Data communication involves the transmission of data between two points using a communication system consisting of a sender, receiver, transmission medium, and protocols. The document discusses the basic components of a communication system including guided media like twisted pair cables, coaxial cables, and fiber optic cables for transmitting data along a physical path, and unguided media like radio waves, infrared, and Bluetooth that transmit through open space. It also describes common communication devices used like modems, network interface cards, routers, and switches/access points to connect computers and transmit data over networks.

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Name: M.Aaqib Imran
Class: IX A
Subject: Computer Science
Data communication is the transmission of data between two points.
A data communication system is a collection of hardware and software
arranged to communicate information from one location to another.
Components of a Communication
System

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These are the five basic components of a Communication System
 Sender: It is a device which sends message to another device. It is
also called the source of the message. It can be computer, telephone,
etc.
 Receiver: It is the device which receives the transmitted message.
It is also called the destination of the message.
 Message:It is the data being transmitted. It can be text, graphics,
image, sound or video
 Transmission medium: It is the physical pathway or channel
through which the message travels. Some examples are coaxial cable,
Fiber optic cable, Microwave, etc.
 Protocol: It is the set of rules between the communicating devices
that governs the process of Data Communication. Without a
protocol, two devices may be connected but they cannot
communicate with each other

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Transmission Media
Guided Media: Guided media uses cabling system that guides
the data signals along a specific path. Different types of guided media
are described below:
1.Twisted Pair Cable: Twisted pair cable consists of pairs
of copper wire around one another. Its transmission speed ranges
from 2 million to 10 million bits per second to 10 billion bits per
second
2.Coaxial Cable:Coaxial cable consists of a thick copper
wire surrounded by a thick insulating layer and another conducting
layer. Its transmission speed ranges from 200 million bits per
second to 500 million bits per second
3.Fiber optic cable: Fiber Optic Cable consists of hair thin
transparent wires. It provides high quality transmission at
extremely high speed. It is used for Data Transmission over long
distances
Unguided Media
Unguided media signals travel through open space and nothing
guides them along any specific path. It has the following examples:
1.Radio Waves: Radio waves are electromagnetic waves that
are propagated by antennas. The transmitter sends signals and the
receiver receives it. They are invisible and undetected to human
beings

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2.Infra Red: Infra Red waves are light energy waves that we
cannot see. It is used for short distance communication. They are
disrupted by anything or object in their way.
3.Bluetooth: Bluetooth is a wireless communication
technology which is commonly used for communication by
portable devices. Bluetooth technology can transmit text, image,
video, audio, etc.
Communication Devices
1. Modem: A modem (modulator–demodulator) is a network
hardware device that modulates one or more carrier wave signals to
encode digital information for transmission and demodulates signals
to decode the transmitted information.
2. Network Interface Card: A Network Interface
Card (NIC) is used to create computer network between computers.
It has two types wired and wireless NIC
3. Router: Router is a communication device that is used for
wired or wireless communication between computers. It is also used
to connect computers to the internet.
4. Switch/Access Point: Switch or access points are
used in connecting computers together in a Local Area Network
(LAN). Switch is used to form wired and Access Point is used to
create a wireless connection