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Florida Institute of technologies
ECE 5233 Satellite Communications
Prepared by:
Dr. Ivica Kostanic
Lecture 1: Introduction to Satellite Systems
(Sections 1.1-1.4)
Spring 2014
Florida Institute of technologies
Page 2
Class overview
Configuration of a satellite systems
Elements of a satellite system
Types of satellite systems
Brief history of satellite communication
Outline
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Satellite communication system
Satellite system consists of
o Earth segment (traffic and control)
o Space segment
Earth segment
o Service provider hub (ground)
o User terminals
Space segment
o Satellite (s)
o Communication links to and from satellites
Page 3
1. Data center of the sat-com provider
2. Central hub (receives data stream and sends it toward satellite)
3. Satellite (receives data stream, amplifies and sends it back towards ground)
4. End user antenna – critical part (small size, high performance)
5. Modem – receives data stream
6. User end network – usually IP network
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Ground segment
Consists of earth stations
Satellite network may have one or more earth stations
Earth station may be transmit-receive or receive only
Earth stations are connected to terrestrial networks (PSTN for CS traffic or Internet for PS)
Usually have very large antennas (up to 30m in diameter)
Earth stations have high quality and redundant links to terrestrial networks
Page 4
Functional block diagram of an earth station
Example of a Ku band earth station antenna
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Space segment
Satellite consist ofo Payload – used in communication
o Platform – facilitates operation of payload
Payloado Receive antenna
o Electronics for communication
o Transmit antenna
Two types of satelliteso “Bent pipes” (transparent)
o Regenerative (base band processing)
Smallest assignable recourseo Satellite transponder
o Satellite usually hosts multiple transponders
o Satellite usually operates in single band (although there are some multiband satellites)
Transmit antenna may be o Single beam – one area of the Earth
o Multi beam – multiple areas of the Earth
Page 5
Basics of “bent pipe” architecture
Satellite with onboard processing
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End user segment
User stations
o Mobile stations (mobile terminals)
o VSAT terminals
o Gateways (connect space segment to terrestrial networks)
User equipment may
o Connect to user stations Example: Satellite TV
o Integrate with user stations Example: Satellite phone
Heavily dependent on the end application
Page 6
Globstar satellite phones
Marine satellite antennas Satellite on the moveSatellite TV equipment
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Types of satellite orbits
Orbit height
o Low Earth Orbit (LEO) Attitude 160-2,000km
Satellite speed ~ 8km/sec
Orbital period ~ 90 min
Example: Globstar, 48 satellites in six planes, 1413km
o Medium Earth Orbit (MEO) Altitude 2,000km -35,786km
Satellite speed 8km/sec to 3 km/sec
Orbital period 2 to 24h
Example: GPS, 24 satellites in 6 planes, 20,200km
o Geosynchronous orbit (GSO) Altitude 35,768km
Satellite speed ~ 3km/sec
Non zero inclination
Orbital period 24 hours
o Geostationary orbit (GEO) GSO satellite in zero inclination orbit
Page 7
Constellation of Globstar system
Constellation of GPS system
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Satellite services
Fixed satellite services (FSS)o PTP or PTMP delivery of signal across the
Globe
Mobile satellite services (MSS)o Delivery of satellite signal to mobile platforms
(either terrestrial, marine or aeronautical)
Broadcast satellite services (BSS)o Broadcast of satellite signal (TV, radio)
Navigation satellite services (NAV)
Earth exploration services (ESS)
Space research services (SRS)
Space operations services (SOS)
Radio determination satellite services (RSS)
Inter-satellite services (ISS)
Page 8
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Frequency bands used for sat-comm
Satellites operate in microwave frequency range Two links
o Uplink – ground to satelliteo Downlink – satellite to ground
Each link uses its own band Uplink operates on higher frequency Microwave frequency bands
o L band: 1-2GHzo S band: 2-4GHzo C band: 4-8GHzo X band: 8-12GHzo Ku band: 12-18GHzo K band: 18-26.5GHzo Ka band: 26.5-40GHz
Majority of existing systems operate in C and Ku Higher frequencies
o More available spectrumo Better antenna directivityo Higher propagation losseso More sophisticated technology
Page 9Frequency chart for communication
satellite services
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Frequency management
Responsibility of International Telecommunication Union ITU
Insures:o Non-interference condition between different
satellite systems
o Fairness between nations in access to the satellite frequencies
Frequency allocation may be o exclusive for given service
o shared between services
Service provisioning usually requires consent of all countries within coverage area of the satellite
Frequency is usually allocated in pairso One frequency for UL
o One frequency for DL
UL frequency is higher
Page 10
ITU Regions
Example: VIASAT license in Ka band as of 2010
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Beginnings of satellite communication
Origins: Arthur Clarke’s article in Wireless World in 1945
WW-II stimulated development of two key technologieso Microwave communication
o Missile technology
First satellite launched in 1957 by USSR o Sputnik, 83.6kg, LEO, atmospheric studies
o Mission duration 3 months
First commercial communication satellite 1967o Intelsat I - EarlyBird, 34.5kg, GEO, communication satellite
o Coverage between US and Europe
o Operated 4 years (deactivated in 1969)
o Launched from KSC
o Could handle 240 voice and 1 TV channel
o Owned by Intelsat (52 countries)
Page 11
Sputnik 1
Intelsat- EarlyBird
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Development of satellite communication
Imagination (1945-1960)o Early days of extensive scientific research
o “Dreaming” of what is possible
Innovation (1960-1970)o Establishment of governmental space exploration
agencies and international satellite consortia
o Development of communication and rocket technology
o First launches
Commercialization (1970-1980)o Satellite communication becomes commercial technology
o Applications: cross continental telephony and satellite TV
Liberalization (1980-1990)o Transformation of international governmental consortia
o Market led approach allowed private investments
o Regulatory framework changes that allowed all of the transformations to take place
Privatization and private ventures (1990 – on)o Communication satellites become mainstream technology led
by private business
o Leading applications: broadcast TV, data backhaul, mobile communications in the air and on the sea, navigation, etc.
o Future – integration of satellite technology with Internet
Page 12
Satellite applications (values in B$)
History channel documentary: Satellites – how they work
https://www.youtube.com/watch?v=eYUxkSFCKZQ
