Oscilloscope, << uh SIHL uh skohp, >> is an electronic instrument used to observe one or more electrical signals. An oscilloscope displays oscillations (back-and-forth changes) in a signal’s voltage. It shows these oscillations as wavy lines or other patterns on a video screen or display. Typically, the lines form a graph showing how the voltage of the signal changes over time.
Oscilloscopes are used in such fields as industry, medicine, and scientific research. Engineers use them to test computers, radios, and other electronic equipment. Physicians use them to study electrical impulses from the brain or heart. People also use oscilloscopes to study oscillations in forms of energy other than electric current, such as light, mechanical motion, and sound. Devices called transducers can convert these forms of energy into an electrical signal, which can then be observed using an oscilloscope.
Most oscilloscopes today use digital technology—that is, they measure the voltage of a signal at various intervals and convert the measurements into numerically encoded data. Such data can be processed, stored, and recalled by a computer. A stored signal can usually be recalled at a faster or slower rate than that at which it was recorded. For example, a seismic wave, the pattern of vibration generated by an earthquake, may be recorded over half a minute and then played back in a fraction of a second. Many digital oscilloscopes use displays similar to those found in flat-screen televisions and computer monitors.
In a traditional analog oscilloscope, on the other hand, the screen is the front of a type of vacuum tube called a cathode-ray tube. Inside the tube, a device called an electron gun projects a beam of electrons onto a fluorescent screen. Any sideways or up-and-down movement of this beam leaves a glowing trail on the screen. A circuit called the time base causes the beam to move repeatedly from left to right. At the same time, the signal to be studied is fed into the oscilloscope, where it causes the electron beam to move up and down. The beam moves up and down as it passes from left to right, repeatedly tracing a pattern that represents the oscillating signal.
