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What is inside a typical satellite?
1. Satellites come in all shapes and sizes and play a variety of roles. For example, weather satellites contain cameras that can return photos of Earth's weather, either from fixed geostationary positions or from polar orbits. Communications satellites allow telephone and data conversations to be relayed through the satellite. The most important feature of a communications satellite is the transponder – a radio that receives a conversation at one frequency and then amplifies it and retransmits it back to Earth on another frequency. A satellite normally contains hundreds or thousands of transponders. Broadcast satellites broadcast television signals from one point to another (similar to communications satellites).
2. Scientific satellites perform a variety of scientific missions. The Hubble Space Telescope is the most famous scientific satellite, but there are many others looking at everything from sun spots to gamma rays. Navigational satellites help ships and planes navigate. Rescue satellites respond to radio distress signals. Military satellites are up there, but much of the actual application information remains secret. Applications may include relaying encrypted communication, nuclear monitoring, observing enemy movements, early warning of missile launches, eavesdropping on terrestrial radio links, radar imaging, photography.
3. Despite the significant differences between all of these satellites, they have several things in common. All of them have a radio system and antenna. At the very least, most satellites have a radio transmitter/receiver so that the ground-control crew can request status information from the satellite and monitor its health. Many satellites can be controlled in various ways from the ground to do anything from change the orbit to reprogram the computer system.
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Each satellite has got its own frequency to receive and send signals which have to be amplified to be received.
One satellite usually operates only one radio transmitter, one radio wave receiver and one frequency.
All the satellites are different in sizes as well as in functions but they usually have the same round form.
The common feature of communications satellites is an installed radio which can get and send signals back to the Earth.
