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Satellite Communications
Introduction
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Ir. Dr. Chan Yee Kit
R4011
[email protected]
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History
Late 19th
century, Marconi demonstratedfeasibility of wireless
communications. WWII 1startificial satellite, SPUTNIK (1957)
Reflecting Satellite, ECHO
(1960) Store and Forward Satellite, COURIER (1960) Active Relay
Satellite, TELSTAR (1962) 1stGeostationary Satellite, SYNCOM
(1963)
1st
Commercial Geostationary Satellite,INTELSAT-1 (1965)
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Satellite Evolution
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Satellite Communications
Space Segment
Earth Segment
Control Segment
Uplink Downlink
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Satellite acts as relay station in space
Signals are transmitted from earth to satellite uplink.Processed
on board the satellite, then transmitted backto earth downlink.
Uplink Downlink
Satellite Communications
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Applications
Easy deployment of receiving stations,particularly at rural
areas with no access toterrestrial systems.
Broadcast / point to multipoint services.
For communication with ships and planes.
Position location and navigation.
Telecommunication applications telephone,
data transfer, etc.
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Architecture of SatelliteCommunication System
Divided into two segment:
Space Segment
Satellite
Control Station Ground Segment
Earth Station
Space Segment
Earth Segment
Control Station
Uplink Downlink
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Satellite Payload: equipment which
provide service(transponder)
RX & TX, antenna,equipment that supporttransmission of
carriers &information
Transparent/Regenerative
Platform (bus) Subsystem for payload tooperate
Space Segment
Control Station
Space Segment - 1
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Satellite Platform
Subsystem Function
Attitude and orbit control Attitude stabilisation;
orbitdetermination
Propulsion Provision of velocity increments
Electric power supply Provision of electrical energy
Telemetry, tracking andcommand
Exchange of housekeepinginformation
Thermal control Temperature maintenance
Structure Equipment support
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Terrestrial facilities for control and monitoring ofthe
satellite: Tracking, telemetry and command station (TT&C)
Satellite Control Center
Station Keeping Check vital function of the satellite
Space Segment
Control Station
Space Segment - 2
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Earth Stations TX earth station, RX earth station, TX-RX earth
station Distinguished by size and type of traffic.
Ground Segment
Ground Segment
Uplink Downlink
Tx Rx
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Radio Regulations
International Telecommunication Union(ITU) as international
radio regulator.
ITU publishes Radio Regulations
World/Regional Radio Conference Master International Frequency
Register
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Services
Fixed Satellite Service (FSS) Mobile Satellite Service (MSS)
Broadcast Satellite Service (BSS)
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FSS
(Richharia, Fig. 1.1)
The FSS applies to systems, which interconnect fixedpoints such
as international telephone exchanges.
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MSS
(Richharia, Fig. 1.3)
The MSS networks provide communication to mobileterminals and
individuals.
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BSS
(Richharia, Fig. 1.4)
The BSS refers to broadcasts by satellite of TV or radioprograms
directly to the public.
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Frequency Allocation
Selection of the operational frequency of the satellite
radiolink is an important issue in a link design. Radio signals
suffer minimum degradation while propagating
through the intervening medium. Degradations includeattenuation,
scintillation, noise contamination, etc.
Other important considerations include the need to comply with
the radio regulations to ensure
coexistence of the various systems and to maximize utilization
ofthe limited RF spectrum resource
economic considerations which are related to the state of
the
technology the availability of the desired bandwidth in the
preferred
frequency band.
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Frequency Allocation
(Malaysian Spectrum Plan, pp. 5)
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Frequency Allocation - 2
Exclusive vs. Shared Primary vs. Secondary
Footnote Allocation
Planned Allocation
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Frequency Allocation - 3
Services Uplink/Downlink UsualTerminology
MSS 1.6/1.5 GHz L band
2/2.2 GHz, 2.6/2.5 GHz S band
FSS 6/4 GHz C band
FSS 8/7 GHz X band
FSS/BSS 14/12 GHz Ku bandFSS/MSS 30/20 GHz Ka band
50/40 GHz V band
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General Procedures
Allocate frequency band based on ITU RadioRegulations, taking
into account the technicaland economic factors.
Resolve internal interference issues.
Notify ITU about the planned system. ITU notifies its members
about the new
system.
Resolve interference issues at the
international level. Notify ITU when coordination completed.
