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Ayesha Khalil
Data communication
& Networks
What is Data?Data consist on raw facts and figures.by using an object data can be easily get. while information is process foam of data. data is not certain while information is certain.
Data
process
information
Electronically transmission of data from one place to another place by using a medium is called data communication.
There are three components of data communication
Data communication
Sender
Medium
receiver
The way of transmission of data from one place to other is called data transmission mode
There is three transmission modesSimplex ModeHalf duplex ModeFull duplex Mode
Data Transmission Modes
Data Transmission Modes
Simplex
mode
• Data can flow only in one direction• Not moved in both direction.one way street• Not perform both action either send or receive data• Direction of flow not changes
Half duple
x
• Data can flow in both directions but not at same time• One way at one time• Device with half duplex mode can send and receive data but not at same time
Full duple
x
• Data can flow in both directions simonstenously• Fast speed and time is not waited
Direction of data flow
Simplex
Half Duplex
Full Duplex
Foams of Data Transmission
Digital Data Transmission Analogue Data transmission
Digital signals are transmitted in sequence of voltage
They represented in binary foams
Continues in foam of wave and this wave is called carrier wave
The number of wave repeats during a specific time is known as frequency.
The height of carrier wave is called amplititude
AsynchronousTransmission
Data is transmitted character by characterThere is regular gap between characters in data transmission
synchronousTransmission
Saved data is transmitted block by blockNo Gap in dataThat’s why it is faster
Types of Data Transmission
A computer network is a set of two or more computers connected through to share information and other resources through cables, satelite,or telephone cables.
There is three types of networks LAN(local area networks) WAN(wide area networks) MAN(metropoletin area networks)
Networks
Networks• Most common type of networks• Used in relatively small areaLan
• Cover large area• Consist two or more lanWan• Covers geographical area• Wan include two or more lan but
cover small area then wanMan
Network TopologiesThe physical layout or the way in which network connection are made is called network topologies.
Bus topology
Ring topology
Star topology
consists of a single cable—called a bus— connecting all nodes on a network without intervening connectivity devices
Click icon to add picture
Bus Topology
each node is connected to the two nearest nodes so the entire network forms a circleone method for passing data on ring networks is token passing
Ring topology
Star topology
Every node on the network is connected through a central device
Questions???