Difference Between Digital and Analog Signals

Difference Between Digital and Analog Signals

Anyone working in signal processing or electronics should know two main categories of devices: analog and digital. But what is something analogous? How is it different from digital?

Besides, what makes something digital?

Table of Contents

What is an analog signal?

An analog signal is an uninterrupted signal in which a quantity that varies over time (such as voltage, pressure, etc.) represents another time variable. In other words, one variable is analogous to another.

The result is that analog systems can represent a theoretically infinite number of values: you can reach any value in the parameters that govern the system.

For example, imagine a dimmer connected to a light bulb. In a perfect analog system, the dimmer will have an infinite number of positions between “off” and “full” – and therefore, an endless amount of output levels per bulb.

The lamp output is analogous to the time dependent variable “dimmer position.”

The difference between analog and digital signal

Digital signals, on the other hand, express the variation of a system variable in reply to an array of discrete values (more like a light with an on / off switch or a three-way bulb with several distinct output levels),

Examples of analog signals

Theoretically, we can use the term “analog signal” to describe any continuous signal that uses a time-varying amount to represent another (like mechanical systems like a dial thermometer). But for our purposes, we most often use it to describe electrical signals.

We use analog signals in a wide range of applications, such as:

  • Audio recording and playback.
  • Live sound system/amplification
  • Older technologies for the transmission of video signals (VGA, S-Video, etc.)
  • Radio signals
  • TV signals (until recently)
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At one point, even analog computers were available. These new computer devices were used to calculate complex scientific and industrial problems before the development of enough powerful digital computers.

They used several physical phenomena (such as electrical or mechanical quantities) to model the issues to be solved.

In almost all cases, digital versions have replaced analog equivalents. A recent example is the ubiquity of digital TV streaming or HDMI video standards.

In 2019, all new consumer TVs were digital, like all consumer computers for many years. However, it should be noted that analog and digital are currently used in sound recording, each with its supporters.


Analog signals represent a continuous variable following another time-based continuous variable. They are capable of generating constant information with a theoretically infinite number of possible values.

We have seen analog signals used in almost all types of signal processing and consumer electronics applications.

In most scenarios, they have been replaced by digital versions, although analog processes are still prevalent in sound recording and digital recording equipment.

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