INTRODUCTION TO SATELLITE

14,668 views

Published on

hiee guyes this is swapnil thaware here i uploaded slide for your knowledge if you want more detail msg me on fb or mail i will help you

thanking you and slideshare.com

Published in: Technology, Business

INTRODUCTION TO SATELLITE

  1. 1. CONTENTS :  What’s mean by satellite ?  History of Satellites :  Layer Of Atmosphere :  Generalized communication system :  What are the components of a satellite?  How Satellites Work ?  How do satellite stay in orbit ?  Why satellite are launched 36,000 Km from centre of earth ?  Types of bands :  Types of orbits :  Global position system :  Advantages And Disadvantages Of satellite :  Uses of satellite :  References :
  2. 2. what’s mean by sateLLIte ? Passive Satellites Active satellites I. Natural satellites II. artificial satellites. • A passive satellite only reflects received signals back to earth. • Ex.moon is a natural • Active satellites are complicated structures having a processing equipment called Transponder . • An active satellite acts as a REPEATER A Satellite is a solid object which revolves around some body due to the effect of gravitational forces OR a satellite is an object which has been placed into orbit by human endeavour.
  3. 3. History of Satellites : • First satellite that was used for communication purpose in INDIA was - ARYABHATTA (19 April 1975) • The first geostationary communication satellite - SYNCOM 3(19 Aug 1963). • Father of geostationary communication satellite is -HAROLD ROSEN (Aircraft engineer) The world's first artificial satellite is the Sputnik 1 was launched in 1957
  4. 4. Layer Of Atmosphere :  TROPOSPHERE : STRATOSPHERE : MESOSPHERE : THERMOSPHERE : EXOSPHERE :
  5. 5. INFORMA TION SOURCE Uses of informa tion TRANN SMITT ER Receiv erChannel 1 2 3 4 1= Message signal. 2 = tranmitted signal. 3 = received signal. 4 = message signal. Generalized communication system : NOISE OCCUR
  6. 6. What are the components of a satellite? • Many satellites are powered by rechargeable batteries. • Small thrusters provide attitude i.e. stabilize the satellite's position in space.
  7. 7. How Satellites Work : I. A Earth Station sends message in GHz range (Uplink). II. Satellite Receive and retransmit signals back. (Downlink) III. Difference between Downlink and Uplink frequency is 2 GHz.
  8. 8. Why geostationary satellite are launched 36,000 km from the center of the earth? • 1.Gravitational force= attraction between any two objects, given by • 2.Centrifugal force=an outward-directed force that normally balances the inward- directed centripital force There are two relevant forces involved in this problem
  9. 9. Equate that 2 eqn= i.e. The tangential velocity of the satellite (vs) is related to its orbital period, T so, Eqating that 2 eqn= As we know Then T=? and sqaring We know: G = 6.67 x 10-11 Nm2kg-2 me = 5.97 x 1024 kg we = 7.29 x 10-5 rad s-1 Hence, substituting the above constants into gives: R = 35,786 km for center of earth Near about 36,000 km.
  10. 10. How do satellites stay in orbit? Satellites stay in orbit due to the balance of two factors: i. Velocity and ii. Gravitational pull between the Earth and the satellite.  Satellites never fall into the Earth this because Earth is round and curves.
  11. 11. Satellite Frequency Bands :  There is a inverse relationshi between frequency and wavelength. • Different kinds of satellites use different frequency bands. • L–Band: 1 to 2 GHz, • S-Band: 2 to 4 GHz • C-Band: 4 to 8 GHz • X-Band: 8 to 13 GHz • Ku-Band: 13 to 18 GHz • K-Band: 18 to 28 GHz • Ka-Band: 28 to 40 GHz As wavelength increases (and frequency decreases), larger antennas (satellite dishes) are necessary to gather the signal.
  12. 12. C-band :• C-band is the most common frequency spectrums used by today’s satellite. • C-band satellite transmissions occupy the 4 to 8 GHz frequency range. • C-band antenna is approximately 2-3 meters in diameter
  13. 13. Ku-band : • Ku-band satellite transmissions occupy the 13 to 18 GHz frequency range. • Ku-band antennas can be as small as 18 inches in diameter • These very high frequency transmissions mean very small wavelengths and very small diameter receiving antennas.
  14. 14. TYPES OF ORBITS Low-Earth-Orbit (LEOs) Medium-Earth-Orbit (MEOs) Geostationary (GEOs)
  15. 15. Low-Earth-Orbit (LEO)  Altitude (600-1000 KM)  satellite gives it a better signal strength  Advantages: Reduces transmission delay  Disadvantages: Smaller coverage area. Shorter life span (5-8 yrs.)
  16. 16. Little LEOs Applications  0.8 GHz range  Small, low-cost  Used for short communications.
  17. 17. Middle-Earth-Orbiting (MEO) MEOs orbits between the altitudes of 8,000 - 20,000 km above the earth. MEO satellites have a larger coverage. These orbits are primarily reserved for communications satellites that cover the North and South Pole.  MEOs are placed in an elliptical (oval-shaped) orbit.
  18. 18. Geosynchronous-Earth-Orbit (GEO)  From the ground level the satellite appears fixed.  GEO satellites have a 24 hour view of a particular area.  Coverage to 40% of area Of planet by this satellite
  19. 19. The Global Positioning System : EQUATORIAL ORBIT : POLAR CIRCULAR ORBIT : EACH SATELLITE COVER 40% AREA SATELLITE MAKES AN ANGLE OF 120 WITH EACH OTHER.
  20. 20. ADVANTAGES AND DISADVANTAGES OF SATELLITE: ADVANTAGES : DISADVANTAGES : • Make repeated observations over a given area . • At a time satellites observe a larger coverage • Minimum Satellite lifetime is about 10-15 years. • Poor spatial resolution in the polar regions. – Launching satellites into orbit is costly.
  21. 21. Uses of satellite: • IT IS USED FOR LONG DISTANCE COMMUNICATION. • IT IS SPEEDY AND RELIABLE. • IT IS USED FOR WEATHER FORECASTING. (study of atmosphere ,rain ,sunshine at any place at perticular time) • IT IS USED FOR TRANSMIT T.V. SIGNAL OVER LARGE DISTANCE COMMUNICATION. • POLAR SATELLITE IS USED FOR REMOTE SENSING.
  22. 22. REFERENCES : • http://en.wikipedia.org/wiki/Geosynchronou s_satellie • Geostationary Satellite(Author- Louis E.Frenzel) (Edition- Third) (Publication- Tata McGraw-Hill) • http://web.mit.edu/invent/iow/rosen.html
  23. 23. -- >>BY SWAPNIL G. THAWARE

×