Satellite Communication


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Satellite Communication

  1. 1. Submitted By : Submitted to : Name : Vikas Mr. Praveen Jain Roll No. : 52 Reg. No. : CRO0358769 Batch : March’14 Afternoon Timings : 1:30 PM – 6:00 PM Section : B
  2. 2. We take this opportunity to express our profound gratitude and deep regards to our teachers for their exemplary guidance and monitoring. On the very outset of this project, we would like to extend our sincere & heartfelt obligation towards all the personages who have helped us in this endeavour. Without their active guidance, help, cooperation & encouragement, we would not have made headway in the project. Lastly, we thank Almighty, our parents and friends for their constant encouragement without which this project would not have been possible.
  4. 4. • Satellites are specifically made for telecommunication purpose. They are used for mobile applications such as communication to ships, vehicles, planes, hand-held terminals And for TV & Radio broadcasting. • They are responsible for providing these services to an assigned region (area) on the earth. The power and bandwidth of these satellites depend upon the preferred size of the footprint, complexity of the traffic control protocol schemes and the cost of ground stations. • A satellite works most efficiently when the transmissions are focused with a desired area. When the area is focused, then the emissions don't go outside that designated area and thus minimizing the interference to the other systems. This leads more efficient spectrum usage.
  5. 5. • Satellite’s antenna patterns play an important role and must be designed to best cover the designated geographical area (which is generally irregular in shape). Satellites should be designed by keeping in mind its usability for short and long term effects throughout its life time. • The earth station should be in a position to control the satellite if it drifts from its orbit it is subjected to any kind of drag from the external forces.
  6. 6. • Satellite Communication began in October 1957 with the launch by the USSR a Small Satellite called Sputnik 1(4.10.1957). • 3.11.1957 Sputnik 2 with LAIKA. • 12.4.1961 VOSTOK 1 with JURI GAGARIN. • First true communication satellites (telestar 1 & 2) were launched in July 1962 & may 1963.
  7. 7. •10/1964 Syncom 2 : first geo satellite , 7.1/1.8 GHZ (one TV-channel & several 2- way telephone connection). •1987 TVSAT : First DBS-satellite(direct broadcast satellite, Television- Broadcasts directly to home). SPUTNIK 1
  8. 8. There are broadly three types of satellites on the basis of orbits that are used for communication: • Geostationary or geosynchronous earth orbit (GEO) • Low Earth Orbit (LEO) satellites • Medium Earth Orbit (MEO) satellites GEOSTATIONARY OR GEOSYNCHRONOUS EARTH ORBIT (GEO) • GEO satellites are synchronous with respect to earth. Looking from a fixed point from Earth, these satellites appear to be stationary. • These satellites are placed in the space in such a way that only three satellites are sufficient to provide connection throughout the surface of the Earth (that is; their footprint is covering almost 1/3rd of the Earth). • The orbit of these satellites is circular.Eg:KALPANA-1 ,a weather satellite launched by ISRO in 12 September , 2002
  9. 9. LOW EARTH ORBIT (LEO) SATELLITES • These satellites are placed 500-1500 kms above the surface of the earth. As LEOs circulate on a lower orbit, hence they exhibit a much shorter period that is 95 to 120 minutes. • LEO systems try to ensure a high elevation for every spot on earth to provide a high quality communication link. • Each LEO satellite will only be visible from the earth for around ten minutes. Eg:ENVISAT is one example of an Earth observation satellite that makes use of this particular type of LEO. • These satellites are mainly used in remote sensing an providing mobile communication services (due to lower latency) due to simplicity and cost effectiveness.
  10. 10. • MEOs can be positioned somewhere between LEOs and GEOs, both in terms of their orbit and due to their advantages and disadvantages. Using orbits around 10,000 km, the system only requires a dozen satellites which is more than a GEO system, but much less than a LEO system. • These satellites move more slowly relative to the earth's rotation allowing a simpler system design (satellite periods are about six hours). • Depending on the inclination, a MEO can cover larger populations, so requiring fewer handovers. Eg: Telstar 1, an experimental satellite launched in 1962, orbits in MEO.
  11. 11. • The coverage area of a satellite greatly exceeds that of a terrestrial system. • Transmission cost of satellite is independent of the distance from the center of the coverage area. • Satellite to satellite communication is very precise. • Higher Bandwidths are available for use.
  12. 12. • Launching satellites into orbit is costly. • Satellite bandwidth is gradually becoming used up. • There is a large propagation delay in satellite communication than in terrestrial communication.
  13. 13. • Command Antenna • Communication Antenna • Solar Cells • Batteries • Radio Receivers &Transmitters • Rocket Fuel • Main pocket motor • Rocket Thrusters
  14. 14. A Satellite is basically a self-contained communications system with the ability to receive signals from Earth and to retransmit those signals back with the use of a transponder.
  15. 15. • The main components of a satellite consist of the communications system, which includes the antennas and transponders that receive and retransmit signals, the power system, which includes the solar panels that provide power, and the propulsion system, which includes the rockets that propel the satellite. • A satellite has thrusters that are fired occasionally to make adjustments in its position. • The maintenance of a satellite’s orbital position is called “station keeping,” and the corrections made by using the satellite’s thrusters are called “attitude control.”
  16. 16. • The Transponder (short-for Transmitter-responder) is the “BRAIN” of the satellite that provides connection between the satellite’s Receive and Transmit antennas. • Satellites can have 12 to 96 transponders plus spares, depending on the size of the satellite.
  17. 17. • Main source of power is solar cell panels - new solar cells are increasingly efficient • The solar cell system is backed up by battery system that provides energy during solar eclipses and other periods of outages • Typical power levels of 2 to 5 KWs for Fixed Satellite Systems and 10 to 12 KWs for Mobile and Broadcast Satellite Systems. • Batteries: latest battery technology is represented by Lithium Ion systems that can provide a greater power density for longer periods of time and survive a greater depth of discharge
  18. 18. • Telephone Calls : The first and historically most important application for communications was long distance telephony. The fixed Public Switched Transfer Network relays telephone calls from land line telephones to an earth station, where they are then transmitted to a geostationary satellite. The downlink follows an analogous path . Satellites also play an important role in delivering programming to cell phones and other mobile devices, such as personal digital assistants and laptops . • TV Broadcasting : The most familiar use of satellites is television broadcasting. TV satellites deliver hundreds of television channels every day throughout the world. They are even used to supply television signals to terrestrial transmitters or cable-head end stations for further distribution to the home, or to exchange signals between television studios. The bandwidth required to transmit multiple programmes at the same time can easily be provided using satellites.
  19. 19.  Radio :Satellite radio offers audio services in some countries, notably the United States. Mobile services allow listeners to roam a continent, listening to the same audio programming anywhere. A satellite radio or subscription radio (SR) is a digital radio signal that is broadcast by a communications satellite, which covers a much wider geographical range than terrestrial radio signals.  Internet Access :After the 1990s, satellite communication technology has been used as a means to connect to the Internet via broadband data connections. This can be very useful for users who are located in remote areas, and cannot access a broadband connection, or require high availability of services.
  20. 20. • Satellite Phones & Emergency Communication: When terrestrial communications fail due to natural disasters , they provide communication . They serve civilian’s in rural areas where communication network dos not exist by providing telephony service. Satellite phones can be accomplished in many different ways. On larger scale often there will be local telephone system in the isolated area with a link to a telephone system in a main land area. • Military Sector : Satellite Communication provides robust and sophisticated secure communications system for the military . Examples of military systems that use communication satellites are the MILSTAR , the DSCS , and the FLTSATCOM of the United States, NATO satellites, United Kingdom satellites (for instance Skynet) , and satellites of the former Soviet Union.. India has launched its first Military Communication satellite GSAT-7.
  21. 21. • As earlier discussed, the actual journey into space began October 4, 1957, when the Soviet Union launched Sputnik 1, the world's first orbital spacecraft, which orbited the world for three months. • A month later the Soviets launched Sputnik 2 and its passenger Laika, a dog. • This further led to many other significant developments in the field of satellite communication.
  22. 22. Satellite Launched Nation Sputnik 1 October 4, 1957 Soviet Union Project SCORE December 18, 1958 USA TIROS 1 April 1, 1960 USA Echo 1 August 12, 1960 USA Courier 1B October 4, 1960 USA OSCAR 1 December 12, 1961 USA Teslstar 1 July 10, 1962 USA Relay 1 December 13, 1962 USA Syncom 2 July 16, 1963 USA Syncom 3 August 19, 1964 USA
  23. 23. • Future communication satellites will have more onboard processing capabilities, more power, and larger-aperture antennas that will enable satellites to handle more bandwidth. • Further improvements in satellites’ propulsion and power systems will increase their service life to 20 – 30 years from the current 10 – 15 years.
  24. 24. ASTROLINK • Lockheed martin’s proposed astrolink system will have nine geostationary satellite in five orbit locations. • Each satellite total capacity is 7.7 Gab/s. by placing two satellite at the same location and operating them with orthogonal polarizations, a total capacity of 15 Gab/s is achieved over America. • Cross-links between satellite operating at 60 GHz provides a means of routing traffic round the globe ;each link has a capacity of 1 Gab/s. CYBERSTAR • Loral’s proposed cyber star system represents a lower cost, less risky approach to the market. • Loral proposes to launch just three geostationary satellite positioned to reach the world’s largest population centers.
  25. 25. company system orbit coverage Satellite capacity( Gab/s) Intersatelite link Onboard switching Lockheed martin Astrolink GEO Global 7.7 1 Gb/s FPS Loral Cyberstar GEO Limited global 4.9 1 Gb/s BBS Hughes Galaxy/ spaceway GEO global 4.4 1 Gb/s BBS
  26. 26. • • • • • •