Satellite Communication Systems

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Satellite Communication Systems
Satellite
Communication Systems
mgr inż. Krzysztof Włostowski
Instytut Telekomunikacji PW
[email protected]
Satellite Communication
Satellite Communication combines the missile
and microwave technologies
The space era started in 1957 with the
launching of the first artificial satellite
(sputnik)
Electronics and Information Technology
Advantages of Satellite Communication
LARGE CAPACITY
One satellite = 10 transponders = 10x120 Mbit/s
Total transmission capacity = 1 Gbit/s
DISTANCE INSENSITIVE COST
WIDEBAND SERVICE
allows for transmission of:
- TV
- high bit date rate
BROADCAST TRANSMISSION CAPABILITY:
allows for point to multipoint distribution of information
Electronics and Information Technology
History of satellite communication
1957
1963
1965
1976
1982
first satellite SPUTNIK: 85 kg in Earth orbit
first geostationary satellite SYNCOM
first commercial geostationary satellite Satellit „Early
Bird“ (INTELSAT I): 240 duplex telephone channels l
three MARISAT satellites for maritime communication
first mobile satellite telephone system INMARSAT-A
(starts fully operational GEO global systems, for mobile maritime service)
1988
First Land Mobile Satellite System
OMNITRACS starts to provide in North America land mobile satellite
messaging and localization services
1991
ITALSAT (Italy)
The first satellite with on board processing and multibeam coverage
1993
1999
first digital satellite telephone system
global satellite systems for small mobile phones
Electronics and Information Technology
Satellite Communication
Major Organisations:
• INTELSAT(1964),
global (about 140 countries),
INTELSAT
FSS and BSS systems
• EUTELSAT (1977) 47 countries (Europe and former USSR countries),
FSS and BSS systems
• INMARSAT (1979) global, mobile systems
• SES Astra (1988) private, DTH-TV
Electronics and Information Technology
Satellite Orbits
LEO
GEO
MEO
LEO:
MEO:
GEO:
500 - 1500 km
5,000 - 15,000 km
35,786 km
Electronics and Information Technology
LEO: Low Earth Obit
MEO: Medium Earth Orbit
GEO: Geostationary Earth Orbit
Satellite Orbits
GEO
advantages:
- the satellite appears to be fixed (immovable) when viewed from the Earth,
no tracking required for earth station antennas
- about. 40% of the earth`s surface is in view from the satellite
disadvantages:
- high attenuation level (power loss) (200dB) on the path
- large signal delay (238-284ms)
- polar regions (latitudes > 81 deg.) are not covered
LEO
advantages:
- much smaller attenuation compare GEO satellites
- low signal delay
disadvantages:
- short period satellite visibility (through earth station),
many times during the day
- Doppler effect
- many satellites are required for establishing continuous transmission
Electronics and Information Technology
Frequency Bands
Uplink
(GHz)
Downlink
(GHz)
C
X
Ku
5,925-6,425
7,900-8,400
14,000-14,500
Ka
27,500-30,000
3,700-4,200
7,250-7,750
10,950-11,200
11,450-11,700
17,700-20,200
L
1,6265-1,6605
1,530-1,559
Band
FSS transponders: Typical values
Bandwidth: 36 to 72 MHz
EIRP 30 to 52 dBW
Electronics and Information Technology
6/4
8/7
14/11
30/20
mobile
Space segment
PAYLOAD FUNCTIONS:
collect microwave signals from given zone of earth
amplify radiofrequency carrier
convert carrier frequency fro uplink to downlink frequency
transmit microwave signals to given zone of earth
Electronics and Information Technology
Satellite characteristics
•
•
Transponder frequency and bandwidth
G/T (dB/K) in each point of satellite reception
coverage
•
EIRP (dBW) Effective Isotropic Radiated Power.
It is satellite PTGT product.
•
Transponder operation point. It works in saturation in
order to use all available power
Electronics and Information Technology
Satellite Transponder
C - band transponder
14 GHz
12 GHz
Amp
Amp
Receiving
Antenna
Mixer
Mixer
Local
Local
Oscillator
Oscillator
Uplink
Electronics and Information Technology
Amp
Amp
Transmitting
Antenna
Downlink
Satellite Services
FSS Fixed Satellite Services (VSAT
networks,..)
MSS Mobile Satellite Services (Inmarsat
systems,...)
BSS Broadcasting Satellite Services ( TV,
DVB..)
RDSS Radiodetermination Satellite Services
(GPS)
Electronics and Information Technology
Applications
Traditionally
• radio and TV broadcast satellites
• military satellites
• navigation and localization (GPS)
• weather satellites
Telecommunication
• global telephone connections
• backbone for global networks
• connections for communication in remote
places or underdeveloped areas
• global mobile communication
Electronics and Information Technology

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