wireless transmission media used in communications include broadcast radio, microwaves, satellites & infrared. They are used when it is impractical & impossible to install cables. The following are the various types of unbounded transmission media.
1. Microwave:-
microwaves are radio waves that provides high speed signals transmission. It transmits signals from one microwaves station to another. Microwaves are limited to line of sights transmission which means that microwaves must be transmitted in a straight line. For e.g.- microwave transmission is used in wide open area such as deserts or lakes between building in a close geographical areas.
2. Satellite:-
A communication satellite is basically a microwave relay station placed in outer space. A satellite receives radio signals are a given frequency band changes their frequency & transmit them. The message signal is transmitted form the earth station through an up link through the satellite. It is amplified, translated to the downlink frequency in a transponders presents in the satellite and sent back to another earth station. The frequency transmitted from the ground station to the satellite is known as uplink & the frequency at which a satellite transmits amplified signals to the ground stations is known as down link frequency.
3. Infrared:-
It is a type of electro magnetic wave of large wave length & small frequency then visible light then its frequency is low. It is used in optical fiver communication, wireless LAN, mobiles & many other electronic devices.
4. Bluetooth:-
A proposed radio frequency specification that may portable devices may used for short range wireless communication is called Bluetooth. With Bluetooth devices such as laptop, handheld computers etc can have wireless communication with each other.
No comments:
Post a Comment