Training Presentation by Lokesh Jain

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    Lokesh Jain

    B.TECH. VII SEM. (ECE)

    EC-1

    MNIT, Jaipur

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    A

    Practical Training

    Presentationon

    Doordarshan Kendra, Jaipur

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    Contents:-

    1. Introduction

    2. Basics Of Tv (Pal) Signal

    3.Pre-Production

    -Light-Camera-Microphones

    4.Production-CCU

    -MSR-VM

    5. Satellite Communication

    6. Setup In Rajasthan

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    History-

    In 1930, radio broadcasting was started.

    In March 1935, Govt. took over charge of broadcasting.

    In 1936 All India Radio(AIR) came into the force.

    In 1956 AIR changed to Aakashwani.

    Doordarshan started in India in 1959 with black & white

    transmission.

    In 1982, B&W transmission was converted fully into colour

    transmission during asian games.

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    The first Television Programme was viewed by the

    people of Rajasthan on 1st August 1975 under the

    Satellite Instructional Television Experiment in the

    districts of Kota, Sawai Madhopur and Jaipur.

    On 1st March 1977, Upgrah Doordarshan Kendra

    (UDK) was set up at Delhi.

    The programmes were produced at UDK for Jaipur .

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    Intro cont...

    On 1st June 1987, Jaipur Doordarshan Kendra was set up atJhalana Doongri and transmission started on 6th July 1987.

    Initially the Kendra produced only 30 minutes of programmingand this was gradually increased to about 4 hours.

    From 2nd Oct. 1993, the LPTS located at Ajmer, Udaipur,Jodhpur and Bikaner and HPT at Bundi were connected withDDK Jaipur via satellite.

    Doordarshan Jaipur is the only Programme Production Center inRajasthan. The studios are housed at Jhalana Doongri, Jaipurand the transmitter is located at the Nahargarh Fort.

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    BASICS OF TV (PAL) SIGNAL-

    Video is nothing but a sequence of pictures.

    The impression made by any light seen by the eye persists

    for a small fraction of second(1/16s) .

    If enough pictures are presented to the eye during the

    interval, the eye will integrate them and it create illusion of

    motion. This is called Persistent of Vision.

    In PAL TV system repetition rate is 25 frame/sec.

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    In case of TV camera scene is focused on the photosensitive

    surface of the pick up device and a optical image is formed.

    Like CCD device.

    Electron beam scans the charge image and produces optical

    image.

    Scanning is done in both horizontal & vertical direction

    simultaneously.

    Hor/ Ver scanning freq are 15625 & 50 Hz.

    The frame is divided in two fields.

    Odd lines are scanned first and then even lines.

    The odd and even lines are interlaced.

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    Interlacing reduces flicker.

    Frame rate is 25 Hz, Field rate is 50 Hz.

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    Work at DDK is divided into 3 parts-

    1. Pre-production

    2. Production

    3. Post-production

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    Pre-Production(TV Studio)-

    A television studio is an installation in which

    television or video productions take place .

    1. Light2. Camera

    3. Microphone

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    STUDIO LIGHTING-

    Parameters of lights are-Quantity- Amount of radiated energy by the source of lightQuality- Type of light source used

    Contrast ratio- Difference between highly lighted and darkest

    part of the scene.

    Colour temperature- Different lights and colors have their owntemperature.

    Source TemperatureSun Light 5600 KelvinStudio Lamp 3200 Kelvin

    Domestic Lamp 2780 KelvinFire 1930 KelvinFluorescent 6500 KelvinCloudy Day 6500 Kelvin

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    Balancing of Lighting-Key Light 100%Fill Light 85%Back Light 110%Back Ground Light 50% - 60%

    Types of Lights-

    Key light- the main light used to highlight any object or to

    give attention towards the person.

    Fill light- used to suppress the shadow made by key light.

    Back light- used to seperate artist from the background andso to produce 3d visualization by lighting the head and

    shoulders.Background light- used to highlight the background of thescene or to create color background on white cyclorama.

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    CAMERA-

    A typical video camera have following sections-

    Lens

    Optical Block

    Transducer or pick up device

    Electronics

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    Production-

    1.Camera Control Unit(CCU)

    2.Master Switching Room(MSR)

    3.Vision Mixer(VM)

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    Camera Control Unit

    The output of Studio cameras ispre-amplified and then connected

    to the camera control unit (CCU)through long multi-core cable (35

    to 40 cores).

    Many Parameters of Video SignalsLike Voltage level, color correctionare controlled From CCU.

    .

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    Master Switching Room

    It is the heart of the studio.

    Most of the switching electronics is kept.e.g. camera base stations, switcher main

    frame, Satellite receivers, MW link, & mostof the patch panels.

    Signal is routed through MSR.

    Signal can be Monitored at various stages.

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    VISION MIXER-

    A vision mixer(production switcher) is one of the primary device

    used to produce a television program.

    Production switcher is used to either switch or cut between two

    video sources, or to combine them in a variety of ways.

    The principal methods used to combine video are- Mixing,

    Wiping,& Keying.

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    Satellite in general is a Follower. A heavenly body whichfollows a planet is called a satellite.

    Wireless World in 1945, A radio relay satellite in an

    equaqtorial orbit with of 24 hours would remain stationarywith respect to earths surface and make possible longdistance radio links.

    Birth of satellite commnication in Oct.,1957.

    Started in 1960.

    Started in India in 1975 .

    First Indian Satellite INSAT launched in 1982 .

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    Satellite Transmission

    Frequency bands

    Frequency band Range

    C-band 4-8GHzX-band 8-12 GHzKu-band 12-18GHzKa-band 27-40GHz

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    Satellite Transmission:

    C - Band

    Frequency band 4.0 to

    8.0 GHz

    Large sized dish required

    for reception

    Useful to SystemProviders / Cable

    Operators

    Ku -Band

    Frequency Band 12.5 to

    18 GHz

    Smaller dish ( 6090

    Cms) needed for

    reception

    Most useful for DTH

    application

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    Satellite

    User

    Terrestrial Network

    Earth Station

    User

    Terrestrial Network

    Earth Station

    Basic Satellite System

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    Why uplink frequency is always higher

    than downlink frequency ?

    1) To avoid Interference between Uplink and Down link.

    2) Because the Satellite has a limited RF Power outputand Transmission Loss diminishes as frequencydecreases

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    Earth Station is a very important part of satellitecommunication system for broadcasting of signals.

    It is an uplink center from which the signals are fed to Satellite

    for distribution in a specified area covered by the Satellite.

    The signal is up-linked from the Earth Station and received by

    many down link centers in TV broad casting via PDA.

    Earth Stations is purely Digitization version.

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    Major Components of Digital Earth Station:-

    PDA (Parabolic Dish Antenna)

    Wave Guide / Low Loss Cable

    HPA (TWT, Klystrons)

    Up & Down converter

    Modulator & Demodulator

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    Encoder

    LNADown-

    ConverterDecoder

    Modulator

    Demodulator

    Up

    ConverterHPA

    Base

    Band

    equip-

    ment

    TerrestrialNetwork

    Antenna

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    Up-Converters:-

    Up-Conversions is required to raises the frequency of signalin desired band:- C-band, Extended C-band or Ku bandBefore transmisson.

    I/P of Up-Converter is 70 MHz. O/P is fed to the HPA.

    The Up- Conversion may be done in stages or in one stagedirectly.

    Normally L-band monitoring point is also provided in