, now being principally digital, internally. Modern ones are similar to a logic analyzer, in that the incoming signal is sampled, and the samples stored, and displayed on an LED or LCD screen. The only difference from a logic analyzer is that a analog-to-digital converter is the first stage of processing of the input signal, so many more values of the input data are possible.