Satcom

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Satcom
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Satellites

• Most communication satellites in use today are
  geostationary.
• They orbit the earth directly over the equator,
  approximately 22 000 miles (35 400 km) up.
• At this altitude, one complete trip around the
  earth (relative to the sun) takes 24 hours.
• A single geostationary satellite can "see"
  approximately 40 percent of the earth's surface.
• Three such satellites, spaced at equal intervals
  (120 angular degrees apart), can provide coverage
  of the entire civilized world.

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Sattelite Data-rates

• A single transponder on one of these satellites
  (the part of the satellite that transmits signals
  back to Earth, of which a typical satellite has
  32) is capable of handling approximately 100
  million bits of information per second.
• This means that if the transponder is accessed
  for only 90 seconds per day, close to a billion
  bytes of data would be transferred - the
  equivalent of 865 000 double-spaced pages.

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Inmarsat
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Inmarsat A
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Stabilized Antenna

• 86 kg, 100 cm model for Ku -band to the
• 500 kg, 240 cm C-band antenna

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Inmarsat-A (1)

• Inmarsat-A is 20 years old. Yet it has stood up
  well and actually benefited from improved and
  newer technologies.
• (The Inmarsat-A mobile Satellite communications
  (satcoms) system provides
• two-way direct-dial phone (high quality voice),
  fax, telex, electronic mail and data
  communications to and from
• anywhere in the world with the exception of the
  poles.
• It also provides distress communication
  capabilities.

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Inmarsat-A (2)

• It is based upon analogue technology. It supports
  data rates of between 9,600 bps through up to
  64,000 bps depending upon different elements of
  your end-to-end connection.
• Terminals receive and transmit in the L-band
  (1.5/1.6GHz).
• The Inmarsat-A service comprises 3 components
• The mobile-earth station (MES) An Inmarsat-A
  terminal is a small, self-contained satellite
  earth station comprising a lightweight parabolic
  antenna, electronic units, power supply
  interface, and direct-dial telephone, fax and
  telex connections.

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Inmarsat-A (3)

• The satellites The transmission and reception of
  signals are co-coordinated by four network
  co-ordination stations (NCS), one for each
  satellite coverage region
• Atlantic Ocean East and West,
• Indian Ocean
• and Pacific Ocean.
• The Land-Earth station (LES) A call from a
  mobile or transportable Inmarsat-A terminal is
  routed via the Inmarsat satellite system to a
  land earth station (LES) for connection to the
  national and international phone and data
  networks.

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Inmarsat-B (1)

• Inmarsat-B is seen as as the eventual successor
  to the highly successful Inmarsat-A analogue
  system, although the two will continue to
  co-exist well into the next century.
• THE SYSTEM
• Compared with Inmarsat-A, Inmarsat-makes improved
  use of satellite power and bandwidth, enabling
  service providers to offer users much lower
  charges while maintaining high quality and
  reliability.

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Nera Saturn Bm MK2
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A basic Inmarsat-B mobile terminal can provide

• direct-dial,
• High quality telephone,
• Group 3 facsimile,
• telex,
• 64kbit/s and 56kbit/s high speed connections.
• 9.6kbit/s 128 kbit/s data

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Inmarsat C

• Data or message-based.
• Anything that can be coded into data bits can be
  transmitted via Inmarsat-C.
• Rate 600 bits/sec.
• Frequencies are 1626.5-1645.5MHz (transmit),
  1530.0-1545.0Mhz (receive).
• A two-way packet data service via lightweight,
  low-cost termials that are small enough to be
  hand carried or fitted to any vessel, vehicle or
  aircraft.

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Inmarsat C Usage

• SafetyNET maritime safety information to
  vessels at sea and
• Position reporting
• Safety/emergency alerting
• GMDSS Inmarsat-C can be used to meet Global
  Maritime Distress and Safety System requirements.
• Internet e-mail

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Inmarsat E

• The Inmarsat-E system provides global maritime
  distress alerting.
• Distress alerts transmitted from Inmarsat-E
  Emer-gency Position Indicating Radio Beacons
  (EPIRBs) are relayed through Inmarsat satellites.
  
• Following reception of the distress alert, it is
  immediately forwarded automatically to a Maritime
  Rescue Coordination Centre (MRCC).
• The time taken from the transmission of a
  distress alert to reception at the MRCC is within
  five minutes and typically under two minutes.

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Inmarsat E (2)

• The Inmarsat-E system supports Float Free
  EPIRBs which incorporate thefollowing features
• GPSposition which is accurate towithin 200 meters
• automatic activation when the EPIRB is released
  by floating free
• remote activation and informationinput from
  vessels bridge or other manned situation
• optional Search and Rescue Radar Transponder
  (SART)
• optional 121.5MHz locator beacon
• high intensity, low duty cycle flashing light.

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EPIRB

• The size of the EPIRB is between 22cm and 70cm
  high and weighs about 1.2kg
• Carriage of a satellite EPIRB is required by the
  International Maritime Organisations (IMO)
  Global Maritime Distress and Safety System
  (GMDSS).
• The carriage requirement for satellite EPIRBs
  came into effect on August 1 1993.

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Inmarsat M

• Inmarsat MLaunched in 1993, the first satcom
  service supporting satellite phones for
  telephone, Group 3 telefax, data and group-call
  services.
• Inmarsat mini-MA system specifically for satcom
  phones providing voice, telefax and data
  communications at 2.4 kbit/s.

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Inmarsat Priser i USD
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(No Transcript)
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Virtek CommBox
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• Email server
• Transmits mail in bulks to reduce costs, when
  sending low priority mail
• Very short connect time
• High data compression
• Recovery function, continues transfers from where
  the transfer interrupt occured
• E-mail can be delivered automatically or manually
  
• Network TCP/IP router
• Very short connect time
• High data compression
• Full routing between ship and office. All
  machines on the ship will be accessible from all
  machines in the office.

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VSAT

• Typically, a permanent digital link is
  established between 2 locations. This is
  available on a 7 day 24 hour basis. Cost is fixed
  irrespective of how much it is used. There are no
  additional call charges
• Maximum baudrate 2Mbit/sec.

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VSAT

• Usually the VSAT is configured to connect the
  LAN at the remote site to the main company
  network. Users at the remote site (or vessel)
  then have full Email, file transfer and internet
  services as they would in the office.
• The data is carried as a lower priority than the
  voice and the speed of the remote network will
  vary according to the loading on the VSAT system.
  

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VSAT

• Some of the common configurations we deploy are
        64k bits/s to support - smaller vessel
  with 4 phone lines and 6 network users
        128k bits/s to support - drill rig or
  seismic vessel with 6 phone lines and 10 network
  users       192k bits/s to support - remote site
  with 10 phone lines and 15 network
  users      256k bits/s to support - remote site
  with 16 phone lines and 20 network users

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GlobalStar
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Globalstar

• 48 Low Earth Orbiting (LEO) satellites picks up
  signals from over 80 of the Earth's surface,
  everywhere outside the extreme polar regions and
  some mid-ocean regions.
• Several satellites pick up a call, and this "path
  diversity" assures that the call does not get
  dropped even if a phone moves out of sight of one
  of the satellites.

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Globalstar

• Globalstar is a consortium of leading
  international telecommunications companies
  originally established in 1991 to deliver
  satellite telephony services through a network of
  exclusive service providers. Voice calling
• Short Messaging Service (SMS)
• Global roaming
• Facsimile
• Data transmission 9,6 Kbps

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GMDSS

• Global Maritime Distress and Safety System
• Since the time of the Titanic, Marine Radio has
  become the key element in Marine Search and
  Rescue (SAR).
• The 1979 IMO Assembly decided that a new global
  distress and safety system should be established
  in conjunction with a coordinated SAR
  infrastructure to improve safety of life at sea.

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Concepts of the GMDSS (SOLAS) 1

• transmitting ship-to-shore Distress Alerts by at
  least two separate and independent means, each
  using a different radio communication service
• receiving shore-to-ship Distress Alerts
  transmitting and receiving ship-to-ship Distress
  Alerts
• transmitting and receiving search and rescue
  co-ordinating communications

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Concepts of the GMDSS (SOLAS) 2

• transmitting and receiving on-scene
  communications
• transmitting and receiving locating signals
• receiving maritime safety information
• transmitting and receiving general
  radiocommunications relating to the management
  and operation of the vessel
• transmitting and receiving bridge-to-bridge
  communications

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GMDSS communication

• The GMDSS utilises both satellite and terrestrial
  (ie conventional) radio systems

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• Sea Area A1 requires short range radio services -
  VHF is used to provide voice and automated
  distress alerting via Digital Selective Calling
  (DSC).
• Sea Area A2 requires medium range services -
  Medium Frequencies (MF - 2 MHz) are used for
  voice and DSC.
• Sea Areas A3 and A4 require long range alerting -
  High Frequencies (HF - 3 to 30 MHz) are used for
  voice, DSC and Narrow Band Direct Printing (NBDP
  - aka radio telex).

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Digital Selective Calling (DSC)

• DSC is, basically, a paging system that is used
  to automate distress alerts sent over terrestrial
  (ie non-satellite) VHF, MF and HF marine radio
  systems.
• The whole process is automated - the DSC system
  instructs the transmitter to change to the
  required DSC channel
• tHE DSC controller sends the information for
  broadcasting.
• The entire process takes only 3 to 5 seconds.

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Digital Selective Calling (DSC)

• Information sent
• the priority of the call - DISTRESS, URGENCY,
  SAFETY or ROUTINE
• the address - ie all ships or a single
  ship/station
• the identification of the ship in distress
• the position of the ship in distress and
• the nature of the distress.