Vertical sensitivity

An oscilloscope displays a waveform with voltage level shown on the vertical or y axis, and the time base on the horizontal or x axis. The oscilloscope screen is divided into horizontal and vertical lines or divisions, typically on 1 cm spacing, to provide calibration for the waveform on display. Scaling for these divisions is not fixed; it can be set to accommodate the amplitude and frequency of the measured signal, and display it comfortably within the available screen area.

Accordingly, the vertical sensitivity of the oscilloscope is a parameter that can be adjusted, typically with a potentiometer on the oscilloscope’s control panel, to set the voltage per division to a suitable level. For example, if the measured waveform is known to have an amplitude of +/- 7.5 V, the vertical sensitivity could be set to 2.5 V/division. This will make adequate use of the available viewing area on the screen, without saturation.

The smallest voltage a general-purpose oscilloscope can detect is typically about 2 mV per vertical screen division; its sensitivity may be reduced to a figure such as 5 V/div.

The ground reference or zero level must also be set up correctly to position the waveform as required on the screen. For a symmetrical waveform, the zero level can be adjusted to a mid-position in the screen, providing equal room for displaying its positive and negative halves.