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8/24/2014 TRAINING REPORT DOORDARSHAN KENDRA

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9th July 2013

Posted 9th July 2013by Kunal Kishor

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9th July 2013

Training Report

On

DOORDARSHAN KENDRA

Submitted in the partial fulfillment of the requirement for the award of

degree of

Bachelors of Technology

in Electronics & Communication Engineering

Submitted by:

Name: KUNAL KISHOR

Name and Location of Company: DOORDARSHAN KENDRA
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MUZAFFARPUR

ACKNOWLEDGEMENT

I want to thanks to Mr. R. sahni sir and Mr. B.S. chaudhary sir because he give me right

concept to complete this training .Also I want to thanks doordarshan Kendra because

different types of metterials are present there help me a lot .

Doordarshan Kendra has provided such a big support in marking this training work

because it would be possible without the books available in the industry

INDEX

Chapter

1. Introduction.

2. History.

3. Satellite Communication.

3.1 Satellite orbits.

3.2Antenna.

4. Propagation modes.


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5. TV studio .

5.1 Procedure in recording.

5.2 Procedure in transmission.

5.3 Video Signal Generation.

5.4 CCVS.

5.5 Components of TV studio.

6. TV Camera.

6.1 Camera lens.

6.2 Transducer.7. Lighting.

8. Microphone.

8.1 Types of microphone.

9. Video chain.

10. Audio chain.

11. Vision Mixer.

11.1 switchin .

12. MSR.

13. Earth Station.

13.1 componenet.

14. Transmitter.

15. Receiver.

16. ENG.

17. OB Van.


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18. DD Direct+ DTH.

19. Future scope.

20. Conclusion.

Abbreviation CCVS COLOR COMPOSITE VIDEO CHAIN

ENG ELECTRONICS NEWS GATHERING

LOS LINE OF SIGHT

MSR MASTER SWITCHING ROOM

VM VIDEO MIXER

CG COMPUTER GRAPHICS

PDA PARABOLIC DISH ANTENNA

IRD INTEGRATOR RECEIVER

DECODER

LNA LOW NOISE AMPLIFIER

LNBC LOW NOISE BLOCKCONVERTER


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Electronics &

Communication

Chapter 1-

INTRODUCTION

Doordarshan is the public television broadcaster of India and a division of Prasar Bharti,

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.

Doordarshan Kendra is amilestone in the field of entertainment and education media

source. Doordarshan, muzaffarpur is the Program Production Center and transmition ..

The studios are housed at same campus and the transmitter is located at the

muzaffarpur.

AIR and Doordarshan aims to provide information, education and entertainment for

the public. Its network of 1400 terrestrial transmitters cover more than 90.7% of

India's population.

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Electronics &

Communication

Chapter 2-

HISTORY

The birth of broadcasting in India has started on an experimental basis in year 1921

whenTimes of India in collaboration with P&T department broadcasts a musical

programme. In the year 1930 radio broadcasting started operating under the Indian

broadcasting company. Government took over the charge of broadcasting in March

1935, a separate office of the controller of broadcasting was created. The land mark in

the history of broadcasting is change of name of the Indian broadcasting to AIR in 1936and in same year Delhi station was formed. From 1936 onwards the development of

AIR was very slow, nine stations were opened up in different places like Delhi,

Calcutta, Bombay, madras, lucknow and tiruchi. From 1956 onwards AIR was

popularly known as akashwani.

On 12thNovember 1947 the voice of Gandhi ji was broadcasted in AIR and since then

it is celebrated as broadcasting day. Television (Doordarshan) started in India in the

year 1959 with black and white transmission. The black & white transmission was

converted fully into colour in 1982 during Asian games.

Electronics &

Communication

Chapter 3- SATELLITE

no. Dynamic V iew s template. Pow ered by Blogger.
http://www.blogger.com/


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COMMUNICATION

In telecommunications, the use of artificial satellites to provide communication links

between various points on Earth. Satellite communications play a vital role in the global

telecommunications system. Approximately 2,000 artificial satellites orbiting Earth relay

analog and digital signals carrying voice, video, and data to and from one or many

locations worldwide.

Satellite communication has two main components: the ground segment, which consists

of fixed or mobile transmission, reception, and ancillary equipment, and the space

segment, which primarily is the satellite itself. A typical satellite link involves the

transmission or uplinking of a signal from an Earth station to a satellite. The satellite then

receives and amplifies the signal and retransmits it back to Earth, where it is received

and re-amplified by Earth stations and terminals. Satellite receivers on the ground

include direct-to-home (DTH) satellite equipment,mobile reception equipment in

aircraft, satellite telephones, and hand held devices.

3.1 SATELLITE ORBITS:

a) GEOs = Geostationary Earth Orbits.

b) LEOs -= Low Earth Orbits. c) MEOs = Medium

Earth Orbits.

1. Geostationary orbit

A circular orbit 35,785 km (22,236 miles) above Earths Equator in which a satellites

orbital period is equal to Earths rotation period of 23 hours and 56 minutes. A

spacecraft in this orbit appears to an observer on Earth to be stationary in the sky. This

particular orbit is used for meteorological and communications satellites. The

geostationary orbit is a special case of the geosynchronous orbit, which is any orbit with

a period equal to Earths rotation period.

2. Low- Earth-orbiting satellites

A Low Earth Orbit (LEO) typically is a circular orbit about 400 kilometers above the

earths surface and, correspondingly, a period (time to revolve around the earth) of

about 90 minutes. Because of their low altitude, these satellites are only visible from within

a radius of roughly 1000 kilometers from the sub-satellite point. In addition, satellites in


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low earth orbit change their position relative to the ground position quickly. So even for

local applications, a large number of satellites are needed if the mission requires

uninterrupted connectivity.

Satellite communication

Started in 1960.

Uses Geo Stationary Satellite.

Operates in C-Band & Ku-Band.

Started in India in 1975.

First Indian Satellite INSAT launched in 1982.

Gulf War brought satellite television to prominence

3.2-Antennas:-

Antenna (or aerial) is a transducer that transmits or receives electromagnetic waves. In

other words,antennas convert electromagnetic radiation into electrical current, or vice

versa. Antennas generally deal in the transmission and reception of radio waves.

Types of antenna:

Isotropic antenna (idealized)

Radiates power equally in all directions

Dipole antennas

Half-wave dipole antenna (or Hertz antenna)


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Quarter-wave vertical antenna (or Marconi antenna)

Parabolic Reflective Antenna

A parabolic antenna is a high-gain reflector antenna used for radio, television and

datacommunications, and also for radio location (radar),on the UHF and SHF parts of

the electromagnetic spectrum. The relatively short wavelength of electromagnetic

radiation at these frequencies allows reasonably sized reflectors to exhibit the

desired highly directional response for both receiving and transmitting. A

typical parabolic antenna consists of a parabolic reflector with a small feed

antenna a tits focus. To find the focus, reflect the light of a flashlight off of the

dish. When the reflected beam is parallel, the flashlight is at the focus. The

reflector is a metallic surface formed into a paraboloid of revolution and

(usually) truncated in a circular rim that forms

the diameter of the antenna. This paraboloid possesses adistinct focal point

by virtue of having the reflective property of parabolas in that a point light

source at this focus produces a parallel light beam aligned with the axis of

revolution. The feed antenna at the reflector's focus is typically a low-gain

type such as a half-wave dipole or a small waveguide horn.

Electronics

& Communication

Chapter 4 PROPAGATION

MODEDS


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Ground-wave propagation

Sky-wave propagation

Line-of-sight propagation

Electronics &

Communication

Chapter 5 - TV

STUDIO

Doordarshan has two studio halls. One is used as News Room and the other

one is used for shooting various programs. Artificial sets are created in the

studio hall according tor equirements of the program to be shooted.

5.1-PROCEDURE IN REORDING

Set is designed in studio as per conceptual thought of program

producer.

Floor plan is envisaged. Lighting, Audio and placement of the cameras is arranged as per floor

plan.

Pre testing of cameras, microphones, VCRs etc. is done before

recording.

Recording begins and desired camera / mike are selected through VM/

Audio console as per command of producer. Program is recorded on

VCR.

5.2-PROCEDURE IN TRANSMISSION

The programs are transmitted as per the daily cue sheet.

Normal transmission hours are 1600-2000 Hrs.

Cue sheet is discussed daily by program and technical staff for details


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in it and for any last moment changes if any.

After getting D-link caption from Delhi end program is played from

VCR /Server. The program is uplinked by Earth Station.

The program is also transmitted to transmitter at HPT Nahargarh via

MW link.

During our slot, both live as well as recorded programs are transmitted.

Around 2000 Hrs after getting linking caption from DD# 1, the signal

from DD#1 is selected and accordingly transmitted by HPT/ ES.

5.3-Video signal generation

Video is nothing but a sequence of pictures. The image we see is maintained in our eye

for 1/16sec. So if we see images at the rate more than 16 pictures/sec, our eyes cannot

recognize the difference and we see the continuous motion. In movies camera and movie

projector it is found that 24 fps is better for human eyes. TV system could also use this

rate but in PAL system 25fpm is selected. In TV cameras image is converted in

electrical signal using photosensitive material. Whole image is divided into many micro

particles known as pixels. These pixels are small enough so that our eyes cannot

recognize pixels and we see continuous image. Thus, at any particular instance there are

almost infinite numbers of pixels that need to be converted in electrical signal

simultaneously for transmitting picture details. How ever this is not possible practical

because it is no feasible to provide a separate path for each pixel. In practice this

problem is solved by method known as Scanning in which information is converted

one by one pixel, line by line and frame by frame.

5.4-COLOUR COMPOSITE VIDEO SIGNAL

Active waveform comprises of 2 signals:


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Luminance(Y)-black and white

Chrominance(C)- colour signal

5.5-COMPONENTS OF TV STUDIO

Camera

Lighting

Microphones

Vision mixer and Audio consoles

MSR

VCR /Servers

Acoustics

Post production and video effects

supporting services like AC, UPS

Chapter 6- TV

CAMERA

A TV Camera consists of three sections:

a) A Camera lens and optical block

b) A transducer or pick up device

c) Electronics

6.1-CAMERA LENS

The purpose of the camera lens is to focus the optical energy at the


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face plate of a pickup device i.e. to form an optical image. The lens

has following sections:

1.Main focus section

2. Zoom section with manual or servo mode operation.

3.Servo drive assembly for Zoom and iris control.

4. Aperture section with manual or auto mode.

5. Back focus section with adjustment facilities for back and micro

focus.

6.2- TRANSDUCER PICK UP DEVICE

R, G & B signals, as separated by the optical block are converted to electrical signal in

the transducer section of the camera. It is then processed in camera electronics to give CCVS

(color composite video signal) output.

Chapter 7-

LIGHTING

Lighting for television is very exciting and needs creative talent. There is always a

tremendous scope for doing experiments to achieve the required effect. Light is a kind

of electro magnetic radiation with a visible spectrum from red to violet i.e. wavelength

from 700 nm to 380


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Nm respectively.

Basic three pointing lighting

Key light:- It gives shape and modeling by a casting shadow. It is treatedas a sun in

the sky and should cast only one shadow.

Fill light:- Controls the lighting contrast by filling in shadows.It can also provide catchlights in the eyes.

Back light:-Separates the body from the background, gives roundness to the subject

and reveals texture.

Background lights:- Separates person from the background and reveals

background interest and shape.

Lighting equipments:-

HMI lights compared to standard incandescent lights deliver five times the light output

per watt. They generate less heat, which is an important consideration when shooting

inside in a confined space. (HMI stands for Hydrargyrum Medium Arc-length Iodide).

The light on the left side of this picture is a HMI light; the one on the right a standard

quartz light.

Cycs (large, seamless, neutral backgrounds) can be lit from the top and bottom with

cyclights.The one here sits on the studio floor and is directed up at the background.

Chapter 8-

MICROPHONES

A microphone is an acoustic-to-electric transducer or sensor that converts sound in to

an electrical signal.

8.1- TYPES OF MICROPHONES


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1.CONDENSER MICROPHONE:-

In a condenser microphone also called a capacitor microphone or electrostatic

microphone, the diaphragm acts as one plate of a capacitor, and the vibrations produce

changes in the distance between the plates.

2. ELECTRET CONDENSER MICROPHONE

An electret microphone is a relatively new type of capacitor microphone invented at Bell

laboratories in 1962 by Gerhard Sessler and Jim West. An electret is a ferroelectric

material that has been permanently electrically charged or polarized. The name comes

from electrostatic and magnet; a static charge is embedded in an electret by alignment of

the static charges in the material, much the way a magnet is made by aligning the

magnetic domains in a piece of iron.

3. DYNAMIC MICROPHONE:-

Dynamic microphones work via electromagnetic induction. They are robust, relatively in

expensive and resistant to moisture. This coupled with their potentially high gain before

feedback makes them ideal for on-stage use. Moving-coil microphones use same

dynamic principle as in loudspeaker, only reversed.

4. RIBBON MICROPHONE:-

Ribbon microphones use a thin, usually corrugated metal ribbon suspended in a

magnetic field. The ribbon is electrically connected to the microphone's output, and its

vibration within the magnetic field generates the electrical signal. Ribbon microphones

are similar to moving coil microphones in the sense that both produce sound by means

of magnetic induction.

5. PIEZO ELECTRIC MICROPHONE:-

A crystal microphone or piezo microphone uses the phenomenon of piezoelectricity -

the ability of some materials to produce a voltage when subjected to pressure

- to convert vibrations into an electrical signal.

6. LASER MICROPHONE:-

Laser microphones are often portrayed in movies as spy gadgets. A laser beam is aimed


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at the surface of a window or other plane surface that is affected by sound. The slight

vibrations of this surface displace the returned beam, causing it to trace the sound wave.

The vibrating laser spot is then converted back to sound. In a more robust and

expensive implementation, the returned light is split and fed to an interferometer, which

detects movement of the surface.

7. FIBER OPTIC MICROPHONE:-

A fiber optic microphone converts acoustic waves into electrical signals by sensing

changes in light intensity, instead of sensing changes in capacitance or magnetic fields as

with conventional microphones.

Chapter 9-

VIDEO CHAIN

The video we see at our home is either pre-recorded in studio or live telecasted. Block

diagram shown in fig illustrates different chains of video recording, video playback,

news, and live broadcasting. In First chain we will understand studio program recording.

Camera output from the studio hall is sent to CCU where many parameters of videosignals are controlled. Output signal of CCU after making all corrections is sent to VM

in PCR-1 (production control room).Output of 3 to 4 cameras comes here and final

signal is selected here using VM according to a directors choice.

The final signal from VM is sent to VTR. VTR uses both analog and digital tape

recording system. At the time transmitting this pre recorded program cassettes is played

in to respective in VTR room. Signal from VTR is sent to PCR-2. PCR-2 has one VM,

video monitoring system, and CG (Computer Graphics). From PCR-2, signal travels


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CUT

The cut is an instantaneous switch from one picture to another. It avoids the frame roll &

flash evident, on picture at the moment of cutting.

MIX

It uses additive mixing. The transitions here are less pronounced. As the faders are

operated, the established picture fades away, while the new picture progressively.

Chapter 12- MASTER

SWITCHING ROOMMaster switching room (MSR) is used for transmission media. 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 outsidestudio 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. Signal can be monitored at various

stages.

AUDIO CONSOLE

It has many input sources such as microphones, VCR/server, IRDs, tone generators.

Out of these i/p, any source can be taken on o/p Audio level of Sources can be

adjusted and audio effects can be added.

Chapter 13- EARTH

STATION

The digital earth station operates in the frequency range of 5.85 GHz to 6.425 GHz

for transmission and 3.625 to 4.24 GHz for reception of signals. The whole system

operates with DVB/MPEG2 Standards. The base band processor subsystem and base

band monitoring subsystem operates in fully digital domain. An OFC carries digital base


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band signal from studio to earth station site to minimize the noise and interference. It is

controlled by a PC called NMS PC. The compression segment has an

MPEG encoder, digital multiplexer and digital modulator. The monitoring and receiving

segment comprises of two digital receivers for receiving and decoding program. The

output of modulator (70 MHz) is sent to an up converter. The up converted signals are

sent to an HPA. Then this signal is given to a PDA (parabolic dish antenna) for up

linking to satellite. The uplinked signal is received again by the same PDA for monitoring

purposes. The signal between earth station and satellite are given along line of sight

which means there must be a clear path from earth to satellite. The uplink signal is fed

from the earth station by a large PDA. The satellite is equipped with its own dish

antenna which receives the uplink signals and feeds them to a receiver. The signal is then

amplified and changed to a different frequency which is downlink frequency. This is

done to prevent interference between uplink and downlink signals. The down linked

signal is then again sent to the transmitter which again retransmits it. Each satellite has a

transponder and a single antenna receives all signals and another one transmits all signals

back. A satellite transmits signals towards earth in pattern called the satellite footprint of

the satellite. The footprint is strongest at centre and the footprint is used to see if the

earth station will be suitable for the reception of the desired signal. Converts The parts

of the DES are Antenna subsystem including LNA Antenna control unit, beacon

tracking unit, beacon tracking receiver and up converter system high power

amplifier and power system. The system operates in 2 +1mode and is compliant with

DVBMPEG 2standards. The base band processor subsystem and base band

monitoring system operates in digital domain. An OFC contains the digital base band

signal for studio to earth station to minimize noise interference The network management

system or NMS monitors and controls baseband equipments compression equipments

and test instruments like video audio generation and video audio analyzer. They are

provided to ensure quality of transmission and help trouble shoot.The base band

segment comprises of baseband subsystems at studio site and base band subsystem at

earth station site. This baseband segment processes two video Programmes. The base

band segment is monitored and controlled using a PC placed near the base band earth

station equipments called base band NMS PC. The compression segments comprises

of Mpeg encoders in 2 +1 configuration for providing redundancy. It also comprises of

digital multiplexers and digital modulators in 1 +1 configuration. The compression

segment is monitored and controlled by compression NMS PC. The receive and

monitoring segment consists of two digital receivers for receiving and decoding of the

video programs and one ASI to SDI decoder for decoding of the transport stream for

monitoring video programs at the multiplexers output. RF NMS PC is placed near the

receive monitoring segment and video audio generator placed in the base band segment.


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For monitoring of video programs professional video monitor, LCD video monitor and

audio level monitor are provided in the base band segment. An operator console has

one 14 professional video monitor a video audio monitor unit for quantitative monitor

of video programs and a personal computer for centralized merit and contention of earth

station sub system.

13.1 COMPONENTS

PDA(parabolic dish antenna)

IRD(Integrator receiver decoder)

Multiplexer

Encoder

FEED

LNA(Low noise amplifier)/LNBC(low noise block converter)

Waveguide

HPA(TWTA, SSTA, Klystron)

Up Converter

Digital Earth Station

Earth station is the main part which communicates with satellite in which up linking and

downlinking of the signal into/ from the satellite takes place for TV transmission. Earth

station is a purely digitization version. The signal is uplinked from the earth station and

received by many downlink centers in TV broadcasting. It is a very important part of

satellite communication system for broadcasting of signals. A ground-based receiving or

transmitting/ receiving station in a satellite communications system. The counterpart to

the earth station is the satellite in orbit, which is the "space station." Earth stations usedish-shaped antennas, the diameters of which can be under two feet for satellite TV to

as large as fifty feet for satellite operators. Antennas for space exploration have

diameters reaching a hundred feet.

Multiplex, Modulate and Up convert

An earth station is generally made up of a multiplexor, a modem, up and down

converters, a high power amplifier (HPA) and a low noise amplifier (LNA). Almost all


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transmission to satellites is digital, and the digital data streams are combined in a

multiplexor and fed to a modem that modulates a carrier frequency in the 50 to 180

MHz range. An up converter bumps the carrier into the gigahertz range, which goes to

the HPA and dish. Down convert,

Demodulate and De multiplex

For receiving, the LNA boosts the signals to the down converter, which lowers thefrequency and sends it to the modem. The modem demodulates the carrier, and the

digital output goes to the demultiplexing device and then to its destinations.

Earth Station classification

Analog Earth Station


ASNG

DSNG

C-band or Ku-band

Problems of Analog

One programme per channel/transponder

Comparatively noisy

Ghosts in Terrestrial Transmission

Lower quality with respect to VCD, DVD digital medium

Fixed reception

Why Digital?

More programmes per channel/Transponder i.e. spectrum efficient.

Noise-Free Reception.

Ghost elimination.

CD quality sound & better than DVD quality picture.


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Reduced transmission power.

Flexibility in service planning.

Process involved in transmission of signal

Up-Conversion

High power amplification

Transmission

Reception Up-Converters

The up-conversion is required to raise the frequency of the signal in desired band:

C- band, Extended C-band or Ku-band before transmission. The input to up converteris 70 MHz (output of modulator) and output of Up-converter is fed to HPA. The up-

conversion may be done in stages or in one stage directly. The 70 MHz signal is first

converted into L band and then L band signal raised to desired frequency band.


The high power amplifier is used for the final power amplification of the digital RF signal

in C-band/Ku band that is fed to the antenna. The important parameters of HPAs are:

1. Frequency range

2. Output power at flange

3. Bandwidth

4. Gain variation (1.0db (max.) for 40 MHz (narrow band)

5. 2.50db for full bandwidth.

The different types of HPAs are

1. KHPA - Klystron High Power Amplifier

2. TWTA -Traveling Wave Tube Amplifier

3. SSPA- Solid state Power Amplifier


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Chapter 14-

TRANSMITTER

The most widely used narrow beam antennas are reflector antennas. The shape is

generally a paraboloid of revolution.

For full earth coverage from a geostationary satellite, a horn antenna is used. Horns are

also used as feeds for reflector antennas.

A small earth terminal, the feed horn is located at the focus or may be offset to one side

of the focus.

Large earth station antennas have a sub reflector at the focus. In the Cassegrain design,

the sub reflector is convex with an hyperboloid surface, while in the Gregorian design it

is concave with an ellipsoidal surface.

These antennas are used to transmit signal from earth station to satellite.

Chapter 15-

RECEIVER



1.

For full earth coverage from a geostationary satellite, a horn antenna is used. Horns arealso used as feeds for reflector antennas.

2. They are basically used to receive signals from the satellite which were transmitted by

transmitter.

3. All the waves which fall on receiver are being focused on the feeder which is placed at

the center of receiver antenna.

4. This feeder collects all the waves and sends to master switching room through cable

sand wires.


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5. After that again down conversion and decoding of signals takes place and in this manner

we receive our information.

Chapter 16 ELECTRONIC NEWS

GATHERING

ENG gather news from different outside locations.

Its components:

1. Camera

2. Tripods

3. Mikes

4. Lights

5. Camera battery

6. Camera charger

7. Camera adapter

8. Headphone

9. Camera cassette

The job of journalists is fulfilled only when their news reaches the viewers, this is why

they long for great challenge ability to be present anywhere, anything. This means

faster news from anywhere anytime to everywhere. Further there is a need to send news

footages in the shortest possible time and practically from any location. Technologically,

Doordarshan has always been far ahead of its competitors. When it came to remote


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newsgathering, Doordarshan has set precedence by using innovative and cost effective

methods.

Chapter

17- OB Van

Outside broadcasting is the production of television or radio programmes (typically to

cover news and sports events) from a mobile television studio. This mobile control room

is known as an "Outside Broadcasting Van", "OB Van", "Scanner" (a BBC term),

"mobile unit", "remote truck", "live truck", or "production truck". Signals from cameras

and microphones come in to the OB Van for processing and transmission. A typical OB

Van is usually divided into 5 parts:

The 1st and largest part is the production area where the director, technical director,

assistant director, character generator operator and producers usually sit in front of a

wall of monitors. This area is very similar to a Production control room. The technical

director sits in front of the video switcher. The monitors show all the video feeds from

various sources, including computer graphics, cameras, video tapes, video servers and

slow motion replay machines. The wall of monitors also contains a preview

monitor showing what could be the next source on air and a program monitor that

shows the feed currently going to air or being recorded. Behind the directors there is

usually a desk with monitors for the editors to operate. It is essential that the directorsand editor are in connection with each other during events, so that replays and slow-

motion shot scan be selected and aired.

The 2nd part of a van is for the audio engineer; it has a sound mixer. The audio

engineer can control which channels are added to the output and will follow instructions

from the director.

The 3rd part of van is video tape. The tape area has a collection of VTRs and may also

house additional power supplies or computer equipment.

The 4th part is the video control area where the cameras are controlled by 1 or 2

people to make sure that the iris is at the correct exposure and that all the cameras look

the same.

The 5th part is transmission where the signal is monitored by and

engineered for qualitycontrol purposes and is transmitted or sent to other


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trucks.

Chapter 18- DD

Direct+ DTH

DD Direct:

Carries all channels of DD directly to homes.

Also carries few private channels and radio channels of AIR.

Features:-

Cost effective alternate to cable TV.

One time expenditure for procuring receive system by viewer.

No monthly/activation charges from subscriber.

No smart card/CAM module required for reception.

Receive Eqpt. consists of a 60/90cm Dish Antenna, a Block converter

and a Set Top Box (STB). STB readily available in the open market.

Dealers of the equipment available all over the country.

Indicative cost of the receive system Rs 3000 to Rs 3500.


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Cost likely to come down further with volumes.

Doordarshan, the national television service of India, is devoted to public

service broadcasting. It is one of the largest terrestrial networks in the world. In

my Industrial training at Doordarshan Kendra, Jaipur, I have gained useful

knowledge which will surely be of great help in future. This training gave me

an opportunity to learn the practical aspects of the knowledge of my field ofinterest, Electronics and communication.

Chapter 19 :

Fututre scope

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 viewer of India ,watching

Doordarshan. It has good future scope in communication world. Because largest

network 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.

In Doordarshan, all the electronic devices used are to be operated by skilled engineers.

It provides with good pay scales.

The selection for the posts is through UPSC examinations.

Chapter


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20 conclusion


broadcasting.

It is one of the largest terrestrial networks in the world. In my Industrial training at

Doordarshan Kendra, muzaffarpur, I have gained useful knowledge which will surely be

of great help in future.

This training gave me an opportunity to learn the practical aspects of the knowledge of

my field of interest, Electronics and communication.


Location: Jalandhar, Punjab, India

0 Add a comment

9th July 2013

Training Report

On

DOORDARSHAN KENDRA

Submitted in the partial fulfillment of the requirement for the award of

degree of

Bachelors of Technology
http://reportsummertraining.blogspot.com/2013/07/v-behaviorurldefaultvmlo.htmlhttp://maps.google.com/maps?q=Jalandhar%2C%20Punjab%2C%[email protected],75.57618290000005&z=10https://plus.google.com/112273954873096052071


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in

Electronics & Communication Engineering

Submitted by:

Name: KUNAL KISHOR

Name and Location of Company: DOORDARSHAN KENDRAMUZAFFARPUR

ACKNOWLEDGEMENT

I want to thanks to Mr. R. sahni sir and Mr. B.S. chaudhary sir because he give me right

concept to complete this training .Also I want to thanks doordarshan Kendra because

different types of metterials are present there help me a lot .

Doordarshan Kendra has provided such a big support in marking this training work

because it would be possible without the books available in the industry

INDEX

Chapter

1. Introduction.


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2. History.

3. Satellite Communication.

3.1 Satellite orbits.

3.2Antenna.

4. Propagation modes.

5. TV studio .

5.1 Procedure in recording.

5.2 Procedure in transmission.

5.3 Video Signal Generation.

5.4 CCVS.

5.5 Components of TV studio.

6. TV Camera.

6.1 Camera lens.

6.2 Transducer.

7. Lighting.

8. Microphone.

8.1 Types of microphone.

9. Video chain.

10. Audio chain.

11. Vision Mixer.

11.1 switchin .

12. MSR.

13. Earth Station.


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13.1 componenet.

14. Transmitter.

15. Receiver.

16. ENG.

17. OB Van.

18. DD Direct+ DTH.

19. Future scope.

20. Conclusion.

Abbreviation CCVS COLOR COMPOSITE VIDEO CHAIN

ENG ELECTRONICS NEWS GATHERING

LOS LINE OF SIGHT

MSR MASTER SWITCHING ROOM

VM VIDEO MIXER

CG COMPUTER GRAPHICS

PDA PARABOLIC DISH ANTENNA

IRD INTEGRATOR RECEIVER

DECODER

LNA LOW NOISE AMPLIFIER


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LNBC LOW NOISE BLOCK

CONVERTER

Electronics &

Communication

Chapter 1-

INTRODUCTION

Doordarshan is the public television broadcaster of India and a division of Prasar Bharti,

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.

Doordarshan Kendra is amilestone in the field of entertainment and education media

source. Doordarshan, muzaffarpur is the Program Production Center and transmition ..

The studios are housed at same campus and the transmitter is located at the

muzaffarpur.

AIR and Doordarshan aims to provide information, education and entertainment for

the public. Its network of 1400 terrestrial transmitters cover more than 90.7% of

India's population.


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Electronics &

Communication

Chapter 2-

HISTORY

The birth of broadcasting in India has started on an experimental basis in year 1921

whenTimes of India in collaboration with P&T department broadcasts a musical

programme. In the year 1930 radio broadcasting started operating under the Indian

broadcasting company. Government took over the charge of broadcasting in March

1935, a separate office of the controller of broadcasting was created. The land mark in

the history of broadcasting is change of name of the Indian broadcasting to AIR in 1936

and in same year Delhi station was formed. From 1936 onwards the development of

AIR was very slow, nine stations were opened up in different places like Delhi,

Calcutta, Bombay, madras, lucknow and tiruchi. From 1956 onwards AIR was

popularly known as akashwani.

On 12thNovember 1947 the voice of Gandhi ji was broadcasted in AIR and since then

it is celebrated as broadcasting day. Television (Doordarshan) started in India in the

year 1959 with black and white transmission. The black & white transmission was

converted fully into colour in 1982 during Asian games.


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Electronics &

Communication

Chapter 3- SATELLITE

COMMUNICATION

In telecommunications, the use of artificial satellites to provide communication links

between various points on Earth. Satellite communications play a vital role in the global

telecommunications system. Approximately 2,000 artificial satellites orbiting Earth relay

analog and digital signals carrying voice, video, and data to and from one or many

locations worldwide.

Satellite communication has two main components: the ground segment, which consists

of fixed or mobile transmission, reception, and ancillary equipment, and the space

segment, which primarily is the satellite itself. A typical satellite link involves the

transmission or uplinking of a signal from an Earth station to a satellite. The satellite then

receives and amplifies the signal and retransmits it back to Earth, where it is received

and re-amplified by Earth stations and terminals. Satellite receivers on the ground

include direct-to-home (DTH) satellite equipment,mobile reception equipment in

aircraft, satellite telephones, and hand held devices.

3.1 SATELLITE ORBITS:

a) GEOs = Geostationary Earth Orbits.

b) LEOs -= Low Earth Orbits. c) MEOs = Medium

Earth Orbits.

1. Geostationary orbit

A circular orbit 35,785 km (22,236 miles) above Earths Equator in which a satellites

orbital period is equal to Earths rotation period of 23 hours and 56 minutes. A

spacecraft in this orbit appears to an observer on Earth to be stationary in the sky. This

particular orbit is used for meteorological and communications satellites. The


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geostationary orbit is a special case of the geosynchronous orbit, which is any orbit with

a period equal to Earths rotation period.

2. Low- Earth-orbiting satellites

A Low Earth Orbit (LEO) typically is a circular orbit about 400 kilometers above the

earths surface and, correspondingly, a period (time to revolve around the earth) of

about 90 minutes. Because of their low altitude, these satellites are only visible from within

a radius of roughly 1000 kilometers from the sub-satellite point. In addition, satellites in

low earth orbit change their position relative to the ground position quickly. So even for

local applications, a large number of satellites are needed if the mission requires

uninterrupted connectivity.

Satellite communication

Started in 1960.

Uses Geo Stationary Satellite.

Operates in C-Band & Ku-Band.

Started in India in 1975.

First Indian Satellite INSAT launched in 1982.

Gulf War brought satellite television to prominence

3.2-Antennas:-

Antenna (or aerial) is a transducer that transmits or receives electromagnetic waves. In

other words,antennas convert electromagnetic radiation into electrical current, or vice

versa. Antennas generally deal in the transmission and reception of radio waves.

Types of antenna:


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Isotropic antenna (idealized)

Radiates power equally in all directions

Dipole antennas

Half-wave dipole antenna (or Hertz antenna)

Quarter-wave vertical antenna (or Marconi antenna)

Parabolic Reflective Antenna

A parabolic antenna is a high-gain reflector antenna used for radio, television and

datacommunications, and also for radio location (radar),on the UHF and SHF parts of

the electromagnetic spectrum. The relatively short wavelength of electromagnetic

radiation at these frequencies allows reasonably sized reflectors to exhibit the

desired highly directional response for both receiving and transmitting. A

typical parabolic antenna consists of a parabolic reflector with a small feed

antenna a tits focus. To find the focus, reflect the light of a flashlight off of the

dish. When the reflected beam is parallel, the flashlight is at the focus. Thereflector is a metallic surface formed into a paraboloid of revolution and

(usually) truncated in a circular rim that forms

the diameter of the antenna. This paraboloid possesses adistinct focal point

by virtue of having the reflective property of parabolas in that a point light

source at this focus produces a parallel light beam aligned with the axis of

revolution. The feed antenna at the reflector's focus is typically a low-gain

type such as a half-wave dipole or a small waveguide horn.


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Electronics

& Communication Chapter 4 PROPAGATION

MODEDS

Ground-wave propagation

Sky-wave propagation

Line-of-sight propagation

Electronics &

Communication

Chapter 5 - TV

STUDIO

Doordarshan has two studio halls. One is used as News Room and the other

one is used for shooting various programs. Artificial sets are created in the

studio hall according tor equirements of the program to be shooted.

5.1-PROCEDURE IN REORDING

Set is designed in studio as per conceptual thought of program

producer.

Floor plan is envisaged.

Lighting, Audio and placement of the cameras is arranged as per floor

plan.

Pre testing of cameras, microphones, VCRs etc. is done before

recording.


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Recording begins and desired camera / mike are selected through VM/

Audio console as per command of producer. Program is recorded on

VCR.

5.2-PROCEDURE IN TRANSMISSION

The programs are transmitted as per the daily cue sheet.

Normal transmission hours are 1600-2000 Hrs.

Cue sheet is discussed daily by program and technical staff for details

in it and for any last moment changes if any.

After getting D-link caption from Delhi end program is played from

VCR /Server. The program is uplinked by Earth Station.

The program is also transmitted to transmitter at HPT Nahargarh via

MW link.

During our slot, both live as well as recorded programs are transmitted.

Around 2000 Hrs after getting linking caption from DD# 1, the signal

from DD#1 is selected and accordingly transmitted by HPT/ ES.

5.3-Video signal generation

Video is nothing but a sequence of pictures. The image we see is maintained in our eye

for 1/16sec. So if we see images at the rate more than 16 pictures/sec, our eyes cannot

recognize the difference and we see the continuous motion. In movies camera and movie

projector it is found that 24 fps is better for human eyes. TV system could also use this

rate but in PAL system 25fpm is selected. In TV cameras image is converted inelectrical signal using photosensitive material. Whole image is divided into many micro

particles known as pixels. These pixels are small enough so that our eyes cannot

recognize pixels and we see continuous image. Thus, at any particular instance there are

almost infinite numbers of pixels that need to be converted in electrical signal

simultaneously for transmitting picture details. How ever this is not possible practical

because it is no feasible to provide a separate path for each pixel. In practice this

problem is solved by method known as Scanning in which information is converted


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one by one pixel, line by line and frame by frame.

5.4-COLOUR COMPOSITE VIDEO SIGNAL

Active waveform comprises of 2 signals:

Luminance(Y)-black and white

Chrominance(C)- colour signal

5.5-COMPONENTS OF TV STUDIO

Camera

Lighting

Microphones

Vision mixer and Audio consoles

MSR

VCR /Servers

Acoustics

Post production and video effects

supporting services like AC, UPS

Chapter 6- TV


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CAMERA

A TV Camera consists of three sections:

a) A Camera lens and optical block

b) A transducer or pick up device

c) Electronics

6.1-CAMERA LENS

The purpose of the camera lens is to focus the optical energy at the

face plate of a pickup device i.e. to form an optical image. The lens

has following sections:

1.Main focus section

2. Zoom section with manual or servo mode operation.

3.Servo drive assembly for Zoom and iris control.

4. Aperture section with manual or auto mode.

5. Back focus section with adjustment facilities for back and microfocus.

6.2- TRANSDUCER PICK UP DEVICE

R, G & B signals, as separated by the optical block are converted to electrical signal in

the transducer section of the camera. It is then processed in camera electronics to give CCVS

(color composite video signal) output.


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Chapter 7-

LIGHTING

Lighting for television is very exciting and needs creative talent. There is always a

tremendous scope for doing experiments to achieve the required effect. Light is a kind

of electro magnetic radiation with a visible spectrum from red to violet i.e. wavelength

from 700 nm to 380

Nm respectively.

Basic three pointing lighting

Key light:- It gives shape and modeling by a casting shadow. It is treatedas a sun in

the sky and should cast only one shadow.

Fill light:- Controls the lighting contrast by filling in shadows.It can also provide catch

lights in the eyes.

Back light:-Separates the body from the background, gives roundness to the subject

and reveals texture.

Background lights:- Separates person from the background and reveals

background interest and shape.

Lighting equipments:-

HMI lights compared to standard incandescent lights deliver five times the light output

per watt. They generate less heat, which is an important consideration when shootinginside in a confined space. (HMI stands for Hydrargyrum Medium Arc-length Iodide).

The light on the left side of this picture is a HMI light; the one on the right a standard

quartz light.

Cycs (large, seamless, neutral backgrounds) can be lit from the top and bottom with


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cyclights.The one here sits on the studio floor and is directed up at the background.

Chapter 8-

MICROPHONES

A microphone is an acoustic-to-electric transducer or sensor that converts sound in to

an electrical signal.

8.1- TYPES OF MICROPHONES

1.CONDENSER MICROPHONE:-

In a condenser microphone also called a capacitor microphone or electrostatic

microphone, the diaphragm acts as one plate of a capacitor, and the vibrations producechanges in the distance between the plates.

2. ELECTRET CONDENSER MICROPHONE

An electret microphone is a relatively new type of capacitor microphone invented at Bell

laboratories in 1962 by Gerhard Sessler and Jim West. An electret is a ferroelectric

material that has been permanently electrically charged or polarized. The name comes

from electrostatic and magnet; a static charge is embedded in an electret by alignment of

the static charges in the material, much the way a magnet is made by aligning the

magnetic domains in a piece of iron.

3. DYNAMIC MICROPHONE:-

Dynamic microphones work via electromagnetic induction. They are robust, relatively in

expensive and resistant to moisture. This coupled with their potentially high gain before

feedback makes them ideal for on-stage use. Moving-coil microphones use same

dynamic principle as in loudspeaker, only reversed.

4. RIBBON MICROPHONE:-

Ribbon microphones use a thin, usually corrugated metal ribbon suspended in a

magnetic field. The ribbon is electrically connected to the microphone's output, and its

vibration within the magnetic field generates the electrical signal. Ribbon microphones

are similar to moving coil microphones in the sense that both produce sound by means


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of magnetic induction.

5. PIEZO ELECTRIC MICROPHONE:-

A crystal microphone or piezo microphone uses the phenomenon of piezoelectricity -

the ability of some materials to produce a voltage when subjected to pressure

- to convert vibrations into an electrical signal.

6. LASER MICROPHONE:-

Laser microphones are often portrayed in movies as spy gadgets. A laser beam is aimed

at the surface of a window or other plane surface that is affected by sound. The slight

vibrations of this surface displace the returned beam, causing it to trace the sound wave.

The vibrating laser spot is then converted back to sound. In a more robust and

expensive implementation, the returned light is split and fed to an interferometer, whichdetects movement of the surface.

7. FIBER OPTIC MICROPHONE:-

A fiber optic microphone converts acoustic waves into electrical signals by sensing

changes in light intensity, instead of sensing changes in capacitance or magnetic fields as

with conventional microphones.

Chapter 9-

VIDEO CHAIN


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The video we see at our home is either pre-recorded in studio or live telecasted. Block

diagram shown in fig illustrates different chains of video recording, video playback,

news, and live broadcasting. In First chain we will understand studio program recording.

Camera output from the studio hall is sent to CCU where many parameters of video

signals are controlled. Output signal of CCU after making all corrections is sent to VM

in PCR-1 (production control room).Output of 3 to 4 cameras comes here and final

signal is selected here using VM according to a directors choice.

The final signal from VM is sent to VTR. VTR uses both analog and digital tape

recording system. At the time transmitting this pre recorded program cassettes is played

in to respective in VTR room. Signal from VTR is sent to PCR-2. PCR-2 has one VM,

video monitoring system, and CG (Computer Graphics). From PCR-2, signal travels

from MSR to Transmitter or Earth-station for terrestrial and satellite transmission.

MSR is the main control room between studio and transmitter or receiver.

Chapter 10-

AUDIO CHAIN

In studio program, audio from studio microphones is directly fed to the AUDIO

CONSOLE place in PCR-1. It is used to mix audio from different sources and

maintain its output. From AC, signal is directly recorded on tape with video signal in

VTR. While playing back audio is extracted from tape and fed to another audio console

placed in PCR-2 and then travels with the video signal.

Chapter 11- VISION

MIXER

Vision mixer is the almost final equipment in programme (video) production and its

output is used either for recording or transmission.

Vision mixing is the process of providing a composite signal from various input sources.

It has many input sources such as cameras, VCR/server, Graphics, IRDs. Out of these

i/p, any source can be taken on o/p. It is used to switch or cut between 2 video sources,

or to combine them in a variety of ways.

11.1 TRANSIT ION/SWITCHING

It involves:


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Cut

Mix

Wipe

Fade

Keying

Special effects

CUT

The cut is an instantaneous switch from one picture to another. It avoids the frame roll &

flash evident, on picture at the moment of cutting.

MIX

It uses additive mixing. The transitions here are less pronounced. As the faders are

operated, the established picture fades away, while the new picture progressively.

Chapter 12- MASTER

SWITCHING ROOMMaster switching room (MSR) is used for transmission media. 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. Signal can be monitored at various

stages.

AUDIO CONSOLE

It has many input sources such as microphones, VCR/server, IRDs, tone generators.


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Out of these i/p, any source can be taken on o/p Audio level of Sources can be

adjusted and audio effects can be added.

Chapter 13- EARTH

STATION

The digital earth station operates in the frequency range of 5.85 GHz to 6.425 GHz

for transmission and 3.625 to 4.24 GHz for reception of signals. The whole system

operates with DVB/MPEG2 Standards. The base band processor subsystem and base

band monitoring subsystem operates in fully digital domain. An OFC carries digital base

band signal from studio to earth station site to minimize the noise and interference. It is

controlled by a PC called NMS PC. The compression segment has an

MPEG encoder, digital multiplexer and digital modulator. The monitoring and receivingsegment comprises of two digital receivers for receiving and decoding program. The

output of modulator (70 MHz) is sent to an up converter. The up converted signals are

sent to an HPA. Then this signal is given to a PDA (parabolic dish antenna) for up

linking to satellite. The uplinked signal is received again by the same PDA for monitoring

purposes. The signal between earth station and satellite are given along line of sight

which means there must be a clear path from earth to satellite. The uplink signal is fed

from the earth station by a large PDA. The satellite is equipped with its own dish

antenna which receives the uplink signals and feeds them to a receiver. The signal is thenamplified and changed to a different frequency which is downlink frequency. This is

done to prevent interference between uplink and downlink signals. The down linked

signal is then again sent to the transmitter which again retransmits it. Each satellite has a

transponder and a single antenna receives all signals and another one transmits all signals

back. A satellite transmits signals towards earth in pattern called the satellite footprint of

the satellite. The footprint is strongest at centre and the footprint is used to see if the

earth station will be suitable for the reception of the desired signal. Converts The parts

of the DES are Antenna subsystem including LNA Antenna control unit, beacontracking unit, beacon tracking receiver and up converter system high power

amplifier and power system. The system operates in 2 +1mode and is compliant with

DVBMPEG 2standards. The base band processor subsystem and base band

monitoring system operates in digital domain. An OFC contains the digital base band

signal for studio to earth station to minimize noise interference The network management

system or NMS monitors and controls baseband equipments compression equipments

and test instruments like video audio generation and video audio analyzer. They are


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provided to ensure quality of transmission and help trouble shoot.The base band

segment comprises of baseband subsystems at studio site and base band subsystem at

earth station site. This baseband segment processes two video Programmes. The base

band segment is monitored and controlled using a PC placed near the base band earth

station equipments called base band NMS PC. The compression segments comprises

of Mpeg encoders in 2 +1 configuration for providing redundancy. It also comprises of

digital multiplexers and digital modulators in 1 +1 configuration. The compression

segment is monitored and controlled by compression NMS PC. The receive and

monitoring segment consists of two digital receivers for receiving and decoding of the

video programs and one ASI to SDI decoder for decoding of the transport stream for

monitoring video programs at the multiplexers output. RF NMS PC is placed near the

receive monitoring segment and video audio generator placed in the base band segment.

For monitoring of video programs professional video monitor, LCD video monitor and

audio level monitor are provided in the base band segment. An operator console has

one 14 professional video monitor a video audio monitor unit for quantitative monitor

of video programs and a personal computer for centralized merit and contention of earth

station sub system.

13.1 COMPONENTS

PDA(parabolic dish antenna)

IRD(Integrator receiver decoder)

Multiplexer

Encoder

FEED

LNA(Low noise amplifier)/LNBC(low noise block converter)

Waveguide

HPA(TWTA, SSTA, Klystron)

Up Converter


Earth station is the main part which communicates with satellite in which up linking and

downlinking of the signal into/ from the satellite takes place for TV transmission. Earth


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station is a purely digitization version. The signal is uplinked from the earth station and

received by many downlink centers in TV broadcasting. It is a very important part of

satellite communication system for broadcasting of signals. A ground-based receiving or

transmitting/ receiving station in a satellite communications system. The counterpart to

the earth station is the satellite in orbit, which is the "space station." Earth stations use

dish-shaped antennas, the diameters of which can be under two feet for satellite TV to

as large as fifty feet for satellite operators. Antennas for space exploration have

diameters reaching a hundred feet.

Multiplex, Modulate and Up convert

An earth station is generally made up of a multiplexor, a modem, up and down

converters, a high power amplifier (HPA) and a low noise amplifier (LNA). Almost all

transmission to satellites is digital, and the digital data streams are combined in a

multiplexor and fed to a modem that modulates a carrier frequency in the 50 to 180

MHz range. An up converter bumps the carrier into the gigahertz range, which goes to

the HPA and dish. Down convert,

Demodulate and De multiplex

For receiving, the LNA boosts the signals to the down converter, which lowers the

frequency and sends it to the modem. The modem demodulates the carrier, and the

digital output goes to the demultiplexing device and then to its destinations.

Earth Station classification

Analog Earth Station


ASNG

DSNG

C-band or Ku-band

Problems of Analog

One programme per channel/transponder

Comparatively noisy

Ghosts in Terrestrial Transmission


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Lower quality with respect to VCD, DVD digital medium

Fixed reception

Why Digital?

More programmes per channel/Transponder i.e. spectrum efficient.

Noise-Free Reception.

Ghost elimination.

CD quality sound & better than DVD quality picture.

Reduced transmission power.

Flexibility in service planning.

Process involved in transmission of signal

Up-Conversion


Transmission

Reception Up-Converters

The up-conversion is required to raise the frequency of the signal in desired band:

C- band, Extended C-band or Ku-band before transmission. The input to up converter

is 70 MHz (output of modulator) and output of Up-converter is fed to HPA. The up-

conversion may be done in stages or in one stage directly. The 70 MHz signal is first

converted into L band and then L band signal raised to desired frequency band.


The high power amplifier is used for the final power amplification of the digital RF signal

in C-band/Ku band that is fed to the antenna. The important parameters of HPAs are:

1. Frequency range

2. Output power at flange


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3. Bandwidth

4. Gain variation (1.0db (max.) for 40 MHz (narrow band)

5. 2.50db for full bandwidth.

The different types of HPAs are

1. KHPA - Klystron High Power Amplifier

2. TWTA -Traveling Wave Tube Amplifier

3. SSPA- Solid state Power Amplifier

Chapter 14-TRANSMITTER



For full earth coverage from a geostationary satellite, a horn antenna is used. Horns are


A small earth terminal, the feed horn is located at the focus or may be offset to one side

of the focus.

Large earth station antennas have a sub reflector at the focus. In the Cassegrain design,

the sub reflector is convex with an hyperboloid surface, while in the Gregorian design it

is concave with an ellipsoidal surface.

These antennas are used to transmit signal from earth station to satellite.

Chapter 15-


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RECEIVER



1. For full earth coverage from a geostationary satellite, a horn antenna is used. Horns are


2. They are basically used to receive signals from the satellite which were transmitted by

transmitter.

3. All the waves which fall on receiver are being focused on the feeder which is placed at

the center of receiver antenna.

4. This feeder collects all the waves and sends to master switching room through cable

sand wires.

5. After that again down conversion and decoding of signals takes place and in this manner

we receive our information.

Chapter 16 ELECTRONIC NEWS

GATHERING

ENG gather news from different outside locations.

Its components:

1. Camera

2. Tripods

3. Mikes

4. Lights

5. Camera battery


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6. Camera charger

7. Camera adapter

8. Headphone

9. Camera cassette

The job of journalists is fulfilled only when their news reaches the viewers, this is why

they long for great challenge ability to be present anywhere, anything. This means

faster news from anywhere anytime to everywhere. Further there is a need to send news

footages in the shortest possible time and practically from any location. Technologically,

Doordarshan has always been far ahead of its competitors. When it came to remote

newsgathering, Doordarshan has set precedence by using innovative and cost effective

methods.

Chapter

17- OB Van

Outside broadcasting is the production of television or radio programmes (typically to

cover news and sports events) from a mobile television studio. This mobile control room

is known as an "Outside Broadcasting Van", "OB Van", "Scanner" (a BBC term),

"mobile unit", "remote truck", "live truck", or "production truck". Signals from cameras

and microphones come in to the OB Van for processing and transmission. A typical OB

Van is usually divided into 5 parts:

The 1st and largest part is the production area where the director, technical director,

assistant director, character generator operator and producers usually sit in front of a

wall of monitors. This area is very similar to a Production control room. The technical

director sits in front of the video switcher. The monitors show all the video feeds from

various sources, including computer graphics, cameras, video tapes, video servers and

slow motion replay machines. The wall of monitors also contains a preview

monitor showing what could be the next source on air and a program monitor that

shows the feed currently going to air or being recorded. Behind the directors there is

usually a desk with monitors for the editors to operate. It is essential that the directors

and editor are in connection with each other during events, so that replays and slow-

motion shot scan be selected and aired.


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The 2nd part of a van is for the audio engineer; it has a sound mixer. The audio

engineer can control which channels are added to the output and will follow instructions

from the director.

The 3rd part of van is video tape. The tape area has a collection of VTRs and may also

house additional power supplies or computer equipment.

The 4th part is the video control area where the cameras are controlled by 1 or 2

people to make sure that the iris is at the correct exposure and that all the cameras look

the same.

The 5th part is transmission where the signal is monitored by and

engineered for qualitycontrol purposes and is transmitted or sent to other

trucks.

Chapter 18- DD

Direct+ DTH

DD Direct:

Carries all channels of DD directly to homes.

Also carries few private channels and radio channels of AIR.

Features:-

Cost effective alternate to cable TV.


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One time expenditure for procuring receive system by viewer.

No monthly/activation charges from subscriber.

No smart card/CAM module required for reception.

Receive Eqpt. consists of a 60/90cm Dish Antenna, a Block converterand a Set Top Box (STB). STB readily available in the open market.

Dealers of the equipment available all over the country.

Indicative cost of the receive system Rs 3000 to Rs 3500.

Cost likely to come down further with volumes.

Doordarshan, the national television service of India, is devoted to publicservice broadcasting. It is one of the largest terrestrial networks in the world. In

my Industrial training at Doordarshan Kendra, Jaipur, I have gained useful

knowledge which will surely be of great help in future. This training gave me

an opportunity to learn the practical aspects of the knowledge of my field of

interest, Electronics and communication.

Chapter 19 :Fututre scope


broadcasting. It is one of the largest terrestrial networks in the world. Doordarshan is

the first ISO certified channel in India. The largest viewer of India ,watching

Doordarshan. It has good future scope in communication world. Because largest

network 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.

In Doordarshan, all the electronic devices used are to be operated by skilled engineers.


55/55


It provides with good pay scales.

The selection for the posts is through UPSC examinations.

Chapter

20 conclusion


broadcasting.

It is one of the largest terrestrial networks in the world. In my Industrial training at

Doordarshan Kendra, muzaffarpur, I have gained useful knowledge which will surely be

of great help in future.

This training gave me an opportunity to learn the practical aspects of the knowledge of

my field of interest, Electronics and communication.


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