Direct-Broadcast Services(DBS)

Direct-broadcast satellites (DBS)/ broadcasting satellite service transmit signal for direct reception by the general public , such as satellite television and radio . Satellite signals are sent directly to users through their own receiving antennas or satellite dishes, in contrast to satellite/cable systems in which signals are received by a ground station, re-broadcast to users by cable.

Mobile Satellite Service(MSS)

Mobile satellite services (MSS) refers to networks of communication satellite intended for use with mobile and portable wireless telephones . There are three major types: AMSS(aeronautical MSS), LMSS(land MSS), and MMSS(maritime MSS).

Fixed Satellite Service(FSS)

Satellites providing Fixed-Satellite Services (FSS) transmit radio communication between ground Earth station at fixed locations. Satellite-transmitted information is carried in the form of radio-frequency signals. Any number of satellites may be used to link these stations. Earth stations that are part of fixed -satellite services networks also use satellite news gathering vehicles to broadcast from media events, such as sporting  events or news conferences.

In addition, FSS satellites provide a wide variety of services including paging networks point-of-sale support, such as credit card transactions and inventory control. 

Basic Theory For Satellite Work

For 10,000 years man has wondered about questions such as "What holds the sun up in the sky?" , and "How do they (the sun and the moon) return from the far west back to the far east to rise again each day?" It is only in the last 300 years, our description of course is based on fundamental laws put forth by the English genius Sir Isaac Newton in the late 17th century.The first of newton laws, which was a logical extension of earlier work by Johannes Kepler, proposed that every bit of matter in the universe attracts every other bit of matter with a force which is proportional on the product of there masses and inversely proportional to the square of the distance bet ween the two bits. That is , larger masses attract more strongly and the attraction gets weaker as the bodies are moved farther apart.     

Satellite Communication Network

Satellite communication networks are now an indispensable part of most major telecommunication systems. Satellites have a unique capability for providing coverage over large geographical areas. Modern communication satellites use a variety of orbits including geostationary_orbits, molniya _orbits, other elliptical orbits and low(polar and non-polar) Earth orbits.                                                                                                                                                                       
In recent years, satellite communication systems have begun to face competition from optical fiber systems for point to point communication between large concentrated traffic sources. To retain a competitive edge, it has been necessary to develop various new techniques. Therefore, the phenomenal growth of satellite technology continues, the major growth now in those areas where satellite can provide unique advantages.