SlideShare ist ein Scribd-Unternehmen logo
1 von 57
Downloaden Sie, um offline zu lesen
1

                   Satellite Communications   Jan 5, 2013




SATELLITE
COMMUNICATIONS



                 Dr. C. SARITHA
                 Lecturer in Electronics
                 SSBN Degree College
                 ANANTAPUR
Contents…
                             Introduction
                             Orbit
                             Keplers laws
                             Frequency Allocation
                             Advantages of satellite/
                             Applications
                             Disadvantages
                             Conclusion
Jan 5, 2013   Satellite Communications             2
Introduction

      Satellite is a microwave repeater in the space.
      There are about 750 satellites in the space, most of
       them are used for communication.
      They are:
        Wide area coverage of the earth’s surface.
        Transmission delay is about 0.3 sec.
        Transmission cost is independent of distance.


Jan 5, 2013              Satellite Communications         3
What exactly is a
                        satellite?
     The word satellite originated from the Latin word
     “Satellit”- meaning an attendant, one who is constantly
     hovering around & attending to a “master” or big man.

    For our own purposes however a satellite is simply any
     body that moves around another (usually much larger) one
     in a mathematically predictable path called an orbit.

    Jan 5, 2013          Satellite Communications         4
Components of a satellite




Jan 5, 2013            Satellite Communications   5
What are Communication Satellites?

    A satellite is an object that orbits another large object
     like planet.
     A communication satellite is a station in space that is
     used for telecommunication, radio and television
     signals.
    The first satellite with radio transmitter was in 1957.

Jan 5, 2013              Satellite Communications           6
Communication Satellites




Jan 5, 2013           Satellite Communications   7
The origin of satellite
   The concept of using object in space to reflect signals for
    communication was proved by Naval Research Lab in
    Washington D.C. when it use the Moon to establish a
    very low data rate link between Washington and Hawaii
    in late 1940’s.

   Russian started the Space age by successfully launching
    SPUTNIK the first artificial spacecraft to orbit the
    earth, which transmitted telemetry information for 21
    days in Oct. 1957.

    Jan 5, 2013           Satellite Communications          8
Cont…

       The American followed by launching an experimental
        satellite EXPLORER In 1958.

         In 1960 two satellite were deployed “Echo” &
        “Courier”

        In 1963 first GSO “Syncom” The first commercial GSO
        (Intelsat & Molnya) in 1965 these provides video
        (Television) and voice (Telephone)
    Jan 5, 2013           Satellite Communications           9
Why Use Satellite?

      Satellite communication is just one example of wireless
       communication systems.
      Familiar examples of wireless systems are all around
       us, such as radio, television- broadcasting, mobile and
       cordless telephones.
      These systems rely on a network of ground-based
       transmitters and receivers and for this reason they are
       often referred to as “ terrestrial " systems.
    Jan 5, 2013            Satellite Communications         10
Cont…


    One major use of satellites familiar to everyone is
     satellite television broadcasting.

    Other applications of satellite communications
     include high speed internet, telephony and corporate
     networks for multinational businesses.


Jan 5, 2013            Satellite Communications        11
How do satellites work?
   Two Stations on Earth want to communicate through
    radio broadcast but are too far away to use
    conventional means.

   The two stations can use a satellite as a relay station
    for their communication.

   One Earth Station sends a transmission to the
    satellite. This is called a Uplink.
Jan 5, 2013            Satellite Communications        12
     The satellite Transponder converts the signal and
    sends it down to the second earth station. This
    frequency is called a Downlink.
                              Transponder




Jan 5, 2013           Satellite Communications      13
Concept:




Jan 5, 2013     Satellite Communications   14
• Consider the light bulb as an example:




Jan 5, 2013        Satellite Communications   15
Early satellites
       Telstar
         Allowed live transmission across the Atlantic
       Syncom 2
         First Geosynchronous satellite.

              TELSTAR                                  SYNCOM 2




Jan 5, 2013                 Satellite Communications              16
Orbits
 Circular orbits are simplest.
 Inclined orbits are useful for coverage of equatorial
  regions
 Elliptical orbits can be used to give quasi
  stationary behaviour viewed from earth using
    3 or 4 satellites
 Orbit changes can be used to extend the life of
  satellites.
 Jan 5, 2013          Satellite Communications      17
Satellite orbits
Classification of orbits:




Jan 5, 2013        Satellite Communications   18
How does a satellite stay in it’s orbit?




Jan 5, 2013        Satellite Communications    19
Origin of planetary laws




                                           Derived 3 laws based
                                          upon his observations
                                          of planetary motion.

  Sir. Johannes Kepler

Jan 5, 2013          Satellite Communications                 20
The 3 Laws of Planetary Motion

   Planets move in elliptical orbits with the sun at one
    of the foci.

   The line joining the sun and the planet sweeps out
    equal areas in equal times.

   The cube of the distance of the planet from the sun is
    proportional to the square of the period. r3 ά T2
Jan 5, 2013            Satellite Communications         21
Kepler’s 1st Law: Law of Ellipses




      The orbits of the planets are ellipses with the sun
Jan 5, 2013
                           at one focus
                         Satellite Communications           22
Kepler’s 2nd Law: Law of Equal Areas

 The line joining the planet to the center of the sun sweeps
                 out equal areas in equal times

                                T4                 T3
               T5
                                                         T2
                          A4                 A3
               A5                                   A2        T1
                                                         A1

T6     A6




 Jan 5, 2013            Satellite Communications              23
Kepler’s 3rd Law: Law of Harmonics

 The squares of the periods of
     two planet’s orbits are
  proportional to each other as
  the cubes of their semi-major
              axes:
         T12/T22 = a13/a23
          In English:
  Orbits with the same semi-
    major axis will have the
           same period
Jan 5, 2013           Satellite Communications   24
Elements of Satellite
                Communications

 The basic elements of a communication satellite service
  are divided between;
                Space Segment
               Ground Segment
 The space segment consist of the spacecraft & launch
  mechanism.
 The ground segment comprises the earth station and
  network control center of entire satellite system.
 Jan 5, 2013          Satellite Communications        25
Space Segment
  Space segment consist of a
  satellite in suitable orbit.
 Space segment classified
  on the basis of orbit.
 LEO

 MEO

 GEO

 MONIYA

 HAP
    Jan 5, 2013        Satellite Communications   26
Satellite orbit altitudes




Jan 5, 2013          Satellite Communications   27
Ground Segment
             The ground Segment of each service has
               distinct characteristics.
             Services like;
             FSS
             BSS
             MSS
                Maritime, Aeronautical & Land base
             DBS etc..
Jan 5, 2013                 Satellite Communications   28
     Service Types
         Fixed Service Satellites (FSS)
            Example: Point to Point Communication

         Broadcast Service Satellites (BSS)
            Example: Satellite Television/Radio

            Also called Direct Broadcast Service (DBS).

         Mobile Service Satellites (MSS)
            Example: Satellite Phones
Jan 5, 2013               Satellite Communications         29
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.

Jan 5, 2013           Satellite Communications         30
The Iridium system has 66 satellites in six LEO orbits,
              each at an altitude of 750 km.




Iridium is designed to provide direct worldwide
voice and data communication using handheld
terminals, a service similar to cellular telephony
 Jan 5, 2013           Satellite Communications             31
Advantages:
          A LEO satellite’s proximity to earth compared to
          a GEO satellite gives it a better signal strength
          and less of a time delay, which makes it better for
          point to point communication.

          A LEO satellite’s smaller area of coverage is less
          of a waste of bandwidth.


Jan 5, 2013               Satellite Communications         32
Disadvantages:

      A   network of LEO satellites is needed, which can
        be costly
       LEO satellites have to compensate for Doppler
        shifts cause by their relative movement.
       Atmospheric drag effects LEO satellites, causing
        gradual orbital deterioration.


Jan 5, 2013             Satellite Communications       33
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 similar to LEO satellites in
  functionality.
 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.
Jan 5, 2013           Satellite Communications       34
MEO satellites




The GPS constellation
calls for 24 satellites to
be distributed equally
among six circular
                                                Glonass (Russian)
orbital planes
Jan 5, 2013              Satellite Communications                   35
 Advantage


      •    A MEO satellite’s longer duration of visibility
          and wider footprint means fewer satellites are
          needed in a MEO network than a LEO network.
 Disadvantage


      •    A MEO satellite’s distance gives it a longer time
          delay and weaker signal than a LEO satellite,
Jan 5, 2013               Satellite Communications        36
Geostationary Earth Orbit (GEO)
 These satellites are in orbit 35,863 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.




Jan 5, 2013         Satellite Communications      37
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.


Jan 5, 2013             Satellite Communications         38
Disadvantages:
          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 broadcasting signals to near polar
          regions.
Jan 5, 2013                Satellite Communications         39
Other Orbits
     Molniya Orbit Satellites
       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.

Jan 5, 2013              Satellite Communications          40
Molniya Orbit




Jan 5, 2013      Satellite Communications   41
      High Altitude Platforms (HAPs)

         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.
Jan 5, 2013             Satellite Communications         42
Frequency Allocations

    Frequency bands for satellite services are shared with
     terrestrial services.

      Satellite signal strength is constrained to avoid
     interference by it to others.

    Thus a large antenna and sensitive receiver are needed at
     the earth station.


    Jan 5, 2013           Satellite Communications         43
Cont…
    Frequency sharing techniques are an important study
    area.

    Many satellites have to share a limited frequency
    band (and limited orbital arc) thus coordination in
    frequency and orbital location is important.

     Frequency allocation are done by international
    agreements.
Jan 5, 2013            Satellite Communications           44
Frequency Bands
    Different kinds of satellites use different frequency bands.
     • L–Band: 1 to 2 GHz, used by MSS
     • S-Band: 2 to 4 GHz, used by MSS, NASA, deep space
        research
     • C-Band: 4 to 8 GHz, used by FSS
     • X-Band: 8 to 12.5 GHz, used by FSS and in terrestrial
        imaging, ex: military and meteorological satellites
     • Ku-Band: 12.5 to 18 GHz: used by FSS and BSS (DBS)
     • K-Band: 18 to 26.5 GHz: used by FSS and BSS
     • Ka-Band: 26.5 to 40 GHz: used by FSS
    Jan 5, 2013            Satellite Communications          45
Advantages of satellite over terrestrial
           communication

    The coverage area of a satellite greatly exceeds that
    of a terrestrial system.
    Transmission cost of a 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.



Jan 5, 2013            Satellite Communications         46
Disadvantages of satellites:
    Launching satellites into orbit is costly.

    Satellite bandwidth is gradually becoming used up.

     There is a larger propagation delay in satellite
    communication than in terrestrial communication.


Jan 5, 2013              Satellite Communications         47
Major problems for satellites

       Positioning in orbit
       Stability
       Power
       Communications
       Harsh Environment



Jan 5, 2013              Satellite Communications   48
Applications




Jan 5, 2013     Satellite Communications   49
Applications

   Telephony
      - Fixed points, earth station, Satellite, earth
    station, fixed points.
   Television & Radio
      - e.g. Direct broadcast satellite (DBS) & Fixed
    service satellite (FFS)
   Mobile satellite technology
     - Special antenna called mobile satellite antenna.
       - No matter where or how this antenna is mounted
Jan 5, 2013             Satellite Communications        50
Cont…

    Amateur radio
      - Access to OSCAR satellite.
       - Low earth orbits.
    Internet
      - High Speed.
        - Useful for far away places.
      Military
       - Uses geostationary satellites.
         - Example: The Defense Satellite Communications
Jan 5, 2013             Satellite Communications       51
Jan 5, 2013   Satellite Communications   52
First Launching Of Satellites By
                  Country




Jan 5, 2013        Satellite Communications   53
Jan 5, 2013   Satellite Communications   54
In Conclusion

       Satellites remain the best utilization used for
       communications due to their speed and other
       advantages mentioned in this presentation.




Jan 5, 2013            Satellite Communications      55
Communication satellites bring the world to you
        anywhere and any time…..




 Jan 5, 2013      Satellite Communications   56
Thank You…..!!!!!
Jan 5, 2013        Satellite Communications   57

Weitere ähnliche Inhalte

Was ist angesagt?

satellite-communications
 satellite-communications satellite-communications
satellite-communicationsjhcid
 
Introduction to satellite communication
Introduction to satellite communicationIntroduction to satellite communication
Introduction to satellite communicationPadma Sree
 
Satellite communication
Satellite   communicationSatellite   communication
Satellite communicationSatyajit Das
 
Geostationary Satellite
Geostationary SatelliteGeostationary Satellite
Geostationary SatelliteWaqas !!!!
 
Orbital perturbations
Orbital perturbationsOrbital perturbations
Orbital perturbationsAli Sufyan
 
Mobile satellite communication
Mobile satellite communicationMobile satellite communication
Mobile satellite communicationHimanshu Singh
 
Recent trends in satellite communication
Recent trends in satellite communicationRecent trends in satellite communication
Recent trends in satellite communicationSuriya Prakash
 
Satellite communication Basics
Satellite communication BasicsSatellite communication Basics
Satellite communication BasicsNiranjan Poojary
 
Antennas propagation
Antennas propagationAntennas propagation
Antennas propagationhrishi_tiwary
 
SATELLITE COMMUNICATION AND IT'S APPLICATION IN GPS
SATELLITE COMMUNICATION AND IT'S APPLICATION IN GPSSATELLITE COMMUNICATION AND IT'S APPLICATION IN GPS
SATELLITE COMMUNICATION AND IT'S APPLICATION IN GPSArkaprava Jana
 
Basic of Satellite Communication
Basic of Satellite CommunicationBasic of Satellite Communication
Basic of Satellite CommunicationABHINAV GUPTA
 
Satellite Network
Satellite Network Satellite Network
Satellite Network YOGEESH M
 
Latest trends in satellite communication
Latest trends in satellite communicationLatest trends in satellite communication
Latest trends in satellite communicationjasspreetkaurr
 

Was ist angesagt? (20)

satellite-communications
 satellite-communications satellite-communications
satellite-communications
 
Satellite communication
Satellite communicationSatellite communication
Satellite communication
 
Introduction to satellite communication
Introduction to satellite communicationIntroduction to satellite communication
Introduction to satellite communication
 
Orbital mechanics
Orbital mechanicsOrbital mechanics
Orbital mechanics
 
Satellite systems in communication
Satellite systems in communicationSatellite systems in communication
Satellite systems in communication
 
Satellite communication
Satellite   communicationSatellite   communication
Satellite communication
 
Geostationary Satellite
Geostationary SatelliteGeostationary Satellite
Geostationary Satellite
 
Mobile satellite communication
Mobile satellite communicationMobile satellite communication
Mobile satellite communication
 
Satellite Subsystems
Satellite SubsystemsSatellite Subsystems
Satellite Subsystems
 
Orbital perturbations
Orbital perturbationsOrbital perturbations
Orbital perturbations
 
Mobile satellite communication
Mobile satellite communicationMobile satellite communication
Mobile satellite communication
 
Recent trends in satellite communication
Recent trends in satellite communicationRecent trends in satellite communication
Recent trends in satellite communication
 
Satellite communication Basics
Satellite communication BasicsSatellite communication Basics
Satellite communication Basics
 
Satellite Communication Theory
Satellite  Communication TheorySatellite  Communication Theory
Satellite Communication Theory
 
Satellite
SatelliteSatellite
Satellite
 
Antennas propagation
Antennas propagationAntennas propagation
Antennas propagation
 
SATELLITE COMMUNICATION AND IT'S APPLICATION IN GPS
SATELLITE COMMUNICATION AND IT'S APPLICATION IN GPSSATELLITE COMMUNICATION AND IT'S APPLICATION IN GPS
SATELLITE COMMUNICATION AND IT'S APPLICATION IN GPS
 
Basic of Satellite Communication
Basic of Satellite CommunicationBasic of Satellite Communication
Basic of Satellite Communication
 
Satellite Network
Satellite Network Satellite Network
Satellite Network
 
Latest trends in satellite communication
Latest trends in satellite communicationLatest trends in satellite communication
Latest trends in satellite communication
 

Andere mochten auch

Satellite communication
Satellite communicationSatellite communication
Satellite communicationNeeda Multani
 
Satellite Multiple Access Schemes
Satellite Multiple Access SchemesSatellite Multiple Access Schemes
Satellite Multiple Access SchemesDileep Kadavarath
 
Multipl access and satellite Communication
Multipl access and satellite CommunicationMultipl access and satellite Communication
Multipl access and satellite CommunicationZunAib Ali
 
Medium Access Control
Medium Access ControlMedium Access Control
Medium Access Controlanishgoel
 
WAP- Wireless Application Protocol
WAP- Wireless Application ProtocolWAP- Wireless Application Protocol
WAP- Wireless Application ProtocolSenthil Kanth
 
Wireless Application Protocol ppt
Wireless Application Protocol pptWireless Application Protocol ppt
Wireless Application Protocol pptgo2project
 
Wireless network security
Wireless network security Wireless network security
Wireless network security Aurobindo Nayak
 
Wireless local loop
Wireless local loopWireless local loop
Wireless local loopSANJUU7
 
Wireless Network Security
Wireless Network SecurityWireless Network Security
Wireless Network SecurityGyana Ranjana
 
Satellites presentation
Satellites presentationSatellites presentation
Satellites presentationVikas Sharma
 
Wireless Networking Security
Wireless Networking SecurityWireless Networking Security
Wireless Networking SecurityAnshuman Biswal
 
CELLULAR COMMUNICATION SYSTEM
CELLULAR COMMUNICATION SYSTEMCELLULAR COMMUNICATION SYSTEM
CELLULAR COMMUNICATION SYSTEMSuryani Ilias
 
Code division multiple access
Code division multiple accessCode division multiple access
Code division multiple accessmangal das
 

Andere mochten auch (20)

ongc report
ongc reportongc report
ongc report
 
ONGC final ppt
ONGC final pptONGC final ppt
ONGC final ppt
 
Satellite communication
Satellite communicationSatellite communication
Satellite communication
 
Satellite networks
Satellite networksSatellite networks
Satellite networks
 
Satellite Multiple Access Schemes
Satellite Multiple Access SchemesSatellite Multiple Access Schemes
Satellite Multiple Access Schemes
 
Multipl access and satellite Communication
Multipl access and satellite CommunicationMultipl access and satellite Communication
Multipl access and satellite Communication
 
Medium Access Control
Medium Access ControlMedium Access Control
Medium Access Control
 
WAP- Wireless Application Protocol
WAP- Wireless Application ProtocolWAP- Wireless Application Protocol
WAP- Wireless Application Protocol
 
Wireless Application Protocol ppt
Wireless Application Protocol pptWireless Application Protocol ppt
Wireless Application Protocol ppt
 
Wireless network security
Wireless network security Wireless network security
Wireless network security
 
Wireless local loop
Wireless local loopWireless local loop
Wireless local loop
 
WAP
WAPWAP
WAP
 
Wireless Network Security
Wireless Network SecurityWireless Network Security
Wireless Network Security
 
Mobile network layer (mobile comm.)
Mobile network layer (mobile comm.)Mobile network layer (mobile comm.)
Mobile network layer (mobile comm.)
 
Satellites presentation
Satellites presentationSatellites presentation
Satellites presentation
 
Wireless Networking Security
Wireless Networking SecurityWireless Networking Security
Wireless Networking Security
 
Bluetooth
BluetoothBluetooth
Bluetooth
 
CELLULAR COMMUNICATION SYSTEM
CELLULAR COMMUNICATION SYSTEMCELLULAR COMMUNICATION SYSTEM
CELLULAR COMMUNICATION SYSTEM
 
Ad-Hoc Networks
Ad-Hoc NetworksAd-Hoc Networks
Ad-Hoc Networks
 
Code division multiple access
Code division multiple accessCode division multiple access
Code division multiple access
 

Ähnlich wie Satellite communications

Satellite system
Satellite systemSatellite system
Satellite systemMd Saylab
 
chapter 6 Satellite Systems.pptx
chapter 6 Satellite Systems.pptxchapter 6 Satellite Systems.pptx
chapter 6 Satellite Systems.pptxAmanuelZewdie4
 
Development of satellite technology and its impact on social life
Development of satellite technology and its impact on social lifeDevelopment of satellite technology and its impact on social life
Development of satellite technology and its impact on social lifeAlexander Decker
 
Satellite communications
Satellite communicationsSatellite communications
Satellite communicationskeerthisri19
 
Shreyas S. Patil(Science).ppt
Shreyas S. Patil(Science).pptShreyas S. Patil(Science).ppt
Shreyas S. Patil(Science).pptBillyGaytes
 
Satellite communication alido
Satellite communication alidoSatellite communication alido
Satellite communication alidoSarah Krystelle
 
Satellite system
Satellite systemSatellite system
Satellite systemkona paul
 
Solar system as a radio telescope by the formation of virtual lenses above an...
Solar system as a radio telescope by the formation of virtual lenses above an...Solar system as a radio telescope by the formation of virtual lenses above an...
Solar system as a radio telescope by the formation of virtual lenses above an...eSAT Publishing House
 
Solar system as a radio telescope by the formation of virtual lenses above an...
Solar system as a radio telescope by the formation of virtual lenses above an...Solar system as a radio telescope by the formation of virtual lenses above an...
Solar system as a radio telescope by the formation of virtual lenses above an...eSAT Journals
 
Satalite Communication ppt.pptx
Satalite Communication ppt.pptxSatalite Communication ppt.pptx
Satalite Communication ppt.pptxSANTHAKUMARP5
 
Satellite communication tagasa
Satellite communication tagasaSatellite communication tagasa
Satellite communication tagasaSarah Krystelle
 

Ähnlich wie Satellite communications (20)

Satellite system
Satellite systemSatellite system
Satellite system
 
chapter 6 Satellite Systems.pptx
chapter 6 Satellite Systems.pptxchapter 6 Satellite Systems.pptx
chapter 6 Satellite Systems.pptx
 
Satellites System
Satellites SystemSatellites System
Satellites System
 
Sesión n° 11 com sat
Sesión n° 11   com satSesión n° 11   com sat
Sesión n° 11 com sat
 
Development of satellite technology and its impact on social life
Development of satellite technology and its impact on social lifeDevelopment of satellite technology and its impact on social life
Development of satellite technology and its impact on social life
 
Satellite communications
Satellite communicationsSatellite communications
Satellite communications
 
Shreyas S. Patil(Science).ppt
Shreyas S. Patil(Science).pptShreyas S. Patil(Science).ppt
Shreyas S. Patil(Science).ppt
 
Satcom 2
Satcom 2Satcom 2
Satcom 2
 
Satellite communication alido
Satellite communication alidoSatellite communication alido
Satellite communication alido
 
Satellite system
Satellite systemSatellite system
Satellite system
 
satellite.pptx
satellite.pptxsatellite.pptx
satellite.pptx
 
Unit 1 sc
Unit 1 scUnit 1 sc
Unit 1 sc
 
Satellite System
Satellite SystemSatellite System
Satellite System
 
SATELLITE SYSTEM
SATELLITE SYSTEM SATELLITE SYSTEM
SATELLITE SYSTEM
 
Solar system as a radio telescope by the formation of virtual lenses above an...
Solar system as a radio telescope by the formation of virtual lenses above an...Solar system as a radio telescope by the formation of virtual lenses above an...
Solar system as a radio telescope by the formation of virtual lenses above an...
 
Solar system as a radio telescope by the formation of virtual lenses above an...
Solar system as a radio telescope by the formation of virtual lenses above an...Solar system as a radio telescope by the formation of virtual lenses above an...
Solar system as a radio telescope by the formation of virtual lenses above an...
 
Satalite Communication ppt.pptx
Satalite Communication ppt.pptxSatalite Communication ppt.pptx
Satalite Communication ppt.pptx
 
Satellite System
Satellite SystemSatellite System
Satellite System
 
Note7
Note7Note7
Note7
 
Satellite communication tagasa
Satellite communication tagasaSatellite communication tagasa
Satellite communication tagasa
 

Mehr von SARITHA REDDY

Unit iv microcontrollers final
Unit iv microcontrollers finalUnit iv microcontrollers final
Unit iv microcontrollers finalSARITHA REDDY
 
Introduction to microprocessors notes
Introduction to microprocessors notesIntroduction to microprocessors notes
Introduction to microprocessors notesSARITHA REDDY
 
8051 data types and directives
8051 data types and directives8051 data types and directives
8051 data types and directivesSARITHA REDDY
 
Unit ii microcontrollers final
Unit ii microcontrollers finalUnit ii microcontrollers final
Unit ii microcontrollers finalSARITHA REDDY
 
Introduction to microprocessor notes
Introduction to microprocessor notesIntroduction to microprocessor notes
Introduction to microprocessor notesSARITHA REDDY
 
8051 data type and directives
8051 data type and directives8051 data type and directives
8051 data type and directivesSARITHA REDDY
 
Decimation in time and frequency
Decimation in time and frequencyDecimation in time and frequency
Decimation in time and frequencySARITHA REDDY
 
Addressing modes of 8051
Addressing modes of 8051Addressing modes of 8051
Addressing modes of 8051SARITHA REDDY
 
I o ports and timers of 8051
I o ports and timers of 8051I o ports and timers of 8051
I o ports and timers of 8051SARITHA REDDY
 
Mos and cmos technology
Mos and cmos technologyMos and cmos technology
Mos and cmos technologySARITHA REDDY
 
Clampers and clippers
Clampers and clippersClampers and clippers
Clampers and clippersSARITHA REDDY
 
Electro Magnetic Wave Propagation
Electro Magnetic Wave PropagationElectro Magnetic Wave Propagation
Electro Magnetic Wave PropagationSARITHA REDDY
 
Electronics in daily life
Electronics in daily lifeElectronics in daily life
Electronics in daily lifeSARITHA REDDY
 
BSc I year practicals
BSc I year practicalsBSc I year practicals
BSc I year practicalsSARITHA REDDY
 
Combinational circuits
Combinational circuitsCombinational circuits
Combinational circuitsSARITHA REDDY
 
Applications of op amps
Applications of op ampsApplications of op amps
Applications of op ampsSARITHA REDDY
 

Mehr von SARITHA REDDY (20)

Unit iv microcontrollers final
Unit iv microcontrollers finalUnit iv microcontrollers final
Unit iv microcontrollers final
 
Introduction to microprocessors notes
Introduction to microprocessors notesIntroduction to microprocessors notes
Introduction to microprocessors notes
 
8051 data types and directives
8051 data types and directives8051 data types and directives
8051 data types and directives
 
Unit ii microcontrollers final
Unit ii microcontrollers finalUnit ii microcontrollers final
Unit ii microcontrollers final
 
Introduction to microprocessor notes
Introduction to microprocessor notesIntroduction to microprocessor notes
Introduction to microprocessor notes
 
8051 data type and directives
8051 data type and directives8051 data type and directives
8051 data type and directives
 
Decimation in time and frequency
Decimation in time and frequencyDecimation in time and frequency
Decimation in time and frequency
 
RT linux
RT linuxRT linux
RT linux
 
Addressing modes of 8051
Addressing modes of 8051Addressing modes of 8051
Addressing modes of 8051
 
I o ports and timers of 8051
I o ports and timers of 8051I o ports and timers of 8051
I o ports and timers of 8051
 
Mos and cmos technology
Mos and cmos technologyMos and cmos technology
Mos and cmos technology
 
Logic families
Logic familiesLogic families
Logic families
 
Clampers and clippers
Clampers and clippersClampers and clippers
Clampers and clippers
 
Linked lists
Linked listsLinked lists
Linked lists
 
Arrays
ArraysArrays
Arrays
 
Electro Magnetic Wave Propagation
Electro Magnetic Wave PropagationElectro Magnetic Wave Propagation
Electro Magnetic Wave Propagation
 
Electronics in daily life
Electronics in daily lifeElectronics in daily life
Electronics in daily life
 
BSc I year practicals
BSc I year practicalsBSc I year practicals
BSc I year practicals
 
Combinational circuits
Combinational circuitsCombinational circuits
Combinational circuits
 
Applications of op amps
Applications of op ampsApplications of op amps
Applications of op amps
 

Satellite communications

  • 1. 1 Satellite Communications Jan 5, 2013 SATELLITE COMMUNICATIONS Dr. C. SARITHA Lecturer in Electronics SSBN Degree College ANANTAPUR
  • 2. Contents… Introduction Orbit Keplers laws Frequency Allocation Advantages of satellite/ Applications Disadvantages Conclusion Jan 5, 2013 Satellite Communications 2
  • 3. Introduction  Satellite is a microwave repeater in the space.  There are about 750 satellites in the space, most of them are used for communication.  They are:  Wide area coverage of the earth’s surface.  Transmission delay is about 0.3 sec.  Transmission cost is independent of distance. Jan 5, 2013 Satellite Communications 3
  • 4. What exactly is a satellite?  The word satellite originated from the Latin word “Satellit”- meaning an attendant, one who is constantly hovering around & attending to a “master” or big man.  For our own purposes however a satellite is simply any body that moves around another (usually much larger) one in a mathematically predictable path called an orbit. Jan 5, 2013 Satellite Communications 4
  • 5. Components of a satellite Jan 5, 2013 Satellite Communications 5
  • 6. What are Communication Satellites?  A satellite is an object that orbits another large object like planet.  A communication satellite is a station in space that is used for telecommunication, radio and television signals.  The first satellite with radio transmitter was in 1957. Jan 5, 2013 Satellite Communications 6
  • 7. Communication Satellites Jan 5, 2013 Satellite Communications 7
  • 8. The origin of satellite  The concept of using object in space to reflect signals for communication was proved by Naval Research Lab in Washington D.C. when it use the Moon to establish a very low data rate link between Washington and Hawaii in late 1940’s.  Russian started the Space age by successfully launching SPUTNIK the first artificial spacecraft to orbit the earth, which transmitted telemetry information for 21 days in Oct. 1957. Jan 5, 2013 Satellite Communications 8
  • 9. Cont…  The American followed by launching an experimental satellite EXPLORER In 1958.  In 1960 two satellite were deployed “Echo” & “Courier”  In 1963 first GSO “Syncom” The first commercial GSO (Intelsat & Molnya) in 1965 these provides video (Television) and voice (Telephone) Jan 5, 2013 Satellite Communications 9
  • 10. Why Use Satellite?  Satellite communication is just one example of wireless communication systems.  Familiar examples of wireless systems are all around us, such as radio, television- broadcasting, mobile and cordless telephones.  These systems rely on a network of ground-based transmitters and receivers and for this reason they are often referred to as “ terrestrial " systems. Jan 5, 2013 Satellite Communications 10
  • 11. Cont…  One major use of satellites familiar to everyone is satellite television broadcasting.  Other applications of satellite communications include high speed internet, telephony and corporate networks for multinational businesses. Jan 5, 2013 Satellite Communications 11
  • 12. How do satellites work?  Two Stations on Earth want to communicate through radio broadcast but are too far away to use conventional means.  The two stations can use a satellite as a relay station for their communication.  One Earth Station sends a transmission to the satellite. This is called a Uplink. Jan 5, 2013 Satellite Communications 12
  • 13. The satellite Transponder converts the signal and sends it down to the second earth station. This frequency is called a Downlink. Transponder Jan 5, 2013 Satellite Communications 13
  • 14. Concept: Jan 5, 2013 Satellite Communications 14
  • 15. • Consider the light bulb as an example: Jan 5, 2013 Satellite Communications 15
  • 16. Early satellites  Telstar Allowed live transmission across the Atlantic  Syncom 2 First Geosynchronous satellite. TELSTAR SYNCOM 2 Jan 5, 2013 Satellite Communications 16
  • 17. Orbits  Circular orbits are simplest.  Inclined orbits are useful for coverage of equatorial regions  Elliptical orbits can be used to give quasi stationary behaviour viewed from earth using  3 or 4 satellites  Orbit changes can be used to extend the life of satellites. Jan 5, 2013 Satellite Communications 17
  • 18. Satellite orbits Classification of orbits: Jan 5, 2013 Satellite Communications 18
  • 19. How does a satellite stay in it’s orbit? Jan 5, 2013 Satellite Communications 19
  • 20. Origin of planetary laws Derived 3 laws based upon his observations of planetary motion. Sir. Johannes Kepler Jan 5, 2013 Satellite Communications 20
  • 21. The 3 Laws of Planetary Motion  Planets move in elliptical orbits with the sun at one of the foci.  The line joining the sun and the planet sweeps out equal areas in equal times.  The cube of the distance of the planet from the sun is proportional to the square of the period. r3 ά T2 Jan 5, 2013 Satellite Communications 21
  • 22. Kepler’s 1st Law: Law of Ellipses The orbits of the planets are ellipses with the sun Jan 5, 2013 at one focus Satellite Communications 22
  • 23. Kepler’s 2nd Law: Law of Equal Areas The line joining the planet to the center of the sun sweeps out equal areas in equal times T4 T3 T5 T2 A4 A3 A5 A2 T1 A1 T6 A6 Jan 5, 2013 Satellite Communications 23
  • 24. Kepler’s 3rd Law: Law of Harmonics The squares of the periods of two planet’s orbits are proportional to each other as the cubes of their semi-major axes: T12/T22 = a13/a23 In English: Orbits with the same semi- major axis will have the same period Jan 5, 2013 Satellite Communications 24
  • 25. Elements of Satellite Communications  The basic elements of a communication satellite service are divided between; Space Segment Ground Segment  The space segment consist of the spacecraft & launch mechanism.  The ground segment comprises the earth station and network control center of entire satellite system. Jan 5, 2013 Satellite Communications 25
  • 26. Space Segment  Space segment consist of a satellite in suitable orbit.  Space segment classified on the basis of orbit.  LEO  MEO  GEO  MONIYA  HAP Jan 5, 2013 Satellite Communications 26
  • 27. Satellite orbit altitudes Jan 5, 2013 Satellite Communications 27
  • 28. Ground Segment  The ground Segment of each service has distinct characteristics.  Services like;  FSS  BSS  MSS Maritime, Aeronautical & Land base  DBS etc.. Jan 5, 2013 Satellite Communications 28
  • 29. Service Types  Fixed Service Satellites (FSS)  Example: Point to Point Communication  Broadcast Service Satellites (BSS)  Example: Satellite Television/Radio  Also called Direct Broadcast Service (DBS).  Mobile Service Satellites (MSS)  Example: Satellite Phones Jan 5, 2013 Satellite Communications 29
  • 30. 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. Jan 5, 2013 Satellite Communications 30
  • 31. The Iridium system has 66 satellites in six LEO orbits, each at an altitude of 750 km. Iridium is designed to provide direct worldwide voice and data communication using handheld terminals, a service similar to cellular telephony Jan 5, 2013 Satellite Communications 31
  • 32. Advantages:  A LEO satellite’s proximity to earth compared to a GEO satellite gives it a better signal strength and less of a time delay, which makes it better for point to point communication.  A LEO satellite’s smaller area of coverage is less of a waste of bandwidth. Jan 5, 2013 Satellite Communications 32
  • 33. Disadvantages: A network of LEO satellites is needed, which can be costly  LEO satellites have to compensate for Doppler shifts cause by their relative movement.  Atmospheric drag effects LEO satellites, causing gradual orbital deterioration. Jan 5, 2013 Satellite Communications 33
  • 34. 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 similar to LEO satellites in functionality.  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. Jan 5, 2013 Satellite Communications 34
  • 35. MEO satellites The GPS constellation calls for 24 satellites to be distributed equally among six circular Glonass (Russian) orbital planes Jan 5, 2013 Satellite Communications 35
  • 36.  Advantage • A MEO satellite’s longer duration of visibility and wider footprint means fewer satellites are needed in a MEO network than a LEO network.  Disadvantage • A MEO satellite’s distance gives it a longer time delay and weaker signal than a LEO satellite, Jan 5, 2013 Satellite Communications 36
  • 37. Geostationary Earth Orbit (GEO)  These satellites are in orbit 35,863 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. Jan 5, 2013 Satellite Communications 37
  • 38. 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. Jan 5, 2013 Satellite Communications 38
  • 39. Disadvantages:  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 broadcasting signals to near polar regions. Jan 5, 2013 Satellite Communications 39
  • 40. Other Orbits  Molniya Orbit Satellites  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. Jan 5, 2013 Satellite Communications 40
  • 41. Molniya Orbit Jan 5, 2013 Satellite Communications 41
  • 42. High Altitude Platforms (HAPs)  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. Jan 5, 2013 Satellite Communications 42
  • 43. Frequency Allocations  Frequency bands for satellite services are shared with terrestrial services.  Satellite signal strength is constrained to avoid interference by it to others.  Thus a large antenna and sensitive receiver are needed at the earth station. Jan 5, 2013 Satellite Communications 43
  • 44. Cont…  Frequency sharing techniques are an important study area.  Many satellites have to share a limited frequency band (and limited orbital arc) thus coordination in frequency and orbital location is important.  Frequency allocation are done by international agreements. Jan 5, 2013 Satellite Communications 44
  • 45. Frequency Bands  Different kinds of satellites use different frequency bands. • L–Band: 1 to 2 GHz, used by MSS • S-Band: 2 to 4 GHz, used by MSS, NASA, deep space research • C-Band: 4 to 8 GHz, used by FSS • X-Band: 8 to 12.5 GHz, used by FSS and in terrestrial imaging, ex: military and meteorological satellites • Ku-Band: 12.5 to 18 GHz: used by FSS and BSS (DBS) • K-Band: 18 to 26.5 GHz: used by FSS and BSS • Ka-Band: 26.5 to 40 GHz: used by FSS Jan 5, 2013 Satellite Communications 45
  • 46. Advantages of satellite over terrestrial communication  The coverage area of a satellite greatly exceeds that of a terrestrial system.  Transmission cost of a 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. Jan 5, 2013 Satellite Communications 46
  • 47. Disadvantages of satellites:  Launching satellites into orbit is costly.  Satellite bandwidth is gradually becoming used up.  There is a larger propagation delay in satellite communication than in terrestrial communication. Jan 5, 2013 Satellite Communications 47
  • 48. Major problems for satellites  Positioning in orbit  Stability  Power  Communications  Harsh Environment Jan 5, 2013 Satellite Communications 48
  • 49. Applications Jan 5, 2013 Satellite Communications 49
  • 50. Applications  Telephony - Fixed points, earth station, Satellite, earth station, fixed points.  Television & Radio - e.g. Direct broadcast satellite (DBS) & Fixed service satellite (FFS)  Mobile satellite technology - Special antenna called mobile satellite antenna. - No matter where or how this antenna is mounted Jan 5, 2013 Satellite Communications 50
  • 51. Cont…  Amateur radio - Access to OSCAR satellite. - Low earth orbits.  Internet - High Speed. - Useful for far away places.  Military - Uses geostationary satellites. - Example: The Defense Satellite Communications Jan 5, 2013 Satellite Communications 51
  • 52. Jan 5, 2013 Satellite Communications 52
  • 53. First Launching Of Satellites By Country Jan 5, 2013 Satellite Communications 53
  • 54. Jan 5, 2013 Satellite Communications 54
  • 55. In Conclusion  Satellites remain the best utilization used for communications due to their speed and other advantages mentioned in this presentation. Jan 5, 2013 Satellite Communications 55
  • 56. Communication satellites bring the world to you anywhere and any time….. Jan 5, 2013 Satellite Communications 56
  • 57. Thank You…..!!!!! Jan 5, 2013 Satellite Communications 57