Here is a good site (with more links at the end of the page) for basics of satellite technology:
cis.ohio-state.edu
Here is one nugget from the page:
Basic Elements
Satellite communications are comprised of 2 main components:
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. |
