unit 1:-fundamental of data communication and computer

network
• Data:

Data is defined as information which is stored in the digital form.

• Data communication:-

Data communication means the exchange of data between two devices via some form
of transmission medium which are wired or wireless medium

Or

Data communication is the electronic transfer of data between two or more channel

devices over a communication.

• Characteristics of data communication:-

1. Delivery:-

The data should be delivered to the correct destination and & correct users

2. Accuracy:-

The communication system should deliver the data occurely without introducing any
error

The data may get corrupted during transmission affecting the accuracy of delivered
data

3.Timeliness:-

Data must deliver accurately by the system.

Audio & video data has to be delivered in a timely manner without any delay.

A data delivery is called realtime transmission of data

4.Jitter:-

It is a variation in the packet arrival time. Jitter is when there is a time delay in the
sending at these data packets over your network connection. This is often caused by
network problems and sometime route changes.

The longer data packets take to arrive the more jitter can negatively impact the video
and audio quality
 • process of data communication & it's components:-

fig1. process of data communication

• components of data Communication:-

1.Transmitter (Sender):-

The transmitter is a device that send the data message. The transmitter is any device
that is capable of sending the data (message). It may be computer, mobile, etc.

2.Receiver:-

The receiver receive the data (message) send by the transmitter It can be computer,
mobile, etc.

3. medium:-

It is the path by which the message travels from transmitter to receiver. The
transmission medium can be wired or wireless.

4.protocol:-

protocol is defined as the set of rules agreed by the Transmitters & receiver.

There are different types of protocols used for the communication system.

ex:- TCP, IP, FTP, SMTP, QNS, HTTP, UDP, etc.

5. message:

A message is a data or information to be transmitted from transmitter to receiver

It could be text file audio file, pictures, video file etc.

 • protocols:-

-It is a set of rules that governs (operate) the communication between computers in a
network

protocols are the rules that both transmitter and receiver & all intermediate devices
need to follows & able to communicate effectively

A protocol is a standard procedure & format that two data communication devices
must understand, accept, use to & able to talk to each other.

Types of network protocol.

1. Ethernet
2. local talk
3. fast ethernet
4. Token ring
5. FDDI fiber distributed data transmitter)
6. ATM (Asynchronous transfer mode)
7. Gigabit ethernet.

• Standards:-

- Standards are defined as the guidelines to the product Manufactures & venders to
ensure national & international Interconnectivity.

- Standards are needed for ensuring the interconnectivity & interoperability among
various hardware and software components.

- Without standards, it is not possible to ensure connectivity & interoperability world

wide

• Classification of standards:-

1.De-facto standards:-

It means by facts or by conference the standards that are not approved by any
organization but are widely used are de-Facto standards These are established by
manufacturers
2.De-jure standards:-

De-jure means by law or regulations there are the standards that are recognized
officially by an organization

• Standard organizations:-

Standards are developed jointly by standard creation, committees, forums, &

government regulatory agencies.

The standard organizations are follows: -

1.ISO:-(International standard organizations)

-It is one of the international organization for standardization It creates set of rules &
standards for graphics, document exchange etc.

-It is founded in 1956.

-There are 89 members of the different countries.

2.ITU-T:-(International telecommunication union- telecommunication sector)

- Membership in the ITU-I consists of government authorities & representatives from

different countries.

-ITU-T task is to make technical recommendations about telephone telegraph (post-

office -letters) & data communication interfaces.

3.IEEE:-(Institiute of electrical & electronics engineers)

- It is an international organization founded in the us & It is comprised of electronics,

computer and communication engineers.

- IFEE has a standardization group the develop standards in the areas at the electrical
engineering informatory.

4.ANSI:-(American national standards Institute)

-It is private, Non-governmental, non-profit organization.

-It's members are manufactures, common carries other & interested parties.

-It has no affiliations with the federal government of the US.

5.TIA:-(Felle communication industry association)

It represents manufacturers of communications and information technology products
& services provides for global market place through it's core competencies.

• Bandwidth:

-Bandwidth is a measure of how much information a network can transfer in a given

amount of time

-It is the portion of the electromagnetic spectrum occupied by a signal measured in

Hertz

-The purpose of a communication system is to transfer information from the transmitter

which is located in one place to a receiver

• Data transmission rate:-

-It is the amount of digital data that moved from one place to another in a given time.

-It is the speed at which data is transferred from one device to another device or within
a network

-The data transfer rate refers to the speed at which a device or network component can
send & receive data

-Data transmission rate applies to digital data streams.

• Baud rate:-

-Baud rate is a measurement of how many signal change occur per second in a
communication channel.

-When binary bits are transmitted as an electrical signal with two levels "0" & "1" the bit
rats & the modulation rate.
 • Bit per second:-

- Bit rate is defined as the number of bits transmitted or sent in one second

- It is expressed in bits per second (bps)

- The speed in bps is equal to the number of bits transmitted or received each second

Data transfer rates-

o 1kbps=2^10 bps=1024 bps

o 1mbps=2^20 bps=1024 kbps
o 1gbps= 2^30 bps=1024 mbps
o 1 tbps = 1024 gbps

• Modes of communication (simplex, half duplex, full duplex) :-

1.Simplex:

- In simplex mode of communication, data can flow in one direction only

(Unidirectional).

- In this system the information is communicated in only one direction

- In that one device can transmit Jata & other can only accepts (receives the data

- Computer System-data flow from CPU to monitor or keyboard or mouse to monitor

ex:- Radio or tv broadcasting systems can only transmit they cannot receive
2.Half Duplex communication:-

- In half duplex communication mode each station can transmit of receive the message
(data)

- A half duplex communication is the bidirectional communication which does not take
place simultaneously

- The systems are bi-directional but they can transmit as well asreceive but not
simultaneously.

- At a time these systems can either transmit or receive.

- Each station can transmit & receive, but not at the same time. When one device is
sending the other one is receiving & vice-versa.

- In half duplex transmission, the entire capacity of the channel is utilized by the
transmitting system

ex:- Walkey talkey

3.full duplex communication:-

- In full duplex communication both devices can transmit & receive simultaneously

- These are truly bi-directional Systems as they allow the communication to take place
in both the direction simultaneously

- In that Jink may contain two physically separate transmission paths one for sending &
another for receiving otherwise the capacity of channels are divided between signals
travelling in both directions

ex:-telephone, mobile phones, etc.

• Signals:-

- The signal is an electromagnetic wave that carries information from one point to
another

- It can travel for through different mediums such as air water etc.

- The speed of a signal wave is equal to the speed of light.

Types of signal:

1.Analog signal:-

- Analog signals are continuous time-varying signals.

- It means that these signals are the function of time.

- An analog signals is a signal whose characteristics Such as voltage, amplitude,

frequency vary with time.

- The common shape of an analog signal is the sine wave

ex:- Electrical signal, light signals.

- Every signal requires a medium to propagate

- Electrical signals require cables to propagate from one place to other place

Types of Analog signals!-

1.periodic signal:-

- An analog signal that repeats over a period of time is known as the periodic signal such
as sine wave & Cosine wave

- periodic signals can be easily represented using mathematical equations

2.Aperiodic signal:-

-An Analog signal that does not repeat over a period at time is known as an aperiodic
signals.

- The noise signal is continuous signal but not the repeated pattern.
2.Digital signal :-

-Digital signal are the signal that represents the data in the form of separate values.

-It takes only two water values 0&1 which is known as bits

-The data transmitted in the form & bits

01000110 = 8 bit or 1 byte data.

Types of digital signal:-

1.periodic signal:-

A digital signal that repeats over a period of time is known as periodic signal such as
square wave

2.Aperiodic signal:-

A digital signal that does not repeat over a period of time is known as aperiodic signal.

• Analog & Digital Transmission:-

1.Analog to Digital Conversion:-

- It is the process of converting an analog signal into a digital signal.

- This conversion is essential for processing and storing analog information using digital
systems.

The process is done with the following key concepts:

1. Sampling: The process of taking discrete samples of the analog signal at regular
intervals.

2. Quantization: The process of assigning a discrete numerical value to each sample.

3. Encoding: The process of representing the quantized values in a digital format.

Example: Recording

ABC → 0001100

2) Digital to Analog Conversion:-

It is the process of converting a digital signal, which is a series of values, into an analog
signal, which is a continuous wave.

Example: Song/Movie ----- ABC → Sound (Speaker)

• Computer network:-

The two or more computers are connected together through a communication media
(cables or satellites) is called a computer network.

Or

It is a collection of computer systems which can communicate or interact with each

other through a communication media is called computer network.
Need of computer network:-

- Networking plays an important role in every kind of organization from small to medium
sized industry, companies, airports, hospitals, colleges, universities, etc. and even in
the home. In short networking plays an important role every where computers are used.

- Sharing of information & data over the geographically wide areas.

- Communication between one computer to another computer

- Exchange of data & information among the users via the network.

Characteristics of computer network:-

1.Availability:-

It is typically measured in a percentage basis as -The number of minutes that exists in a

year divided by the number of minutes in a year.

2.Cost:-

It includes the cost of the network components, their installation & and other ongoing
maintenance.

3.Reliability:-

The reliability of the computer components & the connectivity between them.

4.Security:-

Includes the protection of the network components & the data.

5.Speed:-

It means how the data is fast transmitted between networks and points.

• Application of computer network:-

1. Marketing & sales
2. Financial services
3. Manufacturing
4. Directory services
5. information services
6. Electronic data interchange (EDI)
7. Electronic mail
8. Teleconferencing
• Benefits of computer network:-
1. File sharing
2. Resource sharing
3. Inexpensive setup
4. Flexible handling
5. Centralized management
6. Backup data
7. E-mail services.

• Advantages:-
1. File sharing
2. Server-client model
3. Resource sharing
4. Better connectivity and communications

• Disadvantages:-
1. Lack of data security & privacy
2. Presence of computer viruses & malware
3. Lack of independence
4. Lack of robustness (Hardness)
5. Need of efficient handler

• Classification of Network:-
1.LAN (Local area network):-

-It is privately owned networks covering a small geographic area like a home, office
building, a group of buildings & campus.

-It covers the area less than 1km.

-LAN are easily designed & troubleshoot.

The personal computer & workstation in the offices are interconnected via LAN.

-It exchanges information & sharing of resources becomes easy because of LAN.

-The data rate of LAN is 4 to 16 Mbps with the maximum of 100 Mbps.

2.MAN (Metropolitan area network):-

-It is a network covering a larger area than LAN as a network of all computers within a
city.

-A MAN can cover a group of corporate offices or a town or city & can be either privately
or publicly owned.

-A MAN can support both data & voice & may be related to the local cable & TV network.
It means of connecting LAN to LAN.

-It covers the area up to 10km.

3.WAN (Wide area network):-

-Wide area network is a long distance communication network that covers a wide
geographic area such as a state or country.

-It is a network that spans a large geographical area, the most common example is the
internet.

-A WAN provides long-distance transmission of data, voice, image, and video

information over large geographical areas.

-The communication medium used in WAN can be PSTN (public switched telephone
network) or satellite links that may comprise a country or whole world due to the larger
distance involved.

-WAN may use public leased, or private communication devices and can spread over a
wide geographical area.

-WAN the network contains a large number of cables or telephone lines each one
connecting a pair of routers.

4.PAN (Personal area network):-

-PAN means personal area network.

-It is a computer network organized around an individual person.

-It is used for communication among the personal devices.

-Personal area networks typically involve a mobile computer, cellphone, wireless or

Bluetooth network.

-It covers generally a range of less than 10 meters (About 33 feet).

-It is established for the purpose of connecting computer devices of professional use is
known as a personal area network.

5.CAN (Campus area network):-

-It means campus area network.

-It is used to connect buildings across a campus of colleges & universities.

-It is a type of local area network. It is larger than a local area network but smaller than a
metropolitan area network (MAN).
-It is a network that connects two or more LAN’s but that is limited to a specific
geographical area such as a college campus.

-A CAN is a computer network made up of an interconnection of local area networks

within a limited geographical area.