22. satellite communication
It is the key electronic component in a satellite. The transmitter receiver combination in a satellite is known as a Transponder. It performs two major functions 1.> It provides amplification of the signal thus providing a gain of around 110dB. 2> It also does the frequency down conversion or frequency translation of the uplink signal in order to avoid interference between the received and the transmitted signal.
Satellite Basics has described what a communications satellite is, how it works, how to create a satellite network, and who is in the industry, but the most important question still remains. Why use a satellite network?The satellite communications system was initiated following studies in the early 1970s which showed that a system of telecommunication satellites operated from a single ground station could better support the space shuttle and scientific application mission requirements planned for the Nation's space program. In addition,
The system was seen as a means of halting the spiralling costs of upgrading and operating a network of tracking and communications ground stations located around the world. It is simply the communication of the satellite in space with large number of earth stations on the ground. Users are the ones who generate baseband signals, which is processed at the earth station and then transmitted to the satellite through dish antennas.
Now the user is connected to the earth station via some telephone switch or some dedicated link. The satellite receives the uplink frequency and the transponder present inside the satellite does the processing function and frequency down conversion in order to transmit the downlink signal at different frequency.