Satellite Communication

1
Satellite Communication

• www.123seminarsonly.com

2
Satellite

• A satellite is an object that orbits another
  object (known as its primary). The term is often
  used to describe an artificial satellite (as
  opposed to natural satellites, or moons).
• Because all objects exert gravity, the motion of
  the primary object is also affected by the
  satellite. (This observation allows for the
  discovery of extra solar planets.) If two objects
  are sufficiently similar in mass, they are
  generally referred to as a binary system rather
  than a primary object and satellite. The general
  criterion for an object to be a satellite is that
  the center of mass of the two objects is inside
  the other object.
• All masses that are part of the solar system,
  including the Earth, are satellites of the Sun,
  or satellites of those objects, such as the Moon.

3
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 and television broadcasting and 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.
• 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.

One major use of satellites familiar to everyone
is satellite television broadcasting. The
4
Satellite Communication
5
Satellite Communication

• A communications satellite (sometimes abbreviated
  to comsat) is an artificial satellite stationed
  in space for the purposes of telecommunications
  using radio at microwave frequencies. Most
  communications satellites use geosynchronous
  orbits or near-geostationary orbits, although
  some recent systems use low Earth-orbiting
  satellites. A place on the ground with satellite
  dishes used to transmit to or receive from these
  is called an earth station.

6
(No Transcript)
7

• Communications satellites provide a technology
  that is complementary to that of fiber optic
  submarine communication cables. Unlike fiber
  optic communication, satellite communication has
  a propagation delay (also called a path delay) of
  at least 270 milliseconds, which is the time it
  takes the radio signal to travel 35,800 km from
  earth to a satellite and then back to earth.
  Satellite Internet connections average a 600 to
  800 millisecond delay, about ten times that of a
  terrestrial Internet link. This delay is a
  challenge for highly interactive applications
  such as video phones, VOIP or first-person
  shooter online video games.

8
Introduction

• In 1962, the American telecommunications giant
  ATT launched the world's first true
  communications satellite, called Telstar. Since
  then, countless communications satellites have
  been placed into earth orbit, and the technology
  being applied to them is forever growing in
  sophistication

9
Frequency Bands
Band Download Bands MHz Uplink Bands MHz
UHF (Military) 250-270 292-312
C Band (Commercial) 3700-4200 5925-6425
Ku Band (Commercial) 11700-21200 14000-14500
Ka Band (Commercial) 17,700-21200 27500-30,000
Ka Band (Military) 20200-21200 43500-45500
10
Selection of the band

• The selection of the band is not something that
  individual service providers decide, but is
  rather chosen by large satellite operators based
  on different factors
• Availability C-band is still the most widely
  available worldwide. Ku-band is becoming more
  available recently in regions which were less
  covered in the past (South America, Asia, Africa)
  
• C-band is more prone to interference from other
  transmission services that share the same
  frequencies (adjacent satellites or terrestrial
  transmissions) than the higher bands
• While the C-band technology is cheaper in itself,
  it requires larger dishes (1 to 3 m) than Ku- and
  Ka-band (0.6 to 1.8 m) and therefore imposes
  relatively higher (installation) costs on the
  end-user

11

• Ku- and especially Ka-band make better use of
  satellite capacity
• Higher frequency bands (Ku- and especially Ka-)
  suffer significantly more from signal
  deterioration caused by rainfall to ensure
  availability in bad weather conditions, the
  signal has to be much stronger. Note that 0.1 of
  unavailability means in fact that the service
  will be interrupted for almost 9 hours over a
  1-year period. 1 unavailability represents 90
  hours or almost 4 full days

12
Bands of Interest

• C-band is the oldest allocation and operates in
  the frequency range around 6 GHz for transmission
  (uplink) and between 3.7 and 4.2 GHz for
  reception (downlink).Ku-band is the most common
  transmission format in Europe for satellite TV
  and uses around 14 GHz for uplink and between
  10.9 and 12.75 GHz for downlink.Ka-band uses
  around 30 GHz up- and between 18 and 20 GHz
  downlink frequency.C-band and Ku-band are
  becoming congested by an increasing amount of
  users, so satellite service operators are more
  and more turning to the use of Ka-band.

13
Satellite Communications

• 3 Satellite Constellations (microwave, straight
  line signal propogation)
• Low Earth Orbit (LEO) not synchronised (600 to
  1600km)
• Medium Earth Orbit (MEO) not synchronised
  (10000Km)
• Geosynchronous Earth Orbit (GEO) (35,200 km)
  -also known as Geostationary)
  

14
The Orbits

• Orbits GEO, MEO, LEO

15
The GEO

• The most common type of communications
  satellites, particularly the broadcast satellites
  like AfriStar, Intelsat, PanAmSat, Eutelsat and
  ASTRA, are in geosynchronous orbit (from geo
  Earth synchronous moving at the same rate).
  That means that the satellite always stays over
  one spot on Earth. It does this by placing the
  satellite in a position 35,786 km out in space
  perpendicularly above the equator.

16
Geostationary Earth Orbit 36,000 km

Rapid deployment - instant infrastructure
Affordability
17
The MEO

• A medium Earth orbit (MEO) satellite is one with
  an orbit from a few hundred miles to a few
  thousand miles above the Earth's surface.
  Satellites of this type are in a higher orbit
  than low Earth orbit (LEO) satellites, but lower
  than geostationary (GEO) satellites. The orbital
  periods (the time in between two successive
  passes over one particular place on Earth) of MEO
  satellites range from about 2 to 12 hours.

18
The LEO

• A low Earth orbit (LEO) satellite system consists
  of a large number of satellites each in a
  circular orbit at a constant altitude between 320
  and 800 km. Because they orbit so close to Earth,
  they must travel very fast so gravity does not
  pull them back into the atmosphere. Satellites in
  LEOs circle around the Earth at 27,359 km per
  hour. The orbits take the satellites over the
  geographic poles. Each revolution takes from less
  than 90 minutes up to a few hours. The fleet is
  arranged in such a way that from any point on the
  surface at any time at least one satellite is in
  line of sight.

19
The LEO
20
Types of Satellites

• Astronomical satellites are satellites used for
  observation of distant planets, galaxies, and
  other outer space objects.
• Communications satellites are artificial
  satellites stationed in space for the purposes of
  telecommunications using radio at microwave
  frequencies. Most communications satellites use
  geosynchronous orbits or near-geostationary
  orbits, although some recent systems use low
  Earth-orbiting satellites.

21

• Earth observation satellites are satellites
  specifically designed to observe Earth from
  orbit, similar to reconnaissance satellites but
  intended for non-military uses such as
  environmental monitoring, meteorology, map making
  etc.
• Navigation satellites are satellites which use
  radio time signals transmitted to enable mobile
  receivers on the ground to determine their exact
  location. The relatively clear line of sight
  between the satellites and receivers on the
  ground, combined with ever-improving electronics,
  allows satellite navigation systems to measure
  location to accuracies on the order of a few
  metres in real time.

22

• Reconnaissance satellites are Earth observation
  satellite or communications satellite deployed
  for military or intelligence applications.
• Space stations are man-made structures that are
  designed for human beings to live on in outer
  space. A space station is distinguished from
  other manned spacecraft by its lack of major
  propulsion or landing facilities - instead, other
  vehicles are used as transport to and from the
  station. Space stations are designed for
  medium-term living in orbit, for periods of
  weeks, months, or even years.

23

• Weather satellites are satellites that primarily
  are used to monitor the weather and/or climate of
  the Earth.
• Drag-free satellites are satellites that offers
  an environment that is as isolated as possible
  from the forces of nature. A properly designed
  drag-free-satellite proof mass is uncoupled from
  the rest of the Universe to a remarkable degree.
• Miniaturized_Satellites are satellites of
  unusually low weights and small sizes. New
  classifications are used to categorieze these
  satellites minisatellite (500-200kg),
  microsatellite (below 100kg), nanosatellite
  (below 10kg).

24
A Selective Communications Satellite Chronology

• 1945 Arthur C. Clarke Article "Extra-Terrestrial
  Relays"
• 1955 John R. Pierce Article "Orbital Radio
  Relays"
• 1956 First Trans-Atlantic Telephone Cable TAT-1
• 1957 Sputnik Russia launches the first earth
  satellite.
• 1960 1st Successful DELTA Launch Vehicle

25

• 1960 ATT applies to FCC for experimental
  satellite communications license
• 1961 Formal start of TELSTAR, RELAY, and SYNCOM
  Programs
• 1962 TELSTAR and RELAY launched
• 1962 Communications Satellite Act (U.S.)
• 1963 SYNCOM launched
• 1964 INTELSAT formed
• 1965 COMSAT's EARLY BIRD 1st commercial
  communications satellite

26

• 1969 INTELSAT-III series provides global coverage
  
• 1972 ANIK 1st Domestic Communications Satellite
  (Canada)
• 1974 WESTAR 1st U.S. Domestic Communications
  Satellite
• 1975 INTELSAT-IVA 1st use of dual-polarization
• 1975 RCA SATCOM 1st operational body-stabilized
  comm. satellite
• 1976 MARISAT 1st mobile communications satellite
  

27

• 1976 PALAPA 3rd country (Indonesia) to launch
  domestic comm. satellite
• 1979 INMARSAT formed.
• 1988 TAT-8 1st Fiber-Optic Trans-Atlantic
  telephone cable

28
Basic Elements

• Satellite communications are comprised of 2 main
  components

• The Satellite
• The Ground Station.

29
The Earth Station
30
The Earth Station

• Earth station is the common name for every
  installation located on the Earth's surface and
  intended for communication (transmission and/or
  reception) with one or more satellites.
• Earth stations include all devices and
  installations for satellite communications
  handheld devices for mobile satellite telephony,
  briefcase satellite phones, satellite TV
  reception, as well as installations that are less
  familiar, eg VSAT stations and satellite
  broadcast TV stations.
• The term Earth station refers to the collection
  of equipment that is needed to perform
  communications via satellite the antenna (often
  a dish) and the associated equipment
  (receiver/decoder, transmitter).

31
Earth Stations

• High Capacity Stations - Costly, complex
• 
  Services communities large enough to require
• 
  feeder line access to the Earth Station
• Mid-Capacity SES - Used by Corporations
  for Private Networks
• 
  Videoconferencing, electronic mail, data,
• 
  Voice Services. Each earth station can be
• 
  connected to any other station in the network.
• VSAT Network - One Master Earth
  Station and many VSAT
• 
  terminals sharing the MES. Limited to data
• 
  transmissions, digital voice and digital video.
• Receive-Only Earth Station - Voice only, Data
  only, TV Receive only or a
• 
  combination.

32
The parts in the sky

• The two main parts in the sky common to all
  satellites are called the payload and the
  bus.Payload transponders, antennasBus
  physical platform, remote control

33
The Payload

• The payload represents all equipment a satellite
  needs to do its job. This can include antennas,
  cameras, radar and electronics.
• The payload is different for every satellite. For
  example, the payload for a weather satellite
  includes cameras to take pictures of cloud
  formations, while the payload for a
  communications satellite includes large antennas
  to transmit TV or telephone signals to Earth.

34
The Transponder

• The transponder is the key component for
  satellite communications it is the part of the
  payload that takes the signals received from the
  transmitting Earth station, filters and
  translates these signals and then redirects them
  to the transmitting antenna on board.
  Communications satellites carry a large number of
  transponders on board (normally from six to more
  than 24), enabling them to deliver multiple
  channels of communication at the same time. These
  channels are called carriers.

35
The Antenna

• Antennas that receive the original signal from
  the transmitting Earth station and re-transmit
  this signal to the receive stations on Earth.
• The antennas that were used in the past to do
  this were omni-directional (transmitting signals
  in every direction) and not very effective. They
  were replaced by more efficient high-gain
  antennas (most often dish shaped) pointing quite
  precisely towards the areas they were servicing.

36
The Bus

• The bus is the part of the satellite that carries
  the payload and all its equipment into space. It
  is the physical platform that holds all the
  satellite's parts together and that provides
  electrical power, navigation, control and
  propulsion to the spacecraft. The bus also
  contains equipment that allows the satellite to
  communicate with Earth, a kind of 'remote
  control'.

37

38
(No Transcript)
39
The GPS

• The nominal GPS Operational Constellation
  consists of 24 satellites that orbit the earth in
  12 hours. There are often more than 24
  operational satellites as new ones are launched
  to replace older satellites. The satellite orbits
  repeat almost the same ground track (as the earth
  turns beneath them) once each day. The orbit
  altitude is such that the satellites repeat the
  same track and configuration over any point
  approximately each 24 hours (4 minutes earlier
  each day). There are six orbital planes (with
  nominally four SVs in each), equally spaced (60
  degrees apart), and inclined at about fifty-five
  degrees with respect to the equatorial plane.
  This constellation provides the user with between
  five and eight SVs visible from any point on the
  earth.

40
(No Transcript)
41
So What is The Internet ?

• It is a complex web of networks.
• Each network can have millions of inter-connected
  computers which use telephone infrastructure to
  communicate
• No one owns the Internet - Its backbone,
  through which information flows, is owned by a
  number of private companies
• Messages are transmitted through the Internet via
  a computer language called transmission control
  protocol - TCP/IP.
• Each message travels as a packet and has a coded
  address which tells the network its destination
  and also has a block of data content

42

• This packet is transmitted via variety of routes
• Data travels more efficiently using digital
  techniques
• Telstra has been (slowly) digitising its public
  switched telephone network
• How do home computers link to the Internet ?
• Normally via an Internet Server Provider (ISP) -
  a monthly fee is charged for connection and
  maintenance
• These ISPs are connected to a larger network
  service - Network Service Providers (NSPs) which
  are connected using fibre optic cable OR
  satellite links.

43

• There are about 900 ISPs operating in Australia
• Telstra has a large share of the Internet
  wholesale market
• Most ISPs are small and operate a single point
  presence or POP - this is a location which
  comprises modems and a network connection into
  which an ISPs customers dial to make an Internet
  connection.
• High speed Internet requires ISDN

44
(No Transcript)
45
Applications of SattComm

• Radio and TV Broadcasting
• Business radio and TV
• Telephony
• Thin route or trunk telephony
• Mobile satellite telephony
• LEO-based telephony
• GEO-based telephony
• Data, broadband and multimedia services
• IP over satellite for ISPs
• Corporate or institutional VSAT networks
• End-user services for home or small office
• Mobile data communications

46
Radio and TV Broadcasting

• The most familiar use of satellites is television
  broadcasting. TV satellites deliver hundreds of
  television channels every day throughout the
  world. These satellites 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.

47
Satellite Dish Antenna
48
The Eutelsat HotBird position at 13 Degrees East
49
Business radio and TV

• Digital television has made it possible to
  distribute information within organisations and
  companies that are geographically dispersed, or
  to deliver distance education. Similarly, digital
  radio allows for the delivery of radio services
  to relatively small closed user groups.

50
Thin route or trunk telephony

• Telecom operators have been using satellite
  communications for many years to carry
  long-distance telephone communications,
  especially intercontinental, to complement or to
  bypass submarine cables. To the end-user this is
  transparent the phone calls are routed
  automatically via the available capacity at any
  given moment

51
Mobile satellite telephony

• Mobile telephony allows the user to make
  telephone calls and to transmit and receive data
  from wherever he/she is located. Digital cellular
  mobile telephony such as GSM has become a
  worldwide standard for mobile communications, but
  its services lack coverage over areas that are
  sparsely populated or uninhabited (mountains,
  jungle, sea), because it is not economically
  viable or practical for the network operators to
  build antennas there. Satellite telephony seems
  to be able to provide a possible solution to the
  problem of providing voice and data
  communications services to these other locations

52
LEO-based telephony

• Another mobile satellite communications system is
  the Globalstar satellite telephone network.
  Globalstar, which was established in 1991 and
  began commercial service in late 1999, offers
  service from virtually anywhere across over 100
  countries, as well as from most territorial
  waters and several mid-ocean regions. Globalstar
  deploys handheld telephone sets that switch
  between the terrestrial wireless telephone
  network (GSM) and a LEO-based satellite network
  in places where no terrestrial GSM network is
  available.

53
(No Transcript)
54
GEO-based telephony

• An alternative approach to satellite telephony
  uses a geostationary satellite instead of the
  LEO. This results in longer delays (approximately
  half a second) but switching on board the
  satellite reduces this inconvenience as much as
  possible. The Thuraya mobile satellite system was
  launched in 1991, its satellite maintains a
  geo-synchronous orbit at 44 degrees East. Thuraya
  operates effectively in both satellite and GSM
  environments. Its satellite network capacity is
  about 13,750 telephone channels. When within
  reach of a GSM network, Thuraya's mobile phone
  acts as an ordinary GSM handset.

55
Satellite Phones
56
(No Transcript)
57
IP over satellite for ISPs

• Telecoms and connectivity providers have started
  using satellite communications to bypass the
  increasingly clogged terrestrial and submarine
  networks to complement their backbone
  connectivity or to supplement them where they are
  not yet available. This approach takes advantage
  of the fact that satellite is not a real
  point-to-point connection like cable, but a
  connection that allows the delivery to multiple
  points at the same time. This allows for
  simultaneous updating of multiple caching, proxy
  or mirroring servers.

58
(No Transcript)
59
In Much the same way, it is possible to push
Internet content to and even over the edges of
existing networks. When it is necessary to
provide large amounts of content to places that
are poorly connected to the Internet, it is now
possible to push content to local PoPs (Point of
Presence) edge servers. These can then in turn
serve as ISPs to the local users or user
communities
60
Corporate or institutional VSAT networks

• VSAT stands for Very Small Aperture Terminal and
  refers to combined send/receive terminals with a
  typical antenna diameter of 1 to 3.7 m linking
  the central hub to all remote offices and
  facilities and keeping them all in constant
  immediate contact. VSAT networks offer solutions
  for large networks with low or medium traffic.
  They provide very efficient point-to-multipoint
  communication, are easy to install and can be
  expanded at low extra cost. VSAT networks offer
  immediate accessibility and continuous
  high-quality transmissions. They are adapted for
  any kind of transmission, from data to voice, fax
  and video.

61
VSAT Star-shaped Networks
62

• A VSAT network, a corporation can communicate
  freely and constantly with branch offices
• Voice and fax transmissions
• Local Area Network interconnection
• Data broadcasting
• Videoconferencing
• In-house training

63
VSAT Mesh-shaped Networks
64
One-way Satellite Internet Connection
65
Two-way Satellite Internet Connection
66
Thank You VISIT AGAIN