Project Lan 2

8/2/2019 Project Lan 2

1/32

PRESTIGE INSTITUTE OF ENGINEERING AND SCIENCE

INDORE

Department Of Electronics and Communication Engineering

Training on

Communication System and Technology Associated With It

at

DOORDARSHAN KENDRA, INDORE

An industrial training report submitted to

Rajiv Gandhi Prodyogiki Vishwavidhyalaya, Bhopal

in partial fulfillment of the award of

the degree of

Bachelor of Engineering

In

Electronics and Communication

Submitted to: Submitted by:

Mrs. Shraddha Bansal Sanjana Arora

Head Of Department, E.C Roll No: 0863EC081050

1


2/32

PRESTIGE INSTITUTE OF ENGINEERING AND SCIENCE INDORE

Department of Electronics and Communication Engineering

CERTIFICATE

This is to certify that industrial training reportis submitted by

Sanjana Arora students of Final year of Electronics & Communication

year 2011-2012 in partial fulfillment of the requirements of Rajiv Gandhi

Proudyogiki Vishwavidyalaya Bhopal for the award of the Degree ofBachelor of Engineering in Electronics & Communication branch ofPrestige

Institute of Engineering and Science Indore, affiliated to R.G.P.V.

BHOPAL (M.P.)

External Examiner: Internal Examiner:

2


3/32

TRAINING INFORMATION

NAME:Sanjana Arora

YEAR: Fourth year

INSTITUTION:Prestige Institute of Engineering and Science, Indore

PLACE OF TRAINING:Doordarshan Kendra

Meghdoot Park Exchange bldg. Indore, M.P

DESIGNATION OF SUPERVISOR:Principal, BSNL, CTTC Indore

PERIOD OF TRAINIG: FROM 27/06/2011 TO 16/07/2011

DURATION: 3 Weeks

FIELD OF TRAINING: Communication System and Technologies Associated With It

3


4/32

RECOMMENDATION

This dissertation entitled Communication System and Technologies Associated with it

submitted to the Rajiv Gandhi Prodyogiki Vishwavidyalaya, Bhopal, by Sanjana Arora

(0863EC081050) during the academic year 2011-2012, as a partial fulfilment of part of

curriculum in VII Semester of Bachelor of Engineering (Electronics and Communication),

Industrial Training, is a record of students own work carried out by him, under our direct

supervision, in the Department of Electronics and Communication Engineering, Prestige

Institute of Engineering & Science, Indore.

The work contained in the thesis is a satisfactory account of their training

work and is recommended for the completion of curriculum in VII Sem of Bachelor of

Engineering in Electronics and Communication Engineering, Industrial Training Report.

Mrs. Shraddha Bansal

H.O.D, Dept. of EC

4


5/32

ACKNOWLEDGEMENT

It is always a pleasure to remind the fine people in the Engineering Workshops for their

sincere guidance I received to uphold my practical as well as theoretical skills in engineering.

Firstly I would like to thank Mrs. Sraddha Bansal for permitting me to have my industrial

training from Doordarshan Kendra which is a leading industry of Communication Services in

India.

Secondly I would like to thank all the Engineers and technicians of Doordarshan Learning

and Training Center who taught as the engineering of telecommunication, field

demonstration and a detailed study on topic related to Communication Engineering.

Finally I apologize all other unnamed who helped me in various ways to have a good

training.

Knowledge is power and unity is strength.

5


6/32

PREFACE

This report is a brief introduction about Doordarshan, enclosing the topics that deal with all

types of applications & with various aspects related to new researches.

I hope, this report will be extremely expedient for grasping the basic knowledge of various

fields of communication.

The suggestions and constructive criticism for the improvement of the report will be greatly

acknowledge and appreciated for further improvements.

6


7/32

ABOUT DOORDARSHAN KENDRA

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 inthe world in terms of the infrastructure of studios and transmitters.Doordarshan Kendra is a

milestone in the field of entertainment and education media source.DDK, has the Largest

Programmes recording Studio in the Asia. They Broadcast 30 channels in 22 languages overthe country.Doordarshan Kendra Indore is part of the DD India, the largest television

network in the world. Doordarshan with over 5 high power Terrestrial Transmitters,62 low

power,5 very low power transmitter and 3 production centers serve M.P. Inaugurated on 28th

may 2000 by the then broadcast minister Mr. ARUN JATELY. Doordarshan Kendra Indorecurrently produces and telecasts 168hrs of local programmers per week. Now more than

85 percent of the 60,385,118 populations of M.P. With the introduction of DTH almost cent

percent of the population can now receive DDK Gwalior programmers without cable

connection. Doordarshan studios have been established at Gwalior, Bhopal and Indore tofoster regional diversity.

DD National's

Launched :September15, 1959 (in India) May 17, 1971 (in Middle East)

Owned by :Doordarshan

Country : India

Sister channel(s) : DDIndia,DDNews,DDSports,DD Bharati

Website : www.ddindia.gov.in

7
http://en.wikipedia.org/wiki/Indiahttp://en.wikipedia.org/wiki/DD_Sportshttp://en.wikipedia.org/wiki/DD_Bharatihttp://www.ddindia.gov.in/http://en.wikipedia.org/wiki/File:Dd_national.jpghttp://en.wikipedia.org/wiki/DD_Sportshttp://en.wikipedia.org/wiki/DD_Bharatihttp://www.ddindia.gov.in/http://en.wikipedia.org/wiki/India


8/32

1.EARTH STATION

1.1INTRODUCTION

An earth station, ground station, or earth terminal is a terrestrial terminal station designed for

extra planetary telecommunication with spacecraft, and/or reception of radio waves froman astronomical radio source. Earth stations are located either on the surface of the Earth, or

within Earth's atmosphere. Earth stations communicate with spacecraft by transmitting and

receiving radio waves in the super high frequency or extremely highfrequency bands (e.g., microwaves). When an earth station successfully transmits radio

waves to a spacecraft (or vice versa), it establishes a telecommunications link.

When a satellite is within an earth station's line of sight, the earth station is said to have

a view of the satellite. It is possible for a satellite to communicate with more than one earth

station at a time. A pair of earth stations are said to have a satellite in mutual view when thestations share simultaneous, unobstructed, line-of-sight contact with the satellite.

1.2There are currently three classes of earth stations:

Mass capacity station

Designed for large users or inter-exchange carrier applications. This type of earth stationserves a user community with communications needs great enough to require feeder line

access to the earth station. The cost for earth stations in this class runs into millions of

dollars.

Middle range earth station

--Designed for large corporate applications. This type of earth station serves a single large

user (e.g. newspaper publisher, financial institution, etc). The cost for earth stations in this

class runs into the hundreds of thousands of dollars.

Low-end earth station

--Designed for smaller corporate applications. This type of earth station serves a single user

(e.g., retailers, general business, etc) and is typically designed to handle data traffic (e.g.,

point-of-sale information, inventory control, credit authorization, and other types of remote

processing). These types of earth stations are established with a minimal amount ofequipment and a very small aperture terminal (VSAT).

Earth station involves the two terms which are basically the important parameters of thecommunication i.e. UPLINK & DOWNLINK.

8


9/32

1.3UPLINK: The process of gathering any informative part & sending it to the satellite,running on specified frequency is termed as UPLINK. The uplink frequency is 5950MHz.

OUTPUT CHAIN OF EARTH STATION OR UPLINK

1. The information gets recorded is in the analog form which needs tobe converted into digital form for long route transmission by encoder.

2. Moreover, Encoder also enables the compression technique.

3. Many digitalized signals are then feeded to multiplexer (many into one) so that we can

have one output signal at a time.

4. This output signal has poor strength & power & not fit for the long distance transmission

so its need to be pass through modulator where it superimpose on high power carrier signal.

But modulator can raise its frequency up to 70MHz only.

5. After that IF switch selects one of the modulator o/p & divide it to 1:4 ratio.

9


10/32

6. It is then compared with Equalizer signal to limits its parameters like amplitude, phase etc.

and also to compensate the effect of delay in the signal.

7. UPC (Up converter) increases the signal frequency to a range to reach to the satellite. This

is done by mixing the signal with locally generated high frequency signal of oscillator.

8. It is then transmitted to RF selector switch where the signals gets partitioned & provided to

two different HPA.

9. High power Amplifier (HPA) amplifies the signal to 750W.

10. The two signals are combined in combiner and transmitted through hollow rectangular

waveguide (Now-a-days Travelling wave tubes ,TWT are also in use) to antenna & then toSATELLITE.

11. The uplink frequency assigned to Doordarshan service station is 5950 MHz.

12. All these signals are SD i.e. Standard definition, which uses 625 lines.

13. Very few signals are HD i.e. High definitions which uses 720 lines.

1.4 DOWNLINK: The process by which satellite sends the received signals to the

controlling stations is termed as DOWNLINK. The downlink frequency is 3725 MHz.

10


11/32

INPUT CHAIN OF EARTH STATION OR DOWNLINK

1. Down linking is just opposite of up linking.

2. Satellite transmits the signal to be received by the earth station.

3. The signals are then passed through LNA (Low Noise Amplifier), so that we can have less

noise while Rx signal from the satellite Or through LNBC (Low Noise Block Converter) to

down the frequency near to 5150 MHz.

4. It is then divided into 1:4 ratio by the RF divider for the various o/p.

5. RF patch panel are used to monitor the signal at this point.

6. Now, incoming C band signals are converted into L band by C-L band down converter just

to lower down the high frequency signals.

7. It is then divided into 1:4 ratio by the L band divider for the various o/p.

8. These four o/p are then passes through IRDs (Decoder) to convert them back to analog

signals & then passes to Patch panel for monitoring purpose.

9. After this, through 40X40 SDI/ASI routers they are sent to Suit View Leitch (SVL).

10. The o/p of SVL enables us to view 8 channels simultaneously on single LCD (42)

monitor.

11. The down linking procedure is done for monitoring purpose mostly , just to confirm that

whatever we are up linking are actually happening or not.

11


12/32

2.TV STUDIOS

2.1 INTRODUCTION

Doordarshan has studio halls. One is used as News Room and the others are usedfor shooting various programs. Artificial sets are created in the studio hall according to

requirements of the program to be shooting.

2.2 STUDIO PRODUCTION

For Studio production, we use ENG, EFP and DSNG techniques. Here, ENG stands for

Electronic News Gathering and EFP stands for Electronic Field Production and DSNG standsfor Digital satellite News Gathering. In this, we have two types of studio production,

Indoor and Outdoorproduction.

In Indoor Studio Production, the world becomes your side means the atmosphere where weshoot is our control and the effect of all weather conditions such as moisture, temperature etc

is our control. But in Outdoor studio production, we lose some control. The atmosphere andall types of weather effects affect the production. Outdoor production becomes challenge

than Indoor production.

2.3 TELEVISION POST PRODUCTION

In Post Production we add audio/video effects and graphics into project. To incorporate late

ideas into project. To overcome the shortcomings of production stage.Post Production simply means Editing. We use two types of editing. The first one is linear

editing and second one is nonlinear editing.WORKFLOW OF POST PRODUCTION

2.4 Elements Post Production

The elements of Post Production are Editing, Visual effects, Keying and Multilayer

compositing, Filling, Sound effects, Multiform at delivery, Graphics andAnimations.

Linear Editing Systems

In this, one or more tapes containing original footages are transferred segments by segments.

There are two types of Linear Editing.

12


13/32

Cut to Cut Assemble Editing

In Assemble Editing audio/video segments are added complete with the associated control

and time code tracks. It is not useful for recording audio from different sources; Assemble

Editing is simpler and faster and accurate but not flexible.

Cut to Cut Insert Editing

In Insert editing, there is option of audio or video only edits or both of them. This type ofediting is flexible.

Problems with Linear tape editing:

Linear Editing is sequential. Long hours spent on rewinding of tapes, search of

material.

Potential risk of damage to Original footage.

Difficult to insert a new shot in editing.

Difficult to experiment with variations.

Quality loss more in analog even with digital.

Non Linear Editing:

The term Non Linear Editing is referred as NLE. NLE is video editing in digital format with

standard computer based technology. In this, we use Random access, computational and

manipulation capability.

Advantages with NLE

It includes flexibility in all editing functions.

In this, powerful integration of video and graphics, tools for filtering.

It includes equally powerful audio effects and mixing.

We easily copy undo or any changes what we want.

Uses of NLE: Advertising Commercials.

Television Programs.

Documentary Films.

Leading Players of NLE:

13


14/32

Adobe

Discreet

Quintal

Avid

Apple(final cut pro)

Media 100

DPS(Velocity)

2.5 Procedure in recording

1. Set is designed in studio as per conceptual thought of program producer.2. Floor plan is envisaged.

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

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

5. Recording begins and desired camera/mike are selected through VM/Audio console as per

command of producer. Program is recorded on VCR.

2.6 Procedure in Transmission

1. The programs are transmitted as per the daily cue sheet.

2. Normal transmission hours are 1600-2000Hrs.

3. Cue sheet is discussed daily by program and technical staff for details in it and for any last

moment changes if any.

4. After getting D-link caption from Delhi end program is played from VCR/Server. The

program is uplinked by Earth Station.

5. The program is also transmitted to transmitter at via MW link. Then DD channels are

taken on air.

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

2.7 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 cannotrecognize 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

14


15/32

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 seecontinuous image.

Thus, at any particular instance there are almost infinite numbers of pixels that need to beconverted in electrical signal simultaneously for transmitting picture details. However 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 isconverted one by one pixel, line by line and frame by frame.

Color Composite Video Signals

Active waveform comprises of 2 signals:

Luminance (Y)-black and white

Chrominance (C)- color signal

2.8 TV Camera

A TV Camera consists of three sections:

a) A Camera lens and optical blockb) A transducer or pick up device

c) Electronics

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:

15


16/32

1. Main focus section

2. Zoom section with manual or servo mode operation

3. Servo drive assembly for Zoom and iris control4. Aperture section with manual or auto mode

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

Focus.

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.

2.9 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 electromagnetic radiation with a visible spectrum from red to violet i.e.wavelength from 700nm to 3800nm respectively.

Basic three pointing lighting:

Key light: It gives shape and modelling by a casting shadow. It is treated as 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 subjectand 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 lightoutput 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 theright a standard quartz light.

16

Object Side Camera Side1

2

3

4 5


17/32

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.

The basicTungsten Filament Lamp: Tungsten wire has resistance and is cable of

dissipating power as form of heat. If sufficient electrical energy is supplied to raisethe filament temperature above approximately 500C, light is emitted. The filament is

enclosed in a evacuated glass bulb. The tungsten filament has light emitting

characteristics similar to those of a black body radiator, where high temperatureprovides greater efficiency and higher color temperature. But this lamp fails because

of evaporation of filament, the higher the filament temperature and the higher the rate

of evaporation. The evaporation can be reduced by having a suitable gas(which does

not attack the filament)into the bulb. This gas enables them to be run at temperaturesseveral hundred degrees higher than those of vacuum lamps.

Tungsten Halogen lamp: Halogen is a general term for a family of very reactive

elements like fluorine, chlorine, bromine, and iodine. Each of these combine withtungsten in a reversible reaction which is controlled by temperature. At present, the

halogen used is iodine or bromine. Halogen vapors is colorless and at temperaturesbetween 250-8000C combines with the deposited tungsten to form tungsten halide in

vapor form. The glass is made of Quads (silica and glass) . Quads glass is hard and

pure form of glass. The rating of halogen bulb is above 1 KHz. Halogen gas are inertgases means which can not react with easily with each other. Internally, a process

called halo nation starts within glass. The Tungsten Haloids in form of mini particles

are generated by combine of halogen and tungsten and it moves with halogen from

down to up. After certain time, this halo nation process will stop. The life of this bulbbe more than ordinary bulb. It may be noted that Life of bulb be measure in Number

of Switchings.

In Studio, the light should be pointed. It could not spread. A lens can be used. In this,we use three point lighting.

The other types of Lamps are Compact Source Iodide (CSI) Lamp, The HMI metal

halide discharge lamp, and HMI lamp.

2.10 MICROPHONE

A microphone (or called as mic or mike) is an acoustic-to-electric transducer or sensor that

converts sound into an electrical signal. In 1876, Emile Berliner invented the first

microphone used as a telephone voice transmitter. Microphones are used in manyapplications such as telephones, tape recorders, hearing aids, motion picture production, live

and recorded audio engineering, in radio and television broadcasting and in computers for

recording voice, speech recognition, and for non-acoustic purposes such as ultrasonic

checking or knock sensors. Most microphones today use electromagnetic induction (dynamic

microphone), capacitance change (condenser microphone),

17


18/32

Types of micro phones :

Condenser Microphone: In a condenser microphone also called a capacitormicrophone or electrostatic microphone, the diaphragm acts as one plate of a

capacitor, and the vibrations produce changes in the distance between the plates.

Electrostatic Condenser Microphone: An electrostatic is a ferroelectric materialthat 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.

Dynamic Microphone:

Dynamic microphones work via electromagnetic induction. They are robust, relativel

y in expensive and resistant to moisture. This coupled with their potentially high gainbefore feedback makes them ideal for on-stage use. Moving coil microphones use

same dynamic principle as in loudspeaker.

18


19/32

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 thesense that both produce sound by means of magnetic induction.

PiezoelectricMicrophone: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.

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, there turned light is split and

fed to an interferometer, which detects movement of the surface.

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.

Omni directional MicrophoneIn this, gain of microphone remains constant in all directions. Its Pickup angle is 360degree. It is used for recording ambient.

Gun Microphone

It is long and rod shaped microphone. It is highly unidirectional microphone. It isgood for recording single voice in noisy location. Such type of microphone is used in

Political Conference.

19


20/32

Lip Microphone

It is a type of special microphone. It is noise cancelling microphone. It is also known

as Close talking microphone. This type of microphone is used in Match

Commentators.

Lapel Microphone

It is also known as Caller Microphone. It is in Omni directional polar pattern. It may

be Corded or Cordless. It can be powered by batteries or Phantom power. It issuitable for Running Commentary. It is also known as Neck Microphone.

Wireless Microphone

These are ordinary microphone with an FM transmitter. It is Lapel type or handled

type microphone. It is in Omni directional. It is suitable for Stage performance. It

should not be too close or too far from the sound source. A wireless microphonetransmits the audio as a radio or optical signal rather than via a cable. It usually sends

its signal using a small FM radio transmitter to a nearby receiver connected to thesound system

Shotgun microphone

Shotgun microphones are the most highly directional. They have small lobes of

sensitivity to the left, right, and rear but are significantly less sensitive to the side andrear than other directional microphones. This results from placing the element at the

20


21/32

back end of a tube with slots cut along the side; wave cancellation eliminates much of

the off-axis sound. Due to the narrowness of their sensitivity area, shotgun

microphones are commonly used on television and film sets, in stadiums, and forfield recording of wildlife.

2.11 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. Cameraoutput 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.

FIG: Block Diagram

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

21

Studio 1

(Video camera)

CCU PCR 1

Studio 2(Video camera)

PCR 2(Vision mixer)

MSR

VTR

Earth Station

Transmitter


22/32

or Earth station for terrestrial and satellite transmission. MSR is the main control room

between studio and transmitter or receiver.

2.12 AUDIO CHAIN

In studio program, audio from studio microphones is directly fed to the AUDIO CONSOLEplace 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 withthe video signal.

2.13 VISION MIXER

Vision mixer is the almost final equipment in program (video) production and its output isused 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.

There are two types of mixing:

> Additive mixing> Non additive mixing

22

Pre-

Pre-

Pre-

VTR

CD/VCDOutsid

eSatellit

eMW

link

Audioconsole

Program Audio distan.Ampl.

MSR

MSR

MW

FEED

VTR FOR

Program Ampl. ADA


23/32

3.PAL (PHASE ALTERNATE LINE) SYSTEM

3.1 THE COLOUR TELIVISION

It is possible to obtain any desired color by mixing three primary colors i.e., red, blue andgreen in suitable proportion. Thus it is only required to convert optical information of these

three colors to electrical signals and transmit it on different carriers to be decoded by the

receiver. This can then be converted back to the optical image at the picture tube. The

phosphors for all the three colors i.e. R, G and B are easily available to the manufacturers of

the picture tube. So the pick up from the cameras and output for the picture tube shouldconsist of three signals i.e. R, G and B. It is only in between the camera and the picture tube

of the receiver we need a system to transmit this information.

When a CCVS signal passes through a long chain or network (or a defective network) the

chrominance signal may suffer a phase change with respect to burst resulting in wrong hue.

This is because the relationship between burst phase and the instantaneous sub-carrier

superimposed on the Luminance signal will determine HUE or color.If any serious changes occur in this relationship in the transmission path, Assuming a phase

error of (Alpha) after the transmission link for the resultant chrominance signal of nth line. In

the successive line also there is a phase error of (alpha) but the resultant chrominancepolarity is different.

So when we combine the chrominance of nth line and (n +1) th line the net result is

chrominance signal with original phase. This is a major improvement in PAL system over theNTSC system. Even if we do not combine the chrominance outputs of n and n + 1 lines

23


24/32


25/32

5) Generation of pulse called PAL-indent signal of 7.80 kHz.

6) Generating of burst gate or K pulse to define the parking space for burst at the back porch.

7) Adding of 2, 3, 4, Y and sync to generate CCVS i.e., color composite Video signal as

Encoder output.

3.4 PAL DECODER

PAL decoder is a reverse of encoding process. The objectives of recovering R,G & B from

the received signal is achieved in the following steps:

1) Y & S is recovered by decoding video & using LPF and Sync separator circuit of receiver.

2) Chroma is separated by using BPF (centre at 4.43 MHz)

3) Chrome is keyed or gated to get back the burst i.e. SC by using K - Pulse.

4) L.O. 4.43 MHz is phase locked with the recovered burst to make it of same phase as that

of the transmitted one.

25


26/32

5) 4.43 MHz SC is processed further to get the same pulse at 90 degree phase as well.

6) Modulated chroma is demodulated by these two SC at 0 & 90 degree. This will retrieve U& V components.

7) Phase of the V component is restored back to normal by using the concerned informationfrom the transmitted burst.

8) U & V is demodulated back to R-Y & B-Y.

9) Y, R-Y & B-Y are mixed to retrieve R G B which will control the three grids of picture

tube.

3.5 PAL vs. NTSC

NTSC receivers have a tint control to perform color correction manually. If this is not

adjusted correctly, the colors may be faulty. The PAL standard automatically

cancels hue errors by phase reversal, so a tint control is unnecessary. Chrominance phase

errors in the PAL system are cancelled out using a 1H delay lineresulting in lower

saturation, which is much less noticeable to the eye than NTSC hue errors.

26
http://en.wikipedia.org/wiki/NTSChttp://en.wikipedia.org/wiki/Tint_controlhttp://en.wikipedia.org/wiki/Huehttp://en.wikipedia.org/wiki/Delay_linehttp://en.wikipedia.org/wiki/NTSChttp://en.wikipedia.org/wiki/Tint_controlhttp://en.wikipedia.org/wiki/Huehttp://en.wikipedia.org/wiki/Delay_line


27/32

However, the alternation of color information Hanover bars can lead to picture grain

on pictures with extreme phase errors even in PAL systems, if decoder circuits are

misaligned or use the simplified decoders of early designs (typically to overcome royalty

restrictions). In most cases such extreme phase shifts do not occur. This effect will usually be

observed when the transmission path is poor, typically in built up areas or where the terrain is

unfavourable. The effect is more noticeable on UHF than VHF signals as VHF signals tend

to be more robust.

In the early 1970s some Japanese set manufacturers developed decoding systems to avoid

paying royalties to Telefunken. The Telefunken license covered any decoding method that

relied on the alternating subcarrier phase to reduce phase errors. This included very basic

PAL decoders that relied on the human eye to average out the odd/even line phase errors.

One solution was to use a 1Hdelay lineto allow decoding of only the odd or even lines. For

example, the chrominance on odd lines would be switched directly through to the decoder

and also be stored in the delay line. Then, on even lines, the stored odd line would be

decoded again. This method effectively converted PAL to NTSC. Such systems suffered hueerrors and other problems inherent in NTSC and required the addition of a

manual hue control.

PAL and NTSC have slightly divergent color spaces, but the color decoder differences here

are ignored.

3.6 PAL vs. SECAM

SECAM is an earlier attempt at compatible color television which also tries to resolve the

NTSC hue problem. It does so by applying a different method to color transmission, namely

alternate transmission of the U and V vectors and frequency modulation, while PAL attemptsto improve on the NTSC method.

SECAM transmissions are more robust over longer distances than NTSC or PAL. However,

owing to their FM nature, the color signal remains present, although at reduced amplitude,

even in monochrome portions of the image, thus being subject to stronger cross colour. Like

PAL, a SECAM receiver needs a delay line.

27
http://en.wikipedia.org/wiki/Hanover_barshttp://en.wikipedia.org/wiki/Telefunkenhttp://en.wikipedia.org/wiki/Delay_linehttp://en.wikipedia.org/wiki/Huehttp://en.wikipedia.org/wiki/Colorimetryhttp://en.wikipedia.org/wiki/SECAMhttp://en.wikipedia.org/wiki/Hanover_barshttp://en.wikipedia.org/wiki/Telefunkenhttp://en.wikipedia.org/wiki/Delay_linehttp://en.wikipedia.org/wiki/Huehttp://en.wikipedia.org/wiki/Colorimetryhttp://en.wikipedia.org/wiki/SECAM


28/32

4.MASTER SWITCHING ROOM (MSR)

4.1 INTRODUCTION

Master switching room (MSR) is used for transmission media. It is the engineering co-

ordination centre of activity for selecting & routing the signal from various sources totransmitter 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 isrouted through MSR. Signal can be monitored at various stages.

This section is equipped with a 64X64 Digital Routing Switcher where all the signals from

Studio-A, Studio-B, Transmitter, Earth Station, OB Van signal, DSNG etc are routed tovarious areas as per requirements for recording/transmission. One OFC link between MSR

and Earth Station has also been installed.

4.2 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 audioeffects can be added.

28


29/32

5.OB/DSNG VAN

5.1 Introduction

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), "mobileunit", "remote truck", "live truck", or "production truck". Signals from cameras and

microphones come into the OB Van for processing and transmission.

5.2 OB VAN

OB Van is equipped with 8 numbers of Thomson TTV 1657 Digital CCD cameras, 16 inputversatile vision mixers ROSS Synergy with various special effects. 16 channel Sound Craft

make audio mixer with facility of individual channel equalization and limited. In addition to

the above, one computerized MOVE CG for superimposing titles.

Two nos. of broadcast quality VCR having slow motion (TTV3575p), two nos. of RecordingVCRs and one EVS make Live slow motion hard disc recording system is also installed. One

Long haul microwave link is also available with OB Van.

29


30/32

5.3DSNGVAN

The mobile DSNG Van is equipped with 400 W TWT of Xycom and Tandberg E5500encoder in 1+1 mode along with up converters / down converters of ADVENT and base band

equipments. The DSNG van can be operated in both C or Ku band and it has the unique dual

band waveguide in it. The system is operational since November 2002 The 2 meter antennasystem is of advent make having the auto tracking facility controlled through laptop

computer and can track any satellite in very short period automatically. It has a GPS system

with flux gate compass etc used for auto tracking of satellites. The vehicle mounted DSNGVan supplied through BECIL is used in live coverages for up linking.

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 thenext 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, sothat replays and slow-motion shots can 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 fromthe director.

>The 3rd part of van is video tape. The tape area has a collection of VTRs and may alsohouse additional power supplies or computer equipment.

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

30


31/32

6.FUTURE USE OF TRANNING

1. Use in Mobile Communication.

2. Use in Satellite Communication.

3. Use in Live Broadcast. Cultural Programs

Ceremonial Function

Organized Events

Sports Events

4. Use in TV & Radar Communication.

31


32/32

7. CONCLUSION

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

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

In my Industrial training at Doordarshan Kendra, Indore, 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.

Documents

Project Lan 2