A communications satellite is an artificial satellite that relays and amplifies radio telecommunications signals via a transponder; it creates a communication channel between a source transmitter and a receiver(s) at different locations on Earth. Communications satellites are used for television, telephone, radio, internet, and military applications. There are over 2,000 communications satellites in Earth’s orbit, used by both private and government organizations.
There are three different types of satellite systems.
1. International satellite communication system INTELSAT.
2. Domestic satellite system DOMSAT.
3. Search and rescue system SARSAT.
INTELSAT: The INTELSAT Organization was established in 1964 to handle the myriad of technical and administrative problems associated with a world wide telecommunication system. The international regions served by INTELSAT are divided in to the Atlantic Ocean region (AOR), the Pacific Ocean Region (POR), and the Indian Ocean region (IOR). For each region , satellites are positioned in geo-stationary orbit above the particular Ocean, where they provide a transoceanic telecommunication route. In addition to providing trans oceanic routes, the INTELSAT satellites are used for domestic services within any given country and regional services between countries. Two such services are vista for telephony and Intelnet for data exchange.
DOMSAT: Domestic satellites are used to provide various telecommunication services, such as voice, data, and video transmission (T.V channels), with in a country. Satellite cell phones allow global travelers and those in remote areas to avoid landlines and terrestrial cell phone services entirely. Satellite cell phones relay your call to a satellite and down through a hub to the end user. This means that most of the earth's geographical area is now accessible by a satellite cell phone! Third party providers of satellite cell include Satcom Global, Roadpost Satcom, Online Satellite Communications, and others.
SARSAT: SARSAT is one type of Polar orbiting satellites. Polar-orbiting satellites orbit the earth in such a way as to cover the north and south polar-regions. Infinite number of polar polar satellite orbits are possible. Polar satellites are used to provide environmental data, and to help locate ships and aircrafts in distress. This service known as SARSAT, for search and rescue satellite.
**Source: Wikipedia, the free encyclopedia**