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Title: satellite communication
Seminar on INTRODUCTION TO SATELLITE
SWAPNIL G. THAWARE
Under the Guidance of
Prof. HIVRE S. R.
Department Of Information technology
Dr. Babasaheb Ambedkar Technological University,
- Whats mean by satellite ?
- History of Satellites
- Layer Of Atmosphere
- 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
- Global position system
- Advantages And Disadvantages Of satellite
- Uses of satellite
whats mean by sATELLITE ?
- 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.
- Active satellites
- Passive Satellites
- Active satellites are complicated structures
having a processing equipment called Transponder
- An active satellite acts as a REPEATER
- Natural satellites
- artificial satellites.
- A passive satellite only reflects received
signals back to earth.
- Ex.moon is a natural satellite of earth
History of Satellites
- The world’s first artificial satellite is the
- was launched in 1957
- First satellite that was used for communication
purpose in INDIA was -ARYABHATTA (19
- The first geostationary communication satellite
-SYNCOM 3(19 Aug 1963).
- Father of geostationary communication satellite
- -HAROLD ROSEN
- (Aircraft engineer)
Layer Of Atmosphere
- Generalized communication system
Uses of information
- 1 Message signal.
- 2 tranmitted signal.
- 3 received signal.
- 4 message signal.
What are the components of a satellite?
- Many satellites are powered by rechargeable
- Small thrusters provide attitude i.e. stabilize
the satellite’s position in space.
How Satellites Work
- A Earth Station sends message in GHz range
- Satellite Receive and retransmit signals back.
- Difference between Downlink and Uplink frequency
- 2 GHz.
Why geostationary satellite are launched 36,000
km from the center of the earth?
- 1.Gravitational force attraction between any
two objects, given by
- 2.Centrifugal forcean outward-directed force
that normally balances the inward-directed
- There are two relevant forces involved in this
Eqating that 2 eqn
Equate that 2 eqn
We know G 6.67 x 10-11 Nm2kg-2 me 5.97 x
1024 kg we 7.29 x 10-5 rad s-1
Hence, substituting the above constants into
As we know
The tangential velocity of the satellite (vs) is
related to its orbital period, T so,
Then T? and sqaring
R 35,786 km for center of earth Near about
How do satellites stay in orbit?
- Satellites never fall into the Earth this
because Earth is round and curves.
- Satellites stay in orbit due to the balance of
- Velocity and
- Gravitational pull between the Earth and the
Satellite Frequency Bands
- Different kinds of satellites use different
- LBand 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
- There is a inverse relationship between
frequency and wavelength.
- As wavelength increases (and frequency
decreases), larger antennas (satellite dishes)
are necessary to gather the signal.
- C-band is the most common frequency spectrums
used by todays satellite.
- C-band satellite transmissions occupy the 4 to 8
GHz frequency range.
- C-band antenna is approximately 2-3 meters in
- Ku-band satellite transmissions occupy the 13 to
18 GHz frequency range.
- Ku-band antennas can be as small as 18 inches in
- These very high frequency transmissions mean
very small wavelengths and very small diameter
TYPES OF ORBITS
- Low-Earth-Orbit (LEOs)
- Medium-Earth-Orbit (MEOs)
- Geostationary (GEOs)
- Altitude (600-1000 KM)
- satellite gives it a better signal strength
- Reduces transmission delay
- Smaller coverage area.
- Shorter life span (5-8 yrs.)
Little LEOs Applications
- 0.8 GHz range
- Small, low-cost
- Used for short communications.
- 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)
- From the ground level the satellite appears
- GEO satellites have a 24 hour view of a
- Coverage to 40 of area Of planet by this
The Global Positioning System
- EQUATORIAL ORBIT
- POLAR CIRCULAR ORBIT
- INCLINED ORBIT
- EACH SATELLITE COVER 40 AREA
- SATELLITE MAKES AN ANGLE OF 120 WITH EACH OTHER.
ADVANTAGES AND DISADVANTAGES OF SATELLITE
- Make repeated observations over a given area .
- At a time satellites observe a larger coverage
- Minimum Satellite lifetime is about 10-15
- Poor spatial resolution in the polar regions.
- Launching satellites into orbit is costly.
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
- POLAR SATELLITE IS USED FOR REMOTE SENSING.
- Geostationary Satellite(Author- Louis E.Frenzel)
- (Edition- Third)
- (Publication- Tata McGraw-Hill)
— gtgtBY SWAPNIL G. THAWAREAbout PowerShow.com