Brief introduction to satellite communications

Introduction to Satellite Communications,
Presented By Sally Sheridan B.

Introduction to Satellite Communications Presented by Sally Sheridan

Why Satellite?


SATELLITE COMMUNICATIONS ARE:

• Highly Survivable (Physical Survivability and
Robustness)
• Independent of Terrestrial Infrastructure
• Able to Provide The Load Sharing and Surge
Capacity Solution for Larger Sites
• Best for Redundancy: They add a Layer of Path
Diversity and Link Availability


SATELLITE SYSTEMS PERFORM EFFECTIVELY WHEN:
•

Terrestrial infrastructure is damaged, destroyed, or overloaded interconnecting widely
distributed networks.

•

Providing interoperability between disparate systems and networks.

•

Providing broadcasting services over very wide areas such as a country, region, or
entire hemisphere providing connectivity for the “last mile” in cases where ﬁber
networks are simply not available.

•

Providing mobile/transportable wideband and narrow-band communications.

•

Natural disasters or terrorist attacks occur.

•

Satellites are the best and most reliable platform for communications in such
situations ﬁber networks or even terrestrial wireless can be disrupted by tsunamis,
earthquakes, or hurricanes. Satellites are instant communications infrastructure.


•

Ubiquitous Coverage: A group of satellites can cover virtually all of the Earth’s surface.

•

Instant Infrastructure: Satellite service can be offered in areas where there is no terrestrial
infrastructure and the costs of deploying a fiber or microwave network are prohibitive. It can
also support services in areas where existing infrastructure is outdated, insufficient, or
damaged.

•

Independent Of Terrestrial Infrastructure: Satellite service can provide additional bandwidth
to divert traffic from congested areas, provide over flow during peak usage periods, and
provide redundancy in the case of terrestrial network outages.

•

Temporary Network Solutions: For applications such as news gathering, homeland security,
or military activities, satellite can often provide the only practical, short-term solution for
getting necessary information in and out.

•

Rapid Provisioning Of Services: Since satellite solutions can be set up quickly,
communications networks and new services can be quickly recovered And reconfigured. In
addition, you can expand services electronic all without traditional terrestrial networks.

•

As a result, you can achieve a high level of communications rapidly without high budget
expenditures.


CAPABILITIES
•

FIXED-TO-FIXED

FIXED-TO-MOBILE

•

Mobile to mobile

POINT-TO-MULTIPOINT


INTEROPERABILITY
•
•

Satellite communications can interconnect with any other communications
solution
(i.e. LMR, Cellular, WiFi, etc.) via generic crossbanding equipment.


VOICE
•Mobile Satellite Service (MSS) uses portable satellite phones and terminals.
•MSS terminals May be mounted on a ship, an airplane, truck, or an automobile.
•MSS terminals may even be carried by an individual.
•The most promising applications are portable, satellite telephones and broadband Terminals that enable global
service.
•In addition, emerging mobile communication networks will also offer voice, video and data services via
“smart”chips Inserted in handheld devices ( i.e. cellphones, LMR’s, PDA’s, laptops, etc.) that integrate cellular
and satellite technology.

MSS APPLICATIONS:
Mobile Telephony
Push to Talk Radio
Emergency Response Coordination
Dispatch Coordination
Communications On The Move

Asset Tracking
Data Transfer
Lone Worker Protection
Environmental Monitoring
Event Reporting
Messaging


VIDEO/DATA
•
•

Fixed Satellite Service (FSS) has traditionally referred to a satellite service that uses terrestrial terminals
communicating with satellites in geosynchronous orbit.
New technologies allow FSS to communicate with mobile platforms.

FSS APPLICATIONS:
Cellular Restoration
Wi-Fi Restoral
Emergency Phone Bank
Communications On The Move
PSTN Backhaul
Voice-over-IP
Broadband Internet Access
Live Video
Telemedicine
Video Conferencing
FSS APPLICATIONS:


Broadband Connectivity
SATELLITE VSAT NETWORKS:
A satellite Very Small Aperture Terminal (VSAT) network consists of a pre-positioned, fixed, or transportable VSAT that connects to a hub station to provide
broadband communications to hospitals, command posts, emergency field operations and other sites.
VSAT(s) are low-cost, 2 to 4 foot antennas equipped with a fixed mount that can be made survivable to over 100 mph winds.
There are also variants of VSATs that are transportable which can be on-the-air within 30 minutes and require no special Tools or test equipment for
installation.
Remote FSS VSAT equipment requires standard AC power for operation, but comes equipped with lightweight, 1 and 2KW, highly efficient, and selfcontained power generator equipment for continuous operation, regardless of local power availability.
Turnkey FSS communications packages can be provided with satellite bandwidth and ground equipment fully integrated. Internet access and Internet
applications (i.e. VoIP) are supported through the remote VSAT back through the FSS provider teleport location which is connected to the PSTN and/or the
Internet.
A typical VSAT used by a first responder may have full two-way connectivity up to several Mbps for any desired combination of voice, data, video, and
Internet service capability.
VSATs are also capable of supporting higher bandwidth requirements of up to 4 Mbps outbound and up to 10+ Mbps inbound.
The FSS network topology consists of remote point-to-multi-point and two-way satellite IP connectivity.
Delivered bandwidth can support a substantial number of phone lines (i.e. phone bank).

Transportable FSS VSATs
providing high-speed
Internet, data, voice,
and/or video access with
automatic set-up
and simple operation.


VIDEO/DATA
Network Restoration
TERRESTRIAL BROADBAND, LMR, CELLULAR, OR WIMAX AND WIFI INFRASTRUCTURE
RESTORATION:
VSAT networks are able to provide high-speed, two-way emergency communications
restoration in the wake of a natural or man-made disaster when all other forms of
high-speed communication are unavailable.
VSAT networks provide connectivity for restoral and contingency communications,
providing for higher volume VoIP telephony, data, video and Internet access, thereby
connecting remote locations to the rest of the world in a time of crisis.


APPLICATIONS SUPPORTED:
Telco Terrestrial and WiMAX/WiFi Infrastructure Restoration
VSAT networks provide for restoration of the Public Switched Telephone Network
(PSTN) and Internet access to meet emergency communications demand, with
high-speed connections that are independent of the local Telco ground system
infrastructure to re-establish voice, data, and video connectivity.
VSAT networks equally provide for restoration of wireless cellular nodes and
WiMAX (Worldwide Interoperability for Microwave Access) WAN (Wide Area
Network) networks to be re-established for private First Responder networks
or to reconstitute local Telcos and Internet Service Providers (ISPs).
Wireless Handheld Interoperability
FSS VSAT networks are fully compliant to support IP based Ethernet data to/
from P25 wireless handheld radio systems.
FSS VSAT networks may provide for IP phone signaling, acting as a redundant link
between remote ﬁre, rescue and other ﬁrst responder’s operations centers to
support any radio system with IP connectivity,[i.e.700 MHz].


Communications On The Move (COTM)
MOBILE COMMAND AND CONTROL COMMUNICATIONS:
FSS and MSS COTM solutions can provide fully mobile IP data and voice services to vehicles on the move up to
60 mph. The comprehensive FSS COTM offering includes the terminal, teleport, and satellite capacity to
provide high performance COTM IP connectivity.
TYPICAL APPLICATIONS SUPPORTED:
Any vehicle can also serve as a mobile command post while in-route and as a ﬁxed command access point for
personnel upon arrival at the designated location when local Telco terrestrial and wireless infrastructure are
not available.
A full 10 Mbps downlink channel is delivered via FSS to the vehicle and 512
Kbps uplink channel transmitted from the vehicle to the Internet using IP support for voice, video and data
simultaneously.
Support for 802.11x wireless access allows vehicle to function as wireless hot spot access point for a First
Responder convoy while in-route or a ﬁxed hot spot for personnel upon arrival.


Types of Satellites
•
•
•
•
•
•
•

Weather Satellites
Communications Satellites
Observation Satellites
Navigation / GPS Satellites
Military Satellites
Nanosatellites / Microsatellites
Remote Sensing Satellites


Types of Orbits
• Geostationary orbit is when the satellite or
spacecraft is stationary in a single position
relative to the Earth
• Polar Orbit is an orbit in which your spacecraft
or your satellite crosses the orbits in a
longitudinal fashion.
• In a polar orbit, you can circle the Earth several
times during one day.
• Highly Elliptical Orbit: When the satellite
passes Earth quickly and stays away from Earth
fixed in a distant location.


Geostationary Orbit (GEO)
• Satellite has to be placed approximately 22,000 miles
(36,000 km) away from the surface of the Earth in order
to remain in a GEO orbit
• In GEO, the satellite will be on the equator and it will
remain stationary since it will have a period of 24 hours


Geosynchronous Orbit
• Geosynchronous orbit is like a geostationary orbit in the
sense that it has a period of 24 hours.
• However, unlike a GEO, it doesn’t have to be exactly above
the equator, as it can have an angle relative to Earth and the
orbit doesn’t have to be fully circular


Geosynchronous/Geostationary Orbit
• By positioning a satellite so that it has infinite dwell time over
one spot on the Earth, we can constantly monitor the
weather in one location, provide reliable telecommunications
service, and even beam television signals directly to your
home
• The down side of a geosynchronous orbit is that it is more
expensive to put something that high up, and not possible to
repair it from the shuttle
• So you only put something in GEO if you really need to have it
in the same location in the sky at all times.


Polar Orbit
• These orbits have an
inclination near 90 degrees.
This allows the satellite to see
virtually every part of the
Earth as the Earth rotates
underneath it. It takes
approximately 90 minutes for
the satellite to complete one
orbit.


Polar / Geostationary Orbit


Heliosynchronous Orbit
• These orbits allows a satellite to pass over a section of the Earth at the
same time of day.
• Since there are 365 days in a year and 360 degrees in a circle, it means
that the satellite has to shift its orbit by approximately one degree per
day. These satellites orbit at an altitude between 700 to 800 km
• These orbits are used for satellites that need a constant amount of
sunlight


Highly Elliptical Orbit
• An object in orbit about Earth moves much faster when
it is close to Earth than when it is further away.
• If the orbit is very elliptical, the satellite will spend
most of its time near apogee (the furthest point in its
orbit) where it moves very slowly.


Various Satellite Orbits


LEO
• LEO is Low Earth orbit and it is
considered as 160 km to 500 km
of altitude. Technically, in Low
Earth orbit, the drag effects will
always hinder operations.
• For example, ISS is in LEO
(around 386 km – 460 km) and it
needs its orbit readjusted by the
Space Shuttle or by its own
thrusters every 6 months or it
will fall down
• Satellites in LEO will have very
high speeds around 18,000 miles
per hour


Low Earth Orbit Disadvantages
• The first disadvantage is that there is still some atmospheric
drag. Even though the amount of atmosphere is far too little
to breath, there is enough to place a small amount of drag on
the satellite or other object.
As a result, over time these objects slow down and their
orbits slowly decay.
• The second disadvantage has to do with how quickly a
satellite in LEO goes around the Earth. As you can imagine, a
satellite traveling 18,000 miles per hour or faster does not
spend very long over any one part of the Earth at a given
time


MEO

• MEO is Middle Earth Orbit is a
special orbit that is beyond LEO.
• MEO is usually defined as 500
Km – 1000 Km in most literature.
However, previously it was
defined as high as 10,000 km


HEO
• HEO is High Earth orbit
• HEO is defined as orbit above
1000 km in most literature.
It extends to 40,000 km
altitude.
• Mostly in HEO, the drag
effects would be non existent.
Hence, HEO will have a more
stable orbit free from
atmospheric effects, but also
it will require much more
energy to put there

Station Keeping in GEO
• Most GEO satellites are required to remain within a box of +/0.05 degrees, so that it can be kept within operational
parameters.
• Usually with an interval of two weeks, first
E-W corrections are made and then after another two weeks
N-S corrections are made. Hence, this is repeated monthly to
station keep the satellite.


Satellite Communication Applications


T V . Broadcasting
• One of the main uses of communications satellite s is
for TV broadcasting. This way, the TV signal can be
transmitted to a large geographical region without
detailed land transmitters or repeaters.
• Also for a live broadcasting, it is best to use a satellite
for sending a live signal from anywhere on Earth
• DBS is Direct Broadcast Satellite for home viewing
systems


D B S System
• The satellite is the space segment of the DBS (Direct Broadcast
System), the Earth segment consists of the satellite dish as well as the
LNB (LOW NOISE BLOCK) and the satellite receiver


Outdoor Unit of a DBS System
• The outdoor unit consists of a
receiving antenna and a low noise
amplifier / convertor.
• For the antenna, parabolic or offset
reflector is used. The antenna is
designed so that the focus will be in
directly front of the reflector
• Usually 0.6 m to 1.3 m dishes are
enough in the Ku band but for C band
2-3 m recommended


Outdoor Unit of a DBS System (LNB)
• LNB is the Low Noise Block which is the
combination unit consisting of a low
noise amplifier followed by a convertor.
• The LNB provides gain for the broadband
12 Ghz signal and then converts the
signal to a lower frequency range so that
low cost coaxial cable can be used as
feeder to the indoor unit


Indoor Unit
• The indoor unit consists of coaxial cabling as
well as the satellite DBS receiver.
• It will demodulate the signals and convert it
into a form applicable for TV
(PAL/SECAM/NTSC)


Bit Rates and Compression for Broadcasting
TV Signals via Satellite
• Before transmission, all broadcasting signals
must be converted to digital, compressed and
time division multiplexed signals.
• The compressed bit rate and hence the number
of channels depends on the type of the program
material.
• Talk shows where there is little movement
require the lowest bit rate, while sports
channels with lots of movement requires larger
bit rates.


MPEG
• MPEG compression standards
are used to define standards for
transmissions as well as for
storage of moving pictures and
sound.
• MPEG covers bit rate, picture
resolution, time frames for
audio, and the packet details for
transmission.
• In DBS systems, MPEG – 2 is
used for video compression
while MPEG -1 is used for only
audio transmission via DBS.
MPEG 2 can also contain multi
channel audio with stereo.


Satellite Mobile Services
• For communications purposes, satellites are very
useful for providing telephone coverage at any
point in the world.
• Satellites provide full coverage for phone, fax and
internet connection
• Some global satellite mobile services include:
- Asian Cellular System
- Thuraya Global System
- MSAT (for North American coverage)


Thuraya
• Thuraya satellite system serves an
area between 20W and 100E
longitude to 60 N and 2S latitude.
System covers more then 110
countries with a combined population
of 2.3 billion. It spans Europe, North
and Central Africa and some parts of
Southern Africa
• Network capacity is about 13,750
telephone channels.


Iridium Satellite Network
• Iridium satellite systems
are special
communications
satellites for telephony
that uses 66 satellites
grouped in 6 orbital
planes with each
containing 11 satellites.


Iridium and Thuraya Orbits

Iridium Orbit Thuraya Orbit


Large Scale Communications Network


VSAT
• VSAT stands for Very Small
Aperture System
• In essence a VSAT terminal
will be very small and it is
used to create a two way
communication between
that point and the satellite


Applications of VSAT
• There are various different applications of VSAT.
These include:
- Remote ATM locations
- Internet Connectivity in Remote Regions
- Network Connectivity in Remote Regions


G P S Satellites
• GPS stands for Global
Positioning Satellite System.
• It consists of 24 satellites that
circle the Earth.
• By receiving signal from at least
three/four of these satellites,
the receiver position consisting
of latitude, longitude and
altitude can be determined
accurately.


G P S Usage
• Four satellites are used for latitude,
longitude, altitude and for time marking.
• GPS system uses one way transmission from
satellites to users so the user requires only a
GPS receiver


Remote Sensing & Imaging Satellites
• Remote Sensing and
Imaging satellites are
an important part of
our world as full
coverage and mapping
of the Earth has been
done.
• Google Earth is a good
representation of this
as the whole world
has been imaged and
mapped at your
fingertips


Satellite & Internet Communications
• Satellite links have been part of Internet’s connectivity since its
beginning.
• Satellite internet connection is used for satellite direct to home
links as well as in creating a communications path between
continents and major nodes. Inter-satellite links are also used
for internet connectivity
• There is a delay of 0.532 s in GEO satellites. The delay is less in
MEO and LEO but since they are not stationary, 24h coverage is
not possible.


Satellite & Internet Communications
Data Transmission model:


GLOSSARY
ANTENNA
A device for transmitting and receiving signals. An
antenna is part of an Earth Station.
BACKHAUL
A terrestrial communications channel linking an
earth station antenna to a local switching network
or population center.
BANDWIDTH
A measure of spectrum (frequency) use or
capacity. For instance, a voice transmission by
telephone requires a bandwidth of about 3000
cycles per second (3KHz).
CHANNEL
A frequency band in which a specific broadcast
signal is transmitted. Channel frequencies are
specified in the United States by the Federal
Communications
Commission.
DOWNLINK
The link from the satellite down to the Earth Station.
EARTH STATION
The buildings, hardware, software and antennas
used to communicate with a satellite.
FDMA
Frequency Division Multiple Access. A way of sharing
a channel by assigning different frequencies to different
users.
FOOTPRINT
The area of the Earth’s surface from which an
Earth Station can transmit to or receive from a
particular satellite.
FREQUENCY BANDS
Internationally, frequencies are divided into well-defined
bands. For satellites, the relevant bands are:

L-Band
As defined by IEEE std . 521, the frequency
range from 1 to 2 GHz. The L-band term is also used to refer to the 950 to
1450MHz
frequency range used for mobile communications. L-band is used for
Mobile Satellite Services and offers Good penetration through adverse
weather conditions and foliage.
C-Band
The frequency range from 3.7 to 6.2 GHz. Transmissions are less affected
by atmospheric conditions such as snow and rain.
However, C-band transmissions have low power, so Earth Stations must be
rather large to compensate dish size. Applications include public switched
networks and Internet trunking.
X-Band
The frequency range from 8.0 – 12.0 GHz.
The X-band frequency enables high power operations with very small
terminals. Applications Include COTM, manpacks, emergency
communications and airborne and shipboard platforms. X-band is also less
vulnerable to rain fade and adjacent satellite side lobe Interference than
Other frequencies.

Ku-Band
The frequency range from 11.7 to 14.5GHz. Ku-band has higher power
than C-band allowing for smaller dishes to be used. However, the higher
frequency of Ku-band makes it more susceptible to adverse weather
conditions than C-band. Applications include VSAT, rural telephony,
satellite news gathering, videoconferencing, and multimedia.
Ka-Band
The frequency range from 17.7 to 21.2 GHz. Has a higher power than Kuband allowing for smaller dishes to be used and therefore, will be used for
high-bandwidth interactive services such as high-speed Internet,
videoconferencing, and multimedia applications. Ka-band transmissions
are more sensitive to poor weather conditions than Ku-band.


HUB
The master station through which all communications, to, from
and between terminals must ﬂow.

KBPS
Kilobits per second. Refers to transmission speed of 1,000 bits
per second.
KHZ
KiloHertz. One KiloHertz is the equivalent of one thousand Hertz,
or one thousand cycles per second. Used to measure frequency
and bandwidth.
LAN
Local Area Network. A geographically localized network.

MHZ
Megahertz. One Megahertz is equivalent of one million Hertz, or
one
million cycles per second. Used to measure frequency and
bandwidth.
SPOT BEAM
A satellite beam with concentrated geographic coverage.
TDMA
Time Division Multiple Access. A way of sharing a channel by
assigning different time slots to different users.
TERMINAL
One of the communications stations that receives, processes,
and transmits signals between itself and a satellite.
TRANSPONDER
A device located on board the satellite which receives signals
uplinked from an earth station and transmits them back to earth
on a different
frequency.
UPLINK
The link from the earth station up to the satellite.

VSAT
Very small aperture terminal. Refers to small earth stations, with antennas
usually in the 1.2 to 2.4 meter range. Small aperture terminals
under 0.5 meter are sometimes referred to Ultra Small Aperture Terminals
(USAT’s)
WIFI
Wireless Fidelity - A brand originally licensed by the Wi-Fi Alliance to describe
the underlying
technology of wireless local area networks based on the IEEE 802.11
speciﬁcations. A person with a Wi-Fi device, such as a computer, telephone,
or personal digital assistant (PDA) can connect to the Internet when in
proximity of an access point. The region covered by one or several access
points is called a hotspot.
WIMAX
WiMAX is a wireless communications technology that provides highthroughput broadband connections for considerably longer distances than
that offered via WiFi (Wireless Fidelity)
LAN (Local Area Network).
LMR
Land Mobile radio is a term that denotes a wireless communications system
intended for use by terrestrial users in vehicles (mobiles) or on foot
(portables). Such systems are used by emergency first
responder organizations, public works organizations, or companies with large
vehicle fleets or numerous field staff.
PDA
PDA stands for Personal Digital Assistant. A Personal Digital Assistant is a
hand-held device that performs many functions like a digital address book
and organizer.


Thank you for your invaluable time and attention.


Credits
Brief Introduction to Satellite Communications
Presented ,edited, and compilated By:
Eng. Sally Sheridan Bensimon,
Zichron Yaakov, Israel September 2013
For: Gilat Satellite Networks

References
http://www.navymars.org/national/training/nmo_courses/nmoc/module17/14189_ch4.pdf
http://www.escus.info/images/book4_sample.pdf
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http://www.mu.ac.in/myweb_test/Satelight%20Comm..pdf

http://www.intelsat.com/wp-content/uploads/2013/01/5941-SatellitePrimer-2010.pdf
http://www.tu-ilmenau.de/fileadmin/public/iks/files/lehre/UMTS/02_Mobicom-basics-ws12.pdf
http://transition.fcc.gov/pshs/docs-basic/SIA_FirstRespondersGuide07.pdf
http://www.near.aero/nearweb/documents/Voice%20Over%20Internet%20Protocol%20Communication%20System%20for%20Use%20in%20%20Air%20Traffic%20C
ontrol.pdf
http://www.near.aero/nearweb/documents/Voice%20Over%20Internet%20Protocol%20Communication%20System%20for%20Use%20in%20%20Air%20Traffic%20C
ontrol.pdf
http://www.eolss.net/Sample-Chapters/C05/E6-108-10-00.pdf
http://epubs.surrey.ac.uk/741313/1/SIP%20Signalling%20and%20QoS%20for%20VoIP%20over%20IPv6%20DVB-RCS%20Satellite%20Networks.pdf


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