16-01-2012, 04:30 PM
Satellite Communications
1.1 Introduction
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Features offered by satellite communications
. large areas of the earth are visible from the satellite, thus the satellite can form the star point of a communications net linking together many users simultaneously, users who may be widely separated geographically
.Provide communications links to remote communities
.Remote sensing detection of pollution, weather conditions, search and rescue operations.
Polar orbiting satellites
.Orbit the earth such a way as to cover the north and south polar regions
.A satellite in a polar orbit passes above or nearly above both poles of the planet (or other celestial body) on each revolution. It therefore has an inclination of (or very close to) 90 degrees to the equator.
.Since the satellite has a fixed orbital plane perpendicular to the planet's rotation, it will pass over a region with a different longitude on each of its orbits.
.Polar orbits are often used for earth-mapping-, earth observation- and reconnaissance satellites, as well as some weather satellites.
