NCERT Computer: Chapter 5 – Data Communication and Networking Part 3

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Types of Communication Services

Bandwidth is the range of frequencies that is available for the transmission of data. A narrow range of frequencies in a communication system is analogous to a garden hose with a small diameter.

Communication companies such as American Telephone and Telegraph (AT&T) and Western Union are called common carriers, and they provide three general classes of service for both voice and data communication:

1. Narrowband handles low data volumes. Data transmission rates are from 45 to 300 baud. The low-speed devices might use narrow band communications.

2. Voiceband handles moderate data transmission volumes between 300 and 9600 baud. They are used for applications ranging from operating a CRT to running a line printer. Their major application is for telephone voice communication hence, the term voiceband.

3. Broadband handles very large volumes of data. These systems provide data transmission rates of 1 million baud or more. High-speed data analysis and satellite communications are examples of broadband communication systems.

Communication Media

Communication media refers to the means of delivering and receiving data or information. In telecommunication, these means are transmission and storage tools or channels for data storage and transmission.

There are two forms of communication media:

Analog: Includes conventional radio, telephonic and television transmissions

Digital: Computer-mediated communication, computer networking and telegraphy

Following are the major communication devices which are frequently used:

Means of transmission- the physical means

Means of Transmission

Means of transmission- the physical means

Computer Network

A computer network is interconnection of various computer systems located at different place. A computer network is a set of connected computers. Computers on a network are called nodes. Connected computers can share resources, like access to the internet, printers, file servers, and others.

The computer that provides resources to others on a network is known as server. In the network the individual computers, which access shared network resources, are known as nodes.

This image shows computer network

Image of Computer Network

This image shows computer network

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