Satellite Communication

Have you looked up 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 space craft. It orbits the Earth at a fixed distance. Artificial satellites are sent to space on various purposes such as communication, remote sending, 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 we enjoy the thrill of Olympic Games, World Cup Football, Asian Games or the World Cup Cricket Final being played anywhere in the world. How does CNN or BBC new come to us? How does the weather forecast come to us? They all are communicated with the help of satellite orbiting the Earth.

The first artificial satellite, Sputnik 1 was launched by Soviet Russian (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 French, China, India and Japan too started launching their own satellite for various purposes, mainly for communication. In 1945 the honoured 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 space craft orbiting the Earth. The world become a single village as a result of satellite communication. There are commercial communication satellites like TELSTAR, INTELSAT etc. providing communication facilities for the 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 3000 satellites orbiting the Earth.

All these satellites communicated with communication station built at various places on the Earth. Dish antennas are used to communicate between a satellite and a communication center T.V programmes telecast by hundreds of T.V station services the world with help of a dish antenna. In Sri Lanka the main satellite communication center is stationed at Padukka, a few kilometers away from Colombo.