Satellite communications are comprised of 2 main components:
1. 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.
2. 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.
Various Uses of Satellite Communications
a. Traditional telecommunication
b. Cellular.
c. Television signals.
d. Marine communication.
e. Spacebourne Land Mobile
f. Satellite Messaging for Commercial Jets
g. Global Positioning Services
