1

MUFFAKHAM JAH COLLEGE OF

ENGINEERING & TECHNOLOGY

Road No. 3 Banjara Hills, Hyderabad

A Report on Industrial Visit to

Doordarshan Kendra Hyderabad and Doordarshan

Transmitters Complex

Submitted by

Hafsa Dawood

16-04-09-735-001

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ACKNOWLEDGEMENT

Praise and thanks are due to Allah, the Most Beneficent and the Most Merciful, for his guidance

and blessings bestowed upon me. Deepest gratitude to my family for their constant love and

support.

I thank Dr. Kaleem Fathima, Head of Department, ECE, for providing us an opportunity to visit

the Doordarshan Kendra, Ramanthapur and Doordarshan Transmitters Complex, Malakpet.

I’m obliged to Mr. Haneef, Assistant Professor, who has been instrumental in arranging this

industrial visit and who along with Mr. Zuber, Assisstant Professor guided us throughout the

entire tour, providing us with their valuable input.

My sincere thanks to all my teachers for their role in my education.

Finally I thank all my friends for having made this trip a memorable one.

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CONTENTS

Part I – Doordarshan Kendra Ramanthapur

1. Introduction

2. Television Studio

(i) Camera Control Unit

(ii) Production Control Room

(iii) Master Switching Room

3. Earth Station

(i) Up link Segment

(ii) Encoder

(iii) Multiplexer & Modulator

(iv) Transmission

(v) Down link Segment

4. Doordarshan over the years

Part II – Doordarshan Transmitters Complex

1. Doordarshan Transmitters

2. Doordarshan Channels

3. VHF Transmitter

4. UHF Transmitter

5. Receiving Section

6. Transmitting Section

7. Antennae Used

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PART I

5

DOORDARSHAN

KENDRA

HYDERABAD

6

INTRODUCTION

Doordarshan, operated by the Prasar Bharati, is a television broadcaster in India and is an

undertaking of the Government of India. Due to the transmitters and infrastructural facilities of

Doordarshan, it is considered amongst the leading broadcasting organizations throughout the

world. Television came to India on September 15, 1959 with experimental transmission from

Delhi and Doordarshan successfully completed its 50th year on September 2009.

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. It was a modest beginning with a

makeshift studio and low power transmitter. 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 the country and the speech given by the Prime Minister of that time, Indira Gandhi, was

telecast live through out the nation. After this, the 1982 Asian games, Delhi, was also

broadcasted by the channel. Doordarshan gained exceeding popularity during the 1980s with its

new and groundbreaking shows that could easily connect with the urban and rural audiences

alike.

Channels of Doordarshan

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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.

DD News, which was launched by replacing DD Metro, is a 24 hour new 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. 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.

There are seven full fledged centres at Delhi, Mumbai, Kolkata, Chennai, Jalandar, Srinagar,

and Lucknow; eight transmitting centres at Raipur, Jaipur, Mu]affarpur, Gulbarga, Sambalpur,

Hyderabad, Ahmedabad and Nagpur, and relay centres at Gwalior, Kanpur, Pune, Allahabad,

Amritsar, Bengaluru, Mussoorie, Panaji and Asansol. There are also three Upgraha Doordarshan

Kendras (Satellite programme production centres) at Cuttack, Delhi and Hyderabad and also 20

low-power transmitters in many states to provide coverage to national and other programmes

through relays. Doordarshan has 45 transmitters at work, and the programmes reach about 28%

of the population.

Doordarshan Recently, along with Tata Sky, 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. 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 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.

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Television Studio

In general a television studio comprises of

1. Camera Control Unit

2. Production Control Room

3. Master Switching Room

4. Audio Control Unit

The Doordarshan Kendra at Ramanthapur has two studios. The first one is a huge one used for

recording of big events such as musical performances. The second one is used for the

regional transmission of news and for various announcements.

A Television Studio

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Studio Floor

The studio floor is the actual stage on which the actions that will be recorded take place. A studio

floor has the following characteristics and installations:

� decoration and/or sets

� professional video camera (sometimes one, usually several) on pedestals

� microphones

� stage lighting rigs and the associated controlling equipment.

� several video monitors for visual feedback from the production control room (PCR)

� a small public address system for communication

� a glass window between PCR and studio floor for direct visual contact is usually desired, but

not always possible

While a production is in progress, people composing a television crew work the studio floor.

� the on-screen "talent" themselves, and any guests - the subjects of the television show.

� a floor manager, who has overall charge of the studio area stage management, and who

relays timing and other information from the television director.

� one or more camera operators who operate the professional video cameras, though in some

instances these can also be operated from the PCR using remotely controlled robotic pan tilt

zoom camera (PTZ) heads.

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� possibly a teleprompter operator, especially if this is a live television news broadcast

Camera Control Unit

CCU (Camera Control Unit) refers to a range of equipment and operations related to remote

control of video/television camera functions. This can include either partial or complete camera

control. CCU operations are an important component in many types of television production, in

particular multi-camera productions.

The person operating the CCU units is known as a CCU Operator, Vision Controller or (in some

cases) a Technical Director (TD).

Partial CCU Control

This is a common method for controlling camera functions in television production. It is a

professional approach, allowing for maximum control and quality.

Most of the camera functions (framing, focus, etc) are controlled normally by a camera operator,

whilst certain functions (colour balance, shutter speed, etc) are controlled remotely by the CCU

operator. This allows the camera operator to concentrate on framing and composition without

being distracted by technical issues. At the same time the CCU operator, who is a specialist in

the more technical issues, is concentrating on the quality and consistency of the pictures.

In a multi-camera production the CCU operator will usually be responsible for more than one

camera (2-3 cameras is common, but up to 10 is possible). Obviously a large production may

require a number of CCU operators. For example, a 20-camera broadcast could have 5 CCU

operators, each controlling 4 cameras.

The picture below shows a bank of four CCU controllers which are embedded into the desk

workspace in front of the CCU operator. In front of the operator are four monitors showing the

pictures from each camera. These controls are relatively advanced and allow the CCU operator

to:

• Control the iris, shutter speed, black level, gain, etc.

• Adjust colour balances

• Monitor and adjust a wide range of technical parameters

• Send signals to the camera operator

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Sony CCU Controllers

Complete Remote Camera Control

Since the advent of high-performance remote-controlled cameras, CCU can also refer to cameras

which are completely controlled by the CCU operator (the camera itself is unmanned).

Such controllers may include any of the features mentioned above, with the addition of pan/tilt,

zoom and focus controls.

The Technical Director

The Technical Director is the person responsible for setting up and maintaining the technical

parameters of the production's video images. In many cases this is the same person as the CCU

operator, but in any case the two jobs are closely linked.

The TD's responsibilities include making sure all vision sources (cameras, tape machines,

graphic generators, etc) meet the technical requirements for broadcast, and that their outputs are

consistent and stable. In older equipment much of this is done manually by monitoring video

signals with a waveform monitor and vectorscope. In the digital era many of these functions are

performed automatically.

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Fig. Above is the waveform monitor display. The sync pulse is in the center

Fig. The above diagram shows a sync pulse for a color picture

Fig. Above is a vectorscope display of color bars.

Burst is the squiggle pointing straight to the left

Production Control Room

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Facilities in a PCR include:

� A video monitor wall, with monitors for program, preview, VTRs, cameras, graphics and

other video sources. In some facilities, the monitor wall is a series of racks containing

physical television and computer monitors; in others, the monitor wall has been replaced

with a virtual monitor wall (sometimes called a "glass cockpit"), one or more large video

screens, each capable of displaying multiple sources in a simulation of a monitor wall.

� A vision mixer, a large control panel used to select the multiple-camera setup and other

various sources to be recorded or seen on air and, in many cases, in any video monitors on

the set.

� A professional audio mixing console and other audio equipment such as effects devices.

� A character generator (CG), which creates the majority of the names and full digital on-

screen graphics that are inserted into the program lower third portion of the television screen

� Digital video effects, or DVE, for manipulation of video sources. In newer vision mixers, the

DVE is integrated into the vision mixer; older models without built-in DVE's can often

control external DVE devices, or an external DVE can be manually run by an operator.

� A still store, or still frame, device for storage of graphics or other images. While the name

suggests that the device is only capable of storing still images, newer still stores can store

moving video clips and motion graphics.

� The technical director's station, with waveform monitors, vectorscopes and the camera

control units (CCU) or remote control panels for the CCUs.

� In some facilities, VTRs may also be located in the PCR, but are also often found in

the central apparatus room

� Intercom and IFB equipment for communication with talent and television crew

� A signal generator to genlock all of the video equipment to a common reference that

requires colorburst

Master Switching Room

It is the engineering co-ordination center of activity for selecting & routing the signal from

various sources to transmitter and earth station. It is a room where all different sources from the

outside studio comes first here and enroots transmission to different destination like transmitter

& earth station. This room comprises of Routine switcher, Stab amplifier, Video/Audio

distribution amplifier etc. It is the heart of the studio. Most of the switching electronics are kept

here e.g. camera base stations, switcher mainframe, SPG, Satellite receivers,

MW link, DDA & most of the patch panels. Signal is routed through MSR and can be

monitored at various stages

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Master Switching Room

Other Facilities

A television studio usually has other rooms with no technical requirements beyond broadcast

reference monitors and studio monitors for audio. Among them are:

� one or more make-up and changing rooms

� a reception area for crew, talent, and visitors, commonly called the green room.

EARTH STATION

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UP LINK SEGMENT

The earth station is the place from which the TV signals are up linked to the satellite for

reception and re-broadcast . Here digital transmission technique is used and the earth station

handles 3 digital channels within it's IF frequency of 70MHz .The CCVS from the MSR reaches

the earth station through Optical Fiber Cables. The signal is received via a switcher which selects

the appropriate signal . The digital transmitter can simultaneously up link 3 channels. Of these

one of the channel is used for transmission of the regional television channel and another for

internal transmission purposes with New Delhi .The third channel is used to up link programs to

the Delhi studio for the special metro news segments.

ENCODER

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The incoming signal is fed to the encoder panel consisting of MPEG-2 encoders .This digital

equipment compresses the video signal by eliminating the redundant information in the received

signal. This compression enables the usage of 3 separate channels . Hence there are three

encoders along with the necessary switches and signal compression level monitors . The

encoders look like the Home DVD players with a front panel interface .

MULTIPLEXER AND MODULATOR

The compressed signals are fed to a multiplexer unit which combines the three different streams

into a single transport stream . The multiplexer has external controls that enable selection of e

and the clock rate for multiplexing.The output of the multiplexer is modulated using Quadrature

Phase Shift Keying ( QPSK )technique. The IF signal is fed to the Up Converter that increases

the signal frequency to the Giga Hz range to enable satellite communication.

TRANSMISSION

The C - Band transponder used with the satellite INSAT 3A has a up link frequency of 6056 Mhz and a down link frequency of 3831 Mhz . The transponder has a bandwidth of 36 Mhz with

total BW of 40 Mhz and a guard band of 4 Mhz .The up link frequency is then fed to a Klystron

High Power Amplifier which provides the necessary power to the signal for up link to the

satellite. The up link signal has a power of 3KW .The klystron must provide the minimum power

required to be maintained which is specified as the signal Effective Isotropic Radiated Power

(EIRP) and is 30W / 63dBW.The HPA feeds the signal to a parabolic dish through a waveguide.

The waveguide feeds the signal at the Feed Point of the dish .The dish then focuses the EM

waves as a fine pencil beam and directs it to the satellite. The up link uses horizontal polarization

and the down link uses vertical polarization .This up linked signal is received by the transponder

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and is down converted to a slightly lower frequency . This is done in order to reduce the loss of

the signal and is achieved by beating the uplinked signal with a 2 Ghz local oscillator

DOWN LINK SEGMENT

The satellite transmitting antenna also serves as the receiver . In the receiver the conversion

from the C – band to the L – band takes place . The antenna has a Low Noise Block Converter

(LNBC ) unit in the antenna unit itself . This is where the frequency conversion takes place .

Also the received signal is of very low strength due to the high attenuation suffered during

propagation .Hence the LNBC amplifies the signal without causing any distortion to the received

signal .The down link power is fixed at 10W . So the receiving antenna size must be varied to

receive the signal at different regions of the world . Hence the areas that lie at the satellite

footprint receive the signal of good strength. However the areas at the corners tend to receive a

very distorted signal from the satellite. Hence the fringe areas will use receiver dish antennas

of larger diameter. This is so because the received power is directly related to the dish radius.

The areas under direct footprint need only smaller radius dishes. The signal from the antenna unit

is then converted to the common IF frequency of 70 Mhz at the tuner section of the set top box .

The signals are de-multiplexed and then the desired signal is viewed in the monitor .

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Doordarshan over the years

Experimental Service at Delhi (Inaugurated 15.09.1959

By the President of India at Vigyan Bhawan)

School Television 24.10.1961

Daily One Hour Service & Hindi News Bulletin 15.08.1965

Krishi Darshan – Rural Programme 26.01.1967

English News Bulletin 03.12.1971

Commercial Service 01.01.1976

Doordarshan Delinked from Akakshvani 01.04.1976

Delhi Linked with Mussorri 12.08.1977

INSAT-1A Launched 10.04.1982

TV goes Colour & National Programme Introduced 15.08.1982

TV coverage of Asian Games 19.11.1982

INSAT – 1 B Operationalised 15.10.1983

First Sponsored Serial – Hum Log 15.07.1984

DD Metro Launched 09.08.1984

Country wide Classroom Programme produced by UGC 15.08.1984

Second Channel at Delhi 17.09.1984

DD India launched 14.03.1985

Intext Service at Delhi 19.11.1985

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Morning Transmission 23.02.1987

Late Night Film 07.04.1987

Weekly News Bulletin for Hearing Impaired 15.10.1987

Employment News 31.05.1988

INSAT -1C 27.07.1988

Transmitter Complex at Pitampura, Delhi 07.11.1988

Afternoon transmission Programme contribution 26.01.1989

From Bombay

Central Production Centre 06.02.1989

INSAT-1D Operationalised 17.07.1990

News Bulletin introduced in Afternoon Transmission 22.10.1990

IGNOU Telecast 22.05.1991

Recorded version of Question Hour in Parliament 05.12.1991

Introduction of Urdu News 01.05.1992

Metro Channel on Experimental basis 26.01.1993

Satellite link for Metro Kendras 01.04.1993

Extension for Metro Hour & INSAT-2B Operationalised 30.07.1993

World News Separate Bulletin in the Mornings 01.08.1993

Extension of Metro Entertainment Channel 15.08.1993

INSAT-2C Extended Network 07.12.1995

One Hour LIVE Show Delhi LPT 14.11.1997

DD Sports launched ( Round the clock) 01.06.2000

DD Bharati launched 26.01.2002

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DD News 03.11.2003

PART II

21

22

DOORDARSHAN

TRANMITTERS

COMPLEX

Doordarshan network consists of 64 Doordarshan Kendras/Production Centres, 24

Regional News Units, 126 Doordarshan Maintenance Centres, 202 High Power transmitters, 828

Low Power Transmitters, 351 Very Low Power Transmitters, 18 Transposers, 30 Channels and

DTH Service and has a sanctioned strength of 21708 officers and staff of various categories.

Doordarshan Transmitters

Channel HPT LPT VLPT Transposer Total

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National (DD1) 128 747 346 18 1239

DD News 70 81 5 - 156

Others 4 - - - 4

Total 202 828 351 18 1399

Doordarshan Channels

• National Channel (5) : DD1, DD News, DD Bharati, DD Sports and DD Urdu.

• Regional Language Satellite Channel (11) : DD North-East, DD Bengali, DD Gujarati,

DD Kannada, DD Kashir, Dd Malayalam, Dd Sahyadri, DD Oriya, DD Punjabi, DD

Podhigai, and DD Saptagiri.

• Regional State Network (11) : Bihar, Jharkhand, Chhattisgarh, Madhya Pradesh, Uttar

Pradesh, Haryana, Uttrakhand, Himachal Pradesh, Rajasthan, Mizoram and Tripura.

• International Channel (1) : DD India.

Doordarshan has a three-tier programme service - National, Regional and Local.

• The emphasis in the programmes in the National service is on events and issues of

interest to the entire nation.

• The programmes in the regional service focus on events and issues of interest to the

people of that particular State.

• The local service caters to the needs of the populace living in the areas falling within the

reach of a particular transmitter through area specific programmes in the local languages

and dialects.

In addition, the programmes in the national and regional services are also available in satellite

mode to the viewers all over the country.

Programme sourcing: Programmes for different channels of Doordarshan are sourced from :

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• In-house production : Programmes produced by Doordarshan professionals utilizing

Doordarshan infrastructure, including coverage of events 'live' by Doordarshan.

• Commissioned programmes : Programmes produced by persons of proven merit with

funds provided by Doordarshan.

• Sponsored programmes : Privately produced programmes telecast by Doordarshan on

payment of a fee in exchange for Free Commercial Time.

• Royalty programmes : Programmes acquired by Doordarshan from outside producers on

payment of royalty for single or multiple telecasts.

• Acquired Programmes : Programmes/events acquired from foreign companies on

payment of rights fee.

• Educational/Development programmes : Educational and Development programmes

produced by different agencies of the Government.

• Self Financed Commissioning : The initial production cost of these programmes is met

by the private producer. Doordarshan reimburses the production cost to the producer after

commencement of telecast. The programme is marketed by Doordarshan. The scheme

also has provisions for payment of bonus on approved production cost on attainment of

high TRPs, and for reduction of production cost in case of poor performance of

programme.

Terrestrial Coverage of Doordarshan : The coverage of the two terrestrial channels of

Doordarshan is shown below :

Terrestrial Coverage of Doordarshan

Channel

Coverage (%) National average (As on 30.6.2006)

By Area By Population

DDI 79.4 9.4

DD News 24.4 48.5

DD Direct + : Doordarshan's free-to-air Direct-to-Home service DD Direct + was launched by

the Prime Minister on 16 December 2004. Starting with 33 TV channels (Doordarshan/Private)

and 12 Radio (AIR) channels, the capacity of the service was increased 36 TV channels and 20

Radio channels. The signal of this service can be received all over India, except A&N Islands,

with the help of a receiver system. The subscriber base of this service is in excess of 5 million.

National networking service :

• DD National (DD-1),

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• DD News (DD-2),

• DD-Sports,

• DD-Urdu,

• DD-India

• DD-Bharati.

Regional Language Satellite Service : The eleven regional Language Satellite Services are :

• DD-Malayalam

• DD-Saptagiri (Telugu)

• DD-Bengali

• DD-Chandana (Kannada)

• DD-Oriya

• DD-Sahyadri (Marathi)

• DD-Gujarati

• DD-Kashir (Kashmiri)

• DD-Punjabi

• DD-North-East

• DD-Podhigai (Tamil)

At present 40 Doordarshan TV channels including news uplinks are operating through C-band

transponders of INSAT-3A, INSAT-4B, INSAT-3C and INSAT-2E (Additionally IS-10 & IS-

906 INTELSAT leased). All of the Satellite TV channels are digitalized.

Receiving Antenna is LPT (LOW POWER TX) BAND 3, UHF dish antenna with a frequency of

2.5 - 4.5MHz C band signal.

There are two types of transmitters:

1. V.H.F transmitter

2. U.H.F transmitter

VHF TRANSMITTER EXCITER :

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Exciter provides amplitude modulated visual drive of 10MW. Sync peak and a frequency

modulated all drive of 1mW required for the power amplifier stages of 100W TV transmitter at

the designated channel frequencies. It consists of the following individual units:

1. Video signal

2. Low pass filter

3. Video processor

4. Vision modulator

5. IF oscillator

6. Control oscillator

7. Aural modulator

8. Audio signal

9. Power combiner

10. Vestigial side band filter

11. Driver

12. +12V regulated power supply

Video signal:

The video signal is limited to 5 MHz by the low pass filter and group delay by its corrected

group delay introduced by it is corrected by the active group delay equalizer.

Low pass filter:

The LPF is used to limit the video frequency to 5MHz only, and it attenuates the video signal

more than 20dB above 5.5MHz the group delay introduced by steep falling characteristic at 5.5

MHz is corrected using 5-6 active group delay equalizer LPF unit consists of single PCB

consisting of a video amplifier section and clamp pulse generator section.

Video Amplifier:

It amplifies the video signal to level sufficient to modulate the vision carrier in the

visualmodulator unit. The video input to this unit is at level of 1Vp-p clamp pulse

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UHF TRANSMITTER

In this transmitter the frequency range is from 564-574MHz. It requires 500W power.

Linearity corrector :

Linearity corrector operates in the UHF TV band of 470-600MHz and its function is to correct

the non-linearity that occur in power amplifiers operated in this band.

Nonlinearity in TV amplifiers are measured in terms of 3-tone IMD and differential gain . The

linearity corrector is a pre-distorter circuit that is placed ahead of the power amplifier and pre-

corrects the above mentioned distortion so as to reduce them at the power amplifier output.

Up- convertor:

The up-convertor unit combines modulated vision IF an aural IF signals and translates

torespective channels frequency suitable for transmission. The unit has in-built power supply.

Thestatus and fault information are displayed on front panel of the unit.

Splitter:

The linearity corrector output is divide into four equal amplitude and phase outputs to fed four

PA to get the required output power. It is a micro strip circuit desigh based on Wilkinson’s

power divided principles.

Combiner:

The two way power combiner is a sub unit in the 500W transmitter there are such units. Two

way combiner is used to combine the outputs of four amplifiers. For the first level combining

pairs of amplifiers are combined output or pairs of amplifiers is combined in a second kevel of

combining resulting in 600W peak sync output power. All units are identical electrically and

mechanically and are interchangeable. It is based on the Wilkinson’s power combiner principle.

The combiner is realized as a micro strip line on a PCB substrate with a isolation resistor for

isolating all the ports.

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RECEIVING SECTION

The parabolic dish antenna is metal structure with a shape of half circle, and apart from that at a distance a

feed arm is held with support in air to which a low noise amplifier in addition o the low noise block

convertor and the internal relay station there is a digital broadcast receiver in for monitoring and later on re-

transmission of the signal is done in the transmitting section.

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TRANSMITTER SECTION

The broadcasting range of a transmitter depends both on its power (measured in watts) as well as the

frequency of the transmitted signals. With the advent of satellites it is possible to beam signals both in VHF

and UhF (ultra highfrequency) range to geostationary satellites, which can then transmit these signals back

to another far off location on Earth.

30

Various types of antennae used in Doordarshan network are as follows

• Omnidirectional Antennae

• Panel Type Antennae

• Slot Antennae

• Whip Antennae

• Parabolic Reflector Antennae

• Yagi-Uda Antennae

Omnidirectional Antenna Panel Type Antenna

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Slot Antenna Whip Antenna

Parabolic Reflector Antenna Yagi-Uda Antenna

Doordarshan is having TV transmitting antennae of following types:

• Panel type antennae, slot type antennae, super-turnstile antennae

• Parabolic dish antennae for up linking and down linking of RF signal to satellite in the space

• Microwave dish antennae for linking RF signal between two locations.

32

The basic requirements for deciding the quality of antennae includes

• Gain of the antennae

• Radiation pattern of antennae

• V.S.W.R of antenna

• Ruggedness of the antennae

Doordarshan has bought TV transmitting antennae from

• Dielectric, USA

• R.F.S., Australia

• S.W.R., USA

• Jampro, USA

• Katherine, Germany

• SIRA, Italy.

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Conclusion

The industrial visit to Doordarshan Kendra Hyderabad and Doordarshan Transmitters Complex

was a successful one.

We understood the working of a Doordarshan Kendra in detail. We observed the working of a

television studio in detail and the various stages involved in recording a programme. We

witnessed the proceedings of a live news update.

We also learned about the procedure of transmission, reception of a channel.