The document discusses satellite communication and the key components involved. It covers: 1) The three main segments of a satellite link - the transmitting Earth station, the satellite, and the receiving Earth station. 2) Components of Earth stations including antennas, amplifiers, modulators, and more. 3) Factors that impact satellite transmission such as frequency bands, transmission losses, polarization, and more.

1. WELCOME
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2. TOday’s TOpiC
Satellite
Communication
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3. Communication Medium
3
Open wire
Twisted Pair UTP / STP
Coaxial Thicknet / Thinnet
Fiber Optic
Microwave Terrestrial
Transmission
Microwave Satellite Transmission

4. TRaNsMissiON
TERREsTRiaL &
saTELLiTE
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5. ECHO SYNCOM
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6. FREquENCy
BaNds
The up-link is a highly directional, point
topoint link
The down-link can have a footprint
providing coverage for a substantial
area "spot beam“.
Band Up link
(GHz)
D link
(GHz)
Issues
C 6 4 Interference With Ground
Links
Ku 14 11 Attenuation Due to Rain
Ka 30 20 High Equipment Cost
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7. Elevation Angle:
The angle of the horizontal of the
earth surface to the center line of
the satellite transmission beam.
FaCTORs iN saTELLiTE
COMMuNiCaTiON
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8. saTELLiTE TRaNspONdERs
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9. ANALOG
•One program per channel /
transponder
•Comparatively noisy
•Lower quality with respect to VCD,
DVD digital media
•Fixed reception
•Limited coverage
DIGITAL
•More programs per channel /
Transponder i.e. spectrum efficient
•Noise-Free Reception
•CD quality sound & better than DVD
quality picture
•Reduced transmission power
•Flexibility in service planning -quality /
Bandwidth trade off
•Terrestrial free network
saTELLiTE TRaNsMissiON
aNaLOg Vs digiTaL
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10. sigNaLs -aNaLOg Vs digiTaL
ANALOG DIGITAL
SIGNAL Continuous Discrete
REPRESENTATION Continuous Range of
Values
Discontinuous Range of
Values
TRANSMISSION Not Noise Immune Noise Immune
MEMORY Stored in the Form of
Waves
Binary Bits
ENCRYPTION Not easy Easy
LONG DISTANCE
TRANSMISSION
Require amplifiers, and
each amplifier adds
distortion and noise
digital amplifiers
regenerate an exact
signal
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11. BLOCk sChEMaTiC OF a TRaNspONdER
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12. 12
Introduction:
A satellite link is defined as an Earth station - satellite -
Earth station connection.
The Earth station - satellite segment is called the uplink
and the satellite - Earth station segment is called the
downlink.
The Earth station design consists of the Transmission
Link Design, or Link Budget, and the Transmission
System Design.
The Link Budget establishes the resources needed for a
given service to achieve the performance objectives.

13. EARTH STATION
 Earth Station is a uplink center from which the signals are
fed to Satellite for distribution in a specified area covered
by the Satellite.
 The signal is up-linked from the earth station and
received by many down link centers in TV broad casting.
 It is a very important part of satellite communication
system for broadcasting of signals.
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14. 14

15. 1) PDA (Parabolic Dish Antenna)
2) FEED
3) LNA / LNBC
4) Wave Guide / Low Loss Cable
5) HPA (TWTA, SSPA, Klystrons)
6) Up converter
7) Modulator
8) Encoder
9) Multiplexer
10) IRD (Integrated Receiver Decoder)
Major Components of Digital Earth Station
DIgITAl EARTH
STATION
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16. Link Bidget
• Earth Station Uplink • Earth Station Downlink
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17. 17
The satellite link is composed primarily of three
segments:
(i) the transmitting Earth station and the uplink media;
(ii) the satellite; and
(iii) the downlink media and the receiving Earth station.
The carrier level received at the end of the link is a
straightforward addition of the losses and gains in the
path between transmitting and receiving Earth stations.

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19. DVB - DIgITAl VIDEO BROADcASTINg
Digital Video Broadcasting (DVB) is being adopted as the standard for digital
television
Main forms of DVB
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20. 20
Carrier to Noise Ratio
The basic carrier-to-noise relationship in a system establishes the
transmission performance of the RF portion of the system, and is defined
by the receive carrier power level compared to the noise at the receiver
input.
For example, the downlink thermal carrier-to-noise ratio is:
C/N = C -10log(kTB)
Where:
C = Received power in dBW
k = Boltzman constant, 1.38*10-23
W/°K/Hz
B = Noise Bandwidth (or Occupied Bandwidth) in Hz
T = Absolute temperature of the receiving system in °K

21. 21
Transmission Losses
Generally consist of four components:
L = Lo + Latm + Lrain + Ltrack (5)
Where:
Lo = free Space Loss
Latm = atmospheric losses
Lrain = attenuation due to rain effects
Ltrack = losses due to antenna tracking errors

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24. ENcODER
 The video/audio encoding system is fully complaint to DVB/MPEG-standards.
 One encoder is used for only one video/audio channel.
 For more channels more encoders are used.
 The output of the encoders are fed to multiplexer unit for multiple programs
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25. MULTIPLEXER
 The outputs of all the encoders are fed to the Transport
stream multiplexer.
 Multiplexed data from encodes produces a single bit
stream. Supports insertion of conditioner access.
 It is configured by network management system to enable
the efficient use of transmission band width
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26. Up-converters
 The up-conversion is required to raise the frequency of the signal in
desired band: C-band, Extended C-band or Ku-band before
transmission.
 The input to up converter is 70 MHz (output of modulator) and
output of Up-converter is fed to HPA.
 The up-conversion may done in stages or in one stage directly. For
example the 70 MHz signal is first converted into L –band and then
L band signal raised to desired frequency band.
 Normally L-band monitoring point is also provided in Up-converters
for monitoring purposes.
RF STagE In
CoMMUnICaTIon
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27. High Power Amplifier
 The high power amplifier is used for the final power
amplification of the digital RF signal in C-band/ Ku
band that is fed to the antenna.
 The important parameters of HPAs are:
1. Frequency range
2. Output power at flange
3. Bandwidth
4. Gain variation (1.0 db (max.) for 40 MHz (narrow
band)
5. 2.50 db for full bandwidth)
RF STagE In
CoMMUnICaTIon……
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28. 28

29. High Power Amplifier
6. Gain (at rated output)
7. RF output power
8. Gain stability: (+/- 0.25 dB per 24 hrs. (max.) at constant drive,
prime power and temperature. And +/- 1.0 dB max. over
operating temperature range)
9. Input VSWR: 1.3: 1 max, Output VSWR: 1.3: 1 max
RF STagE In
CoMMUnICaTIon…….
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30. High Power Amplifier
The different types of HPAs are:
1.KHPA - Klystron High Power Amplifier
2.TWTA -Traveling Wave Tube Amplifier
3.SSPA- Solid state Power Amplifier
RF STagE In
CoMMUnICaTIon……
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31. kLySTRon
An evacuated electron-beam tube in which an initial velocity modulation imparted
to electrons in the beam results subsequently in density modulation of the beam.
A klystron is used either as an amplifier in the microwave region or as an oscillator.
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32.  An electron gun to form and accelerate a beam of electrons
 A focusing magnet to focus the beam of electrons through the cavities
 Microwave cavities where the electron beam power is converted to microwave power
 A collector to collect the electron beam after the microwave power has been generated
 A microwave input where the microwave signal to be amplified is introduced into the
klystron
 A microwave output where the amplified microwave power is taken out
kLySTRon……
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33. TWTa
 The travelling wave tube is a form of thermionic valve
 Used for wideband RF amplifier designs.
 Used in broadcasting, radar and in satellite transponders.
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34. CRoSS SECTIon oF TWTa
1 Electron Gun
2 RF input
3 Magnet
4 Attenuator
5 Helix
6 R F Out Put
7 Vacuum Tube
8 Collector
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35. SoLId STaTE PoWER aMPLIFIER
 The basic functionality of the amplifier is the same in a high power solid state amplifier.
 Multiple devices are combined into power modules.
 They are combined to develop the needed gain and power.
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36. ELECTRoMagnETIC WavES
 Radio signals are a form of electromagnetic wave
 Electromagnetic waves have both electric and magnetic components that are
inseparable.
 The planes of these fields are at right angles to one another and to the direction of
motion of the wave.
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37. PolarizatioN
 The polarization is effectively the plane in which the electric wave vibrates.
 Vertical and horizontal are the simplest forms of antenna polarization
 They are known as linear polarisation .
Circular polarisation
It can be imagined that a signal propagating from an RF antenna is rotating.
Circular polarisation can be either right or left handed dependent upon the
the direction of rotation of electric vector as seen from the transmitter.
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38.  An other form of polarisation is known as elliptical polarisation .
 It occurs when there is a mix of linear and circular polarisation .
 This can be visualised as the tip of the electric field vector tracing out an
elliptically shaped corkscrew.
PolarizatioN…..
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39. Wave guide
 Waveguides are basically a device for transporting electromagnetic energy.
 Typically, waveguides are hollow rectangular or circular metal tubes.
 They are capable of directing power precisely to where it is needed.
 Can handle large amounts of power and function as a high-pass filter.
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40. Circular waveguide:
This is less common than rectangular waveguide.
They have many similarities in their basic approach.
tyPes of rf Waveguide……
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41. Wave guide…..
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42. aNteNNa directivity aNd gaiN
 RF antennas or aerials do not radiate equally in all directions.
 The actual pattern is dependent upon the type of antenna design.
 Also depends on size, the environment and a variety of other factors.
 The gain can be defined as a ratio of the signal transmitted in the " maximum "
direction to that of a standard or reference antenna.
 This may sometimes be called the " forward gain " .
 The figure that is obtained is then normally expressed in decibels (dB)
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43. .
Parabolic reflector
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44. Parabolic reflector aNteNNa
Advantages :
High gain High directivity
Disadvantages
Requires reflector and drive element
Cost Size
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