Definition: oscilloscope

A test instrument that is used to measure and analyze electronic signals (waves and pulses) displayed on its screen. The x-axis represents time, and the y-axis represents an instantaneous view of the voltage of the input signal. To allow viewing signals across a wide frequency range, the rate and speed at which the sweep of the x-axis occurs is configurable. The sensitivity of the inputs can also be configured to accept signals from microvolts peak-to-peak to many thousands of volts peak-to-peak.

Both analog and digital oscilloscopes are available. In an analog scope, the x-axis is controlled by an internal time base, and the y-axis is directly controlled by the input signal. In a digital model, the input voltage is sampled at a preset frequency. The x-axis represents the samples along a timeline, and the y-axis shows the voltage levels of each sample. See spectrum analyzer.

Using an Oscilloscope

Oscilloscopes are used to examine the voltages on circuit boards, radios, TVs and countless electronic devices. This one is being used to test chips after manufacture. (Image courtesy of VLSI Technology, Inc.)