news details |
|
|
| Satellite communication | | | D.K. Mota | 11/28/2011 2:04:06 AM |
| Long distance communication using conventional techniques like co-axial cable or Microwave systems involves large number of repeaters (To regenerate the original signals). For Radio systems/links, the repeater spacing is limited by line of sight. By using large number of repeaters, performance and reliability are degraded. Large areas could be covered if vertical microwave repeater could be increased by putting it on board an artificial earth satellite.
Science Fiction writer Mr. C. Clarke in an article in "Wireless world" in 1945 proposed that world wide coverage could be obtained by using 3 microwave repeaters placed in Geostationary orbit at the height of about 36,000 kms with a period of24 Hrs and the first artificial satellite "Sputnik-I" was launched by Soviet Union in 1957. Since then large number of Satellites have been launched. The first satellite helped to identify the density of high atmospheric layers thr-ough measurement of it's orbital change and provided data on radio signal distribution in cono-sphere. A geostationary satellite is launched above the equator 36,000 kms above the earth. It's period round the earth coincides with that of earth rotation. Therefore the Satellite looks as if it is stationary from the earth. If three communication satellites are launched equidistantly above the equator, it can serve almost all communication network round the world so Satellites above the Atlantic, pacific and Indian oceasons have been launched.
These Satellites handles hundred of billions of voice, data and video transmission talks across all countries. It also enables communication services to those areas which are virtually INACCESSIBLE by all other conventional forms of communication due to natural physical barriers Satellite communication provide a practical and economical means of long haul communication traffic in a country with a large geographical area.
Advantages of Satellite communications are as under:-
Large coverage: It is possible to cover about 10,000 kms distance irrespective of intervening terrain with a single satellite. High reliability and high quality as there is only one repeater in the satellite network.
Flexibility: Satellite Communication is well suited for changing.
Speed of installation: Installation of earth terminals can be achieved in a short time as compared to laying of OFC/Radio links. Mobile/Emergency communication with ariliftable or Road transportable terminals or emergency communications can be quickly provided. Reliable for long distance land mobile, maritime mobile and aeronautical mobile services are feasible only by means of satellite. And lastly point to multipoint transmission ; signals sent from an earth station can be received at several other earth stations, Simultaneously such as TV Broad casting, Audio and Video distribution and Tele conferencing, Facsimile, data, News etc.
|
|
|
|
|
|
|
|
|
|
|
|
|
| |
| |
|
|
|
|
 |
|
|
|
|
STOCK UPDATE |
|
|
 |
| BSE
Sensex |
 |
| NSE
Nifty |
|
|
| |
CRICKET UPDATE |
|
|
|
|
| |
| |
|
|
| |
|
|
|
|
| |
|
|
|
|
|
|
|
|
|
|
|
|
|
