Informattion About Oscilloscope

An oscilloscope (also known as a scope, CRO, DSO or, an O-scope) is a type of electronic test instrument that allows observation of constantly varying signal voltages, 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). Although an oscilloscope displays voltage on its vertical axis, any other quantity that can be converted to a voltage can be displayed as well. In most instances, oscilloscopes show events that repeat with either no change, or change slowly. Oscilloscopes are commonly used to observe the exact wave shape of an electrical signal. In addition to the amplitude of the signal, an oscilloscope can show distortion, the time between two events (such as pulse width, period, or rise time) and relative timing of two related signals.[1] Oscilloscopes are used in the sciences, medicine, engineering, and telecommunications industry. General-purpose instruments are used for maintenance of electronic equipment and laboratory work. Special-purpose oscilloscopes may be used for such purposes as analyzing an automotive ignition system, or to display the waveform of the heartbeat as an electrocardiogram. Originally all oscilloscopes used cathode ray tubes as their display element and linear amplifiers for signal processing, (commonly referred to as CROs) however, modern oscilloscopes have LCD or LED screens, fast analog-to-digital converters and digital signal processors. Although not as commonplace, some oscilloscopes used storage CRTs to display single events for a limited time. Oscilloscope peripheral modules for general purpose laptop or desktop personal computers use the computer's display, allowing them to be used as test instruments.

How Does an Oscilloscope Work?

  1. Oscilloscope Basics

    • An oscilloscope is a device which graphically displays a repeated waveform in a circuit, such as the signal for a sound. Oscilloscopes display the voltage or amperage of a circuit as a line on a screen. A technician can study the actual wave form, to measure how much time passes between pulses in a circuit, detect the frequency of a signal, or do other useful analyses.

    Vertical Control

    • In all oscilloscopes, the electric signal first travels from a circuit probe into the oscilloscope. It travels first to an amplifier/attenuator circuit. This circuit measures the voltage or amperage of the wave and increases (amplifies) or decreases (attenuates) it, usually based on input by the operator through a control knob. This voltage is then sent to control the vertical sweep. It moves an electron gun up and down as it changes. The further the voltage varies, the more the gun moves.

    Horizontal Sweep

    • The technician also controls the horizontal sweep. The electron gun moves repeatedly from one side of a screen to the other. In many cases, this happens many thousands of times a second. The quicker the sweep, the less time is represented by each pass of the electron gun. This makes a closer, more detailed image, but shows a smaller part of the wave.


    • The display in most oscilloscopes is a cathode ray tube (CRT), the same sort of display traditionally used in televisions. In a CRT, a beam of electrons are shot down a tube at a very high rate of speed. Electromagnets in the tube turn on to deflect the electrons left, right, up or down so that they hit a particular point on the screen. That screen is covered with a phosphor coating - similar to the coatings on the inside of fluorescent lights. When an electron hits the phosphor, the coating absorbs some of its energy. That energy is re-emitted as a photon of light. As the electron beam sweeps across the screen, it creates a glowing image of the waveform.

20th Jan 2015

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