ELEC S211 Fundamentals Of Communications Technology (Free Courseware)

Introduction

In this module, you will learn several basic concepts of communications systems such as major building blocks of a communication system, properties of electromagnetic (EM) waves, and frequency allocation in communication systems. You can quickly review the important terms used in this module in the glossary at the end of this module. As you work your way through the module, you’ll encounter some words or terms that are printed in bold. That is an indication that the term or word is in the glossary.

What are communication systems?

No matter whether a society is old or modern, communication plays an essential role in all sectors of that society. But what does the word communication really mean?

Definition of ‘communication‘
The New Oxford Dictionary of English (1998) (—— (1998) The New Oxford Dictionary of English, Oxford: Clarendon Press.) defines communicate as meaning to ‘share or exchange information, news, or ideas’. The same source defines communications as ‘the means of connection between people and places’ (ibid).

In old Chinese societies (and others for that matter), pigeons were used to carry letters. The small paper message was the sharing of information and the pigeon was the means of connection. Nowadays, you can communicate with your friends by phone, email or MSN. A communication system is built to send information from one location to another.

Information sent by communication systems
Information can be speech, text, images or any form of data, which can, for example, be exchanged by sending emails or teleconferencing using satellite communication, cellular phones, pagers, and so on

The next issue concerns how to transmit the data in a fast and reliable way. These are the main objectives in designing or choosing a communication system and we’ll discuss several communication systems in detail in the later units of ELEC S211.

Building blocks of communication systems

You’ll learn the design and applications of communication systems in this course. So, as you work toward your first reading, the first idea you need to understand is the building blocks of a communication system.

A communication system should consist of at least one source, one sink (destination) and a channel. Examples of communication systems that contain:

1. a single source and a single sink; and
2. a single source and multiple sink;

At one end, the information will be transmitted from the source through a medium (i.e., the channel) to the destination (called the sink), which is the other end point.

Let’s take a chat with your friend as an example:

You (source) voice out a message (information) to your friend (sink) through the air (channel).

That’s to say, you are one of key components in this communication system. Similarly, you should already be aware of other types of communication systems in daily use. All of these systems are essentially similar to the voice conversation described above — the technology used is obviously different. Let’s consider a typical process in a telephone system as an example.