Satellite Communications:

Satellite communications are originally developed to provide long distance telephone service. Nowadays it has become an essential part of the world’s telecom communication system. By use of this satellite communication they serve billions of people with telephone, data as well as video services. It is also used for remote sensing like detection of water pollution, monitoring and reporting of weather conditions. In satellite service provided by satellite communication are fixed satellite service, broadcasting satellite service, mobile satellite service, navigational satellite service and meteorological satellite services. The most important satellite systems are INTELSAT, USDOMSAT AND US National Oceanographic and Atmospheric administration services of polar orbiting satellites. Geostationary orbit is an orbit in which a satellite appears to be stationary with respect to the earth. Satellite communication is classified into two segments. They are ground segment and space segment. The space segment includes tracking telemetry & command, power subsystem, attitude control system, orbital control system, thermal control system, transponders, etc. The ground segment includes stations on ship at sea, aeronautical mobile stations, home TV receives only system, commercial and military land systems. The satellite operation can be divided into two access modes. They are single access mode and multiple access modes. Recently broadcasting directly to home TV receiver using satellite is introduced which is known as Direct Broad Satellite (DBS) service.