syed doordarshan report.docx

7/29/2019 syed doordarshan report.docx

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A REPORT on

PRASAR BHARTI BROADCASTING CORPORATION OF INDIA

DOORDARSHAN KENDRA LUCKNOW

Submitted by:

SYED MOHD MEHNDI

Roll no.-1005231051

Electronics and Communication Engineering

I.E.T Lucknow


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ACKNOWLEDGEMENT

I would like to extend my heartfelt thanks and deep sense of gratitude to all those who

helped me in preparing this report directly or indirectly. I would like to express my sincere

thanks to respected Assistant Engineer R.K. Naithani, I also express my gratitude to Mr.

P.K. Tripathi, Mr. Alok, and Mrs. Sumanwho helped me a lot in understanding the various

processes and concepts involved. It was really a great experience working in the DD Kendra

and learning from such experienced engineers with hands on experience on the subject their

expert guidance and suggestion which helped me to make this report. It gives me immense

pleasure in conveying thanks to all the staff members who helped a lot in completing this

report. I would also like to express my thanks to my friends. I am indebted to them for

providing valuable support and co-operation.

SYED MOHD MEHNDI

Roll no. 1005231051

I.E.T Lucknow


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TABLE OF CONTENTS

1. Overview Page 42. TV Camera Page 63. Composite(CCVS) interface Page 104. Camera and its basic station Page 145. Vision mixer Page 206. Video tape recorder(VTR) Page 207. Earth station simulcast Page 218. Transmitter Page 24


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OVERVIEW

Introduction of Doordarshan lucknow Lucknow Doordarshan started functioning on 27th

Nov. 1975 with an interim setup at 22, Ashok Marg, Lucknow. The colour transmission

service of National Channel (only with Transmitter) started from 15-8-82. While the regularcolour transmission service from studio was started in 1984 with ENG gadgets. During

Reliance Cup, OB Van came to Kendra for outdoor telecast having 4 colour camera chain,

recording equipments, portable microwave link. In March 1989 new studio complex started

functioning. EFP Van came to DDK Lucknow in 1989 with compliment of 3 colour camera

chain and recording setup for outdoor telecast. The entire recording of studio/van have been

replaced to Beta format High Band edit VCR and still in use as the old recording are on H.B.

UP Regional Service telecast with up linking facility from studio (DDK, Lucknow) started in

January 1998 on INSAT-2B. This service was changed to INSAT-2D (T) ARAB SAT. on 14-

7-98. The news feeds are up-linked to Delhi occasionally from Lucknow Earth Station.Studio

program is transmitted from 10 KW-TV transmitter installed at Hardoi Road through

StudioTransmitter Microwave Link. Besides this, one 16 feet PDA is being installed at TV

Transmitter site toreceive the down link signal of Regional Service telecast from studio via

ARAB SAT. on INSAT-2D (T). Site of 22 Ashok Marg, Lucknow is being utilized by

Doordarshan Training Institute (for staff training) having one studio (12m x 6m) and colour

camera chain. The DTI Lucknow was inaugurated in September 1995. In the beginning, only

the development programmes were telecast but later on to enlighten the viewers as per their

needs, expectations, many more informative, educative and entertaining programmes have

been introduced from time to time. Lucknow Doordarshan produced some of the best

programmes in the country as "BIBI NATIYON WALI", "NEEM KA PED" and "HATIM

TAI" etc. To entertain cross-section of the society.


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Technical Overview

DDK Lucknow has the following main departments which manage the production, storage

transmission and maintenance of the two DD National channels.

1. STUDIO2.

2. PRODUCTION CONTROL ROOM (PCR) 3.

3. VIDEO STORAGE AND TRANSMISSION ROOM (VTR) 4.

4. MAIN SWITCHING ROOM (MSR) 5.

5. DIGITAL EARTH LINK STATION6.

TRANSMITTER each of these departments are discussed in detail with due stress to their

Levant engineering aspects. The studio has

Camera and lights and other equipment required for production of a feed.

Camera control unit or CCU

It is in the studio that all aspects related to the production of a video takes place. The DDK has

two large studios and a small studio for news production. The PCR is where the post production

activities like minor editing of feed during a live program takes place. The production

manager sits in the PCR and directs the camera men and selects the angles sound parametersetc. during the production stage in the PCR. It is in the PCR that we can control all the studio

lights and all the microphones and other aspects. The PCR has a vision mixer and an audio

mixer. Its working and other aspects are discussed in detail in the following pages. The PCR

is where the phone in console and other systems are also kept. The VTR is the next section where

copies of all programs are stored. All the programs shot in the camera are simultaneously recorded

in the VTR. Also the VTR plays back all the videos as and when required. Videos of pre-

recorded events are queued up in the VTR and are played back without a break. Videos of famous people and

important events are stored in the central film pool. The MSR stores all the circuitry of the DDK. All


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the camera base units, all the vision mixer base units and all the audio processor base units

are kept in MSR. The audio chain and video chain of MSR is explained in detail. The monitoring and

control of all activities takes place in MSR. It is the MSR which decides what is to go in air.

The MSR also performs some additional functions like logo addition etc. The next station is the

earth station which has an uplink chain, simulcast transmitters, audio processors video

processors, up converters, modulators etc. The earth station is in fully digital domain. The last stage

is the transmitter which has the antenna and facilities for terrestrial transmission.


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TV Camera INTRODUCTION:

A TV Camera consists of three sections.

a) A Camera lens & Optics: To form optical image on the face plate of a pickup device

b) A transducer or pick up device: To convert optical image into a electrical signal

c) Electronics: To process output of a transducer to get a CCVS signal

TYPES OF PICK - UP DEVICESThere are three types of pick up devices based on :a) Photo

emissive material: These material emits electrons when the light falls on them. Amount of

emitted electrons depends on the light. Monochrome cameras used in Doordarshanwere based

on this material. These cameras were called Image Orticon Cameras. These cameras were

bulky and needed lot of light. These are no longer in use at present.

b) Photo conductive material: The conductivity of these material changes with amount of

light falling on them. Such material with variable conductivity is made part of a electrical

circuit.Voltage developed across this material is thus recovered as electrical signal. Earlier

cameras basedon this principle were Videocon Cameras. Such cameras were often used in the

monochrometelevise chain . These cameras had serious Lag & other problems relating to

dark currents.Improvement in these cameras lead to the development of Plumb icon and Sat

icon cameras.

c) Charge coupled devices: These are semiconductor devices which convert light into a

chargeimage which is then collected at a high speed to form a signal.Most of the TV Studios

are now using CCD cameras instead of Tube cameras. Tube cameras havebecome obsolete &

are not in use .Camera sensors CCD basics. The CCD is a solid-state device using special

integrated circuitry technology, hence it is oftenreferred to as a chip camera. The complete

CCD sensor or chip has at least 450 000 pictureelements or pixels, each pixel being basically

an isolated (insulated) photodiode. The action of thelight on each pixel is to cause electrons to

be released which are held by the action of a positivevoltage.

Picture Basics

A television creates a continuous series of moving pictures on the screen. This section will

describe in detail how pictures are created in a television. A camera works exactly on the

same principle applied the other way round. A picture is "drawn" on a television or computer

display screen by sweeping an electrical signal horizontally across the display one line at a

time. The amplitude of this signal versus time represents the instantaneous brightness at that

physical point on the display. At the end of each line, there is a portion of the waveform

(horizontal blanking interval) that tells the scanning circuit in the display to retrace to the left


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edge of the display and then start scanning the next line. Starting at the top, all of the lines on the display

are scanned in this way. One complete set of lines makes a picture. This is called a frame.

Once the first complete picture is scanned, there is another portion of the waveform

(vertical blanking interval, not shown) that tells the scanning circuit to retrace to of the

display and start scanning the next frame, or picture. This sequence is repeated at a fast

enough rate so that the displayed images are perceived to have continuous motion. This is the

same principle as that

Behind the "flip books" that you rapidly flip through to see a moving picture or cartoons that

are drawn and rapidly displayed one picture at a time. Interlaced versus Progressive Scans

These are two different types of scanning systems. They differ in the technique used to coverthe area of the screen. Television signals displays are typically interlaced, and computer

signals and compatible displays are typically progressive (non-interlaced). These two formats

are incompatible with each other; one would need to be converted to the other before any

common processing could be done. Interlaced where each picture, referred to as a frame, is

divided into two separate sub-pictures, and referred to as fields. Two fields make up a frame.

An interlaced picture is painted on the screen in two passes, by first scanning the horizontal

lines of the first field and then retracing to the top of the screen and then scanning the

horizontal lines for the second field in-between the first set. Field 1 consists of lines 1

through 262 1/2, and field 2 consists of lines 262 1/2 through 525. The interlaced principle is

illustrated in Figure 2.Only a few lines at the top and the bottom of each field are shown.


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There are many different kinds of video signals, which can be divided into either television or

computer types. The format of television signals varies from country to country. In the United

States and Japan, the NTSC format isused. NTSC stands for National Television Systems

Committee, which is thename of the organization that developed the standard. In Europe, the

PALformat is common. PAL (phase alternating line), developed after NTSC, isan

improvement over NTSC. SECAM is used in France and stands for sequential color avec

memoire (with memory). It should be noted that thereis a total of about 15 different sub-

formats contained within these threegeneral formats. Each of the formats is generally not

compatible with theothers. Although they all utilize the same basic scanning system

andrepresent color with a type of phase modulation, they differ in specificscanning

frequencies, number of scan lines, and color modulationtechniques, among others. The

various computer formats (such as VGA, XGA, and UXGA) also differ substantially, with

the primary difference inthe scan frequencies. These differences do not cause as much

concern, because most computer equipment is now designed to handle variable scanrates. This

compatibility is a major advantage for computer formats in thatmedia, and content can be

interchanged on a global basis.

In India we use the PAL system. It has 625 lines in each frame anduses interlaced scanning.


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There are three basic levels of baseband signal interfaces. In order of increasing quality, they

are composite (or CCVS), which uses one wire pair; Y/C (or S-video), which uses two wire

pairs; and component, which uses three wire pairs. Each wire pair consists of a signal and a

ground. These three interfaces differ in their level of information combination (or encoding).

More encoding typically degrades the quality but allows the signal to be carried on fewer

wires. Component has the least amount of encoding, and composite the most.


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Composite/CCVS Interface.Composite signals are the most commonly used analog video

interface.Composite video is also referred to as CCVS, which stands for color,

video, blanking, and sync, or composite video baseband signal. Itcombines the brightness info

rmation (luma), the color information (Chroma), and the synchronizing signals on just one

cable. The connector is typically an RCA jack. This is the same connector as that used for

standardline level audio connections. A typical waveform of an all-white NTSC composite video

signal is shown in Figure.

This figure depicts the portion of the signal that represents one horizontal scan line. Each line is

made up of the active video portion and the horizontal blanking portion. The active video portion

contains the picture brightness (luma) and color (Chroma) information. The brightness

information is the instantaneous amplitude at any point in time. From the figure, it can be

see that the voltage during the active video portion would yield a bright-white picture for

this horizontal scan line, whereas the horizontal blanking portion would be displayed as

black and therefore not be seen on the screen. Color information is added on top of the luma signal

and is a sine wave with the colors identified by a specific phase difference between it and the

color- burst reference phase. The amplitude of the modulation is proportional to the


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amount of color (or saturation), and the phase information denotes the tint (or hue) of the

color. The horizontal blanking portion contains the horizontal synchronizing pulse (sync

pulse) as well as the color reference (color burst) located just after the rising edge of the

sync pulse (called the "back porch"). It is important to note here that the horizontal blanking

portion of the signal is positioned in time such that it is not visible on the display screen.

Y/C Interfaces

The Y/C signal is a video signal with less encoding. Brightness (luma),which is the Y signal,

and the color (chroma), the C signal, are carried ontwo separate sets of wires.

Component InterfacesComponent signal interfaces are the highest performance, because they havethe least

encoding. The signals exist in a nearly native format. They alwaysutilize three pairs of wires

that are typically in either a luma (Y) and two-color-difference-signals format or a red, green,

blue (RGB) format. RGBformats are almost always used in computer applications, whereas

color-difference formats are generally used in television applications. The Y signalcontains

the brightness (luma) and synchronizing information, and the color-difference signals contain

the red (R) minus the Y signal and the blue (B)minus the Y signal. The theory behind this

combination is that each of the base R, G, and B components can be derived from thesedifference signals.Common variations of these signals are as follows:

Y, B-Y, R-Y: Luma and color-difference signals.

Y, Pr, Pb: Pr and Pb are scaled versions of B-Y and R-Y. Commonly found in high-

end consumer equipment.

Y, Cr, Cb: Digital-signal equivalent to Y, Pr, Pb. Sometimes incorrectly used in place

of Y, Pr, Pb.

Y, U, V: Not an interface standard. These are intermediate, quadrature signals usedin the formation of composite and Y/C signals. Sometimes incorrectly referred to as a

"component interface.

Some important terms and their meanings in this context are listed below

Aspect Ratio

Aspect ratio is the ratio of the visible-picture width to the height. Standard television and

computers have an aspect ratio of 4:3(1.33). HDTV has aspects ratios of either 4:3 or

16:9(1.78). Additional aspect ratios like 1.85:1or 2.35:1 are used in cinema.


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Blanking Interval

There are horizontal and vertical blanking intervals. Horizontal blanking interval is the time

period allocated for retrace of the signal from the right edge of the display back to the left

edge to start another scan line. Vertical blanking interval is the time period allocated forretrace of the signal from the bottom back to the top to start another field or frame.

Synchronizing signals occupy a portion of the blanking interval.

Blanking LevelUsed to describe a voltage level (blanking level). The blanking level is the nominal voltage of

a video waveform during the horizontal and vertical periods, excluding the more negative voltage

sync tips.ChromaThe color portion of a video signal. This term is sometimes incorrectly referred to as

"chrominance," which is the actual displayed color information.

Color BurstThe color burst, also commonly called the "color subcarrier," is 8 to 10cycles of the color

reference frequency. It is positioned between the rising edge of sync and the start of active

video for a composite video signal.

Fields and FramesA frame is one complete scan of a picture. In NTSC it consists of 525horizontal scan lines. In

interlaced scanning systems, a field is half of a frame; thus, two fields make a frame.

LumaThe monochrome or black-and-white portion of a video signal. This term is sometimes

incorrectly called "luminance," which refers to the actual displayed brightness.

MonochromeThe luma (brightness) portion of a video signal without the color information. Monochrome,

commonly known as black-and-white, predates current color television.

PALPhase alternate line. PAL is used to refer to systems and signals that are compatible with this

specific modulation technique. Similar to NTSC but uses subcarrier phase alternation to

reduce the sensitivity to phase errors that would be displayed as color errors. Commonly used

with 626-line, 50Hzscanning systems with a subcarrier frequency of 4.43362MHz.Pixel


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Picture element. A pixel is the smallest piece of display detail that has aunique brightness and

color. In a digital image, a pixel is an individual pointin the image, represented by a certain number

of bits to indicate the brightness.

RGBStands for red, green, and blue. It is a component interface typically used in computer

graphics systems. Sync Signals/Pulses Sync signals, also known as sync pulses, are negative-

going timing pulses in video signals that are used by video-processing or display devices the

horizontal and vertical portions of the display.

Y Cr Cb

A digital component video interface. Y is the luma (brightness) portion, and Cr and Cb are

the color-difference portions of the signal.

Y/C

An analog video interface in which the chroma (color) information is carried separately from

the luma (brightness) and sync information. Two wire pairs are used, denoted Y and C or

Y/C. Often incorrectly referred to as "S-video."

CAMERA AND ITS BASE STATION

The camera system in DDK Lucknow has the following main components

i) Optical system

ii) Video system

iii) Monitor system

iv) Pulse system

v) Control system

vi) Auto setup system

vii) Power system

viii) Intercommunication system and tally system

ix) Transmission system

Camera has a head unit as well as a base unit. The head unit is located in thestudio and the base unit is located

in the MSR. Also there is a CameraControl Unit (CCU) which is a separate unit in itself which is

used to control the camera. The base station of the camera houses all the electronics

related to the camera. The head unit of the camera is the part which the camera

manhandles in the studio. The head unit of the camera is connected to other parts of the


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system through a triax cable alone. This reduces the clutter in the studio. The triax cable

carries power for the camera. Signals of the pictures to from the camera and also carries the

communications in RF to and from the camera. The head unit of the camera houses the

charge coupled devices (CCD) which take in the light from the viewing area and convert

them to electrical signals. Before the light hits the CCDs in a colour camera, adichroic prism

is used to split the three primary colours RGB into three and cause them to be absorbed by

different CCDs which are kept at the focus of the lens system. They absorb light from each

part of the screen pixel after pixel and for a moving picture frame after frame. The CCDs

improve the apparent limit resolution with the help of spatial pixel shifting. There are 3types

of CCDs available.

Interline transfer (IT)

Frame Transfer (FT)

Frame Interline Transfer (FIT)

The DDK Lucknow studio uses 4 IKEGAMI (HK 399W) cameras in studio 1 and an Ikegami

camera and a SONY camera in Studio 2.TheIkegami camera and Sony both uses FIT type

CCDs. The sonny camera gives a digital output whereas the Ikegami gives out an analog output. The FIT

type CCD has photodiodes, vertical transfer CCDs and Horizontal transfer CCDs , all of which

but photodiodes are covered with metallic film to prevent any kind of exposure to light. The

residual charges in vertical transfer CCD is swept out. If it is not swept out smearing occurs

(light leaks into vertical transfer CCD and is seen as light above and below a bright

object).The charges, the result of light converted by photodiodes are transferred to vertical

transfer CCDs during vertical blanking. Then the charges are transferred to the storage

CCDs at high speed. This reduces smear. FIT is complex but has very little smear.

Light entering sections is covered with metallic film do not cause photoelectric conversion.

But light which is reflected enters the photodio desand may generate false signals called

moir (faded distortion). An optical low pass filter is used for reducing this moir

phenomenon

ON CHIP LENSIt is mounted on the CCD to collect light which is not contributing to photoelectric

conversion. This improves CCD sensitivity. Most CCDs have on


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Unlike pickup tubes the CCD does not have a continuous surface but discrete photodiodes.

This lowers spatial frequencies that are higher than half the sampling frequency on the basis

of sampling theorem. These frequently cause spurious signals which cause moir. The optical

low pass filter is used to attenuate and surpass high pass spatial frequencies. A crystal filter

with the effect of double refraction is used in this

.

SPATIAL PIXEL SHIFTING

This is a method of improving horizontal resolution such that the light receiving element of

channel G is shifted by half pitch compared to that of R.


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and B. This effectively doubles the sampling points and theoretically doubles the upper band

resolution if luminance signal Y= .25R + .50G +.25B holds true. In reality however Y= .25R +

.50G + .25B is required and that does not result in double resolution but can achieve a

satisfactory effect. An inner sampling point also reduces moir.

OVERFLOW DRIVES(OFD)of CCDs are responsible for discharging excessive charges when a

large volume of light falls on the photo diodes Without OFD the charges will overflow to the

adjacent pixels and a phenomenon called blooming occurs. In blooming the ambient are of a

spot image extensively in white


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Appropriate control of OFD allows signal charges to discharge by force midway through the

charge storage process thus performing same role as a shutter.

Standards of shutter

Preset shutter 1/60thof a second for NTSC and 1/60Th of a second to 1/200th of a second for

PALCVSS or continuous variable shutter speed is 1/30.3thto 1/ 57.6th

For NTSC and again 1/61.4 to 1/1996 for NTSC. For PAL 1/25.4 to 1/47.6 and from1/50.4 to

1/1953.In particular 1/100 seconds make it possible to eliminate flicker caused between NTSC

field and 50Hz commercial power supply. New Super V is technology incorporated to

improve vertical resolution. It gives a vertical resolution of 480 TV lines against a normal or 400 TV

lines.

Video System

It has a CCD multi module, a PROC -1 module a PROC-2 module, a Head DPROC and Head pulse

modules. The video system of BS/CCU contains BSMPV, BS DF PROC and BS Pulse modules.

The electric signal that has undergone photoelectric conversion in the CCD element are

transferred to the sample hold circuit in the CCD multi module and output to the A PROC -1 module, undergo

video processing by a A

PROC-2 Head D Proc and Head Pulse module and are transmitted to BS/CCU via the triax

cable adaptor as component (Y, Cr, Cb) signals In self-contained mode they are converted

into encoder signals by the digital encoder ASIC in the Head D PROC module for Output.


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Monitoring SystemThe monitoring System generates various signals to be output to VF, PF and WFM. It is

separate from the main, the system can actually switch R, G and B video signal or display

signal requirements for monitoring the maker or characters.

Pulse SystemThe pulse system is installed in department of camera head and BS/CCU, and is designed to

operate in conjunction with the CCU operation connected to BS/CCU and in the self-

contained mode operated by the camera head alone, in either way the system can be operated

in internal or external synchronization mode.

Control SystemThe camera is normally controlled through the CPUs of the HEAD MPU and BS MPU modules

to keep watching each unit and module.

Production Control Room (PCR)

A major objective of TV program control facilities is to maintain a smooth continuous flow

of program material. The overall control of program is done in production control room by

the producer with the help of a productionassistant, a CCU engineer and an engineer at vision

mixer. They have in front of them, the switching panel of the vision mixer console and a

stack of monitors for the individual cameras, preview monitors of VTRs and transmission

monitor for displaying the switched output, with the aid of which the program is edited.

The PCR usually of the various equipments like:-

Camera Control Unit(CCU)

Vision Mixer(VM)

Video Tape Recorder(VTR)

Audio Mixer(AM)

Camera Control Unit (CCU)

The CCU contains control for

Aperture

Optical Focus

Zoom of the lens system

Beam Focus

Selecting Gain


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Color Temperature

Contours (Camera Details)

Gamma

Vision Mixer (VM)

A vision mixer or video switcher enables the program producer to select the desired sources

or a combination of the sources in order to compose the program. The vision mixer is

typically 10x6 or 20x10 crossbar switcher selecting any one of the 10 or 20 input sources to 6

to10 different output lines. The input sources include: Camera-1, Camera-2, Camera-3,

Telecine-1, Telcine-2, VTR-1, VTR-2, Test Signal etc. The vision mixer provides the

following operational facilities for the editing of the TV programs.

Take--selection of any input source, or cut-switching cleanly from one source to

another.

Dissolve-fading in or fading out.

Lap Dissolve-dissolving from one source to another with an overlap mixing.

Superposition of two sources-keyed caption when the selected inlay is superposed on

the background picture

Video Tape Recorder (VTR)

The standardized two inch tape quadrupled head recording machines arecalled the video tape

recorder and are used for the high quality video taperecording one or half inch helical scan

tape recorders have been used for outdoor field recording. This multipurpose studio digital

video cassettetapes, and is designed to record, play back and edit interlace signals(6251/5251)

as well as record, playback and edit existing DVCPRO signals(25Mbps). Its 625/525

switching functions makes this studio video cassetterecorder which can be used anywhere in

the world. In addition, it corporatedigital compression technology so that the deterioration in

picture qualityand sound quality resulting from dubbing is significantly minimized.

Thecompact, lightweight 4U size makes carry easier, even when mounted in a19 inch rack.

The settings for the units set up can be performed interactivelywhile

viewing the screen menus on the monitor, and editing functionsinclude both assemble and insert editing.


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DIGITAL EARTH STATION SIMULCAST

Frequency range - 5.85 GHz to 6.425 GHz for transmission

3.625 GHz to 4.2 GHz for reception

The digital earth station operates in the frequency range of 5.85 GHz to6.425 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 earthstation 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 (70MHz) 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 a long 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 downlinked 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 center 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 +1

mode and is compliant with DVB MPEG 2 standards. 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


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management system or NMS monitors and controls baseband equipments compression

equipment 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 programmes and

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

programmes 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 programmes 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 programmes and a

personal computer for centralized merit and contention of earth station sub system.

UP CONVERTER (1+1)The UPC will add in any frequency within stated transmission BW in 125 kHz stepped

increments. The IF bandwidth is indented for operation within an 80Mhz BW centered at

70MHz (for +/- 40 MHz) Due to its low phase noise and HF stability the model UC6M2D5

(satellite networks) meets

INTELSAT, DOMSAT, EUTELSAT and regional requirements. It can standalone up

converter or in a 1:1 protection switch option. The uplink frequency for Trivandrum is 6036.5

MHz and downlink is 3811.5 MHz.

AUDIO PROCESSOR

Designed specifically for the demands of television audio, the programmable OPTIMOD-TV8282 digital audio processor meets all requirements of the various systems in use around the


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world. It is impossible to characterize thelistening quality of even the simplest limiter or

compressor on the basis of the usual specifications, because such specifications cannot

adequately describe the crucial dynamic processes that occur under program

conditions.Therefore, the only way to meaningfully evaluate the sound of an audio processor

is by subjective listening tests. Certain specifications are present adhere to assure the engineer

that they are reasonable, to help plan theinstallation, and to help make certain comparisons

with other processingequipment. Some of the specifications are for features that are optional.

TheTXs sampling rate can be synchronized with that of audio processors or can be allowed a

free run of 32 kHz, 44.1 kHz or 48 kHz. The audio signal issent to the digital I/O cards and analog

cards separately. These cards provide pre emphasis truncations required and attenuation on

the digital signal before transmission.

Transmitter

Antenna

A 6.3m diameter antenna with a simplified manual track device features ready erection,

ease of maintenance and high reliability.

Antenna parameters


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pg. 24

Reflector structureThe 6.3 m diameter antenna is made up of 4 quarter segment. Each andevery quarter is made

up of 10 segments fixed on five trusses. Panels which are fixed to the trusses are made up of

fine aluminum expanded mesh strengthened with the help of channel sections and tee


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pg. 25

sections whose ends are fixed to the backup structure. Trusses are composed of aluminum

square tubes and the welded back up made up of hub and 20 trusses. The hubs and trusses are

constructed in such a way that they constitute to the high level of surface accuracy.

Mount structureA simple tubular steel space frame makes up most of the mount structure. It allows rotation

about x-axis as well as y axis. The x axis drive rod is connected between the top of the

mounted structure and the concrete foundation. The y axis drive rod is connected between the

base of the x axis bearing mount and the reflector back up structure on the left hand side as

viewed from the rear of the antenna. The mount is rigidly attached to the concrete base which

is facing north such that it can survive even in wind speeds up to 200 kmph.

Drive mechanismIt has a telescopic pipe arrangement and a screw rod within it along withmanual handle.

There are mechanical angle indicators along the screw rodwhich indicate the exact position

and angle of the antenna with respect to both the axes.

MaterialMost of the parts of the panel and antenna structure are made up of aluminum alloy which

has corrosion resistance and yield strength.

Finish

The reflector is treated in the following order before installation

(a) Etch primer is applied after caustic soda acid treatment

(b) Painted with white matt paint.

The mount is treated with the following

(a) A hot dip which galvanizes all steel parts


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(b) Etch primer treatment

(c) White enamel paint is applied as a last coating.

Fixing the feed onto the antenna

The feed is supported by a set of four pipes called as a quadruped. It is fixed before the whole antenna

structure is hoisted, that is, it is fixed on the ground itself before the whole antenna structure

is fixed. Care should be taken that the feed is at the exact focus of the reflector. A maximum

tolerance of +3mm is allowed for the separation between the actual focus and feed position.

Also the feed entrances and cable output ports are covered with waterproof Teflon sheet to

prevent the entry of moisture into the arrangement.

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