An oscilloscope is previously called as an oscillograph. It can be informally known as a scope, CRO (for cathode-ray oscilloscope), or DSO (for the more modern digital storage oscilloscope). It is a type of electronic test instrument that allows observation of constantly varying signal voltages. The output of a CRO will be usually as a two-dimensional graph of one or more electrical potential differences using the vertical or y-axis, plotted as a function of time (horizontal or x-axis). Many signals (e.g. sine, cosine etc) can be converted to voltages and can be displayed this way. By changing the mode of CRO into transfer characteristics, we can see the transfer characteristics of signals. The transfer characteristics of a signal give the variation of the output wave with respect to the variation to the input wave. The Signals may be either periodic or repeat constantly, so that the multiple samples of a signal which is actually varying with respect to time can be displayed as a steady picture in the CRO. Many oscilloscopes (storage oscilloscopes) are able to capture non-repeating waveforms for a specified period of time, and are able to produce a steady display of the captured segment.
Oscilloscopes are mainly used to observe the correct wave shape of an electrical signal. Oscilloscopes are usually calibrated so that the two axes voltage and time can be easily read as well as possible by the eye. This will yields to the measurement of the peak-to-peak voltage of a waveform. It also allows checking the frequency of periodic signals, the time between pulses, the time taken for a signal to rise to full amplitude, which is usually called as the rise time, and relative timing of several related signals.
The applications of Oscilloscopes are in the fields of sciences, engineering, medicine, and telecommunications industry. For the maintenance of electronic equipment and laboratory work, general-purpose instruments are used. Special-purpose oscilloscopes are used for analyzing an automotive ignition system or to display the waveform of the heartbeat as an electrocardiogram. If we consider some practical example, some computer sound software allows the sound being listened to be displayed on the screen as by an oscilloscope. Thus CRO can be used in many applications in the emerging world technologies. Most of all, the CRO can be considered as the eye of an electronic engineer. In other words an electronic engineer cannot see his outputs without the help of a CRO.
Some special storage CRTs are used to maintain a steady display of a single brief signal in case of advanced storage oscilloscopes. By digital storage oscilloscopes (DSOs) with thin panel displays, fast analog-to-digital converters and digital signal processors, CROs were later largely outdated. DSOs without integrated displays are known as digitizers. Digitizers are available at lower cost, and it uses a general-purpose digital computer to process and display the required waveforms.