What is Satellite Television
Satellite television is the use of satellites for relaying television programs from a source point where these programs originate to a large geographical area.It is widely used today and has become so popular that it has been instrumental in making satellite a household known entity. The operation of it is very simple to understand and is explained below:-
The program signal from its source of origination is first of all transmitted to an Earth station capable of uplink communication with the satellite. This is done by the use of microwave terrestrial links. The earth station than shifts this signal to the satellite uplink frequency which is in the range of GHz and then with the help of transmitting antennas, transmits the signal carrying the program to the Satellite in space. In case the program originates at a remote location which is often the case in sports events coverage, a satellite van station at the spot is used to uplink the signal to the satellite in space in order to avoid unwanted delay. The Satellites used for in the application being discussed are known as Direct Broadcasting Satellites (DBS). These are situated in the geostationary orbit i.e. the relative position of these satellites is fixed with respect to the earth surface. This is because of their orbit location and their time period of revolution around the earth surface, the later being equal to the time period of rotation of the earth around its own axis. In India, INSAT series of satellites are used for this operation. On receiving the signal from the earth station, these satellites then shift the frequency of the signal to a pre-determined downlink frequency. Then this signal is transmitted back to the earth over a wide geographical area. This signal is then received by the antennas that are mounted on the roof tops and then are demodulated and decoded before being relayed on to the television set. These receivers are known as TVRO’s and are widely popular today.
In Community Antenna Television or more popularly known as Cable Television (CATV), instead of using separate antennas for every household, a single antenna in conjunction with head end equipment is used to receive, demodulate and decode the signal before it is distributed to different homes with the help of a network of co-axial wires. Thus in both Cable Television Services and in Direct to Home (DTH) services, Satellite television plays an important role.