Basics of Digital Communication

Basics of Digital Communication

A communication system's goal is to produce data-carrying signals from a source in one location to a user destination in another. Communication systems may be classified into two categories based on the type of signal processing used on the information-carrying signal. They are:

1) Analog Communication System

2) Digital Communication System

The information-carrying analog signal in an analog communication system is constantly changing in both amplitude and time. It is directly used to change the amplitude, phase, or frequency of a high-frequency sinusoidal carrier wave. Analog signals include speech, video, temperature, and pressure signals, among others.

The information-carrying digital signal is processed in a digital communication system so that it may be represented by a series of binary digits (discrete messages). Then it's used to toggle between ON and OFF any aspect of a high-frequency sinusoidal carrier wave, such as amplitude, phase, or frequency. If the input message signal is analog, sampling, quantizing, and encoding are used to transform it to digital form. Digital signals include computer data and telegraph signals. A digital communication system's most distinguishing feature is that it works with a limited number of distinct messages.

Due to the ever-increasing demand for data communication, digital communication technologies are becoming more appealing. Because digital transmission provides data processing choices and flexibility that analog transmission does not. Furthermore, advances in digital technology have resulted in the creation of increasingly powerful microprocessors, larger and larger memory devices, and a growing number of programmable logic devices. Due to the widespread availability of these devices, designing digital communication networks has become much easier.


Information (speech, video, or data) is transmitted along a path (channel) made up of wires, waveguides, or space. A digital communication system's main characteristic is that it delivers a signal waveform from a finite set of potential waveforms over a fixed period. The amplitude and shape of the signal waveform deteriorate throughout propagation. The receiver's goal is to figure out which waveform from a finite number of waveforms was delivered by the transmitter from a noise-perturbed signal.

An ideal binary digital pulse traveling through a transmission wire is shown in the figure. Two fundamental mechanisms influence the waveform's shape.

1) All transmission lines and circuits have a non-ideal frequency transfer function.

2) Electrical noise or other interference alters the pulse waveform much more.

As shown in the figure, both of these methods lead the pulse form to degrade as a function of line length.

 Figure 1 Pulse degradation and regeneration

Some corrective signal processing techniques must be used during propagation before the pulse degrades to an ambiguous condition. Regeneration is the name given to this process.

The pulse is increased by a digital amplifier in Regeneration, which restores its original perfect form. As a result, the pulse is "reborn" or "regenerated." Regenerative repeaters are circuits that execute this function at regular intervals throughout a transmission system.

Sreejith Hrishikesan

Sreejith Hrishikesan is a ME post graduate and has been worked as an Assistant Professor in Electronics Department in KMP College of Engineering, Ernakulam. For Assignments and Projects, Whatsapp on 8289838099.

Post a Comment

Previous Post Next Post