The Active Management Value Ratio: The New Science of Benchmarking Investment...
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1. 1
Unclassified
3June 2008
Introduction
Satellite Orbits
Overview of a satellite system
Link Budget
Digital Communication Technologies
Coverage
Satellite Systems & Applications (Examples)
Satellite CommunicationsSatellite Communications
2. 2
Unclassified
3June 2008
IntroductionIntroduction
Satellite communications systems exist becauseSatellite communications systems exist because
earth is a sphere.earth is a sphere.
– Radio waves travel in straight lines at theRadio waves travel in straight lines at the
microwave frequencies used for widebandmicrowave frequencies used for wideband
communicationscommunications
– Repeater is needed toRepeater is needed to
convey signals very longconvey signals very long
distancesdistances
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3June 2008
Communications satellites is an artificial station inCommunications satellites is an artificial station in
space which operates as a radio relayspace which operates as a radio relay
Introduction (contIntroduction (cont.(.(
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Introduction (contIntroduction (cont.(.(
Satellites are important in: voice communications, video &
radio transmission, navigation (GPS), remote sensing (maps,
weather satellites) etc.
A majority of communication satellites are in geostationary
earth orbit an altitude of 35 786 km
– Satellite in “fixed place”
– Typical path length from earth station to a GEO satellite
is 38 500 km
Satellite systems operate in the microwave and millimeter
wave frequency bands, using frequencies between 1 and 50
GHz
– Above 10 GHz rain causes significant attenuation of the
signal
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3June 2008
History of Satellite Communications –History of Satellite Communications –
Some MilestonesSome Milestones
Satellite communications began in October 1957 with the launch
by the USSR a small satellite called Sputnik 1 (4.10.1957)
– Beacon transmitter, no communications capability
3.11.1957 Sputnik 2 with Laika
12.4.1961 Vostok 1 with Juri Gagarin
First true communication satellites (Telstar I & II) were launched
in July 1962 & May 1963
10/1964 Syncom 2: First GEO satellite, 7.4/1.8 GHz (one TV-
channel or several 2-way telephone connections
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3June 2008
Geostationary orbitsGeostationary orbits
A satellite in a geostationary orbit appears
to be in a fixed position to an earth-based
observer. A geostationary satellite revolves
around the earth at a constant speed once
per day over the equator.
As a result, an antenna can point in a fixed
direction and maintain a link with the
satellite. The satellite orbits in the direction
of the Earth's rotation, at an altitude of
approximately
35,786 km (22,240 statute miles) above
ground. This altitude is significant because
it produces an orbital period equal to the
Earth's period of rotation
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The geostationary orbit is useful for communications
applications because ground based antennas, which must be
directed toward the satellite, can operate effectively without
the need for expensive equipment to track the satellite’s
motion. Especially for applications that require a large number
of ground antennas (such as direct TV distribution), the
savings in ground equipment can more than justify the extra
cost and onboard complexity of lifting a satellite into the
relatively high geostationary orbit
Geostationary OrbitsGeostationary Orbits
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3June 2008
Satellite Orbits [5Satellite Orbits [5[[
Geostationary Orbit (GEO) satellites, i.e. satellites that are stationary
with respect to a fixed point on the earth
– good coverage: Theoretically, only three GEO satellites are
sufficient to serve all the earth.
– the simplest space configuration and simple space control system
– no need for tracking system at the earth stations
– no variation of propagation delay and elevation angle
– negligible Doppler effects
– problematic links feasibility due to the long satellite-user distance
(prohibitive power levels and/or too large on-board antennas could
be required if low power hand-held user terminals are considered)
– high propagation delays for interactive services and mobile-to-
mobile communications (higher than 400 ms recommended by
CCITT in case of double hop communications)
– low minimum elevation angles at high latitudes
(i.e. regions cannot be covered)
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Low-Earth-orbiting SatellitesLow-Earth-orbiting Satellites
A Low Earth Orbit (LEO) typically is a circular orbit about 400 kilometers
above the earth’s surface and, correspondingly, a period (time to revolve
around the earth) of about 90 minutes. Because of their low altitude, these
satellites are only visible from within a radius of roughly 1000 kilometers
from the sub-satellite point. In addition, satellites in low earth orbit change
their position relative to the ground position quickly. So even for local
applications, a large number of satellites are needed if the mission
requires uninterrupted connectivity.
Low earth orbiting satellites are less expensive to position in space than
geostationary satellites and, because of their closer proximity to the
ground, require lower signal strength (Recall that signal strength falls off as
the square of the distance from the source, so the effect is dramatic). So
there is a trade off between the number of satellites and their cost. In
addition, there are important differences in the onboard and ground
equipment needed to support the two types of missions.
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MarkerMarker
Distance aboveDistance above
earth (kmearth (km((
Low EarthLow Earth
Orbit (LEOOrbit (LEO)) Cyan areaCyan area 160160to 2,000to 2,000
MediumMedium
Earth OrbitEarth Orbit
(MEO(MEO)) Yellow areaYellow area 2,0002,000to 34,780to 34,780
InternationalInternational
SpaceSpace
Station (ISSStation (ISS))
Red dottedRed dotted
lineline 500500
GlobalGlobal
PositioningPositioning
SystemSystem
(GPS)(GPS)
satellitessatellites
Green dash-Green dash-
dot linedot line 20,23020,230
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The satellite system is composed of a space segment and
a ground segment
The Space Segment contains one or several active
satellites organized in a constellation
The Control Segment consists of all ground facilities for the
control and monitor the satellites (TTC-tracking, telemetry
and command) and for management the traffic and the
resources onboard the satellite
The Ground Segment consists of all traffic earth stations
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3June 2008
Satellites – Satellite SubsystemsSatellites – Satellite Subsystems
Attitude and Orbit Control System
– Rocket motors to move satellite back to the correct orbit
– Keep antennas point toward to earth
Telemetry, tracking, command and monitoring
– Telemetry system monitor satellite health, tracking system is located
at the earth station and provides information about elevation & azimuth
angles of the satellite
Power system
– Electrical power from solar cells
Communication subsystem
– Major component of communications satellites, one or more
antennas & a set of receivers and transmitters (transponders)
• The linear or bent pipe transponders; amplifiers the received signal &
retransmits it a different, usually lower frequency
• Base-band processing transporters; used with digital signals, converts the
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3June 2008
What Are Satellite PayloadsWhat Are Satellite Payloads??
• The payloads on communicationsThe payloads on communications
satellites are effectively justsatellites are effectively just
repeaters. They receive the signalsrepeaters. They receive the signals
that are transmitted to them and thenthat are transmitted to them and then
retransmit them at a differentretransmit them at a different
frequency back to earthfrequency back to earth
• Modern satellites do more than this.Modern satellites do more than this.
They receive the signals and thenThey receive the signals and then
demodulate them to access the data,demodulate them to access the data,
the data can then be processedthe data can then be processed
before being modulated andbefore being modulated and
retransmitted. The data can beretransmitted. The data can be
stored for later retransmission orstored for later retransmission or
modulated using a different method,modulated using a different method,
even at a different data rateeven at a different data rate
A wireless repeater
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A typical satellite consists of a number of repeaters (transponders), each ofA typical satellite consists of a number of repeaters (transponders), each of
which provides a large-capacity communication channel. Each transponderwhich provides a large-capacity communication channel. Each transponder
has a receiver tuned to a frequency range that has been allocated forhas a receiver tuned to a frequency range that has been allocated for
uplink communication signals from Earth to the satellite. Following theuplink communication signals from Earth to the satellite. Following the
receiver, each transponder consists of a frequency shifter to lower thereceiver, each transponder consists of a frequency shifter to lower the
received signals to a downlink frequency, a filter tuned to the frequency ofreceived signals to a downlink frequency, a filter tuned to the frequency of
the transponder and a power amplifier to transmit signals back to Earththe transponder and a power amplifier to transmit signals back to Earth
The communication capacity of a satellite is determined by the number ofThe communication capacity of a satellite is determined by the number of
transponder channels and the volume of communication that can betransponder channels and the volume of communication that can be
transmitted on each channel. Although this varies from one type of satellitetransmitted on each channel. Although this varies from one type of satellite
to another, the most commonly used satellite in 1995 had 24 transponders.to another, the most commonly used satellite in 1995 had 24 transponders.
Each can carry a colour TV signal (or 6 digitally compressed TV signals) orEach can carry a colour TV signal (or 6 digitally compressed TV signals) or
at least 1200 telephone voice signals in one direction. Each newat least 1200 telephone voice signals in one direction. Each new
generation of satellites tends to have increased communication capabilitygeneration of satellites tends to have increased communication capability
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3June 2008
Control SegmentControl Segment
Communications satellite operations are monitored from control rooms such as thisCommunications satellite operations are monitored from control rooms such as this
one, where minor orbit adjustments can be made and communications functions canone, where minor orbit adjustments can be made and communications functions can
be regularly checked. If problems occur, technicians can attempt repairs or transferbe regularly checked. If problems occur, technicians can attempt repairs or transfer
communications to a different satellitecommunications to a different satellite
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Link budget is actually the sum of all the losses between: Transmitter - Satellite &Link budget is actually the sum of all the losses between: Transmitter - Satellite &
back down to a Receiver.back down to a Receiver.
These losses are reduced by any gain you have at the transmitter, satellite orThese losses are reduced by any gain you have at the transmitter, satellite or
receiver. So in order to see if your signal is still going to be big enough to use after itreceiver. So in order to see if your signal is still going to be big enough to use after it
has been sent to a receiver via satellite, the gains and losses are effectively addedhas been sent to a receiver via satellite, the gains and losses are effectively added
together and the result will be the net gain or loss. A loss means your signal has gottogether and the result will be the net gain or loss. A loss means your signal has got
smaller, and a gain means it has got bigger.smaller, and a gain means it has got bigger.
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3June 2008
Satellite Link DesignSatellite Link Design
The four factors related to satellite system design:
– The weight of satellite
– The choice frequency band
– Atmospheric propagation effects
– Multiple access technique
The major frequency bands are 6/4 GHz, 14/11 GHz and 30/20 GHz
(Uplink/Downlink)
At geostationary orbit there is already satellites using both 6/4 and
14/11 GHz every 2° (minimum space to avoid interference from uplink
earth stations) -> Additional satellites higher BW
Low earth orbit (LEO) & medium earth orbit (MEO) satellite systems
are closer and produces stronger signals but earth terminals need omni
directional antennas
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Satellite Link DesignSatellite Link Design
Low earth orbit (LEO) & medium earth orbit (MEO) satellite systems
are closer and produces stronger signals but earth terminals need omni
directional antennas
The design of any satellite communication is based on
– Meeting of minimum C/N ratio for a specific percentage of time
– Carrying the maximum revenue earning traffic at minimum cost
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Link BudgetsLink Budgets
C/N ratio calculation is simplified by the use of link budgets
Evaluation the received power and noise power in radio link
The link budget must be calculated for individual
transponder and for each link
When a bent pipe transponder is used the uplink and down
link C/N rations must be combined to give an overall C/N
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Satellite Link Design –Satellite Link Design –
Downlink received PowerDownlink received Power
The calculation of carrier to noise ratio in a satellite link isThe calculation of carrier to noise ratio in a satellite link is
based on equations for received signal power Pbased on equations for received signal power Prr andand
receiver noise power:receiver noise power:
PPrr = EIRP + G= EIRP + Grr – L– Lpp – L– Laa – L– Ltata – L– Lrara dBW,dBW,
Where:Where:
EIRPEIRP = 10log= 10log1o1o (P(PttGGtt))
GGrr = 10log= 10log1010 (4(4ππAAee // λλ22
)dB)dB
PathLoss LPathLoss LPP = 10log= 10log1010 [(4[(4 ππAAee // λλ) 2] = 20log) 2] = 20log1o1o (4(4ππR/R/ λλ)dB)dB
LLaa = Attenuation in the atmosphere= Attenuation in the atmosphere
LLtata = Losses assosiated with transmitting antenna= Losses assosiated with transmitting antenna
L = Losses associated with receiving antenna
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Satellite Link Design –Satellite Link Design –
Downlink Noise PowerDownlink Noise Power
A receiving terminal with a system noise temperature
TsK and a noise bandwidth Bn Hz has a noise power Pn
referred to the output terminals of the antenna where
Pn = kTsBn watts
The receiving system noise power is usually written in
decibel units as:
N = k + Ts + Bn dBW,
where:
k is Boltzmann’s constant (-228.6 Dbw/K/Hz)
Ts is the sytem noise temperature in DBK
Bn is the noise Bandwidth of the receiver in dBHz
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3June 2008
Satellite Link Design – UplinkSatellite Link Design – Uplink
Uplink design is easier than the down link in many cases
– Earth station could use higher power tranmitters
Earth station transmitter power is set by the power level required at the
input to the transporter, either
– A specific flux density is required at the satellite
– A specific power level is required at the input to the transporter
Analysis of the uplink requires calculation of the power level at the
input to the transponder so that uplink C/N ratio can be found
With small-diameter earth stations, a higher power earth station
transmitter is required to achieve a similar satellite EIRP.
– Interference to other satellites rises due to wider beam of small
antenna
Uplink power control can be used to against uplink rain attenuation
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3June 2008
Propagation Effects & their ImpactPropagation Effects & their Impact
Many phenomena causes lead signal loss on through the earths
atmosphere:
– Atmospheric Absorption (gaseous effects)
– Cloud Attenuation (aerosolic and ice particles
– Tropospheric Scintillation (refractive effects)
– Faraday Rotation (an ionospheric effect)
– Ionospheric Scintillation (a second ionospheric effect)
– Rain attenuation
– Rain and Ice Crystal Depolarization
The rain attenuation is the most important for frequencies above 10 GHz
– Rain models are used to estimate the amount of degradation (or
fading) of the signal when passing through rain.
– Rain attenuation models: Crane 1982 & 1985; CCIR 1983; ITU-R
p,618-5(7&8)
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3June 2008
Recent Technical AdvancesRecent Technical Advances
Communications satellite systems have entered a period of transition
from point-to-point high-capacity trunk communications between large,
costly ground terminals to multipoint-to-multipoint communications
between small, low-cost stations.
With TDMA, each ground station is assigned a time slot on the same
channel for use in transmitting its communications; all other stations
monitor these slots and select the communications directed to them.
By amplifying a single carrier frequency in each satellite repeater,
TDMA ensures the most efficient use of the satellite's onboard power
supply.
A technique called frequency reuse allows satellites to communicate
with a number of ground stations using the same frequency by
transmitting in narrow beams pointed toward each of the stations.
Beam widths can be adjusted to cover areas as large as the entire
United States or as small as a state like Maryland.
Satellite antennas have been designed to transmit several beams in
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3June 2008
Case DVB-S – Broadcast SatellitesCase DVB-S – Broadcast Satellites
DVB-S (Digital Video Broadcasting
– Geosynchronous orbit
– DVB-S uses QPSK modulation
Satellite locations are specified as degree of longitude:
– ASTRA 1 = 6 satellites: 19.2°E
– Hot bird = 5 satellites: 13°E
– Thor: 0.8°W
DVB-S2 is a newer specification of the standard, ratified by ETSI in
March 2005
– Adaptive coding to optimize the use of satellite transponders
– 4 modulation modes: QPSK, 8PSK, (used in non-linear
transponders near to saturation); 16APSK and 32APSK
– Video codec has also been changed from MPEG-2 to H.264
(a.k.a) MPEG-4 Part 10)
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Case DVB-S – Error CorrectionCase DVB-S – Error Correction
• Figure 5 Error correction in DVB systems. At the receiving side in the typical bit error ratioFigure 5 Error correction in DVB systems. At the receiving side in the typical bit error ratio
after QPSK demodulation is 10after QPSK demodulation is 10-1-1
….. 10….. 10-2-2
, after inner decoding 10, after inner decoding 10-4-4
and after outer decoderand after outer decoder
1010-11-11
. [3] & [4]. [3] & [4]
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On Board Processor SubsystemOn Board Processor Subsystem
The next generation satellites extensively need to use On Board
Processors (OBP) to design cost effective system solution for the
customer needs. The OBP in satellites eliminates the inherent
disadvantages of the “Bent Pipe” transponders. The payloads either
employ partial or full on board processing depending upon the system
design requirements and cost. Full on board processing enables an ATM
like switching process in payloads. The partial processing on board is
used in “Digital Transponders”.
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On Board Processor SubsystemOn Board Processor Subsystem
Generally the processor in satellite provides the following on board
features and capabilities for system enhancements [5]:
– Full network connectivity (Mesh, Star)
– On board switching of signals, beams & coverage areas
– Simplified payloads with efficient use of TWTA/SSPA
– Efficient bandwidth and power level control (Automatic, Selectable)
– On orbit management of network traffic, capacity and QOS
– Flexible system integration, operation and tests
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Satellite System CoverageSatellite System Coverage
The types of network services, customer population and required
system performance, governs the design of satellite system
coverage. The satellite payloads are developed to provide the
services in Local, Regional and Global areas for transmission of
specific contents
Local Coverage
The local coverage contains transmissions in the selected areas
(City or country) to provide the local content delivery services to
meet the demand of customers located in the city. The antenna
spot beams in the satellite provide high gain directivity in specific
coverage areas. The beams are optimized for the maximum system
capacity and performance for local service contents.
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AMOS 3AMOS 3
Manufacturer : Israel Aircraft Industries (IAIManufacturer : Israel Aircraft Industries (IAI))
Orbital Location : 4 WestOrbital Location : 4 West
Launch Date : December 2007 (scheduledLaunch Date : December 2007 (scheduled))
Mission period : 12 yearsMission period : 12 years
##of transponders: 15of transponders: 15
Transponder BW : 72 MHZTransponder BW : 72 MHZ
Beams : ME, EU, US, SteerableBeams : ME, EU, US, Steerable
Frequency BandsFrequency Bands::
Ku band uplink : 14.00 to 14.50 GHZKu band uplink : 14.00 to 14.50 GHZ
Ku band downlink : 10.95 to 11.45 GHZKu band downlink : 10.95 to 11.45 GHZ
Ka band uplink : 29.40 to 30.60 GHZKa band uplink : 29.40 to 30.60 GHZ
Ka band downlink : 19.60 to 20.80 GHZKa band downlink : 19.60 to 20.80 GHZ
G/T at beam centerG/T at beam center::
ME - 15 dB/kME - 15 dB/k
EU - 14.5 dB/kEU - 14.5 dB/k
US - 9 dB/kUS - 9 dB/k
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Applications & ServicesApplications & Services
• Commercial satellites provide a wide range of communicationsCommercial satellites provide a wide range of communications
services. Television programs are relayed internationally, giving rise toservices. Television programs are relayed internationally, giving rise to
the phenomenon known as the “global village.” Satellites also relaythe phenomenon known as the “global village.” Satellites also relay
programs to cable television systems as well as to homes equippedprograms to cable television systems as well as to homes equipped
with dish antennas. In addition, very small aperture terminals (VSATs)with dish antennas. In addition, very small aperture terminals (VSATs)
relay digital data for a multitude of business services.relay digital data for a multitude of business services. IntelsatIntelsat satellitessatellites
now carry over 100,000 telephone circuits, with growing use of digitalnow carry over 100,000 telephone circuits, with growing use of digital
transmission. Digital source coding methods (transmission. Digital source coding methods (seesee
TelecommunicationsTelecommunications) have resulted in a ten-fold reduction in the) have resulted in a ten-fold reduction in the
transmission rate needed to carry a voice channel, thus enhancing thetransmission rate needed to carry a voice channel, thus enhancing the
capacity of existing facilities and reducing the size of ground stationscapacity of existing facilities and reducing the size of ground stations
that provide telephone service.that provide telephone service.
• The International Mobile Satellite Organization (INMARSAT), foundedThe International Mobile Satellite Organization (INMARSAT), founded
in 1979 as the International Maritime Satellite Organization, is a mobilein 1979 as the International Maritime Satellite Organization, is a mobile
telecommunications network, providing digital data links, telephone,telecommunications network, providing digital data links, telephone,
andand facsimile transmissionfacsimile transmission, or fax, service between ships, offshore, or fax, service between ships, offshore
facilities, and shore-based stations throughout the world. It is also nowfacilities, and shore-based stations throughout the world. It is also now
extending satellite links for voice and fax transmission to aircraft onextending satellite links for voice and fax transmission to aircraft on
international routes.international routes.
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• A group of satellites working in concert thus is known as aA group of satellites working in concert thus is known as a
satellite constellation. Two such constellations which weresatellite constellation. Two such constellations which were
intended for provision for satellite phone services, primarilyintended for provision for satellite phone services, primarily
to remote areas, were the Iridium and Globalstar. Theto remote areas, were the Iridium and Globalstar. The
Iridium system has 66 satellites. Another LEO satelliteIridium system has 66 satellites. Another LEO satellite
constellation known as Teledesic, with backing fromconstellation known as Teledesic, with backing from
Microsoft entrepreneur Paul Allen, was to have over 840Microsoft entrepreneur Paul Allen, was to have over 840
satellites. This was later scaled back to 288 and ultimatelysatellites. This was later scaled back to 288 and ultimately
ended up only launching one test satelliteended up only launching one test satellite
• The GPS system….The GPS system….
Satellite ConstellationSatellite Constellation
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• Global Positioning System (GPS) satellites orbit high aboveGlobal Positioning System (GPS) satellites orbit high above
the surface of Earth at precise locations. They allow a userthe surface of Earth at precise locations. They allow a user
with a GPS receiver to determine latitude, longitude, andwith a GPS receiver to determine latitude, longitude, and
altitude. The receiver measures the time it takes for signalsaltitude. The receiver measures the time it takes for signals
sent from the different satellites (A, B, and C) to reach thesent from the different satellites (A, B, and C) to reach the
receiver. From this data, the receiver triangulates an exactreceiver. From this data, the receiver triangulates an exact
position. At any given time there are multiple satellites withinposition. At any given time there are multiple satellites within
the range of any location on Earth. Three satellites arethe range of any location on Earth. Three satellites are
needed to determine latitude and longitude, while a fourthneeded to determine latitude and longitude, while a fourth
satellite (D) is necessary to determine altitudesatellite (D) is necessary to determine altitude
The GPS System (contThe GPS System (cont((
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The satellites orbit the earth with a speed of 3.9 km per second and have a
circulation time of 12 h sidereal time, corresponding to 11 h 58 min earth
time. This means that the same satellite reaches a certain position about 4
minutes earlier each day. The mean distance from the middle of the earth is
26560 km. With a mean earth radius of 6360 km, the height of the orbits is
then about 20200 km. Orbits in this height are referred to as MEO –
medium earth orbit.
The satellites are arranged on 6 planes, each of them containing at least 4
slots where satellites can be arranged equidistantly. Today, typically more
than 24 satellites orbit the earth, improving the availability of the system.
The number and constellation of satellites guarantees that the signals of at
least four satellites can be received at any time all over the world
The GPS System (contThe GPS System (cont((
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3June 2008
AmerHis – A New Era in SatelliteAmerHis – A New Era in Satellite
CommunicationsCommunications
AmerHis is an advanced communications system, based around the Alcatel
9343 DVB On-Board Processor, carried by Hispasat’s Amazonas satellite.
This processor has the capacity to provide the demodulation, decoding,
switching, encoding and modulation for the four transponders on
Amazonas. Each Ku-band transponder covers one of the four geographical
regions served by the satellite, namely: Europe, Brazil and North and South
America, as shown in Figure 2.
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3June 2008
System ConfigurationSystem Configuration
The initial terrestrial system configuration will include:
A Management System (MS), consisting of a Network Control Centre
(NCC) and associated management control, responsible for managing
the onboard resources and user terminals.
User Terminals (RCTs) oriented towards the commercial demonstration
of new services.
Gateways (RSGWs) that will provide the system with access to
terrestrial networks.
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3June 2008
Figure 4 – AmerHis provides
connectivity between spot-beam
coverage areas without the need
for double hops between ground
and spacecraft
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3June 2008
The combination of onboard
processing (OBP) and a full
compatibility with the open
standards of DVB-S (downlink)
and DVB-RCS (uplink) gives the
telecommunications satellite
unprecedented potential
compared with the conventional
bent-pipe architectures. The
AmerHis system
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3June 2008
OBP AdvantagesOBP Advantages
Provision of direct “end-to-end” connectivity between any two users in
different regions through a single satellite hop. This allows real-time
voice and video services, as well reducing bandwidth usage.
Full flexibility both for the interconnection of coverage areas and
payload-capacity management, allowing optimum exploitation of
available onboard resources (so-called dynamic bandwidth on
demand). The system supports predictable symmetric (up-and
downlink) traffic, as well as bursty traffic generated by a large number
of uses, owing to the dynamic resource a location process.
The regenerative nature of this AmerHis payload and the utilization of
DVB-S saturated carriers on each downlink provide substantial
performance improvements when using the AmerHis enabled
transponders. These improvements are reflected both in their
enhanced throughput capacity and the reduced receive-antenna size
requirements for users.
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3June 2008
Applications/ ServicesApplications/ Services
AmerHis is a win-win solution for Interactive
Network Access Providers (INAPs) service
providers and customers. The much greater
flexibility for managing and selling capacity is such
that all of the main players will benefit from this
advanced technology. Real and non-real time
multimedia services and applications can be
provided on readily available DVB-S/DVB-RCS
compatible terminals. The system permits the
assignment of resources to different sub-networks
in a very flexible manner and allows user
transmission rates ranging from 512 kbit/s to 8
Mbit/sec. The system supports IP-based as well as
native MPEG-based services, with efficient
mechanisms for the provision of uni-and multi-cast
services, and the possibility to define various
quality-of-service (QoS) levels to meet differing
user needs.
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Applications/ ServicesApplications/ Services
Video ServicesVideo Services
The AmerHis payload offers multiplexing and de-multiplexing of MPEG-2
transport streams and is therefore not only capable of offering IP
services over MPEG-2, but also allows the routing of video. Contribution
links can be made from different uplink stations and, depending on the
onboard switch configuration, duplicated and sent to multiple
destinations if necessary, using the DVB-S standard for Direct-to-Home
(DTH) services. Business television services, occasional-use services
and video contributions with smaller terminals can all be supported more
easily by exploiting these capabilities.
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System ElementsSystem Elements
Space Segment – The regenerative payloadSpace Segment – The regenerative payload
The AmerHis payload is a novel set of On-Board Processing (OBP)
technologies which is being flown on the Amazonas satellite for the first
time. The key feature of AmerHis is that the payload is regenerative and
provides unique connectivity possibilities via its switchboard in the sky’
functionality.
A redundancy ring allows switching between transparent and
regenerative modes with the four DVB transponders.
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The uplink format to the OBP is MF-TDMA
according to the DVB-RCS standard
(MPEG-2 option) with a granularity of up to
64 carriers per transponder (0.5 Mbps
each). Data rates of 0.5, 1, 2, 4 & 8 Mbps
are combinable in the same transponder.
The coding scheme is Turbo Code with a ¾
or 4/5 coding rate.
The down-link format is according to the
DVB-S standard with a maximum data rate
of 54 Mbps (per transponder). The Forward
Error Correction (FEC) uses Reed-Solomon
and convolutional coding with ratios of ½,
2/3, ¾, 5/6, or 7/8.
