communications satellite

communications is an artificial satellite stationed in space for the purpose of telecommunications. Modern communications satellites use a variety of orbits including geostationary orbits, Molniya orbits, otherelliptical orbits and low (polar and non-polar) Earth orbits.For fixed (point-to-point) services, communications satellites provide a microwave radio relay technology complementary to that of submarine communication cables. They are also used for mobile applications such as communications to ships, vehicles, planes and hand-held terminals, and for TV and radio broadcasting,


Basic Elements
Satellite communications are comprised of 2 main components:
1. The Satellite
2. The Ground Station
The Satellite

The satellite itself is also known as the space segment, and is composed of three separate units, namely the fuel system, the satellite and telemetry controls, and the transponder. The transponder includes the receiving antenna to pick-up signals from the ground station, a broad band receiver, an input multiplexer, and a frequency converter which is used to reroute the received signals through a high powered amplifier for downlink. The primary role of a satellite is to reflect electronic signals. In the case of a telecom satellite, the primary task is to receive signals from a ground station and send them down to another ground station located a considerable distance away from the first. This relay action can be two-way, as in the case of a long distance phone call. Another use of the satellite is when, as is the case with television broadcasts, the ground station's uplink is then downlinked over a wide region, so that it may be received by many different customers possessing compatible equipment. Still another use for satellites is observation, wherein the satellite is equipped with cameras or various sensors, and it merely downlinks any information it picks up from its vantagepoint.

The Ground Station.
This is the earth segment. The ground station's job is two-fold. In the case of an uplink, or transmitting station, terrestrial data in the form of baseband signals, is passed through a baseband processor, an up converter, a high powered amplifier, and through a parabolic dish antenna up to an orbiting satellite. In the case of a downlink, or receiving station, works in the reverse fashion as the uplink, ultimately converting signals received through the parabolic antenna to base band signal.

And The Various use of Satellite Communication are

1. Cellular
2. Television Signals
a. C-Band
b. Digital
3. Marine Communications
4. Spacebourne Land Mobile
5. Satellite Messaging for Commercial Jets
6. Global Positioning Services


to get full report and presentation of satellite communication
please visit this link
http://studentbank.in/report-satellite-c...ull-report
http://studentbank.in/report-optical-sat...ars-report

for more info read
en.wikipediawiki/Communications_satellite
http://cse.wustl.edu/~jain/cis788-97/ftp...e_nets.pdf