SATELLITE COMMUNICATION By:-Bhagyalakshmi.Yagnik Roll.no:-13b120

W HAT IS SATELLITE COMMUNICATION..?? Satellite communication is a process in which signal transferring between the sender and receiver is done with the help of a satellite. The first active satellite was launched by Russia in 1957.

H OW DOES IT WORK..?? In this process, the signal which is basically a beam of modulated microwaves is sent towards the satellite. Then the satellite amplifies the signal and sends it back to the receiver’s antenna present on the earth’s surface. As all signal transferring occurs in space, it is known as Space Communication.

An Advanced Extremely High Frequency communications satellite relays secure communications for United States and other allied countries.

Two of the satellites which are commonly used as:- Passive Satellite:- It is just a plastic balloon having a metal coated over it. It redirects the signal coming from the source & points in the direction of the receiver. It is also known as passive sphere. Our earth also has a passive satellite i.e moon. Active Satellite:- It basically does the work of amplifying the coming microwave signals. In active satellites an antenna system, transmitter, power supply and a receiver is used. They allow for a signal that is much more clear.

T HERE ARE 4 OTHER TYPES OF SATELLITES :- Geostationary satellites(GEO):-About 19,300 nautical miles from earth’s surface Medium-earth orbit satellite(MEO): nautical miles Low-earth orbit satellite(LEO):-200 nautical miles Satellites versus fiber

Geostationary Satellites(GEO):- Satellites placed in this orbit can “stand still” with respect to certain location on earth. That is, if a viewer on earth were to look up into the sky and spot a satellite in GEO, it would seem as if it isn’t moving. Revolves around the earth at earth’s own angular velocity(360 degrees/24 hrs, in an equitorial orbit)

Low-earth orbit satellite(LEO) :- It is a circular orbit about 200 kms above earth’s surface Alike GEO, it is not stationary and so more satellites would be needed to cover a certain area. They change their position relative to ground position quickly. Less expensive to launch into an orbit & don’t require high signal strength

Medium-earth orbit satellite(MEO):- Similar to LEO in their functionality Visible for much longer periods than LEO satellites & thus fewer satellites are needed. Possess larger coverage area than LEO satellites. One disadvantage is that, it gives a longer time delay and weaker signal compared to a LEO satellite.

Satellite communications are still used in many applications. Remote islands such as Saint Helena & Easter Island where no submarine cables are in service need satellite telephones. Other land use for satellite phones are rigs of sea, a back up for hospitals, military & recreation. Ships at sea often use satellite phones and planes. Used in audio services. Used in mobile services which allows listeners to roam a continent, listening the same audio programming anywhere.

Useful for users who are located in remote areas, and cannot access a broadband connection, or require high availability of services. Used for military communication applications, such as Global command and control systems.