Satellite communication Basics
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This document provides an overview of satellite communication and satellite systems. It discusses different types of transmission systems including radio, coaxial cable, and optical fiber systems. It describes how radio systems use electromagnetic waves to transmit signals and the portions of the frequency spectrum used. The document outlines the layers of the atmosphere and how the ionosphere and troposphere can propagate radio waves. It also categorizes different types of radio communication including ionosphere communication, line of sight microwave communication, and troposphere scatter communication. The document discusses advantages of satellite communication and components of a satellite communication network including the space and ground segments. It covers topics like satellite orbits, frequency bands used, and multiple access techniques in satellite systems.
Satellite communication Basics
- 1. Satellite Communication 05/02/14 RTTC SATCOM 1 OVERVIEW OF SATELLITE COMMUNICATION AND SATELITE SYSTEM
- 2. Satellite Communication 05/02/14 RTTC SATCOM 2
- 4. Satellite Communication 05/02/14 RTTC SATCOM 4 Transmission System can be placed under three broad categories Radio SystemRadio System Co-axial cable systemCo-axial cable system Optical fibre systemOptical fibre system Radio SystemRadio System Deals with electronic radiation of electromagnetic energy from one point to another through atmosphere or free space It is possible only in certain portion of frequency spectrum Frequency from 9Khz to 400Ghz
- 5. Satellite Communication 05/02/14 RTTC SATCOM 5 Earth Layers of Atmosphere Different layers of the atmosphere play a role in propagating radio waves 18Km 70Km 500Km
- 6. Satellite Communication 05/02/14 RTTC SATCOM 6 Ionosphere and troposphere are useful for radio communication in certain frequency range Radio communication can be placed under four categories Skywave or Ionosphere communicationSkywave or Ionosphere communication LOS MW CommunicationLOS MW Communication Troposphere scatter communicationTroposphere scatter communication Satellite communicationSatellite communication
- 7. Satellite Communication 05/02/14 RTTC SATCOM 7 Ionosphere communicationIonosphere communication It deals with frequency range of 3-30Mhz which are classified as HF band Altitude(Km) Electron density F1 F2 E D IONOSPHERE EarthT R R
- 8. Satellite Communication 05/02/14 RTTC SATCOM 8 LOS MW CommunicationLOS MW Communication IS CHARCTERSIED BY ► the useful range of frequencies lie between 150Mhz- 150Ghz ► it is line of sight communication limited by horizon due to the curvature of the earth ► Signal propagation is affected by free space attenuation ► Frequency / Phase modulation technique are employed ► Spread spectrum or Time sharing techniques are used
- 9. Satellite Communication 05/02/14 RTTC SATCOM 9 d0 Optical horizon dr radio horizon OPTICAL & RADIO HORIZON A Microwave link A B R R
- 10. Satellite Communication 05/02/14 RTTC SATCOM 10 Troposphere scatter communicationTroposphere scatter communication Are single hop systemAre single hop system Operates over length greater than LOS distanceOperates over length greater than LOS distance Scatter region Atmospheric turbulence and local variation of refractive index in the tropospheric region causes scattering of electromagnetic waves
- 11. Satellite Communication 05/02/14 RTTC SATCOM 11 50Km 10000Km 750Km Troposphere scatter 1500Km Ionosphere Reflection SATELLITE CO M M UNICATIO N
- 12. Satellite Communication 05/02/14 RTTC SATCOM 12 Earth Global Coverage
- 13. Satellite Communication 05/02/14 RTTC SATCOM 13 Advantages Of Sat. Com 1. Large Coverage Area 2. High Quality 3. High Reliable 4. High Capacity 5. Flexibility 6. Easy For installation 7. Emergency Communication 8. Point to Multipoint transmission
- 14. Satellite Communication 05/02/14 RTTC SATCOM 14 Sat. Com Network 1. Space Segment Uplink Downlink 2. Ground Segment
- 15. Satellite Communication 05/02/14 RTTC SATCOM 15 Sat. Com Network Frequency for space communication depends on 1. Band width required 2. Noise consideration 3. Propagation factor 4. Technology Most of the sat.Com uses 6/4Ghz frequency band 1. Less Atmospheric Absorption2. Less noise both galactic and manmade3. Less Space loss compared to high frequency
- 16. Satellite Communication 05/02/14 RTTC SATCOM 16 59000-64000Mhz & 54000-58000Mhz59000-64000Mhz & 54000-58000MhzV BandV Band Inte.SatInte.Sat 40000-51000Mhz & 40000-41000Mhz40000-51000Mhz & 40000-41000MhzV BandV Band INSATINSAT6725-7025Mhz & 4500-4800Mhz6725-7025Mhz & 4500-4800MhzExt “C”BandExt “C”Band 27500-30000Mhz & 17700 – 21200Mhz27500-30000Mhz & 17700 – 21200Mhz““K”BandK”Band 14000-14500 & 10950-11200Mhz14000-14500 & 10950-11200Mhz 11450-11700Mhz11450-11700Mhz ““Ku” BandKu” Band 7900-8400Mhz &7250-7750Mhz7900-8400Mhz &7250-7750Mhz““X” BandX” Band INSATINSAT5925-6425Mhz & 3700-4200Mhz5925-6425Mhz & 3700-4200Mhz““C” BandC” Band INSATINSAT2500-2700Mhz2500-2700Mhz““S” BandS” Band 1830-2700Mhz1830-2700Mhz““L” BandL” Band Frequency band for Sat. Com
- 17. Satellite Communication 05/02/14 RTTC SATCOM 17 Equator 4000miles A 35786KmB Geographical Advantage Time Delay Uplink35786Km 250msec D ow nlink 35786K m 250m sec
- 18. Satellite Communication 05/02/14 RTTC SATCOM 18 Geostationary Satellite Altitude:35786Km Direction :moves in eastern direction as earth Period of revolution is 23Hr 56min34sec Equator
- 19. Satellite Communication 05/02/14 RTTC SATCOM 19 Broadcasting mode of operation
- 20. Satellite Communication 05/02/14 RTTC SATCOM 20 Kinds of Communication Satellites depends on type of orbit and freq. band used. Communication Satellite can be classified by the orbit used and also by frequency band used. natural laws that control the movement of satellites. These are based on Kepler's laws 1.The orbit plane of any earth satellite must bisect the Earth centrally. 2.The Earth must be at the centre of any orbit.
- 21. Satellite Communication 05/02/14 RTTC SATCOM 21 The choice of orbit is restricted to three basic types. 1.polar, 2.equatorial 3.inclined
- 22. Satellite Communication 05/02/14 RTTC SATCOM 22 Communication SystemsCommunication Systems Satellite communication systems areSatellite communication systems are classifiedclassified 1.Communication system Multiplexed telephone channels with one (i) carrier frequency system, and (ii) Single channel per carrier system. 2.Modulation system Analog modulation (Frequency Modulation system), and Digital modulation system
- 23. Satellite Communication 05/02/14 RTTC SATCOM 23 3.System configuration Pre–assignment system Demand assignment system, and MULTIPLE ACCESS TECHNIQUES the number of earth stations to be interconnected is such larger than the number of transponders the capacity of a transponder is much more than what is required between a pair of earth stations;
- 24. Satellite Communication 05/02/14 RTTC SATCOM 24 Types of Multiple Access Frequency Division Multiple Access (FDMA) Time Division Multiple Access (TDMA) Code Division Multiple Access (CDMA)
- 25. Satellite Communication 05/02/14 RTTC SATCOM 25 1. FDMA 36Mghz36Mghz E/S DE/S DE/S CE/S CE/S BE/S BE/S AE/S A Transponder BW is divided into smaller frequency bands and assigning them to different E/S E/S transmitting the carriers towards the satellite within the assigned frequency bands Retransmitting the carriers from satellite after frequency translation and amplification by a common transponder E/S receives all the carriers which contain telephony channels meant for the E/S
- 26. Satellite Communication 05/02/14 RTTC SATCOM 26 1. FDMA A-B A-C A-D Station A FM Satellite ABCD ABCD FM FM FM Station C DA B A-C
- 27. Satellite Communication 05/02/14 RTTC SATCOM 27 TDMA P B C D PSKTDMA BUFFER TIMING INFORMATION To UP-Converter B C D
- 28. Satellite Communication 05/02/14 RTTC SATCOM 28 TDMA P B C D PSKTDMA BUFFER TIMING INFORMATION To Down-Converter B C D P A B D P A C B
- 29. Satellite Communication 05/02/14 RTTC SATCOM 29 EQUIPMENT CONFIGURATION OFCOMMUNICATION
- 30. Satellite Communication 05/02/14 RTTC SATCOM 30 SPACE SEGMENT A satellite consists of essentially two parts Communication payload Support subsystems Communication payload for communication satellites comprises 1.communication transponders 2.transmit/receive antennas.
- 31. Satellite Communication 05/02/14 RTTC SATCOM 31 Major support subsystems include : Structure Attitude and orbit control systems Electrical power system Thermal control system Telemetry and Telecommand system
- 32. Satellite Communication 05/02/14 RTTC SATCOM 32