DOORDARSHAN KENDRA Bareilly training report

1. A
SUMMER TRAINING
REPORT
ON
BASICS OF DOORDARSHAN KENDRA, BAREILLY
A report submitted in partial fulfilment of requirement
for the seventh semester of the degree of
BACHELOR OF TECHNOLOGY
In
ELECTRONICS AND COMMUNICATION ENGINEERING
Submitted By
Dharmveer Singh
Roll No.1101413021
1
A Report Submitted to
Mr. Abhishek Srivastava
DEPARTMENT OF ELECTRONICS AND COMMUNICATION
ENGINEERING
SRMS COLLEGE OF ENGINEERING AND TECHNOLOGY
BAREILLY- 243202
September 2014

2. ACKNOWLEDGEMENT
A research work owes its success from commencement to completion, to the people in
love with researchers at various stages. Let me in this page express my gratitude to all
those who helped us in various stage of this study. First, I would like to express my
sincere gratitude indebtedness to Mr. Ashok Sachan for allowing me to undergo the
summer training of 30 days at Doordarshan Kendra, Bareilly (DDK, Bareilly).
I am grateful to our guide Mr. Rakesh Kumar Gupta for the help provided in
completion of the project, which was assigned to me. Without his friendly help and
guidance it was difficult to develop this project.
I am also thankful to Mr. Abhishek Srivastava for his true help, inspiration and for
helping me to preparation of the final report and presentation.
Last but not least, I pay my sincere thanks and gratitude to all the Staff Members of
ONGC for their support and for making our training valuable and fruitful.
SUBMITTED TO: SUBMITTED BY:
ABHISHEK SRIVASTAVA DHARMVEER SINGH
(Assistant Professor) (1101413021)
2

3. 3

4. PREFACE
Doordarshan is an Indian public service broadcaster, a division of Prasar Bharati. It is
one of the largest broadcasting organisations in India in terms of the studio and
transmitter infrastructure. Recently, it has also started broadcasting on Digital
Terrestrial Transmitters. Doordarshan operates 21 channels – two All India channels –
DD National and DD News, 11 Regional language Satellite Channels (RLSC), four
State Networks (SN), an International channel, a Sports Channel DD Sports and two
channels Rajya Sabha TV & Lok Sabha TV for live broadcast of parliamentary
proceedings. On DD National (DD-1), Regional programs and Local Programs are
carried on time-sharing basis. DD News channel, launched on 3 November 2003,
which replaced the DD Metro formally known as (DD-2) Entertainment channel,
provides 24-Hour news service. Doordarshan is one of the largest broadcasting
organizations in India in terms of the infrastructure of studios and transmitters.
Doordarshan Kendra, Bareilly has a setup for the transmission of television
programmes directed from the other Doordarshan Kendra namely DD Delhi, DD
Lucknow. Also DD Kendra, Bareilly also has a set up for the recording and
transmission of programmes like talk shows etc. The DDK has the necessary and
sufficient stages for the television coverage. The Kendra has the television studio,
production control room, transmitters (10kW, 20kW), control room, antenna (155
metre high). In the beginning, only the development programmes were telecast but later
on to enlighten the viewers as per their needs, expectations, many more informative,
educative and entertaining programmes have been introduced from time to time.
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5. LIST OF CONTENTS
TITLE PAGE NO.
PREFACE……………………………………………………………………………iv
LIST OF FIGURE……………………………………………………………...…...vi
CHAPTER 1...........................................................................................................(1-5)
1.1 Introduction..............................................................................................................1
1.2 History of Doordarshan……………………………………………………………2
1.2.1 Early Programmes of Doordarshan………………………………………….2
1.2.2 Channels of Doordarshan……………………………………………………4
1.2.3 National Programmes on Doordarshan………………………………….......5
1.2.4 Active Doordarshan…………………………………………........................5
1.2.5 International Broadcasting of Doordarshan………………………………....5
CHAPTER 2.........................................................................................................(6-36)
2.1 Basics of Doordarshan Kendra……………………………………………....….....6
2.1.1 Fundamentals of monochrome and colour TV transmission…………….......6
2.1.2 PAL Colour Television System (Colour Television) .....................................8
2.2 Doordarshan Kendra Setup....................................................................................14
2.2.1 Studio Centre.................................................................................................14
2.2.2 Production Control Room (PCR) ................................................................17
2.2.3 Video Storage & Transmission Room (VTR) ..............................................20
2.2.4 Master Switching Room (MSR) ..................................................................22
2.2.5 Transmitter ...................................................................................................25
2.2.6 Antenna ........................................................................................................33
Chapter 3.....................................................................................................................37
3.1 Training Summary..................................................................................................37
Chapter 4.....................................................................................................................38
4.1 Conclusion..............................................................................................................38
REFERENCES ........................................................................................................39
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6. LIST OF FIGURE
FIG NO. TITLE PAGE NO.
1.1 Classic Serials of Doordarshan..............................................................................3
1.2 Channels of Doordarshan.......................................................................................4
2.1 Additive Colour Mixing.........................................................................................8
2.2 One line display of TV signal...............................................................................10
2.3 Colour Composite Video Signal (CCVS)............................................................11
2.4 Separation of H & V pulses from CVS................................................................12
2.5 Block Diagram of PAL encoder...........................................................................13
2.6 TV Transmission..................................................................................................13
2.7 TV Studio............................................................................................................16
2.8 Camera Control Unit............................................................................................18
2.9 Sound Mixer.........................................................................................................19
2.10 Vision Mixer........................................................................................................20
2.11 Functional Diagram of MSR................................................................................22
2.12 BEL MARK III 10kV Transmitter.......................................................................25
2.13 High Power Transmitter.......................................................................................26
2.14 Low Power Transmitter........................................................................................26
2.15 Transmitter Classification based on Power..........................................................27
2.16 Block diagram of BEL MARK III 10kW Transmitter.........................................27
2.17 Exciter..................................................................................................................29
2.18 Types of Antennas................................................................................................35
2.19 Antenna at DDK, Bareilly....................................................................................36
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7. CHAPTER 1
7
1.1 INTRODUCTION
Doordarshan is an Indian public service broadcaster, a division of Prasar Bharati. It
is one of the largest broadcasting organizations in India in terms of the studio and
transmitter infrastructure. Recently, it has also started broadcasting on Digital
Terrestrial Transmitters. On 15 September 2009, Doordarshan celebrated its 50th
anniversary. The DD provides television, radio, online and mobile services
throughout metropolitan and regional India, as well as overseas through the Indian
Network and Radio India. For the London Olympics, live telecasts of the opening and
closing ceremonies of the games were broadcast on its national channel. DD sports
channel has provided round the clock coverage of sport events. Doordarshan is the
public television broadcaster of India and a division of Prasar Bharati, and nominated
by the Government of India. It is one of the largest broadcasting organizations in the
world in terms of the infrastructure of studios and transmitters. Prasar Bharati, its
parent body has all board members appointed by the Government of India acting
through the Information and Broadcasting Ministry. This control is evident in a
budget that allows expenditure on "propaganda and public relations".
Doordarshan is a network of 1400 terrestrial transmitters covers more than 90.7% of
India's population. There are about 46 Doordarshan studios producing TV
programmes today.
Doordarshan Kendra is a milestone in the field of entertainment and education media
source. Doordarshan Kendra, Bareilly is the Program Production Center and
transition. The studios are housed at same campus and the transmitter is located at the
Bareilly. AIR and Doordarshan aims to provide information, education and
entertainment for the public. DD India is broadcast internationally via satellite. It is
available in 146 countries worldwide; however, information on receiving this channel
in other countries is not easily available. Due to the transmitters and infrastructural
facilities of Doordarshan, it is considered amongst the leading broadcasting
organisations throughout the world.

8. 8
1.2 HISTORY OF DOORDARSHAN
Doordarshan started with a tentative telecast on September 1959 from Delhi. The
infrastructure at that time was small supported by a temporary studio. Regular
transmission commenced on 1965, and formed a part of All India Radio. By 1972, the
telecast was expanded to Amritsar and Mumbai. Doordarshan was the only channel
available at time and by 1975, it was available in seven cities around the nation. In
1976, it was detached from All India Radio and was fully managed from New Delhi,
by two different Director Generals. In 1982, colour television sets became available in
country and the speech given by the Prime Minister of that time, Indira Gandhi, was
telecast live throughout the nation. After this, the 1982 Asian games, Delhi, was also
broadcasted by the channel.
1.2.1 Early Programmes of Doordarshan
Doordarshan gained exceeding popularity during the 1980s with its new and
groundbreaking shows that could easily connect with the urban and rural audiences
alike. Shows like Hum Log, Yeh Jo Hai Zindagi, Buniyaad, Nukkad, along with the
epics like Ramayana and Mahabharata were watched by viewers throughout the
country. Later programmes like Bharat Ek Khoj, Chitrahaar, Sword of Tipu Sultan,
Rangoli, The Great Maratha, Ek Se Badkar Ek, Shaktimaan and Superhit Muqabla
also were watched widely.
Other popular programmes included thrillers like Byomkesh Bakshi, Karamchand,
Barrister Roy, Tehkikaat, Reporter and Suraag. Family oriented shows like Wagle ki
Duniya, Fauji, Mr. Yogi, Talaash, Kashish, Srimaan Srimati, Dekh Bhai Dekh,
Zabaan Sambhal Ke, Swabhimaan, Shanti, Saagar, Lifeline, Udaan, Circus, Sansaar,
Jaspal Bhatti`s Flop Show, Meri Awaaz Suno, Sangharsh, Gul Gulshan Gulfam, Sea
Hawks, Tu tu mein mein and Junoon were also widely accepted. Mythological
programmes like Dastan-E-Hatim Tai, Chandrakanta, Alif Laila were also very
popular among the viewers.
Shows targeted at kids were also much appreciated. Programmes like Captain Vyom,
a Desi version of Star Wars, Potli Baba Ki, Malgudi Days, Stone Boy, Tenali Raman,
Sigma, Vikram Betaal, Kile ka Rahasya and Dada Dadi ki Kahaniyan are worth

9. mentioning. Many popular international programmes were also aired, after being
dubbed in Hindi, such as Johnny Soko and his flying robot, Street Hawk, Knight
Rider, Superhuman Samurai Cyber Squad, and animated shows like the jungle book,
He-Man and the masters of universe, Spiderman, Disney adventures were also
admired by the young audience.
Fig1.1 Classic Serials of Doordarshan
9

10. 10
1.2.2 Channels of Doordarshan
Doordarshan currently has 21 channels, 11 regional channels and 2 national channels
(DD National and DD News), 1 sports channel (DD Sports), 1 international channel
and a few more. DD National broadcasts both regional and national programmes. DD-Sports
exclusively telecast various sporting tournaments and events, which are of
national and international significance. It also broadcasts local sports like Kabaddi,
Kho-Kho etc. DD News, which was launched by replacing DD Metro, is a 24 hour
news channel.
The array of channels offered by Doordarshan include- DD National, DD Sports, DD
News, Rajya Sabha TV, DD-Lok Sabha, DD Bharti and many regional channels such
as, DD Gujarati, DD Bangla, DD Punjabi, DD Kashir, DD Malayalam, DD Odia, DD
Podhigai, DD Saptagiri, DD Sahyadri, DD Urdu and DD NorthEast.
Fig1.2 Channels of Doordarshan

11. 1.2.3 National Programmes on Doordarshan
The objective of a common programme broadcast, which will cater to people in
different states, was achieved by Mr. Sathe, Minister for Information and Broadcast,
in the 90 minute National programme, on August 15, 1982. This was to consist of
news in Hindi and English, and programmes reflecting music, dance and other aspects
of life, literature and culture of all regions. Although few programmes have bee n
appreciated by the viewers, but in general it is believed that the output has lacked
quality and standard.
11
1.2.4 Active Doordarshan
Recently, along with Tata Sky, Doordarshan has launched an Interactive Service,
which is offered as a special channel on Tata sky. It is an Interactive Service of Tata
Sky to show 4 TV Channels of Doordarshan which are not available on Tata sky as
normal channels. DD Podhigai, DD Gujarati and DD Punjabi are offered in this
service. Doordarshan also has launched its own Direct-To-Home service, named DD
Direct Plus.
1.2.5 International Broadcasting of Doordarshan
Doordarshan had also started broadcasting internationally via Satellite and has a
presence in almost 146 countries, globally. But there were some technical problems
on the availability of the channel in some countries. The programmes and timie slot
are not as similar as the broadcast in India. In July 2008, transmissions in U.K. and
U.S. were stopped.
Now more than 90.7 percent of population of the country can receive Doordarshan
programmes through a network of nearly 1400 terrestrial transmitters. Around 46
Doordarshan Studios are producing TV software. The Doordarshan televises through
the Official and Associate Official languages, and its regional channels televise
through the state dominant languages and dominant minority languages.

12. CHAPTER 2
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2.1 BASICS OF TV TRANSMISSION
2.1.1 Fundamentals of monochrome and colour TV transmission
Picture formation
A picture can be considered to contain a number of small elementary area of light or
shade which are called Picture elements. The elements thus contain visual image of
the scene. In the case of a TV camera the scene is focused on the photosensitive
surface of pick up device and an optical image is formed. The photoelectric properties
of the pickup device convert the optical image to a electric charge image depending
on the light and shade of the scene (picture element). Now it is necessary to pick up
this information and transmit it. For this purpose scanning is employed. Electron
beam scans the charge image and produces optical image. The electron beam scans
the image line by line and field by field to provide signal variations in a successive
order. The scanning is both in horizontal and vertical direction simultaneously. The
horizontal scanning frequency is 15,625 Hz and the vertical scanning frequency is 50
Hz. The frame is divided into two fields. Odd lines are scanned first and then the even
lines. The odd and even lines are interlaced. Since the frame is divided into two fields
the flicker reduces. The frame rate is 25Hz (Field rate is the same as power supply
frequency).
Number of TV Lines per Frame
I f t he numbe r o f TV l ine s is high la r ge r ba ndwidt h o f video a nd
hence larger R.F. channel width is required. If we go for larger RF channel width the
number of channels in the R.F. spectrum will be red uc ed. Ho we ve r , wi t h
mo re no. o f TV l ine s o n t he sc r e e n t he c lar it y of the picture i.e.
resolut ion improves. Wit h less no. of TV lines per frame the c lar it y is
poor.T he c a p a b i l i t y o f t he s ys t e m t o r e s o l ve ma x imum n umb
e r o f pic ture e lements a long scanning lines de termines the hor izonta l
r e s o l u t i o n . I t me a n s h o w m a n y a l t e r n a t e b l a c k a n d

13. w h i t e e leme nts ca n be there in a line. Le t us a lso take another fa ctor. I t
is re a l is t ic to a im a t eq ua l ve r t ic a l a nd hor izo nt a l
re so lut io n. The re fore , t he numb e r o f a l te r na t e b la ck a nd whi te
dots o n l ine can be 575 x 0.69 x 4/3 which is equal to 528. It means there are 528
divided by 2 cyclic changes i.e. 264 cycles. These 264 cycles are there during 52
microseconds. Hence the highest frequency is 5 MHz Therefore the horizo ntal
resolution of the system is 5 MHz As similar calculation for 525 lines system limits
the highest frequenc y to 4 MHz and hence the hor izonta l re solut ion of same
value. I n view o f t he abo ve t he ho r izo nta l ba nd wid t h o f s igna l in
625lines system is 5 MHz
2.1.2 The PAL Colour Television System (Colour Television)
It is possible to obtain any desired colour by mixing three primary colours i.e. Red,
Blue and green in a suitable proportion.
Additive Colour Mixing
The figure shows the effect of projecting red, green, blue beams of light so that they
overlap on screen. Input is the primary colour (i.e. red, green, blue) into matrix circuit
as Y, R-Y, and B-Y.
Y=0.30R+0.59G+0.11B
13
U=0.477(R-Y)
V=0.895(B-Y)

14. Fig. 2.1 Additive Colour Mixing
It is possible to obtain any desired colour by mixing three primary colours i.e., red,
blue and gree n in suitable propor t ion. Thus it is only required to convert
optical information of these three colours to electrical signals and transmit it on
different carriers to be decoded by the receiver. This can then be converted back
to the optical image at the picture tube. The phosphors for all the three colours i.e. R,
G and B are easily available to the manufacturers of the picture tube. So the pick up
from the cameras and output for the picture tube should consist of three signals i.e.
R, G and B. It is only in between the camera and the picture tube of the receiver we
need a system to transmit this information.
Colour te levis ion has the constra int of compa t ibil it y and reverse
compat ibility wit h the monoc hrome te levis ion system whic h makes it
s light ly complic ated. Compa t ib i l i t y me a ns t ha t whe n colour TV s igna l
is radia ted the monoc hrome TV se ts should a lso displa y Bla ck & White
picture s. This is achieved by sending Y as monoc hrome informat ion a long
wit h the c hroma s ignal. Revere compa t ibility mea ns that when black and
white TV s ignal is radia ted the colour TV sets should displa y the black
and white pictures.
If we transmit R, G, B the reverse compatibility cannot be achieved. Let us see how:
14

15. 15
If we transmit Y, R, B and derive G then,
Since,
Y = 0.3R + 0.59G + 0.11B
G = 1.7Y - 0.51R - 0.19B
In such a case what happens with colour TV set when we transmit black & white
signal, R and B are zero, but G gun gets 1.7 Y. The net result is black and white
pictures on a colour TV screen appear as Green pictures. So reverse compatibility is
not achieved.
Colour Difference Signals
To achieve reverse compatibility, when we transmit Y, R-Y and B-Y i n s t e a d o f
Y, R & B, we d o no t t a k e G - Y a s t h i s w i l l a lwa ys b e muc h
lo we r t h a n R- Y a nd B- Y a nd he nc e w i l l ne e d mo r e
a mp l i f i c a t io n a nd w i l l c a us e a no i s e i n t o t he s ys t e m. G-Y
can be derived electronically in the TV receiver. Previously we have seen,
G = 1.7Y - 0.51R - 0.19B
G-Y = -0.51( R-Y ) – 0.19( B-Y )
Thus, colour difference signals fulfil the compatibility and reverse compatibility,
because in this case the colour difference signals are zero. If the original signal is
monochrome (i.e. R = B = G). So if we take,
R - Y = R - (0.3 R + 0.59 R + 0.11 R) = 0
Similarly,
B - Y = 0
As such colour diffe rence s igna ls are ze ro for white or any shade of gray
whereas; Y carries the entire Luminance information. I t is to b e noted whi le
R, G, B s igna ls a lwa ys ha ve pos i t ive value R-Y, B-Y and G-Y s igna ls

16. can e ither be pos it ive or negat ive or even zero. The R-Y and B-Y
chrominance s igna ls ma y be recovered a t the te levis ion re ce iver by
suitable synchronous demodulat ion. But sub-car r ie r is to be generated by
the loca l osc il lator. This generated sub-carr ie r in the rec e iver must have
same frequenc y as that of t ra nsmit ted sub-carr ier and a lso the same
phase. This is achieved by t ra nsmit t ing 10 cycles of sub-carr ier frequency
ont h e b a c k p o r c h o f H s y n c hr o n i z i n g p u l s e . T h i s 1 0 c yc l e s
s ub - carrier signal is known as BURST or colour BURST.
Fig 2.2 One line display of TV signal
16
Video Signal
Video is nothing but a sequence of picture .The image we see is maintained in our eye
for a 1/16 sec so if we see image at the rate more than 16 picture per sec our eyes
cannot recognize the difference and we see the continuous motion.
In TV cameras image is converted in electrical signal using photo sensitive mater ial.
Whole image is divided into many micro particles known as Pixels. These pixels
small enough so that our eyes cannot recognize pixel and we see continuous image
,thus at any instant there are almost an infinite no. of pixel that needs to be converted
in electrical signal simultaneously for transmitting picture details. However this is not

17. practicable because it is no feasible to provide a separate path for each pixel in
practice this problem is solved by scanning method in which information is converted
in one by one pixel line by line and frame by frame.
Fig 2.3 Colour Composite Video Signal (CCVS)
Colour Composite Video Signal is formed with Video, sync and blanking signals. The
level is standardized to 1.0 V peak to peak (0.7 volts of Video and 0.3 volts of sync
pulse). The Colour Composite Video Signal (CCVS) has been shown in figure.
17
Frequency Content of TV Signal
The TV signals have varying frequency content. The lowest frequency is zero. (when
we are transmitting a white window in the entire active period of 52 micro seconds
the frequency is Zero).In CCIR system B the highest frequency that can be
transmitted is 5 MHz even though the TV signal can contain much higher frequency
components. (In film the reproduction of frequencies is much higher than 5 MHz and
hence clarity is superior to TV system.) long shots carry higher frequency components
than mid close ups and close ups. Hence in TV productions long shots are kept to
minimum. In fact TV is a medium of close ups and mid close ups. DC Component of
video signal and DC restoration
A TV signal is a continuously varying amplitude signal as the picture e lements give
rise to varying level which depends on how much of incident light the picture
elements can reflect and transmit the light signal to the TV camera. Hence the video

18. signal has an average value i.e. a DC component corresponding to the average
brightness of the scene to scene.
Fig 2.4 Seperation of H & V pulses from CVS
RF Transmission of Vision and Sound Signals
TV Transmission takes place in VHF Bands I and III and UHF Bands IV and V.
Picture is amplitude modulated and sound is frequency modulated on different
carriers separated by 5.5 MHz Also for video amplitude modulation negative
modulation is employed because of the following main advantages.
Pictures contain more information towards white than black and hence the average
power is lower resulting in energy saving. (Bright picture points correspond to low
carrier amplitude and sync pulse to maximum carrier amplitude). Interference such as
car ignition interfering signals appears as black which is less objectionable.
Picture information is in linear portion of modulation characteristic and hence does
not suffer compression. Any compression that may take place is confined to sync
pulse only. The design of AGC circuit for TV Receiver is simpler. AM produces
double side bands. The information is the same in both side bands. It is enough to
transmit single side band only. Carrier also need not be transmitted in full and a pilot
carrier can help. However, suppressing the carrier and one complete side band and
transmitting a pilot carrier leads to costly TV sets.
18
Sound Signal Transmission
In CCIR system B sound carrier is 5.5 MHz above the vision carrier and is frequency
modulated. The maximum frequency deviation is 50 KHz. Also the ratio of vision and
sound carriers is 10:1 (20:1 is also employed in some countries) If we assume
maximum audio signal is 15 KHz the band width is 130 KHz. According to Carson’s

19. Rule the bandwidth is 2 x (Maximum frequency deviation + highest modulating
frequency). However, calculated value (using Bessel’s function) of Bandwidth is 150
KHz i.e. 75 KHz on either side of sound carrier. In CCIR system picture IF is 38.9
MHz and sound. If is 33.4 MHz At the receiver end it is necessary to ensure that
signal frequencies in the region of the vestigial side band do not appear with double
amplitude after detection. For this purpose the IF curve employs NYQUIST slope.
Fig 2.5 Block Diagram of PAL encoder.
Fig 2.6 TV Transmission
19

20. 2.2 DOORDARSHAN KENDRA SETUP
Doordarshan Kendra, Bareilly has the following main departments which manage the
production, storage, transmission and maintenance of the two Doordarshan channels
i.e. DD National and DD News channels.
 Studio Centre
 Production Control Room (PCR)
 Video Storage & Transmission Room (VTR)
 Main Switching Room (MSR)
 Transmitter
 Antenna
Each of these departments are discussed in detail with due stress to the relevant
engineering aspects.
20
2.2.1 Studio Centre
A Studio centre of Doordarshan has the following objectives:
To originate programmes from studios either for live telecast or for recording on a video tape.
 To knit various other sources of programs available at the production desk i.e.,
camera output from studios, feed from other kendras, outdoor, playback from
pre recorded tape, film based programs slides, video graphics and characters
generator etc.
 This knitting or live editing includes generation of special effects and desired
transitions between various sources.
 Processing/distribution of different sources to various destinations in technical
areas.
 Routing of mixed programme for recording/transmission via master switching
room and Micro Wave to the transmitter or any other desired destinations.

21. Action area
This place requires large space and ceiling as compared to any other technical area.
Action in this area includes staging, lighting, performance by artists, and arrangement
to pick up picture and sound. Hardware required for these activities in a studio
(typical size 20 x20x8.5 cubic meters) are:
 Very efficient air conditioning because of lot of heat dissipation by studio light
and presence of large number of persons including invited audience performing
artists and operational crew.
 Uniform and even flooring for smooth operation of camera dollies and boom
21
microphone etc.
 Acoustic treatment keeping in mind that a television studio is a multipurpose
studio with lot of moving person and equipment during a production.
 Supporting facilities like properties, wardrobe, and makeup etc.
 Effective communication facilities for the floor crew with the production control
area.
 Studio cameras (three to four) with one of the cameras fitted with teleprompter
system and pressure dolly.
 Luminaries and suspension system having grids or battens (hand/motorised
operation).
 Cyclodrama and curtain tracks for blue and black for chroma keying and limbo
lighting respectively.
 Audio and video monitoring facilities.
 Digital Clock Display.

22. Fig 2.7 TV Studio
Operational requirement from the technical crew may vary from programme to
programme. These requirements for lighting, audio pick up and special effects etc.
depends upon the programme requirement such as establishing a period, time, formal
or informal situation.
22

23. 23
2.2.2 Production Control Room (PCR)
Activities in this area are:
 Direction to the production crew by the producer of the programme.
 Timing a production telecast.
 Editing of different sources available at the production desk.
 Monitoring of output/off air signal.
This is the nerve centre for a television station. Activities in this area include:
 Sync pulse generation and distribution.
 Distribution of stabilised power supply to different technical areas with protection
devices.
 Distribution of sources to various destinations.
 Video processing and routing.
 Electronics for camera chain, video switchers, special effect generator, and test
signal and pattern generator.
 Monitoring facilities.
 Patch panel for video and audio lines.
Technical areas associated with Central Apparatus Room (CAR) are:
Sync Pulse-Generator (SPG)
It is essential that all the video sources as input to the switcher are in synchronism i.e.,
start and end of each line or all the frames of video sources is concurrent. This
requirement is ensured by the sync pulse generator (SPG). SPG consists of highly
stable crystal oscillator. Various pulses of standard width and frequency are derived
from this crystal electronically which form clock for the generation of video signal.
These pulses are fed to all the video generating equipment to achieve this objective of
synchronism. Because of its importance, SPG is normally duplicated for change over
in case of failure.
Genlock (slaving)
Often in a production it is necessary to mix between two sources whose waveforms
are not synchronised. This is not possible until the local SPG has been synchronised

24. with the external source so that the locally produced signals arrive at the mixer in
synchronisation with the external source. When this occurs mixing is possible,
captions, and credits produced locally can be superimposed on external sources. For
non Synchronous sources mixing and super imposition is not possible and the signal
can only be ‘cut to’ with a resulting disturbance in outgoing sync pulses which may
cause frame rolls on monitors and certainly disturbance to VTR machine which is
recording. To overcome this problem, SPG is fitted with a GENLOCK facility, which
allows the master oscillator to lock to the incoming waveform from the remote source,
which then synchronises both waveforms.
Camera Control Unit (CCU)
The television cameras which include camera head with its optical focusing lens, pan
and tilt head, video signal pre-amplifier view finder and other associated electronic
circuitry are mounted on cameras trolleys and operate inside the studios. The output
of cameras is pre-amplified in the head and then connected to the camera control unit
(CCU) through long triax cable. All the camera control voltages are fed from the CCU
to the camera head over the Triax cable. The view- finder signal is also sent over the
camera cable to the camera head view- finder for helping the cameraman in proper
focusing, adjusting and composing the shots.
Fig 2.8 Camera Control Unit
24

25. The video signal so obtained is amplified, H.F. corrected, equalized for cable delays,
D.C. clamped, horizontal, and vertical blanking pulses are added to it. The peak
white level is also clipped to avoid overloading of the following stages and avoiding
over modulation in the transmitter.
Light Control
The scene to be televised must be well illuminated to produce a clear and noise free
picture. The lighting should also give the depth, the correct contrast and artistic
display of various shades without multiple shadows. The lighting arrangements in a
TV studio have to be very elaborate. A large number of lights are used to meet the
needs of ‘key’, ‘fill’, and ‘back’ lights etc. Lights are classified as spot and soft
lights. These are suspended from motorized hoists and telescopes. The up and down
movement is remotely controlled. The switching on and off the lights at the required
time and their dimming is controlled from the light control panel inside a lighting
control room using SCR dimmer controls.
Sound mixing and control
As a rule, in television, sound accompanies the picture. Several microp hones are
generally required for production of complex television programs besides other audio
sources also called marred sound from VTR, and audio tape/disc replays. All these
audio sources are connected to the sound control console. The sounds from different
sources are controlled and mixed in accordance with the requirement of the program.
Split second accuracy is required for providing the correct audio source in
synchronisation with the picture thus requiring lot of skill from the engineer.
Fig 2.9 Sound Mixer
25

26. 2.2.3 Video Storage & Transmission Room (VTR)
Vision mixing and switching
Unlike films, television media allows switching between different sources
simultaneously at the video switcher in Production control room operated by the
Vision Mixer on the direction of the program producer. The producer directs the
cameramen for proper shots on various cameras through intercom and the vision
mixer (also called VM engineer) switches shots from the selected camera/cameras
with split second accuracy, in close cooperation with the producer. The shots can be
switched from one video source to another video source, superimposed, cross faded,
faded in or faded out electronically with actual switching being done during the
vertical intervals between the picture frames. For most of the Video Switcher Mixing
between the sources is possible only if the sources are having timing accuracy
between 50 ns to 200 ns and Burst phase for SC with an accuracy of 1.5 to 5 deg.
Fig 2.10 Vision Mixer
The vision mixer provides for the following operational facilities for editing of TV
programs:-
i.) TAKE: Selection of any input source
ii.) DISSOLVE: Fading out of one source of video and fading in another
26
source of video.
iii.) SUPERPOSITION OF TWO SOURCES: Keypad caption when selected
inlay is superimposed on the background picture.
iv.) SPECIAL EFFECTS: A choice of a number of wipe patterns for split
screen or wipe effects.

27. The selected output can be monitored in the corresponding pre-view monitor. All the
picture sources are available on the monitors. The preview monitors can be used for
previewing the VTR; camera, test signals etc. with any desired special effect, prior to
its actual switching. The switcher also provides cue facilities to switch camera tally
lights as an indication to the cameraman whether his camera is on output of the
switcher.
Character Generator (CG)
Character Generator provides titles and credit captions during production in Roman
script. It provides high resolution characters, different colours for colorizing
characters, background, edges etc. The selected output can be monitored in the
corresponding pre-view monitor. All the picture sources are available on the
monitors. The preview monitors can be used for previewing the VTR; camera, test
signals etc. with any desired special effect, prior to its actual switching. The switcher
also provides cue facilities to switch camera tally lights as an indication to the
cameraman whether his camera is on output of the switcher. Most of the TV centres
have professional quality Betacam SP and DVC Pro recorders. For broadcast quality
playback it has in built correction electronics i.e. a processor which comprises
velocity error compensation, drop-out compensation and time base correction. It also
comprises a digital variable motion unit enabling still reproduction, slow motion and
visible search operation.
Digital Library System
A digital library system can grab and store pictures electronically from live video or
video tape recorder in the form of stills. Thus it is an electronic store for still TV
pictures. A picture is frozen and recorded in memory. It can be numbered in stacks
or individually. Any picture can be sized, cropped and can be provided with a border
of any colour. The memory can be expanded by using multiple disk drives.
Access to Electronic Still Storage System
Some PCRs have access to the electronic still storage system. One replay remote
control of the digital library system is mounted on the video production control table
at the PCR. Still pictures stored in the library system can be recalled and used in
production by selecting them by their addresses either from the local or from the
remote control panel after recomposing if desired.
27

28. 28
2.2.4 Master Switching Room (MSR)
MSR is the Mater Switching Room fuser for transmission of media. It is the
engineering co-ordination centre for a TV station. This room is the centre of activity
for selecting & routing the signal from various sources to transmitter. The Master
Switching Room is certainly room where all different sources from the outside studio
come first here & enroots transmission to different destination lik e Transmitter. The
different incoming sources are TVRO signal (DD-1, DD News) from transmitter, any
live coverage signal or the signal being transmitted from any other of the Doordarshan
studios which are switched here. The output signals are fed to the transmitter for
transmission purpose and some signals are distributed and given to various PCR, VTR
or any other appropriate places.
Fig 2.11 Functional Diagram of MSR
This room comprises of Routine switcher, stab amplifier, Video/Audio distribution
amplifier, frame synchroniser, digital/satellite clock monitoring system, logo
generator vector scope, video monitor. The programmes from TVRO & OB program
are also taken to MSR switcher unit to form part of the 16 inputs. On 16 x 8 switcher
is used for its activity like on air transmission, networking monitoring, etc.

29. The control console panel consisting of controls for routing switcher, stab amplifier,
frame synchronizer etc are stored here & also wave from monitors, vectroscope, video
monitors, logo generators, patch panel for final monitoring. The switcher unit and
other video equipments are in a standard rack.
29
16 x 8 Audio/Video Switcher
16 x 8 switcher has maximum of 16 inputs and 8 independent outputs any one of the
input signals can be switched to any one or to all the channels at the same time using a
common control panel can use it as an audio follow video switcher.
HUM Suppressor
A HUM Suppressor is used for reducing the spurious signals of different potential at
the sending and receiving ends of the transmission lines.
Colour Stabilising Amplifier
Colour Stabilising Amplifier is employed in the video chain for regenerating noise
free sync and blanking free components from an incoming video signal. It is also use
to provide controls for adjusting various components in a video signal so that the
composite colour signal can be adjust to a standard value.
Pulse Distributer
It is used to obtain no. of synchronizing and blanking signals from an output of a sync
generator. With any one SPG centrally located a mechanism of pulse distribution is
required. With each and every 75 ohm destination requires a dedicated 75 ohm
source. If this is not done then cables will be incorrectly terminated, signals will have
the wrong amplitude and will suffer from reflection. Use of PDA provides multiple
feeds to various destinations.

30. 30
Frame Synchronizer
It is used to synchronize the different input signals. The synchronizer is one of the
many television units to use digital storage techniques. The signal to be synchronized
is written in to the store as its own rate and timings. It is read from the storage with
respect to station sync. At the timing and rate of studio centre, thus making it
synchronous. If there are too many outstation feeds a synchronizer with each will
allow mixing them with the other studio sources.
Vectrometer
Every colour has a specific amplitude and phase relations. This should be maintained
to get correct output on the screen. This can be checked on vectrometer, which shows
the amplitude & phase of R, G & B colours. It looks like RADAR screen. It gives the
idea about amplitude and phase of different colours.
Sima Router
Every input and every output is given a specific code. The selected input and the
corresponding output code can be checked on the sigma router.
Change Over Unit
It is used to provide facilities for selecting video signals from one of the two sources.
The changeover of all the inputs can be done from panel or from a remote point.
Waveform Monitor
Waveform Monitor is used to check and monitor video level at exactly 1 Vpp & to
monitor the audio level at 0 dB. The audio level should be kept less than 0 Db. This is
then amplified in low power transmitter.

31. 31
2.2.5 Transmitter
A transmitter can be a separate piece of electronic equipment, or an electrical circuit
within another electronic device. A transmitter and receiver combined in one unit is
called a transceiver. The term transmitter is often abbreviated "XMTR" or "TX" in
technical documents. The information is provided to the transmitter in the form of an
electronic signal, such as an audio (sound) signal from a microphone, a video (TV)
signal from a TV camera, or in wireless networking devices a digital signal from a
computer. The transmitter combines the information signal to be carried with the
radio frequency signal which generates the radio waves, which is often called the
carrier. This process is called modulation. The information can be added to the carrier
in several different ways, in different types of transmitter. In an amplitude modulation
(AM) transmitter, the information is added to the radio signal by varying its amplitude
(strength). In a frequency modulation (FM) transmitter, it is added by varying the
radio signal's frequency slightly. Many other types of modulation are used.
Fig 2.12 BEL MARK III 10kV Transmitter
The antenna may be enclosed inside the case or attached to the outside of the
transmitter, as in portable devices such as cell phones, walkie-talkies, and auto
keyless remotes. In more powerful transmitters, the antenna may be located on top of
a building or on a separate tower, and connected to the transmitter by a feed line
(transmission line).

32. Classification Of Transmitters According To Power
Fig 2.13 Transmitter Classification transmitter based on Power
Fig 2.14 High Power Trasnsmitter
32
A/D,D/A
CONVERTER
DIGITAL VIDEO
COMPENSATOR
VISUAL
MODULATOR
SYNTHESIZER
IF CORRECTOR
VISUAL MIXER
AURAL MIXER
AURAL MODULATOR

33. VISUAL A Fig 2.15 Low Power Transmitter
33
IF
IF
A MOD MOD A OUT DRIVER #A

34. Fig 2.16 Block diagram of BEL MARK III 10kW Transmitter
Various functional stages are described as follows:
34
Crystal Oscillator and Buffer Stage
The crystal oscillator with buffer stage is generally kept together and is shielded by a
metal cover to isolate from other circuits. This crystal oscillator employs a pentode
tube 6 AU 6 or its equivalent, connected as a triode. The frequency of oscillation is
controlled by a quartz crystal and by a variable trimmer capacitor.
The frequency of the medium wave transmitter should be highly stable. For medium
wave transmitter operating in the range of 540 kHz to 1602 kHz, the variation of a
transmitter frequency should be within a tolerance of + 10 Hertz. To maintain a high
stability of the transmitter frequency it is necessary that the oscillator should oscillate
at a particular frequency against variations in voltage and ambient temperature. Hence
the crystal is kept in a constant temperature ovens whose temperature is controlled by
a thermostat and maintained at a 75o + 1.5o C. The oscillator frequency changes
considerably under initial transient condition that is when power is switched ON.

35. However, it is essential to keep it always ready at a stable condition. To facilitate this
separate power supply is provided to feed the oven which can be switched ON and
OFF with the help of a snap switch S3 (Oven) located on the AE panel of the
transmitter. Two crystal units X1 and X2 housed separately in different ovens Z1 and
Z2 viz. a normal and a stand by unit are provided. Either one of them can be selected
by means of change over switch S2.
Exciter
This stage is operated as a class - C amplifier, employing air cooled tetrode type BEL
400 and drives P.A. stage. Screen supply is taken from plate supply. The output is a
tuned circuit consists of a fixed capacitor C 29 (Value of C29 depends on the
operating frequency) and coil L3. L3 is having a flipper, through it, fine tuning can be
made. This stage is modulated about 10 to 20%. A small secondary tap from the
modulation transformer supplies the necessary audio and super- imposes on the DC
Plate supply. When the triodes are anode modulated, the grid must be overdriven in
the carrier condition in order that the drive level will be adequate to sustain the peak
anode current at 100% modulation. Alternatively the drive must be modulated. Hence
the 10 to 20% modulation. With tetrode the same effect is achieved by modulating the
screen enabling the anode current peaks to be attained with the same level as that
required for the carrier only condition. To some extent this ceases the grid dissipation
limit.
35

36. Fig 2.17 Exciter
36
Power Amplifier Stage
This is a class - C power amplifier obtaining the required output by means of three
parallel connected forced air cooled, directly heated triode tubes type BEL 3000. As a
triode tube is used in this stage, neutralization technique is adopted to neutralize, the
grid-plate capacitance. The output circuit is formed by PI (π) and 'L' section made up
of coils and condensers. There is a variable coil to tune the output. A second harmonic
filter is connected at the output which attenuates the harmonics. This filter is a simple
L C circuit tuned to the second harmonic frequency. The output circuit also matches
the plate impedance of about 1100 ohms to the feeder impedance of 230 ohms, which
is carried out at the time of installation of the transmitter using Impedance Bridge.
Crystal Oscillator

37. To oscillate at a consistent frequency, the crystal is kept in a oven. The temperature of
the oven is maintained between 68 to 72o C and the corresponding indication is
available in the meter panel. Crystal oven is heated by + 12 V. One crystal oscillator
with a standby has been provided. It gives an output of 5 V square wave which is
required to drive the Transistor Power Amplifier. The crystal oscillator works
between 3 MHz and 6 MHz for different carrier frequencies. Different capacitors are
used to select different frequency ranges. In addition, variable capacitor is used for
varying the frequency of the crystal within a few cycles. The oscillator frequency is
divided by 2, 4, or 8 which is selected by jumpering the appropriate terminals. The
oscillator Unit gives 3 outputs, one each for RF output, RF Monitoring and RF output
indication.
37
High Pass Filter
The audio input from the speech rack is fed to active High Pass Filter. It cuts off all
frequencies below 60 Hz. Its main function is to suppress the switching transistors
from the audio input. This also has the audio attenuator and audio muting relay which
will not allow AF to further stage till RF is about 70 kW of power.
AF Pre Amplifier
The output of the High Pass Filter is fed to the AF Pre-amplifier, one for each
balanced audio line. Signal from the negative feedback network from the secondary of
the modulation transformer and the signals from the compensator also are fed to this
unit.
AF Pre-Corrector
Pre- amplifier output is fed to the AF Pre-correctors. As the final modulator valve in
the AF is operating as Class B, its gain will not be uniform for various levels of AF
signal. That is the gain of the modulator will be low for low level, input, and high for
high level AF input because of the operating characteristics of the Vacuum tubes.
Hence to compensate for the non linear gain of the modulator. The Pre-corrector
amplifies the low level signal highly and high level signal with low gain. Hum
compensator is used to have a better signal to noise ratio.

38. 38
AF Driver
Two AF drivers are used to drive the two modulator valves. The driver provides the
necessary DC Bias voltage and also AF signal sufficient to modulate 100%. The
output of AF driver stage is formed by four transistor in series as it works with a high
voltage of about -400 V. the transistors are protected with diodes and Zener diodes
against high voltages that may result due to internal tube flashovers. There is a
potentiometer by which any clipping can be avoided such that the maximum
modulation factor will not be exceeded.
AF Final Stage
AF final stage is equipped with ceramic tetrodes CQK-25. Filament current of this
tube is about 210 Amperes at 10V. The filament transformers are of special leakage
reactance type and their short circuit current is limited to about 2 to 3 times the
normal load current. Hence the filament surge current at the time of switching on will
not exceed the maximum limit. A varistor at the screen or spark gaps across the grid
are to prevent over voltages. As the modulator valve is condensed vapour cooled
tetrodes, deionised water is used for cooling. The valve required about 11.5 litres/min.
of water. Two water flow switches WF1 and WF2 in the water lines of each of the
valves protect against low or no water flow. Thermostats WT1 and WT2 in each
water line provide protection against excessive water temp. by tripping the transmitter
up to stand-by if the temperature of the water exceeds 70o C.
Modulation condenser and modulation choke have been dispensed with due to the
special design of the modulation transformer. Special high power varistor is provided
across the secondary winding of the modulation transformer to prevent transformer
over voltages.
Corrector / Divider unit
This unit comprises of 2 sections namely linearity corrector unit and 2 way hybrid
divider. The pre-corrected RF signal is fed to the 2 way hybrid divider which gives 2
outputs which are 90 degree phase difference

39. 39
Dual Driver Unit
This unit houses 2 independent chain of amplifiers capable of delivering +37dBm
output.
2-Way Combiner Unit
It comprises of 2 way 90 degree hybrid combiner, a dummy load, a directional
coupler and a peak power circuit. The combiner unit combines the 80W unit output to
give around 130W visual RF output.

40. 40
2.2.6 Antenna
To transmit and receive a RF signal an antennae is required to be used. In other
words, antennae convert electromagnetic waves into electrical currents and vice versa.
Antennae are used in systems such as radio and TV broadcasting, point-to-point radio
communication, mobile, radar, and space exploration etc. Antennae are most
commonly employed air but can also be operated under water or even through soil
and rock at certain frequencies for short distances. Physically, an antenna is simply an
arrangement of one or more conductors usually called elements in this context. In
transmission, an alternating current is created in the elements by applying a voltage at
the antennae terminals, causing the elements to radiate an electromagnetic field. In
reception, the inverse occurs: an electromagnetic field from another source induces an
alternating current in the elements and a corresponding voltage at the antenna's
terminals.
Some receiving antennae (such as parabolic and horn types) incorporate shape
reflective surfaces to collect EM waves from free space and direct or focus them onto
the actual conductive elements. The performance of an array depends on the number
of elements in the array (generally more elements yields better performance), the
weighting vector used, and the geometry of the a rray. An antennae array (often called
a 'phased array') is a set of 2 or more antennae. The signals from the antennae are
combined or processed in order to achieve improved performance over that of a single
antenna. The antennae array can be used to:
 Increase the overall gain
 Provide diversity reception
 Cancel out interference from a particular set of directions
 Steer the array so that it is most sensitive in a particular direction
 Determine the direction of arrival of the incoming signals
 To maximize the Signal to Interference plus Noise Ratio (SINR)

41. Various types of antennae used in Doordarshan network are as follows:
41
Omnidirectional Antennae
An omnidirectional antenna is an antennae system which radiates power uniformly in
one plane with a directive pattern shape in a perpendicular plane. This pattern is often
described as donut shaped.
Panel Type Antennae
Panel type antennae used Panel Arrays can be designed to provide customized
radiation patterns with or without beam tilt and null fill for specific coverage
requirements. Panel arrays are used for the band I, II, III, IV and V TV and FM. These
types of antennae have been extensively used in Doordarshan network.
Slot Antennae
Slot antennae are used typically at frequencies between 300 MHz and 24 GHz. These
antennas are popular because they can be cut out of whatever surface they are to be
mounted on, and have radiation patterns that are roughly omnidirectional. The
polarization is linear (H or V). The slot size, shape and what is behind it (the cavity)
offer design variables that can be used to tune performance. Doordarshan generally
uses cylindrical slot antennae for transmission.
Whip Antennae
A whip antenna is the most common example of monopole antennae, i.e. antennae
with a single driven element and a ground plane. The whip antenna is a stiff but
flexible wire mounted, usually vertically, with one end adjacent to a ground plane.
The whip antennae can also be called a half-dipole antenna, and as such, has a
toroidal radiation pattern where the axis of the toroid centres about the whip. The
length of the whip determines its wavelength, although it may be shortened with a
loading coil anywhere along the antennae. Whips are generally a fraction of their
actual operating wavelength, with half-wave and quarter-wave whips being very
common. These antennae are widely used, especially for mobile applications and
hand-held radios.

42. 42
Parabolic Reflector Antennae
The most well-known reflector antenna is the parabolic reflector antennae, commonly
known as a satellite dish antennae. Parabolic reflectors typically have a very high gain
(30-40 dB is common) and low cross polarization. They also have a reasonable
bandwidth, with the fractional bandwidth being at least 5% on commercially available
models, and can be very wideband in the case of huge dishes (which can operate from
150 MHz to 1.5 GHz).The smaller dish antennae typically operate somewhere
between 2 and 28 GHz. The large dishes can operate in the VHF region (30-300
MHz), but typically need to be extremely large at this operating band.
Fig 2.18 Types of Antennas
Yagi Antennae
A Yagi-Uda Antennae, commonly known simply as a Yagi antennae or Yagi, is a
directional antennae system consisting of an array of a dipole and additional closely
coupled parasitic elements (usually a reflector and one or more directors). The dipole
in the array is driven, and another element, typically 10 percent longer, effectively
operates as a reflector. Other parasitic elements shorter than the dipole may be added
in front of the dipole and are referred to as directors. This arrangement gives the
antennae directionality that a single dipole lacks.

43. Fig 2.19 Antenna at DDK, Bareilly
Doordarshan is having TV transmitting antennae of following types: panel type
antennae, slot type antennae, super-turnstile antennae; parabolic dish antennae for
uplinking and down linking of RF signal to satellite in the space; and microwave dish
antennae for linking RF signal between two locations.
43

44. CHAPTER 3
44
4.1 TRAINING SUMMARY
The Vocational Training at Doordarshan Kendra, Bareilly gave useful knowledge
which will surely help in future. This training provided an opportunity to learn the
various aspects related to practical implementation of the theoretical concepts of the
field, Electronic and Communication.
Training at DDK, Bareilly taught about the basic existing technology and the
procedures utilised for the television transmission and reception at the Bareilly
Kendra. The working of equipments for the measurement of different parameters like
current, voltage, voltage standing wave ratio, power, waveform etc was also a part of
this four week training. Training at Doordarshan included the basic knowledge about
the different stages starting from capturing the video in the studio or the outside
coverage then addition of special effects or the enhancement through the devices like
audio and video mixers and finally making way to the transmitter section for the
broadcasting of the captured signals. Every stage included in the Doordarshan Kendra
has its own and unique importance and cannot be neglected.

45. CHAPTER 4
45
4.1 CONCLUSION
Doordarshan, the national television service of India, is devoted to public service
broadcasting. It is one of the largest terrestrial networks in the world. Doordarshan is
the first ISO certified channel in India. The largest proportion of viewers of India,
watch Doordarshan. It has good future scope in communication world because largest
network is covered by the Doordarshan only. As now a days there is a huge
competition and everything is getting digitized there is a wide scope for electronics
and communication engineers to show their skills and keep the technology up to date.
Doordarshan, the national television service of India, is devoted to p ublic service
broadcasting. It is one of the largest terrestrial networks in the world.

46. REFERENCES
46
[1] www.ddindia.gov.in
[2] www.scribd.com
[3] www.google.com/imghp
[4] Matter provided at DDK, Bareilly