• Satellite technology has progressed tremendously over the last 50
years since Arthur C. Clarke first proposed its idea in 1945 in his
article in Wireless World.
• Today, satellite systems can provide a variety of services including
broadband communications, audio/video distribution networks,
maritime navigation, worldwide customer service and support as
well as military command and control.
• Satellite systems are also expected to play
an important role in the emerging 4G
global infrastructure providing the wide
area coverage necessary for the
realization of the “Optimally Connected
Anywhere, Anytime” vision that drives the
growth of modern telecom industry.
What is a Satellite..?
• A satellite is something that orbits
• Moon is a natural satellite
• satellites are made by scientists and
What Does a Satellite Do..?
•A satellite orbits Earth
•it helps people communicate and learn more
about our planet.
Telephone, Mobile, Fax…etc.
History of SSaatteelllliittee CCoommmmuunniiccaattiioonnss
•Satellite communications began in October 1957 with the launch by the
USSR a small satellite called Sputnik 1 (4.10.1957)
•Beacon transmitter, no communications capability
•3.11.1957 Sputnik 2
•12.4.1961 Vostok 1
•First true communication satellites (Telstra I & II) were launched in July
1962 & May 1963
•10/1964 Syncom 2: First GEO satellite, 7.4/1.8 GHz (one TV-channel or
several 2-way telephone connections
•1987 TVSAT: First DBS-satellite (Direct Broadcast Satellite, Television-broadcasts
directly to home)
Kinds of a Satellite
1) LEO, or Low Earth Orbit
100 to 300 miles, very fast, travel about 17,500 m/h
2) MEO, or Medium Earth Orbit
Oval orbit, travel about 17,500 m/h, larger than LEOs, stay a
longer time, orbit 6,000 to 12,000 miles.
3) GEO, or Geostationary Earth Orbit
distance 22,282 miles ,circle the Earth in 24 hours
cover a large part of the planet,
three satellites can cover the globe .
• LEO satellites are much closer to the earth
than GEO satellites, ranging from 500 to
1,500 km above the surface.
• LEO satellites don’t 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
A LEO satellite’s 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
A LEO satellite’s 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
Atmospheric drag effects LEO satellites,
causing gradual orbital deterioration.
•A MEO satellite is in orbit somewhere between
8,000 km and 18,000 km above the earth’s surface.
•MEO satellites are similar to LEO satellites in
•MEO satellites are visible for much longer periods of
time than LEO satellites, usually between 2 to 8
•MEO satellites have a larger coverage area than
•These satellites are in orbit
35,863 km above the earth’s
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
A GEO satellite’s distance from earth
gives it a large coverage area, almost a
fourth of the earth’s surface.
GEO satellites have a 24 hour view of a
These factors make it ideal for satellite
broadcast and other multipoint
A GEO satellite’s 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 broadcasting
signals to near polar regions
Molniya Orbit Satellites:
Used by Russia for decades.
Molniya Orbit is an elliptical orbit. The
satellite remains in a nearly fixed
position relative to earth for eight
A series of three Molniya satellites can
act like a GEO satellite.
Useful in near polar regions.
High Altitude Platform (HAP):
One of the newest ideas in satellite
A blimp or plane around 20 km above the
earth’s surface is used as a satellite.
HAPs would have very small coverage
area, but would have a comparatively
Cheaper to put in position, but would
require a lot of them in a network.
Satellite Frequency Bands
There are three most commonly used
satellite frequency bands:
1. C-band : transmissions between 4 to 8 GHz
frequency range , size of an antenna 2-3 meters in
2. Ku-band : transmissions between 11 to 17
GHz frequency range, antennas can be as small as
18 inches in diameter.
3. Ka-band: transmissions between 20 to 30
GHz frequency range. These very high frequency
and very small antennas.
Advantages of Satellites
• The advantages of satellite communication
over terrestrial communication are:
The coverage area of a satellite greatly
exceeds that of a terrestrial system.
Transmission cost of a satellite is independent
of the distance from the center of the coverage
Satellite to Satellite communication is very
Higher Bandwidths are available for use.
Disadvantages of Satellites
• The disadvantages of satellite
Launching satellites into orbit is costly.
Satellite bandwidth is gradually becoming
There is a larger propagation delay in satellite
communication than in terrestrial
Applications of a
1) Uses in the Wars .
2) Uses in the geologic and ceremonial .
3) Uses in the Communications .
4) Uses in the system GPS .
5) Uses in the espial .
6) Uses in the transmission of the
And a lot of applications .