2. CONTENTS :
What’s mean by satellite ?
History of Satellites :
Generalized communication system :
What are the components of a satellite?
How Satellites Work ?
How do satellite stay in orbit ?
Why satellite are launched 36,000 Km from centre of earth ?
Types of bands :
Types of orbits :
Advantages And Disadvantages Of satellite :
Uses of satellite :
3. what’s mean by sATELLITE ?
Passive Satellites Active satellites
I. Natural satellites
II. artificial satellites.
A passive satellite only
reflects received signals back
to earth.
Ex.moon is a natural satellite
of earth
Active satellites are
complicated structures
having a processing
equipment called
Transponder .
An active satellite acts as a
REPEATER
A Satellite is a solid object which revolves around some
body due to the effect of gravitational forces OR
a satellite is an object which has been placed into
orbit by human endeavour.
4. History of Satellites :
First satellite that was used
for communication
purpose in INDIA was
-ARYABHATTA (19 April
1975)
The first geostationary
communication satellite
-SYNCOM 3(19 Aug 1963).
The world's first artificial satellite is the Sputnik 1
was launched in 1957
6. What are the components of a satellite?
Many satellites are
powered by
rechargeable
batteries.
Small thrusters
provide attitude i.e.
stabilize the satellite's
position in space.
7. How Satellites Work :
I. A Earth Station
sends message in
GHz range (Uplink).
II. Satellite Receive and
retransmit signals
back. (Downlink)
III. Difference between
Downlink and
Uplink frequency is
2 GHz.
8. 1.Gravitational force=
attraction between any
two objects
2.Centrifugal force=an
outward-directed
force that normally
balances the inward-
directed centripital
forceThere are two relevant
forces involved in this
problem
Why geostationary satellite are launched 36,000 km from thecenter of
the earth?
9. How do satellites stay in orbit?
Satellites stay in orbit
due to the balance of
two factors:
i. Velocity and
ii. Gravitational pull between
the Earth and the satellite.
Satellites never fall into
the Earth this because Earth
is round and curves.
10. Satellite Frequency Bands :
There is a inverse
relationship between
frequency and wavelength.
Different kinds of satellites
use different frequency
bands.
L–Band: 1 to 2 GHz,
S-Band: 2 to 4 GHz
C-Band: 4 to 8 GHz
X-Band: 8 to 13 GHz
Ku-Band: 13 to 18 GHz
K-Band: 18 to 28 GHz
Ka-Band: 28 to 40 GHz
As wavelength
increases (and
frequency decreases),
larger antennas
(satellite dishes) are
necessary to gather
the signal.
11. C-band :
C-band is the most
common frequency
spectrums used by
today’s satellite.
C-band satellite
transmissions occupy
the 4 to 8 GHz
frequency range.
C-band antenna is
approximately 2-3
meters in diameter
12. Ku-band: Ku-band satellite
transmissions occupy the 13 to
18 GHz frequency range.
Ku-band antennas can be as
small as 18 inches in diameter
These very high frequency
transmissions mean very small
wavelengths and very small
diameter receiving antennas.
16. Middle-Earth-Orbiting (MEO)
MEOs orbits between the
altitudes of 8,000 - 20,000 km
above the earth.
MEO satellites have a larger
coverage.
These orbits are primarily
reserved for communications
satellites that cover the North and
South Pole.
MEOs are placed in an elliptical (oval-shaped)
orbit.
17. Geosynchronous-Earth-Orbit (GEO)
From the ground level
the satellite appears
fixed.
GEO satellites have a 24
hour view of a particular
area.
Coverage to 40% of area
Of planet by this
satellite
18. ADVANTAGES AND DISADVANTAGES OF SATELLITE:
ADVANTAGES : DISADVANTAGES :
Make repeated
observations over a given
area .
At a time satellites observe a
larger coverage area.
Minimum Satellite lifetime
is about 10-15 years.
Poor spatial resolution
in the polar regions.
Launching satellites
into orbit is costly.
19. Uses of satellite:
IT IS USED FOR LONG DISTANCE COMMUNICATION.
IT IS SPEEDY AND RELIABLE.
IT IS USED FOR WEATHER FORECASTING.
(study of atmosphere ,rain ,sunshine at any place at
perticular time)
IT IS USED FOR TRANSMIT T.V. SIGNAL OVER LARGE
DISTANCE COMMUNICATION.
POLAR SATELLITE IS USED FOR REMOTE SENSING.