1. 1
A Report on
Satellite communication and Digital earth station
INDUSTRIAL TRAINING
Doordarshan Indore
Submitted at
Rajiv Gandhi Technical University, Bhopal
In partial fulfillment of the degree
Of
Bachelor of Engineering
In
Electronics and Instrumentation
Electronics and Instrumentation Department
MEDI-CAPS INSTITUTE OF TECHNOLOGY
AND MANAGEMENT INDORE- 453331
2013-14

2. 2
A Report on
Satellite communication and Digital earth station
INDUSTRIAL TRAINING
Doordarshan Indore
Submitted at
Rajiv Gandhi Technical University, Bhopal
In partial fulfillment of the degree
Of
Bachelor of Engineering
In
Electronics and Instrumentation
Submitted by: Submitted to:
Rakshit Choubey Mr. Vinit Gupta
(0812EI101043) Industrial Training In charge
Electronics and Instrumentation Department
MEDI-CAPS INSTITUTE OF TECHNOLOGY
AND MANAGEMENT INDORE- 453331
2013-14

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Certificate
This is to certify that Mr./Miss Rakshit Choubey, student of B.E.
(Electronics and Instrumentation Engineering) , 4th Year, VII Semester ,
Medi-Caps Institute of Technology and Management has pursued his/her
Industrial Training course on TV Transmitter, Studio Equipment, Earth
Station and their associated equipments from 17/06/2013 to 12/07/2013
from Doordarshan Kendra , Indore .
Industrial Training In charge

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ACKNOWLEDGEMENT
I take this opportunity to thank Mr. Abhay Shrivastava (Assistant engineer) for his
valuable guidance and encouragement throughout the course of my training on “Satellite
communication and Digital earth station“.
Also I would like to express my gratitude to Mr. Vivek D. Kasture for offering all the
facilities, sincere co-operation, guidance, timely encouragement and thankful advice.
I am also thankful to all the Doordarshan Indore staff members who gave their time for our
training program and helped us learn some practical and theoretical aspects of our project.

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CONTENTS
Cover Page
Institution Certificate
Acknowledgement
Industry Certificate
Chapter No. Subject Page No.
1. Brief Introduction of Organization 7
2. Purpose behind visit 9
3. Machines/Equipments – Working & Specifications 10
4. Details of the Project under taken 18
5. Conclusion 24
List of Figures and Tables
References

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1. BRIEF INTRODUCTION OF ORGANISATION
Doordarshan (DD) is country’s Public Service Television and has the distinction of being
one of the world’s largest terrestrial networks. DD is the biggest media organization in the
country covering over 90.1 % of its population and 78.2 % of its area. Doordarshan operates
24 channels – Four All India Channels, Eleven Regional Languages Satellite Channels,
Eight Hindi Belt Network and One International Channel.
DD started off its operations with a Public Service Aim behind it…
• To inform
• To educate
• To entertain
Its countrymen and hence got the distinction of a PUBLIC SERVICE BROADCASTER
Doordarshan. Three-tier program service Doordarshan has a three-tier program service
National, Regional and Local. The NATIONAL Program include News, Current Affairs,
Science, Cultural Magazines, Sports, Music, Dance, Drama, Serials and Feature Films. The
REGIONAL Programs carried on all the Transmitters in the different states of India also
deal with similar programs, but in the language and idiom of the particular Region/State.
The LOCAL Programs are area specific and cover local issues featuring local people.
National and Regional Program Services of Doordarshan are also available on Satellite and
DTH.
1.1 History of Doordarshan
In 1959, Philips (India) made an offer to the Government of a transmitter at a reduced cost.
Earlier, Philips had demonstrated its use at an exhibition in New Delhi. The Government
decided employing it on an experimental basis “to train personnel, and partly to discover
what TV could achieve in community development and formal education”. A UNESCO
grant of $20,000 for the purchase of community receivers and a United States offer of some
equipment proved much too tempting to resist, and on September 15, 1959, the Delhi
Television Centre went on air for half an hour, three days a week and inaugurated by Sh.
Rajendra Prasad, President of India from Vigyan Bhawan.

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The range of the transmitter was forty kilometers round and about Delhi. Soon programs
began to be beamed twice a week, each of 20 minutes’ duration. The audience comprised
members of 180 ‘teleclubs’ which were provided sets free by UNESCO. Entertainment and
information programs were introduced from August 1965, in addition to some social
education programs for which purpose alone TV had been introduced in the capital. The
Federal Republic of Germany helped in setting up a TV production studio. By 1970, the
duration of the service was increased to three hours, and included, besides news,
information and entertainment programs, two weekly programs running to 20 minutes each
for ‘teleclubs’, and another weekly program of the same duration called ‘KrishiDarshan’ for
farmers in 80 villages.‘KrishiDarshan’ programs began in January 1967 with the help of the
Department of Atomic Energy, the Indian Agricultural Research Institute, the Delhi
Administration and the State Governments of Haryana and Uttar Pradesh. The programs
could easily be picked up in these States, as the range of the transmitter was extended to 60
kilometers. By the end of the decade there were more than 200,000 sets in Delhi and the
neighboring states. Today, Doordarshan operates 30 channels in 22 languages and is one of
the largest Terrestrial Network in the World.

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2. PURPOSE BEHIND VISIT
 The main purpose of the industrial training was to understand and experience real
life situations in industrial organizations and their related environment.
 To learn the formal and in-formal relationships in an industrial organization so as to
promote favorable human relations and teamwork.
 To gain hands-on experience on the equipments used in the industry and to relate
them with the knowledge we gained during our engineering.
 During the visit we learned various safety practices used in the industry.

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3. EQUIPMENTS - WORKING AND SPECIFICATIONS
3.1 SPECIFICATIONS:-
Doordarshan Kendra, Indore is equipped with studio, two high power transmitters for
primary channel coverage. The transmitters are of 10kW power, one is for DD National and
other is for DD News telecasting.
3.1.1 Technical Details of Transmitter
Table.1 Transmitter DD National:
Date of commissioning
Replaced by Rhode & Schwarz transmitter
28-11-1984 (Bel transmitter)
18-07-05
Make and type Rohde &Schwarz
NM7100E/V
Frequency 203.23 MHz for visual & 208.73 MHz for
aural
Output power 10kW for visual and 1 kW for aural
Primary coverage area 65-70 km radially
Table.2 Transmitter DD News:
Date of commission 03-07-2000
Make and type Thom cast 45321.165-981A
Service relayed DD-news
Band and channel VHF-III, CH#11
Frequency 217.250017 MHz for visual &
222.750015 MHz for aural.
Output power 10kW for visual and 1 kW for aural
Primary Coverage area 65-70 km radial

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3.2 WORKING:-
Microphones:
Microphones are transducers that convert acoustical energy into electrical energy. The three
main types of microphones (according to their principles of operation) are:
 Dynamic(moving coil)
 Ribbon
 Condenser
Dynamic Microphones:
Dynamic mics consist of a diaphragm suspended in front of a magnet to which a coil of
wire is attached. The coil sits in the gaps of the magnet. Vibrations of the diaphragm make
the coil move in the gap causing an AC to flow. Coils of wire are used to increase the
magnitude of the induced voltage and current. The mass of the coil-diaphragm structure
impedes its rapid movement at high frequencies (where there is usually low response).A
resonant peak is usually found at around 5 kHz, making it a favorite with vocalists.
Fig.1 Fig.2
Ribbon microphones:
It consists of a thin strip of conductive corrugated metal(ribbon) between magnetic plates
.Vibration of the ribbon according to the acoustic wave induces a current. Its electrical
output is very small and needs to be stepped up by a transformer .The lightness of the
ribbon guarantees a flat frequency response for mid and high frequencies up to 14kHz. It
resonates at very low frequencies (around 40Hz). It is very delicate and well suited for the
recording of acoustic instruments.

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Condenser microphones:
A capacitor is an electrical device able to store electrical charge between
two closely-spaced conductors (plates).Capacitance (C) measures how much charge (Q) is
stored for a given voltage (V), such that C = Q/V. Capacitance is inversely proportional to
the distance (d) between plates.In condenser mics, the front plate is the diaphragm which
vibrates with the sound. The charge (Q) is fixed, thus changes in the distance d between
plates result on changes of voltage (V).
Condenser mics can be extremely high quality. The diaphragm can be very light, rendering
a flat frequency response (with a small resonance peak at above 12kHz). Output of
condenser mics is much higher than for dynamic mics. High output makes it more robust to
noise.
To charge the capacitor a source of power is needed (usually phantom power - to be
discussed later in the course).An alternative to using a power source is to introduce a
permanent electrostatic charge during manufacture, resulting on the “electret” mic.Electret
microphones can be very small, high quality (back electrets) and cheap, e.g. Tie-clip TV
microphones.
Fig.3 Condenser microphone
Characteristics of microphones:
• Professional microphones have a low-impedance usually around of 200 ohms - this
enables the use of long leads.
• Another important characteristic is sensitivity, i.e. a measure of the electrical output (in
volts) per incoming SPL.
• Sensitivity is usually given in terms of a reference SPL, e.g. 94 dB or 1 Pascal (Pa).
• Condenser microphones (5-15 mV/Pa) are more sensitive than moving coils (1.5-3
mV/Pa) and ribbons (1-2 mV/Pa).

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• More amplification is needed for moving-coils and ribbons (which are thus more
susceptible to interference). Also, low-sensitivity mics need high-quality (low noise) amps
and mixers.
• All microphones generate some noise. This is usually expressed in “A-weighted” self-
noise (given in dBA).
• High-quality condenser and moving-coil mics achieve self-noise of 17-18dBA. Ribbon
mics’ noise can be of the order of 23dBA, which means that for quite signals low-noise
amps need to be used. A
self-noise in the region of 25dBA results in poor performance.
Directional Response :
1.Microphones are designed to have a directional response pattern. This pattern is
characterized by a polar diagram showing magnitude of the output (in dB) vs angle of
incidence .An omni-directional microphone picks up sound equally in all directions .This is
achieved by opening the diaphragm at the front and completely enclosing it at the back. At
high frequencies the wavelength is comparable to the size of the capsule, resulting in a loss
of gain off front center. Smaller capsules result in better high frequency performance.TV
tie-clip microphones are usually omni electrets.
Fig.4 Fig.5
2.Figure eight or bidirectional microphones have an output close to cos(θ), where θ = angle
of incidence. This directional pattern is mostly associated with ribbon microphones (open
both at the front and rear).The response is thus the result of the pressure difference between
diaphragm front and rear (which is why response is null at 90/270°) The long wavelengths
at low frequencies (resulting in small phase differences) cause a reduction of the output.
Because of the ribbon’s shape, ribbon mics have a better polar response when upright or
upside down, than when positioned horizontally.

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3.Cardiod microphones result from the combination of omnidirectional and bidirectional
patterns.Their output is close to 1 + cos(θ).They are unidirectional. The response is obtained
by leaving the diaphragm open at the front while using acoustic labyrinths in the rear to
cause differences of phase and amplitude in the incoming sound. Mid frequency response is
usually very good.
.
Fig.6 Fig.7
4. There are a number of specialized microphones such as so-called shotgun microphones
or parabolic microphones which are highly directional. A shotgun mic, example, is cardiod
with a long barrel with openings aimed at causing canceling phase differences.
CCD-CAMERA:
Camera captures the real image into electrical form.The transducer used in modern Cameras
is CCD chips.CCD = Charge Coupled Device. Replaces photographic film and
photomultiplier tubes. Consists of a thin silicon wafer divided into thousands (or millions)
of tiny light sensitive squares (photosites). Each photosite corresponds to an individual
pixel in the final image. Turns light (photons) into electrons (charge) – photoelectric effect
– analog device.Each photosite has a positively charged capacitor that attracts the electrons.
Uses movement of charge within the device. Output – voltage from each photosite
dependent on number of photons that penetrated the silicon surface. Output voltage
converted to a digital signal (electronics).Instead of taking a picture – records an
image.CCD chip was developed in 1969 by AT&T’s Bell Labs.
Working of CCD:
At beginning of exposure Capacitors are positively charged and disconnected (bias)
Shutter is opened  Photons enter silicon crystal lattice and are absorbed – raising

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some electrons from a low-energy valence band to a high energy conduction band (in other
words, some electrons are liberated from their silicon atoms) .Electrons are attracted to
nearest positively charged capacitor – partially discharges capacitor (changes voltage).
Degree of discharge is proportional to number of photons that hit each photosite during the
exposure  At end of exposure, the electrons at each photosite are passed to a charge-
sensing node, amplified, and passed to read-out electronics to be digitized and sent to the
computer.
For silicon – energy difference between valence (tightly bound electrons) and conduction
band (free electrons) is 1.1 ev. Only photons with energy greater than 1.1 ev will be
detected (11000 Angstroms, in the infrared).At shorter wavelengths, silicon becomes more
reflective, so photons never enter silicon crystal. Blue cut off is about 3000
Angstroms.CCDs are linear (# of electrons is proportional to number of photons) as long as
you don’t have too many electrons. Charge can leak from one photosite to the next if there
are too many electrons bleeding. Photosites are arranged in rows and columns. Size of
photosites varies.
Fig.8 Basic structure of CCD

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The output digital signal from CCD is stored in a memory chip and is sent to processor for
image processing.
Audio Mixer:
Audio are used to combine the input signal from various microphones units. The output
signal obtained is transmitted to distant station by transmitter.
Fig.10
Diagram shows the 3-channel sound mixer circuit using three Norton-opamps. The input
levels can be set by potentiometers P1 or P3. Furthermore, each input level can be trimmed
with the help of trimmers pots P4 to P6 to adapt each input to the source. The resistors at the
non-inverting inputs of the opamps work as DC bias and set the DC output at 50 percent of
the power supply for this powered audio mixer. All three input signals are summed by the

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fourth opamp A4 through the resistors R3, R7 and R11. The commom volume level is
cotrolled through the potentiometer P7.
You can switch an input channel on or off through the switches S1 and S3. An input
channel is turned off when its switch is closed. It is also possible to replace these
mechanical switches with transistor gates. By doing so, you can build an analog multiplexer
circuit that can be easily expanded by several inputs
TRANSMITTER:
"Transmitter" is a telemetry device which converts measurements from a sensor into a
signal, and sends it, usually via wires, to be received by some display or control device
located a distance away.
Fig.11 Transmitter
Above block diagram shows a frequency modulated transmitter.In frequency modulation
(fm) the modulating signal combines with the carrier to cause the frequency of the resultant
wave to vary with the instantaneous amplitude of the modulating signal. Figure shows you
the block diagram of a frequency-modulated transmitter. The modulating signal applied to a
varicap causes the reactance to vary.

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4. DETAILS OF PROJECT UNDERTAKEN
Introduction
A satellite is essentially a space-based receiving and transmitting radio. In other words, it
sends electromagnetic waves, carrying information over distances without the use of wires.
Since its function is to transmit information from one point on Earth to one or more other
points, it actually functions as a “radio-frequency repeater.”
A satellite receives radio-frequency signals, uplinked from a satellite dish on the Earth,
known as an Earth Station or Antenna1. It then amplifies the signals, changes the frequency
and retransmits them on a downlink frequency to one or more Earth Stations.
Basic Working of a Satellite Communication System
 Two Stations on Earth want to communicate through radio broadcast but are too far
away to use conventional means.
 The two stations can use a satellite as a relay station for their communication
 One Earth Station sends a transmission to the satellite. This is called a Uplink.
 The satellite Transponder converts the signal and sends it down to the second earth
station. This is called a Downlink.
Fig.12 Satellite communication system

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Frequency Bands and Capacity Allocation
1. Frequency Bands
Different kinds of satellites use different frequency bands.
L–Band: 1 to 2 GHz, used by MSS
S-Band: 2 to 4 GHz, used by MSS, NASA, deep space research
C-Band: 4 to 8 GHz, used by FSS
X-Band: 8 to 12.5 GHz, used by FSS and in terrestrial imaging, ex: military and
meteorological satellites
Ku-Band: 12.5 to 18 GHz: used by FSS and BSS (DBS)
K-Band: 18 to 26.5 GHz: used by FSS and BSS
Ka-Band: 26.5 to 40 GHz: used by FSS
2. Capacity Allocation
 FDMA
Satellite frequency is already broken into bands, and is broken in to smaller channels in
Frequency Division Multiple Access (FDMA).
Overall bandwidth within a frequency band is increased due to frequency reuse (a frequency
is used by two carriers with orthogonal polarization).
The number of sub-channels is limited by three factors:
 Thermal noise (too weak a signal will be effected by background noise).
 Inter modulation noise (too strong a signal will cause noise).
 Crosstalk (cause by excessive frequency reusing).
FDMA can be performed in two ways:

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 Fixed-assignment multiple access (FAMA): The sub-channel assignments are of
a fixed allotment. Ideal for broadcast satellite communication.
 Demand-assignment multiple access (DAMA): The sub-channel allotment
changes based on demand. Ideal for point to point communication
 TDMA
Time Division Multiple Access breaks a transmission into multiple time slots, each one
dedicated to a different transmitter. TDMA is increasingly becoming more widespread in
satellite communication. TDMA uses the same techniques (FAMA and DAMA) as FDMA
does.
Advantages of TDMA over FDMA:
 Digital equipment used in time division multiplexing is increasingly becoming
cheaper.
 There are advantages in digital transmission techniques. Ex: error correction.
 Lack of inter modulation noise means increased efficiency.
Elements of Satellite Communication
Essentially, a satellite system consists of three basic sections:
1. The uplink
2. The satellite transponder
3. The downlink
1. The Uplink Model (Uplink Transmitter):
An Earth station transmitter is designed to accept information signals of whatever kind
(including voice signals, radio or television broadcasts, and data), use them to modulate a
carrier, possibly add error detection or correction coding, and amplify and radiate the
modulated signal toward a satellite. This shows, for example, the elements that might

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constitute a satellite news gathering (SNG) uplink station
Fig.13 Uplink model
The primary component within the section of a satellite system is the earth station
transmitter. A typical earth station transmitter consists of an IF modulator, an IF to RF
microwave up-converter, a high power amplifier (HPA).The IF modulator converts the
input baseband signals to either an FM, a PSK or a QAM modulated intermediate
frequency. The up-converter (mixer and BPF) converts the IF to an appropriate RF carrier
frequency. The HPA provides adequate input sensitivity and output power to propagate the
signal to the satellite transponder. The HPA’s commonly used are klystrons and TNT’s.
2. The Satellite Transponder:
The circuitry in the satellite that acts as the receiver, frequency changer, and transmitter is
called a transponder. This basically consists of a low noise amplifier, a frequency changer
consisting a mixer and local oscillator, and then a high power amplifier. The filter on the
input is used to make sure that any out of band signals such as the transponder output are
reduced to acceptable levels so that the amplifier is not overloaded. Similarly the output
from the amplifiers is filtered to make sure that spurious signals are reduced to acceptable
levels. Figures used in here are the same as those mentioned earlier, and are only given as
an example. The signal is received and amplified to a suitable level. It is then applied to the
mixer to change the frequency in the same way that occurs in a super heterodyne radio
receiver. As a result the communications satellite receives in one band of frequencies and
transmits in another.

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In view of the fact that the receiver and transmitter are operating at the same time and in
close proximity, care has to be taken in the design of the satellite that the transmitter does
not interfere with the receiver. This might result from spurious signals arising from the
transmitter, or the receiver may become de-sensitized by the strong signal being received
from the transmitter. The filters already mentioned are used to reduce these effects.
Fig.14 Satellite transponder
Signals transmitted to satellites usually consist of a large number of signals multiplexed
onto a main transmission. In this way one transmission from the ground can carry a large
number of telephone circuits or even a number of television signals. This approach is
operationally far more effective than having a large number of individual transmitters.
Obviously one satellite will be unable to carry all the traffic across the Atlantic. Further
capacity can be achieved using several satellites on different bands, or by physically
separating them apart from one another. In this way the beam width of the antenna can be
used to distinguish between different satellites. Normally antennas with very high gains are
used, and these have very narrow beam widths, allowing satellites to be separated by just a
few degrees.
A transponder is a part of a satellite, which is a combination of transmitter and receiver. The
main function of transponder is frequency translation and amplification. Based on the
frequency translation process, there are three basic transponder configurations. These are
single conversion transponder, double conversion transponder and regenerative transponder.
The uplink signal is received by the receiving antenna. The received signal is first band
limited by Band Pass Filter (BPF), then it is routed to Low Noise Amplifier (LNA).

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The amplified signal is then frequency translated by a mixer and an oscillator. Here only the
frequency is translated from high-band up-link frequency to the low-band down link
frequency. The mixer output (down link signal) is then applied to BPF then it is amplified
by a High Power Amplifier (HPA). This down link signal is then transmitted to receiver
earth station through a high power transmitting antenna.
3. The Downlink Model (Downlink Receiver):
An earth station receiver includes an input BPF, an LNA and an RF to IF down converter.
Fig.15 Downlink model
The BPF limits the input noise power to the LNA. The LNA is a highly sensitive, low noise
device. The RF-to-IF down converter is a mixer, BPF combination which converts the
received RF signal to an IF frequency.
The most common frequencies used for satellite communications are 6/4 and 14/12 GHz
bands. The first number indicates the uplink (earth station-to-transponder) frequency and
the second number is downlink (transponder-to-earth station) frequency. Since C band is
most widely used, this band is becoming overcrowded. A typical C band transponder can
carry 12 channels, each with a bandwidth of 36 MHz.

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5. CONCLUSION
Industrial training was based on the topic “TV Transmitter, Studio Equipment, Earth Station
and their associated equipments”. I have learned different ways of communication and the
instruments used in the industry. I would like to conclude that I have gained some
knowledge which I cannot obtain from the books or references. The experience in the
industry during five weeks is valuable for me. I have learned to be responsible for my
position and be punctual.
With the help of all this knowledge, I will be able to work in an industry. I am very thankful
to Mr. Vivek D. Kasture (Training coordinator) for his valuable guidance.

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LIST OF FIGURES AND TABLES
List of Tables
Table.1 Transmitter DD National Page 10
Table.2 Transmitter DD News Page 10
List of Figures
Fig.1 Cross section of dynamic microphone Page 11
Fig.2 Ribbon microphone Page 11
Fig.3 Condenser microphone Page 12
Fig.4 Polar plot Page 13
Fig.5 Polar plot Page 13
Fig.6 Polar plot Page 14
Fig.7 Polar plot Page 14
Fig.8 Basic structure of CCD Page 15
Fig.9 Principle behind CCD chip readout Page 16
Fig.10 Audio mixer circuit Page 16
Fig.11 Transmitter Page 17
Fig.12 Satellite communication system Page 18
Fig.13 Uplink model Page 21
Fig.14 Satellite transponder Page 22
Fig.15 Downlink model Page 23

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REFERENCES
 Microphones, VET-Entertainment, Freshwater Senior Campus
 Bernd Girod, Information Systems Laboratory, Department of Electrical
Engineering, Stanford University
 International Journal of Advanced Research in Computer Science and Software
engineering, Volume 2, Issue 1, January 2012
 Djordje Mitrovic, University of Edinburgh