Basic concept of an oscilloscope

The oscilloscope is one of the most famous and used items of test equipment, as it allows signal voltages to be displayed on a screen in a two dimensional format. This enables test and design engineers to understand the operation of a circuit while viewing the waveforms on the screen. Thus, the scope offers far more details than other test equipment.

The scope has become an essential tool in electronics laboratory and various other environments. Sometimes a lab may require several scopes with different specifications to accommodate the vast array of applications and measurements that have to be performed.

The main concept of an oscilloscope is to display waveforms in two dimensional format. The scope’s horizontal axis is used as a time axis, while its vertical axis is usually utilized to plot the incoming voltage. In this manner, users can view waveform voltage as a function time while sine wave axis is displayed in a graphical format with the horizontal axis featuring a line undulating line with time.

Although it is useful to view a single waveform, various measurement techniques and measurements demand the display of more than one waveform. This has proved valuable when comparing waveforms and observing the different ways waveforms interact and in instances when events occur on several waveforms. The current market today offers the benefits of dual channel or multi-channel oscilloscopes that enable users to view two or more waveforms at the same time.

While the traditional way of displaying waveforms is measuring the time on the horizontal axis and the instantaneous voltage on the vertical axis, plotting two voltages against each other is also possible now. Thus, users can now view a Lissaious figure while looking at relative voltages and phases of two different waveforms.

Modulating the intensity of the image via a third waveform will enable the oscilloscope to display three dimensional images of the waveform.

One of the most important elements of any test equipment is the display. The scope’s display, which originally consists of a cathode ray tube, demands very high voltages. Bright steady display of waveforms for a prolonged period of time could damage the phosphor. Hence, “worn” areas can be seen with the waveform on display.

Prior to the advent of digital technology, users utilize special storage oscilloscopes that depend on a specialized storage cathode ray tube to store images. It operates by holding a charge directly on the screen so that the scanned area will remain illuminated. The image’s “persistence” can be changed so that the time that image stayed on screen could also be altered. This method is usually used in slow moving waveforms that require illuminated areas to achieve a long persistence to visualize the waveform’s outline.

With the influx of optimized display technology and the rise in the level of digital forms of signal processing there has been a shift to other types of display — which generally last the lifetime of the oscilloscope and are less prone to damage — such as electroluminescent and LCD displays.