What Does an Oscilloscope Measure? (Explained)

Avatar of Murray Slovick
Murray Slovick
Administrator at - OscilloscopeTools

Being an Electrical engineer, Murray never limits himself with the job he’s doing. He constantly explores new branches of technology that are relevant to his...Read more

An oscilloscope is an essential equipment for building and testing anything dealing with electrical systems and electronics. It is used by most people across different industries, from automotive, aerospace, communication, computer, etc. An oscilloscope has a screen that displays the waveform of an electrical signal, allowing you to analyze further.

So, what does an oscilloscope measure? Primarily, an oscilloscope measures voltage. However, some oscilloscopes have advanced measurement tools that can quickly detect a signal’s characteristics such as amplitude, frequency, current, etc.

Generally, an oscilloscope can measure both voltage-based and time-based characteristics. Most modern oscilloscopes do the calculation for you. This means you will find a frequency reading when taking voltage measurements.

If you’re still confused about what an oscilloscope measures, you’ve come to the right place. This article explains all about oscilloscopes, types, what they measure, and why it is important. Stay with us.

What Is an Oscilloscope?

An oscilloscope is electronic measuring equipment that lets you measure characteristics of a given signal such as voltage, current, amplitude, frequency etc. It was invented in 1893 by Andre Blondel, a French physicist. The primary oscilloscope function is to measure voltage. It has a display unit that shows a graphical representation of how voltage changes over time.


The display unit on the oscilloscope allows you to determine the behavior of the circuit you are testing; whether or not it’s working correctly. Also, it allows you to detect any faults within the circuit, like noise.

What is an oscilloscope

In most applications of oscilloscopes, the display shows a graph of how a signal’s characteristics change over time. The vertical scale (y-axis) represents the voltage, while the horizontal scale (x-axis) represents time. The brightness or intensity of the screen is often referred to as the Z-axis.

How Does an Oscilloscope Work

An oscilloscope resembles a tiny television set with a grid on its screen and more control knobs. The front panel has control units divided into horizontal, vertical, display, inputs and trigger sections.

How does an oscilloscope work

A traditional analogue oscilloscope works by exposing the voltage of a signal being measured to a beam of an electron moving across its screen. The voltage then redirects the electron beam up and down the vertical scale proportionally, creating a waveform on the display. This, in turn, shows an instant image of the waveform on the screen.

On the contrary, a modern digital oscilloscope samples the created waveform (as explained above); and uses an ADC (Analogue-To-Digital Converter) to convert the signal’s voltage into digital information. The digital information is then used to reconstruct the waveform on display.

Types of Oscilloscope

While an oscilloscope displays a graphical representation of an electrical signal, how the representation is formed varies with the type of scope used. There are two major types of oscilloscopes available. These are:

Digital Oscilloscope

A digital oscilloscope converts signals’ characteristics into digital information (1s and 0s). An analog-to-digital converter does it; thus, eliminating the use of CRT screens. Instead, it uses a modern LCD. It allows for more advanced features by reducing the design complexity.

The analogue-to-digital converter makes it possible to carry out advanced signal manipulation. As a result, digital scopes can perform the most complicated mathematical operations within a short period.

Analog Oscilloscope

Analog oscilloscope is the oldest type of oscilloscope. It employs high gain signal amplifiers to create a waveform image to a CRT display (Cathode Ray Tube). Most analogue scopes have a couple of vertical channels, horizontal channels, CRT modules, trigger systems, and a time base.

The vertical channel of an analogue scope includes a vertical amplifier, an attenuator, a preamplifier, and an analog delay line. The amplifier outputs the created waveform to the screen, which remains connected to the signal. The horizontal channel has external and internal work modes. The trigger systems have an adjustment system for increasing or decreasing the levels.

What Does an Oscilloscope Measure

“What is an oscilloscope used to measure?” This is a common question among most oscilloscope users. Besides the fundamental features of oscilloscope testing, most scopes have built-in measurement tools, which are handy when you want to quickly quantify the amplitude, frequency, and other characteristics of a waveform.

What Does an Oscilloscope Measure

Generally, you can use an oscilloscope to measure voltage-based and time-based characteristics as shown below:

Voltage-based Characteristics

  • Min and Max Voltage – The oscilloscope shows you the minimum and the maximum voltage of a signal you are testing.
  • Amplitude – It is the measure of a signal’s magnitude. Amplitude measurements include peak-to-peak amplitude, which measures the difference between a low and high voltage of a signal, and peak amplitude, which measures how low or high a signal is beyond 0 volts (V).
  • Mean and Average Voltage – It calculates the mean or average voltage of a signal. It can further calculate the average of a signal’s maximum and minimum voltage.
  • DC Voltage – Most modern scopes have a provision for measuring direct current voltage.
  • Current – You can use an oscilloscope to measure the current of a signal by measuring the amount of voltage lost by a resistor or using a current probe.

Time-based Characteristics

  • Frequency and Period – Frequency refers to the number of times a waveform repeats itself in a second. A period refers to the reciprocal number of seconds each recurring waveform takes. While the highest frequency an oscilloscope can measure may vary, it’s usually within the 100MHz (1E6 Hz) range.
  • Rise and Fall time – The duration which a waveform takes to move from a low to a high point is called a rise time; a fall time is the opposite. These signal characteristics are essential when considering how slow or fast a circuit responds to signals.
  • Duty Cycle – It is a ratio that indicates how long an “on” versus “off” state of a signal is.

Why is an Oscilloscope Important?

An oscilloscope is very useful since it allows you to examine time-varying electrical signals. These signals might be fast or slow-moving. However, the scop has delay and amplification features that make it possible to observe such signals.

Why is an Oscilloscope Important

Here are a few reasons that make an oscilloscope such important equipment:

  • An oscilloscope enables you to observe signals that come straight from connected devices by allowing instantaneous display of waveforms.
  • An oscilloscope can be utilized as an electrocardiogram. You can use it to troubleshoot and test circuits on electronic devices, e.g., Televisions, radios, computers, etc.
  • By using an oscilloscope, you get a more detailed analysis of the circuit of the signal you are testing; thus. It’s easy to identify a non-functional or faulty part.

In a nutshell, an oscilloscope is a must-have device that enables you to carry out maintenance and repair tasks on electronic components effectively.


An oscilloscope is an indispensable piece of equipment for electricians across the globe. Since it plots and measures the waveform of an electrical signal, it is essential in electrical diagnostics.

Hopefully, after reading this article, you now understand what an oscilloscope is, what it measures and why it’s important. Generally, a basic oscilloscope has horizontal, vertical, display and trigger systems that allow you to measure particular signals. Keep in mind that there are different scopes, but they are majorly categorized into two; digital and analog. Before you buy one, ensure it suits your work demands.

Being an Electrical engineer, Murray never limits himself with the job he’s doing. He constantly explores new branches of technology that are relevant to his field. Besides his profession, he’s a hobbyist blogger, and researcher. He creates this site “Oscilloscopetools” because he wants to share his expertise about oscilloscope tools with a broader audience who don’t have much knowledge about these tools.

Leave a Comment