Presented By
Mr. Shaik Ahemedali
Assistant Professor
Department of ECE
To know about the major concepts of satellite
communications, orbital mechanics and launching
vehicles.
To know about the various satellite subsystems and
satellite links design.
To know about the modulation techniques to establish
communication link.
To know about the satellite stations and navigation
system.
What is satellite?
What is satellite communication?
Satellite Architecture.
Elements for satellite communication.
Orbits for satellite communication.
Evolution of satellite communication.
Services of satellite communication.
Frequency Bands and Beams.
Advantages of satellite communication.
Applications of satellite communication.
The future of satellite communication.
Conclusion
An artificial body placed in orbit around the earth to
collect information or for communication.
How Is a Satellite Launched into an Orbit?
All satellites today get into orbit by riding on a rocket.
Astronautics
Pioneers in Satellite Communication
Konstantin Tsiolkovsky (1857 - 1935)
Russian visionary of space flight First described the multi-stage rocket as
means of achieving orbit.
Hermann Noordung (1892 - 1929)
Postulated the geostationary orbit.
Arthur C. Clarke (1917 19 March 2008)
Postulated the entire concept of international satellite telecommunications
from geostationary satellite orbit including coverage, power, services,
solar eclipse.
"Wireless World" (1945)
Satellite History Calendar
1957
October 4, 1957: - First satellite - the Russian Sputnik 01
First living creature in space: Sputnik 02
1958
First American satellite: Explorer 01
First telecommunication satellite: This satellite broadcast a taped message: Score
1959
First meteorology satellite: Explorer 07
1960
First successful passive satellite: Echo 1
First successful active satellite: Courier 1B
First NASA satellite: Explorer 08
April 12, 1961: - First man in space
1962
First telephone communication & TV broadcast via satellite: Echo 1
First telecommunication satellite, first real-time active, AT&T: Telstar 1
First Canadian satellite: Alouette 1
On 7
th
June 1962 at 7:53p the two-stage rocket; Rehbar-I was successfully launched from
Sonmiani Rocket Range. It carried a payload of 80 pounds of sodium and soared to about 130
km into the atmosphere. With the launching of Rehbar-I, Pakistan had the honour of
becoming the third country in Asia and the tenth in the world to conduct such a launching
after USA, USSR, UK, France, Sweden, Italy, Canada, Japan and Israel.
Rehbar-II followed a successful launch on 9
th
June 1962
1963
Real-time active: Telstar 2
1964
Creation of Intelsat
First geostationary satellite, second satellite in stationary orbit: Syncom 3
First Italian satellite: San Marco 1
Satellite History Calendar
1965
Intelsat 1 becomes first commercial comsat: Early Bird
First real-time active for USSR: Molniya 1A
1967
First geostationary meteorology payload: ATS 3
1968
First European satellite: ESRO 2B
July 21, 1969: - First man on the moon
1970
First Japanese satellite: Ohsumi
First Chinese satellite: Dong Fang Hong 01
1971
First UK launched satellite: Prospero
ITU-WARC for Space Telecommunications
INTELSAT IV Launched
INTERSPUTNIK - Soviet Union equivalent of INTELSAT formed
1974
First direct broadcasting satellite: ATS 6
1976
MARISAT - First civil maritime communications satellite service started
1977
EUTELSAT - European regional satellite
ITU-WARC for Space Telecommunications in the Satellite Service
1979
Creation of Inmarsat
Satellite History Calendar
1980
INTELSAT V launched - 3 axis stabilized satellite built by Ford Aerospace
1983
ECS (EUTELSAT 1) launched - built by European consortium supervised by ESA
1984
UK's UNISAT TV DBS satellite project abandoned
First satellite repaired in orbit by the shuttle: SMM
1985
First Brazilian satellite: Brazilsat A1
First Mexican satellite: Morelos 1
1988
First Luxemburg satellite: Astra 1A
1989
INTELSAT VI - one of the last big "spinners" built by Hughes
Creation of Panamsat - Begins Service
On 16 July 1990, Pakistan launched its first experimental satellite, BADR-I from China
1990
IRIDIUM, TRITIUM, ODYSSEY and GLOBALSTAR S-PCN projects proposed - CDMA designs
more popular
EUTELSAT II
1992
OLYMPUS finally launched - large European development satellite with Ka-band, DBTV and Ku-
band SS/TDMA payloads - fails within 3 years
1993
INMARSAT II - 39 dBW EIRP global beam mobile satellite - built by Hughes/British Aerospace
1994
INTELSAT VIII launched - first INTELSAT satellite built to a contractor's design
Hughes describe SPACEWAY design
DirecTV begins Direct Broadcast to Home
1995
Panamsat - First private company to provide global satellite services.
Satellite History Calendar
1996
INMARSAT III launched - first of the multibeam mobile satellites (built by GE/Marconi)
Echostar begins Diresct Broadcast Service
1997
IRIDIUM launches first test satellites
ITU-WRC'97
1999
AceS launch first of the L-band MSS Super-GSOs - built by Lockheed Martin
Iridium Bankruptcy - the first major failure?
2000
Globalstar begins service
Thuraya launch L-band MSS Super-GSO
2001
XM Satellite Radio begins service
Pakistans 2
nd
Satellite, BADR-B was launched on 10 Dec 2001 at 9:15a from Baikonour
Cosmodrome, Kazakistan
2002
Sirius Satellite Radio begins service
Paksat-1, was deployed at 38 degrees E orbital slot in December 2002, Paksat-1, was
deployed at 38 degrees E orbital slot in December 2002
2004
Teledesic network planned to start operation
2005
Intelsat and Panamsat Merge
VUSat OSCAR-52 (HAMSAT) Launched
2006
CubeSat-OSCAR 56 (Cute-1.7) Launched
K7RR-Sat launched by California Politechnic University
2007
Prism was launched by University of Tokyo
2008
COMPASS-1; a project of Aachen University was launched from Satish Dawan Space Center,
India. It failed to achieve orbit.
Whose Satellite Was the First to Orbit
Earth?
The Soviet Sputnik satellite was the first to orbit
Earth, launched on Oct. 4, 1957.
Sputnik 1, the first satellite, shown with four whip antennas
Sputnik 2 - Mission
Some scientists believed humans would be unable to
survive the launch or the conditions of outer space, so
engineers viewed flights by non-human animals as a
necessary precursor to human missions.
Laika was a Soviet space dog that became the first
animal to orbit the Earth as well as the first animal
to die in orbit.
Manned spacecraft
On 12 April 1961, aboard the Vostok 1, Yuri Gagarin
became both the first human to travel into space, and
the first to orbit the earth.
INDIAN SATELLITE
IN July 18, 1980,
India launched the satellite Rohini 1
on an Satellite Launch Vehicle (SLV) rocket from the Sriharikota Island launch site
A communications satellite is a radio relay station in
orbit above the earth. (or) A communication satellite is
a microwave repeater station in space that is used for
telecommunication , radio and television signals.
It receives, amplifies, and redirects analog and digital
signals carried on a specific radio frequency.
Introduction to Satellite Communications
A communications satellite is an orbiting artificial earth satellite that
receives a communications signal from a transmitting ground station,
amplifies and possibly processes it, then transmits it back to the earth
for reception by one or more receiving ground stations.
Communications information neither originates nor terminates at the
satellite itself. The satellite is an active transmission relay, similar in
function to relay towers used in terrestrial microwave
communications.
The commercial satellite communications industry has its beginnings
in the mid-1960s, and in less than 50 years has progressed from an
alternative exotic technology to a mainstream transmission
technology, which is pervasive in all elements of the global
telecommunications infrastructure. Todays communications satellites
offer extensive capabilities in applications involving data, voice, and
video, with services provided to fixed, broadcast, mobile, personal
communications, and private networks users.
Satellite communications play a vital role in the global
telecommunications system.
Two major elements of Satellite Communications
Systems are:
Space Segment
Ground Segment
Satellite-Related Terms
Earth Stations antenna systems on or near earth
Uplink transmission from an earth station to a satellite
Downlink transmission from a satellite to an earth
station
Transponder In a communications satellite, a
transponder gathers signals over a range of uplink
frequencies and re-transmits them on a different set of
downlink frequencies to receivers on Earth, often
without changing the content of the received signal or
signals.
Space Segment includes:
Satellite
Means for launching satellite
Electrical Power System
Mechanical structure
Communication transponders
Communication Antennas
Attitude and orbit control
system
The ground segment consists of:
Earth Stations
Rear Ward Communication links
User terminals and interfaces
Network control Centre
Transmit equipment.
Receive equipment.
Antenna system.
Satellite Control Centre function:
Tracking of the satellite
Receiving data
Eclipse management of satellite
Commanding the Satellite for station
keeping.
Determining Orbital parameters from
Tracking and Ranging data
Switching ON/OFF of different subsystems
as per the operational requirements
During early 1950s, both passive and active satellites were
considered for the purpose of communications over a large
distance.
Passive satellites though successfully used in the early years
of satellite communications, with the advancement in
technology active satellites have completely replaced the
passive satellites.
Passive Satellites
A satellite that only reflects signals from one Earth
station to another, or from several Earth stations to
several others.
It reflect the incident electromagnetic radiation
without any modification or amplification.
It can't generate power, they simply reflect the incident
power.
Passive Satellites
The first artificial passive satellite Echo-I of NASA
was launched in August 1960.
Disadvantages
Earth Stations required high power to transmit signals.
Large Earth Stations with tracking facilities were expensive.
A global system would have required a large number of
passive satellites accessed randomly by different users.
Control of satellites not possible from ground.
The large attenuation of the signal while traveling the large
distance between the transmitter and the receiver via the
satellite was one of the most serious problems.
Active Satellites
In active satellites, it amplify or modify and retransmit the signal
from the earth.
Satellites which can transmit power are called active satellite.
Have several advantages over the passive satellites.
Require lower power earth station.
Less costly.
Not open to random use.
Directly controlled by operators from ground.
Active Satellites
Disadvantages
Requirement of larger and powerful rockets to
launch heavier satellites in orbit.
Requirement of on-board power supply.
Interruption of service due to failure of electronics
components
Satellite orbits
Orbit
The path a Satellite follows around a planet is defined
as an orbit.
Satellite Orbits are classified in two broad categories :
Non-Geostationary Orbit (NGSO)
Geo Stationary Orbit (GSO)
Early ventures with satellite communications used satellites in Non-
geostationary low earth orbits due to the technical limitations of the launch
vehicles in placing satellites in higher orbits.
( )
Complex problem of transferring signal from one satellite to another.
Less expected life of satellites at NGSO
Requires frequent replacement of satellites compared to satellite in GSO.
Disadvantages of NGSO
There is only one geostationary
orbit possible around the earth
Lying on the earths equatorial
plane.
The satellite orbiting at the same
speed as the rotational speed of
the earth on its axis.
Advantages:
Simple ground station tracking.
Nearly constant range
Very small frequency shift
Disadvantages:
Transmission delay of the order of 250 msec.
Large free space loss
No polar coverage
Satellite orbits in terms of the
orbital height:
According to distance from earth:
Geosynchronous Earth Orbit (GEO)
Medium Earth Orbit (MEO)
Low Earth Orbit (LEO)
GEO: 35,786 km above the earth
Geostationary Earth Orbit (GEO)
From the ground level the satellite appears fixed.
These satellites are in orbit 35,786 km above the earths
surface along the equator.
Objects in Geostationary orbit revolve around the earth at
the same speed as the earth rotates. This means GEO
satellites remain in the same position relative to the surface
of earth.
A GEO satellites distance from earth gives it a large
coverage area, almost a fourth of the earths surface.
GEO satellites have a 24 hour view of a particular
area.
These factors make it ideal for satellite broadcast
and other multipoint applications
Minimal doppler shift
A GEO satellites distance also cause it to have both
a comparatively weak signal and a time delay in the
signal, which is bad for point to point
communication.
GEO satellites, centered above the equator, have
difficulty for broadcasting signals to near polar
regions
Launching of satellites to orbit are complex and
expensive
Geostationary Communication Satellites in Orbit Today
MEO: 8,000-20,000 km above the earth
A MEO satellite is in orbit somewhere between
8,000 km and 20,000 km above the earths surface.
MEO satellites are similar to LEO satellites in
functionality.
MEO satellites are visible for much longer periods of
time than LEO satellites, usually between 2 to 8
hours.
MEO satellites have a larger coverage area than
LEO satellites.
A MEO satellites longer duration of visibility and wider
footprint means fewer satellites are needed in a MEO
network than a LEO network.
A MEO satellites distance gives it a longer time delay
and weaker signal than a LEO satellite, though not as
bad as a GEO satellite.
The GPS constellation calls for 24 satellites to be
distributed equally among six circular orbital planes
LEO: 500-2,000 km above the
earth
LEO satellites are much closer to the earth than
GEO satellites, ranging from 500 to 2000 km above
the surface.
LEO satellites dont stay in fixed position relative to
the surface, and are only visible for 15 to 20 minutes
each pass.
A network of LEO satellites is necessary for LEO
satellites to be useful
LEO Satellite Coverage
The Iridium system has 66 satellites in six LEO orbits,
each at an altitude of 750 km.
Iridium is designed to provide direct worldwide voice and
data communication using handheld terminals, a service
similar to cellular telephony but on a global scale
A LEO satellites proximity to earth compared to a
GEO satellite gives it a better signal strength and less
of a time delay, which makes it better for point to point
communication.
A LEO satellites smaller area of coverage is less of a
waste of bandwidth.
A network of LEO satellites is needed, which can be
costly
LEO satellites have to compensate for Doppler shifts
cause by their relative movement.
Atmospheric drag effects LEO satellites, causing
gradual orbital deterioration.
One-way satellite services are:
Broadcast Satellite Service: Radio, TV, Data broadcasting.
Safety services : Search & Rescue, Disaster Warning
Radio Determination Satellite Service(Position location)
Standard frequency and time signal satellite service
Space Research Service.
Space operations service.
Earth Exploration Satellite Service.
Two-way satellite services are:
Fixed Satellite Service: Telephone, fax, high bit rate
data etc.
Mobile Satellite Service: Land mobile, Marine time
mobile, Aero-mobile, personal communications.
Satellite News Gathering.
Inter Satellite Service.
Universal: Satellite communications are available virtually everywhere.
Versatile: Satellites can support all of today's communications needs.
RELIABLE: Satellite is a proven medium for supporting a company's
communications needs.
SEAMLESS: Satellite's inherent strength as a broadcast medium makes it
perfect.
FAST: Since satellite networks can be set up quickly, companies can be fast-
to-market with new services.
Conti..
Flexible
Expandable
High Quality
Quick Provision of Services
Mobile and Emergency Communication
Suitable for both Digital and Analog Transmission
Telephone
Television
Digital cinema
Radio
Internet access
Military
Weather forecasting
Common Frequency Bands
Frequency Bands Available for
Satellite Communications
Future communication satellites will have
more onboard processing capabilities,
more power, and
larger-aperture antennas
that will enable satellites to handle more bandwidth.
The demand for more bandwidth will ensure the long-term
viability of the commercial satellite industry well into the 21st
century.
In addition, other technical innovations such as
low-cost reusable launch vehicles are in
development.
Further improvements in satellites propulsion and
power systems will increase their service life to 20
30 years from the current 1015 years.
Note:
A geostationary orbit is a type of geosynchronous orbit. A
geosynchronous orbit can be any orbit, like with an elliptical
path, that has a period equal to the Earths rotational period,
whereas a geostationary orbit has to be a circular orbit and
that too placed above the equator.
By going through the above slides we came to
know that satellite is mostly responsible for:
Telecommunication transmission
Reception of television signals
Whether forecasting
Which are very important in our daily life.
