DATA TRANSMISSION MODES
Data transmission modes defines the way in which data is need to be transmitted. Ut means whether data is to be transmitted one bit at time or data is to be transmitted as a group of bits.
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| DATA TRANSMISSION MODES |
TYPES OF DATA TRANSMISSION MODES:-
1. Parallel Transmission
2. Serial Transmission
1. Parallel Transmission:- In a parallel transmission, group of bits are send at a time consisting of 0's and 1's. Thus, ‘n’ cables or transmission lines are needed to transmit ‘n' bits at a time.
2. Serial Transmission:- In a serial transmission, only one bit can be send at a time. Thus, only one cable or transmission line us needed to transmit a single bit at a time.
Types of serial transmission are:-
i)Asynchronous Serial Transmission
ii)Synchronous Serial Transmission
iii)Isochronous Serial Transmission
i)Asynchronous Serial Transmission:- In asynchronous serial transmission, bits are divided into small groups that are referred as bytes [1byte=8bits] and then each byte is transmitted independently. The sender transmit the group of bits to the receiver at any time and the receiver does not know when the bits has arrived. Two control bits i.e. start and stop bits are used for this purpose.
“Start bit that informs the receiver that the sender is sending message and Stop bit that informs the receiver that the message is ended".
ii)Synchronous Serial Transmission:- In synchronous serial transmission, larger groups are transmitted instead of sending each byte containing the separate start and stop bits. All the groups that are needed to be transmitted are grouped together, so that they all can be send with each other.
iii)Isochronous Serial Transmission:- In isochronous serial transmission, data arrives at a fixed rate. It means uneven time delays between data transmission does not occurs.
TRANSMISSION MEDIA:-
Transmission media lies below the physical layer. Transmission media acts as an interface between the sender and the physical layer. When information is transmitted from the source to the destination, the transmission media is used.
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| TRANSMISSION MEDIA |
TYPES OF TRANSMISSION MEDIA:-
1. Guided Transmission Media
2. Unguided Transmission Media
1. Guided Transmission Media:- Guided media are the wired media, such as copper wires, fibre wires, etc. The signals travels across the cable in the form of electrical signals or light signals.
Types of Guided Transmission Media are:-
i)Twisted Pair Cable
ii)Coaxial Cable
iii)Fiber-optic Cable (FOC)
i)Twisted Pair Cable:- Twisted pair cable is the most commonly used media for data transmission. As the name indicates, twisted pair cable consist if two insulated copper wires, twisted with each other. These copper wires are about 1mm thick.
Types of twisted pair cable are:-
a)Shielded Twisted Pair (STP) Cable
b)Unshielded Twisted Pair (UTP) Cable
ii)Coaxial Cable:- Coaxial cable is considered as co-ax, coaxial cable has a cylindrical shape. Coaxial cable consist of shielded conductor, surrounded by an insulator. The whole coaxial cable is covered by some kind of plastic cover.
Types of coaxial cable are:-
a)Baseband Coaxial Cable
b)Broadband Coaxial Cable
iii)Fiber-optic Cable (FOC):- Fiber-optic cable, signals or data is transmitted in the form of light. It means light signals are used for data transmission.
2. Unguided Transmission Media:- Unguided media are the wireless media, such as microwaves, radio waves and infrared rays. The signals travels in the free space. It means unguided media transmits electromagnetic waves without the use of any physical media or cable. Thus, the unguided media is also referred as wireless media.
Types of Unguided Transmission Media are:-
i)Microwaves
ii)Radio waves
iii)Infrared Rays
i)Microwaves:- Microwaves transmission is the line of sight transmission. It means microwaves travels in straight line. Microwaves transmits data without the use of cables.
ii)Radio waves:- Radio waves transmission is the sky mode transmission. It means radio waves propagates through sky mode. Radio waves transmits data without the use of cables.
Types of radio waves are:-
a)Short waves
b)Very High Frequency (VHF) waves
c)Ultra High Frequency (UHF) waves
iii)Infrared Rays:- Infrared rays are used for short distance, such as remote controls of televisions, DVDs, electronic cars, games and etc.
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