Satellite Microwave

Satellite Microwave 

 

 A satellite consists of several transponders(frequency bands),which receive signals from one frequency band.This action is called up-link.After this action,the satellite will amplify or repeat the signals to the other frequency band.This action is called down-link.A satellite link is like a microwave link.Satellite will link two or more ground stations,like point-to-point link or broadcast link.The most important applications for satellite communication will be long-distance telephone transmission,private business networks,and television distribution.

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Data Communication Services

Public Switched Data Network(PSDN)

In public switched data network all data to be transmitted is first assembled into one or more message units.called packets.These packets include both the source and the destination network address.The destination is determined by the destination address within the packet,where the packet will be finally passed to the destination.

Integrated Service Digital Network(ISDN) 

ISDN(Integrated Service Digital Network)is a fully digital transmission over ordinary telephone copper wire as well as over other media.Home and business users who install an ISDN adapter(in place of a modem)can see highly graphic Web pages arriving very quickly(up to 128Kbps).ISDN requires adapter at both ends of the transmission so your access provider also needs an ISDN adapter.

 







Modem 

There are two levels of service:the Basic Rate Interface(BRI)intended for the home and small enterprise,and the Primary Rate Interface(PRI),for larger organizations.
                                                                               USB modem

ADSL(Asymmetric Digital Subscriber Line)

ADSL(Asymmetric Digital Subscriber Line) is a technology for transmitting digital information at a high bandwidth on existing phone lines to homes and businesses.
Unlike regular dial up phone service,ADSL provides continuously available,"always on" connection.ADSL simultaneously accommodates analog(voice) information on the same line.ADSL is generally offered at downstream data rates from 512Kbps to about 6 Mbps.

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Satellite Communication

Hello visitors!!!!!!!!!!!Read following and up your Knowledge..

Have you looked at the sky on a cloudless clear night?What do you see there high up in the sky?There are millions of stars hiding the secrets of the universe.Among them them,if you look at the sky very carefully for sometime,you can see blinking stars moving from north to south or south to north and you will understand that their movement is very fast.What are they?Why are they moving so fast They are man made stars;they are called artificial satellites.

So.....I think to post today satellite Communication................An artificial satellite is a spacecraft.It is orbits the Earth at a fixed distance.Artificial satellite are sent to space on various purposes such as communication,remote sensing,military purpose,space astronomy.However,the main purpose of satellites is communication.They bring the world together.It is with the help of communication satellites that  we enjoy the thrill of Olympic Games,World cup football,Asians Games or the World Cup Cricket Finals How does CNN or BBC news come to us?How does the weather forecast come to us?They all are communicated with the help of satellites orbiting the Earth.

The first artificial satellite,Sputnik 1 was launched by Soviet Russia(USSR) on 4th October 1957.It was a competition between the USSR and the United States of America(USA) at the beginning.Later,other countries like France,China,India,,and japan too started launching their own satellites for various purposes,mainly for communication.In 1945 the honored Sri Lankan citizen Arthur C.Clarkemade a very famous statement about making communication possible with countries all over the world with the help of a spacecraft orbiting the Earth.The world became a single village as a result of satellite of satellite communication.There are commercial communication satellites like TEL STAR,INTELSAT etc.providing communication facilities for the whole world.

 Geostationary satellites orbit the Earth at a distance of 35900 Km and take 24 hours to orbit.That`s why they appear almost at the same time of the day in the sky.If you observe the sky for a few days you will be able to see these artificial starts orbiting the Earth every day at the same time.At the moment there are more than 3000 satellites orbiting the Earth.

 All these satellites communicate with communication stations build at various places on the Earth.Dish antennas are used to communicate between a satellite and communication center.In countries where there are satellite television services people can receive T.V.program-mes telecast by hundreds of T.V. stations all over the world with the help of a dish antenna.

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