Sunday, May 29, 2011

SATELLITE COMMUNICATION








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, 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.








An artificial satellite is a spacecraft. It orbits the Earth at a fixed distance. Artificial satellites are sent to space on various purposes such as communication, remote sensing, military purposes, 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 Foot Ball, Asian Games or the World Cup Cricket Final. 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 Clarke made 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 communication. There are commercial communication satellites like TELSTAR, 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 stars orbiting the Earth everyday at the same time. At the moment there are more than 3000satellites orbiting the Earth.







All these satellites communicate with communication station built at various place on the Earth. Dish antennas are used to communicate between a satellite and a communication centre. In countries where there are satellite television services people can receive T. V. programmes telecast by hundred of T. V. stations all over the world with the help of a dish antenna. In Sri Lanka the main satellite communication centre is stationed at Padukka, a few kilometers away from Colombo.

SATELLITE COMMUNICATION












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, 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.











An artificial satellite is a spacecraft. It orbits the Earth at a fixed distance. Artificial satellites are sent to space on various purposes such as communication, remote sensing, military purposes, 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 Foot Ball, Asian Games or the World Cup Cricket Final. 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 Clarke made 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 communication. There are commercial communication satellites like TELSTAR, 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 stars orbiting the Earth everyday at the same time. At the moment there are more than 3000satellites orbiting the Earth.












All these satellites communicate with communication station built at various place on the Earth. Dish antennas are used to communicate between a satellite and a communication centre. In countries where there are satellite television services people can receive T. V. programmes telecast by hundred of T. V. stations all over the world with the help of a dish antenna. In Sri Lanka the main satellite communication centre is stationed at Padukka, a few kilometers away from Colombo.