Geostationary Earth Orbit (GEO) Satellite Systems • A geostationary orbit is a special type of geosynchronous orbit. • When an object is in geostationary orbit, it is orbiting at the same speed as the Earth rotates, but it orbits around the equator.

1. SATELLITE
SYSTEM

2. SATELLITES
CONTENTS
 History
 Launching of Satellites
 Satellites/How Satellites Work
 Types:
• Low-Earth-Orbit (LEOs)
• Medium-Earth-Orbit (MEOs)
• Geostationary (GEOs)/Basic of GEOs
 Localization of Mobile Stations
 Hand-Over In Satellite System
 Applications

3. HISTORY
The First Satellites
 The theory of satellites was simple enough - shoot something out into space
at the right speed and on the correct trajectory and it will stay up there,
orbiting Earth, for years - if not forever.
 If the orbit is the right distance in space the satellite will keep pace with the
rotation of the Earth.
 Early in October 1957 communications stations started picking up a regular
beeping noise coming from space.
 The signals were coming from Russia's Sputnik 1, the world's first manmade
satellite.
 It was January 1958, before a Jupiter rocket successfully launched Explorer 1,
the first American satellite

4. 1957 First Artificial Satellite (Sputnik)
 The first artificial satellite was Sputnik 1, launched by the
Soviet Union on October 4, 1957.
 At about the size of a basketball, Sputnik 1 was equipped
with a radio transmitter that gave off a beeping signal
 Helping the Soviets to track it on its 98- minute orbit and
to signal to the world that the U.S.S.R. was the leader in
space

5. First Artificial Satellite (Sputnik)

6. 1960 First Orbiting Observations
(TIROS-1 Weather Satellite)
 The first aerial images of the Earth from space were
taken by TIROS 1 (Television InfraRed Observation
Satellite).
 TIROS 1 was launched in 1960 to find out if it was
possible to watch cloud cover and weather patterns
from space.
 Although it was an experimental satellite, TIROS
images were immediately put to use by
meteorologists

7. (TIROS-1 Weather Satellite)

8. 1972 First Surveying Satellite
(Landsat)
 The first Landsat satellite was called the Earth Resources
Technology Satellite, or ERTS.
 Since its launch on July 23, 1972, six Landsat have followed,
with the latest, Landsat 7, lifting off on April 15, 1999.
 Over the years successive Landsat have not only carried better
land-viewing sensors
 They have created a valuable archive of images that are being
used to see how the land is changing over the years.
 Landsat 7 carries the Enhanced Thematic Mapper Plus, which
scans the Earth in eight bands of visible and invisible light

9. 1974 First Geostationary Satellite
(GOES)
 Best known as weather satellites
 The first GOES (Geostationary Operational Environmental
Satellite) was launched on October 16, 1975.
 Their high orbits and visible-light and infrared sensors
allow for constant surveillance of weather patterns over
the entire planet and have enabled GOES to revolutionize
the science of weather prediction.
 sGOES-10, launched in 1998, images the 48 contiguous
U.S. states every five minutes.

10. SATELLITE
 A Satellite is a solid object which revolves around some heavenly body
due to the effect of gravitational forces which are mutual in nature.
 For example, Earth is a satellite because it orbits the sun. Likewise, the
moon is a satellite because it orbits Earth. Usually, the word "satellite"
refers to a machine that is launched into space and moves around Earth
or another body in space.
 We can categorize satellites in two types, namely Passive Satellites and
Active satellites.

11. Passive Satellites
The passive satellite is a reflector which receives the signal from the
transmitting earth station and scatters the signal in
all the directions.
A passive satellite can be further subdivided into two
types, namely Natural satellites and artificial satellites.
Natural Satellites:
A natural satellite is an object that orbits a planet or
Other body larger than itself and which is not man-made.
Such objects are often called moons.
Artificial Satellites:
An artificial satellite is an object that people have
made and launched into orbit.

12. Active Satellites
• It has its own transmitting and receiving antennas.
• It amplifies the signal received from earth station or
ground station and retransmits the amplified signal back to
earth.
• In addition to amplification, it performs frequency
translation of the received signal before retransmission.
• It is known as passive repeater due to its functionality.

13. HOW SATELLITE WORKS
 A Earth Station sends message in GHz range. (Uplink)
 Satellite Receive and retransmit signals back.
(Downlink)
 Other Earth Stations receive message in useful
strength area. (Footprint)

14. HOW SATELLITE WORKS

15. HOW SATELLITE WORKS
 Satellites provide links in two ways.
 Firstly a satellite provide point to point communication link between
one ground station and the other. One ground station transmit signal to
the other satellite and next ground station receives them from the
satellite.
 Secondly, satellite receives signals from one ground station and
transmits to them to the number of ground receivers.
 Most satellite use frequency bandwidth through from 5.92 to 6.4GHz
from transmission of data from earth to the satellite and a frequency
bandwidth from 3.7 to 4.1GHz for transmission from satellite to the
earth.

16. LOW-EARTH-ORBIT (LEO)
Low earth orbits (LEO) are satellite systems used in telecommunication,
which orbit between 400 and 1,000 miles above the earth's surface. They
are used mainly for data communication such as email, video
conferencing and paging.
Most communication applications use LEO satellites because it takes less
energy.
 Advantages:
 Reduces transmission delay
 Eliminates need for bulky receiving equipment.
 Disadvantages:
 Smaller coverage area.
 Shorter life span (5-8 years.) than GEOs (10 years).

17. Middle-Earth-Orbiting (MEO)
 MEOs orbits between the altitudes of 5,600 and 9,500 miles.
 These orbits are primarily reserved for communications satellites
that cover the North and South Pole.
 Unlike the circular orbit of the geostationary satellites, MEOs are
placed in an elliptical (oval-shaped) orbit.
 Satellites of this type orbit higher than low earth orbit (LEO) satellites
 Advantages:
 Compared to LEO system, MEO requires only a dozen satellites.
 Simple in design.
 Requires very few handovers.
 Disadvantages:
 Satellites require higher transmission power.
 Special antennas are required.

18. Geostationary-Earth-Orbit (GEO)
 Orbit is synchronous with the earths rotation.
 From the ground the satellite appears fixed.
 Altitude is about 23,000 miles.
 Coverage to 40% of planet per satellite.
 Advantages:
 It is possible to cover almost all parts of the earth with just 3 geo satellites.
 The life-time of a GEO satellite is quite high usually around 15 years.
 Disadvantages:
 Larger antennas are required for northern/southern regions of the earth.
 High transmission power is required.

19. Basics of GEOs
 Geostationary satellites are commonly used for communications and
weather-observation. The typical service life expectancy of a
geostationary satellite is 10-15 years. Because geostationary satellites
circle the earth at the equator, they are not able to provide coverage at
the Northernmost and Southernmost latitudes.
-Weather images can be displayed.
-Television broadcasts are uninterrupted.
-Used to track major developments such as hurricanes 24 hours a day.
-It takes longer for the signal to get to earth and back to satellite.
-Increased difficulty of telephone conversations.
-GEOs are not positioned in the farthest northern and southern orbits.

20. Types of Satellites
 Weather satellites help meteorologists predict the weather or see what's happening at the
moment.
 Communications satellites allow telephone and data conversations to be relayed through the
satellite.
 Broadcast satellites broadcast television signals from one point to another (similar to
communications satellites).
 Scientific satellites, like the Hubble Space Telescope, perform all sorts of scientific missions.
 Navigational satellites help ships and planes navigate.
 Rescue satellites respond to radio distress signals
 Earth observation satellites check the planet for changes in everything from temperature to
forestation to ice-sheet coverage.
 Military satellites are up there, but much of the actual application information remains secret.

21. Localization of Mobile Stations
 Mechanism similar to GSM
 Gateways maintain registers with user data:
– HLR (Home Location Register)
– VLR (Visitor Location Register):
 (Last known) location of the mobile station
– SUMR (Satellite User Mapping Register):
 Positions of all satellites
 Satellite assigned to a mobile station

22. Hand-over in Satellite Systems
Additional situations for hand-over in satellite systems compared to cellular
terrestrial mobile phone networks caused by the movement of the satellites
– Intra-satellite hand-over
• Hand-over from one spot beam to another
• Mobile station still in the footprint of the satellite, but in another cell
– Inter-satellite hand-over
• Hand-over from one satellite to another satellite
• Mobile station leaves the footprint of one satellite

23. – Gateway hand-over
• Hand-over from one gateway to another
• Mobile station still in the footprint of a satellite, but gateway
leaves footprint
– Inter-system hand-over
• Hand-over from the satellite network to a terrestrial cellular
network
• Mobile station can reach a terrestrial network again which might be
cheaper, has a lower latency

24. APPLICATIONS
 Weather Forecasting
 Radio and TV Broadcast
 Military satellites
 Satellite for navigation(GPS)
 Global telephone connection
 Global mobile communication

25. Thankyou 