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satellite final.ppt
- 1. Bilal Salman Taha Satellite Communication
- 2. Introduction Satellite Orbits Satellite Communication Systems Satellite Subsystem Ground Station Satellite Application
- 3. A satellite is a physical object that orbits, or rotates about, some celestial body. Satellites occur in nature, and our own solar system is a perfect example. Satellites are launched and orbited for a variety of purposes, The most common application is communication in which the satellite is used as a repeater. Introduction to Satellite Communication
- 4. Introduction to Satellite Communication
- 5. Introduction to Satellite Communication
- 6. Satellite orbits Classification of orbits:
- 8. Satellite orbits Satellite orbits are also classified based on their heights above the earth: • Geostationary Earth Orbit (GEO) • Low Earth Orbit (LEO) • Medium Earth Orbit (MEO) • Molniya Orbit • High-Altitude Platform Orbit
- 10. Satellite orbits Geostationary Earth Orbit (GEO) These satellites are in orbit 35,786 km above the earth’s surface along the equator. Objects in Geostationary orbit revolve around the earth at the same speed as the earth rotates. This means GEO satellites remain in the same position relative to the surface of earth.
- 11. One of these can cover 1/3 of the earth. Completes a trip around world in 24 hours hence stationary. Satellite orbits Geostationary Earth Orbit (GEO)
- 12. Satellite orbits Geostationary Earth Orbit (GEO)
- 13. Satellite orbits Low Earth Orbit (LEO) LEO satellites are much closer to the earth than GEO satellites, ranging from 500 to 1,500 km above the surface. LEO satellites don’t stay in fixed position relative to the surface, and are only visible for 15 to 20 minutes each pass. A network of LEO satellites is necessary for LEO satellites to be useful.
- 14. Satellite orbits Medium Earth Orbit (MEO) A MEO satellite is in orbit somewhere between 8,000 km and 18,000 km above the earth’s surface. MEO satellites are visible for much longer periods of time than LEO satellites, usually between 2 to 8 hours. MEO satellites have a larger coverage area than LEO satellites.
- 15. MEO satellites are visible for much longer periods of time than LEO satellites, usually between 2 to 8 hours. MEO satellites have a larger coverage area than LEO satellites.
- 16. Used by Russia for decades. Molniya Orbit is an elliptical orbit. The satellite remains in a nearly fixed position relative to earth for eight hours. A series of three Molniya satellites can act like a GEO satellite. Useful in near polar regions. Satellite orbits Molniya Orbit
- 17. Satellite orbits High Altitude Platform (HAP) One of the newest ideas in satellite communication. A blimp or plane around 20 km above the earth’s surface is used as a satellite. HAPs would have very small coverage area, but would have a comparatively strong signal. Cheaper to put in position, but would require a lot of them in a network.
- 18. Blimp Satellite
- 19. Satellite Communication Systems
- 20. General block diagram of a communication satellite.
- 21. The major subsystems consists of : - Solar Panel Power Subsystem Communication Subsystem Telemetry, Command, and Control Subsystems
- 22. Ground Station The ground station, or earth station, is the terrestrial base of the system.
- 23. An earth station consists of five major subsystems: the antenna subsystem, The receive subsystem, the transmit subsystem, the ground control equipment (GCE) subsystem, and the power subsystem Ground Station
- 24. Satellite Applications The main application for satellites today is in communication. Satellites used for this purpose act as relay stations in the sky. They permit reliable long-distance communication worldwide. They solve many of the growing communication needs of industry and government. Another major communication application is TV.
- 25. Direct Broadcast Satellite (DBS). Satellite Cell Phones. Digital Satellite Radio Surveillance Satellites Global Navigation Satellite Systems Satellite Applications
- 26. Reference: Balmain, E. C. J. a. (PHI, 1968, Reprint 2003). ANTENNAS AND WAVE PROPAGATION. Elbert, B. R. (2008). Introduction to Satellite Communication (Third Edition ed.). Roddy, D. (2001 by The McGraw-Hill , Satellite Communications). Satellite Communications (Third Edition ed.): McGraw-Hill. (Elbert, 2008) (Balmain, PHI, 1968, Reprint 2003)
- 27. Thank You By : Abhinay , Akshay , Bhargav , Dushyant ,Harish Paidi , Koushik , Kousthubh EEE – D2
Editor's Notes
- The earth and other planets are satellites rotating about the sun. The moon is a satellite to the earth. A balance between the inertia of the rotating satellite at high speed and the gravitational pull of the orbited body keeps the satellite in place. Celestial سماوي
- Inclined المائل Equatorial استوائي If a satellite were launched vertically from the earth and then released, it would fall back to earth because of gravity. For the satellite to go into orbit around the earth, it must have some forward motion. For that reason, when the satellite is launched, it is given both vertical and forward motion. The forward motion produces inertia, which tends to keep the satellite moving in a straight line. However, gravity tends to pull the satellite toward the earth. The inertia of the satellite is equalized by the earth’s gravitational pull. The satellite constantly changes its direction from a straight line to a curved line to rotate about the earth. If a satellite’s velocity is too high, the satellite will overcome the earth’s pull and go out into space. It takes an escape velocity of approximately 25,000 mi/h to cause a spacecraft to break the gravitational pull of the earth. At lower speeds, gravity constantly pulls the satellite toward the earth. The goal is to give the satellite acceleration and speed that will exactly balance the gravitational pull. The closer the satellite is to earth, the stronger the effect of the earth’s gravitational pull. So in low orbits, the satellite must travel faster to avoid falling back to earth.
- مولنيا
- along the equator. على طول خط الاستواء Advantages A GEO satellite’s distance from earth gives it a large coverage area, almost a fourth of the earth’s surface. GEO satellites have a 24 hour view of a particular area. These factors make it ideal for satellite broadcast and other multipoint applications Minimal doppler shift Disadvantages A GEO satellite’s distance also cause it to have both a comparatively weak signal and a time delay in the signal, which is bad for point to point communication. GEO satellites, centered above the equator, have difficulty for broadcasting signals to near polar regions Launching of satellites to orbit are complex and expensive.
- مولنيا
- Blimp منطاد
- these satellites are relay stations for earth sources. The original signal being transmitted from the earth station to the satellite is called the uplink, and the retransmitted signal from the satellite to the receiving stations is called the downlink. Usually the downlink frequency is lower than the uplink frequency. A typical uplink frequency is 6 GHz, and a common downlink frequency is 4 GHz.
- Telemetry القياس عن بعد
- Terrestrial ارضي