TABLE OF CONTENTS Satellite communications allows the most remote places to receive Internet, telephones, faxes, video and telecommunications via satellite connections. The infrastructure, bandwidth, and availability of satellite communications, and the possibility of combining satellite communications with other types of communications systems makes this method an ideal candidate for providing ubiquitous communications to everyone worldwide.
Communication satellites, which consist of a space platform and the payload, are positioned in a geostationary orbit. The payload is the equipment and various other devices that are mounted on the space platform. The same satellite may contain multiple payloads for multiple applications, including different data links operating with their own frequencies and antennas.
Each satellite is equipped with attitude control to ensure that the antennas are all pointed towards the earth and that the antenna beam is focused on the intended area on the earth (see Figure 10 1).
Any disturbances that may occur will change both the attitude of the geostationary satellite and the orbit of the satellite by a slight amount. The attitude stabilizers that are on board the satellite compensate for the changes in attitude, which is the positioning of the satellite for the antennas. The orbit of the satellite is changed due to movements in the north and south plane in a figure eight pattern over a twenty-four hour period.
