Before Understanding the meaning of Analog and Digital signal, firstly we have knowledge about Signal.


A signal is an electromagnetic or electrical current that is used for carrying data from one system or network to another. The signal is a function that conveys information about a phenomenon.

In electronics and telecommunications, it refers to any time-varying voltage that is an electromagnetic wave which carries information. A signal can also be defined as an observable change in quality such as quantity. There are two main types of signals: Analog signal and Digital signal

Analog Signal:-

At its base, an analog signal is a continuous signal in which one time-varying quantity (such as voltage, pressure, etc.) represents another time-based variable. In other words, one variable is an analog of the other. The result is that analog systems allow for a theoretically infinite number of values to be represented: it can achieve any value within the parameters governing the system.

As an example, imagine a dimmer switch tied to a light bulb. In a perfect analog system, the dimmer will have an infinite number of positions between “off” and “full” – and a correspondingly infinite number of levels of output by the lightbulb. The output by the bulb is analogous to the time-dependent variable “position of the dimmer switch.”

Examples of analog signals:

Conventional (old) transmitters, transducers convey data in analog mode.

The signals include audio signals transmitted through wires, video signals broadcasted using older technology, radio signals, and analog watches.

Digital Signal:-

A digital signal – a must for computer processing – is described as using binary (0s and 1s), and therefore, cannot take on any fractional values. As illustrated in the graphic below, digital signals retain a uniform structure, providing a constant and consistent signal. Because of the inherent reliability of the digital signal, technology using it is rapidly replacing a large percentage of analog applications and devices. For example, the wristwatch, showing the time of day, with its minute, hour, and sweeping second hands, is being replaced by the digital watch, which offers the time of day and other information using a numerical display. A typical digital signal is represented below. Note the equally dispersed 1s and 0s.

Examples of digital signals:

  • Smart transmitters using various protocols transmit data through analog and digital signals.
  • Digital watches.
  • Digital video signals.
  • CD’s.
  • DVD’s.
  • Computer.
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