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APRACTICAL TRAINING REPORT

ON

PRESENTEDBY:

YOGESHKUMAR

ww.powerpointpresentationon.blogspot.com
http://www.powerpointpresentationon.blogspot.com/http://www.powerpointpresentationon.blogspot.com/

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Sunday, July, 18, 2010 GLOBAL INSTITUTE OF TECHNOLOGY

Doordarshan Kendra is a part ofDepartment of Information andBroadcasting (Govt. of India)

. Doordarshan Setup in Rajasthan

It Consists Of Following Setup Studio Centre : 1 Uplink Station : 1 Transmitters : 99

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TELIVISON STUDIO

Studio floorThe studio floor is where production actuallyoccurs. The studio floor is an open area, whichcontains the television cameras,' microphones,

lighting equipments sets and crew.

Control roomThe control room there is the programmer's

director, assistant director, technical director, audioengineer and video engineer works

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T.V. PICTURE

A picture can be considered to contain a number of small elementary areasof light or shade which are called picture element.

The scene is focused on the photo-sensitive surface of pickup device and aoptical image is formed.

The photo electric properties of the pickup device convert the optical imageto a electric image charge depending on the light & shade of the scene.

To transmit this information scanning is employed.

The electron beam scans the image from left to right(line by line) and from top to bottom (frame by frame)or field by field. The scanning is done both inhorizontal direction and vertical directionsimultaneously.

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The horizontal scanning frequency is15625 Hz. The vertical scanningfrequency is 50 Hz.

The frame is divided into two fields,odd lines are scanned first and thenthe even lines are interlaced.

The frame is divided into 2 fields.

The field rate is 50 Hz. The frame rate is25 Hz (field rate is same as the powersupply).

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CameraA TV camera consist of the following sections:

A Camera lens and optics :To form optical image on theface Plate of a pick up device. A transducer or pick up device :To convert optical image into

an Electrical signal. Electronics :To process output of a

transducer

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LIGHTING In a television studio it is necessary to illuminate each

area of action separately besides providing an averagelevel of brightness over the entire scene.

Different types of light..

Eye light Rim light Kickkar light Limbo light

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Material Used for recording . FERRO MAGNETIC MATERIALS

(Fe2O3/Fe2O4) ARE USED

. THESE MATERIALS HAS SPECIALCHARACTERISTIC OF MAGNETICRETAINTIVITY.

DIFFERENCE BETWEEN AUDIO/VIDEORECORDERS

Characteristic Audio Rec. Video Rec.

Frequencies 20 Hz to 20 KHz 20Hz to 5 MHz

No. of octaves 10 18

Timing Accuracy Not so important Very Important

Rec. Medium Limitations No Yes

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A VCR HAS TWO SPEEDS1. Linear speed: It is the speed at which tape runs. It decides the tape lengthrequired/consumed for a particular duration.For Beta cam edit VCR it is 10.15 Cm/Sec.Tape length for 30 Min. Cassette= 10.15x30x60 Cm2. Writing Speed: It is the speed at which signal information is written on thetape by the Head.W. Speed =3.14xDrum Diameter in m x Drum Speed in rpsFor Beta cam edit VCR, Drum Diameter = 74.4mmDrum speed =25 rpsW. Speed =3.14x (74.4/1000) x25 =5.75 m/ Sec.

Video tape Formats

It defines the arrangement of magnetic information on the tape. It specifies: 1. Tape width 2. No. of tracks for Video, Audio, CTL, TC & Cue 3. Their electrical characteristic and orientation. 4. Track width.

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A vision mixer or production switcher is one of the primarydevices used to produce a television program. Productionswitchers are essential to all live operations.

Production switcher is used to either switch or cut between twovideo sources, or to combine them in a variety of ways.

The principal methods used to combine video are- Mixing,Wiping, & Keying.

BASIC FUNCTIONS OF A SWITCHER Cut operation or switching between two sources.

Mixing or dissolve. Wiping. Keying.

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It allows having changeover from onevideo source to another sourceinstantaneously. Switching between one

source to another is done during verticalinterval period to make the changeoverinvisible on the screen.

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MIXING

Mixing is an additive combination of two video sources.

Two input sources are mixed in proportion in a summingamplifier as decided by the position of the control fader.

Two extreme positions give either of the source atoutput. Middle of the two fader gives mixed output of thetwo sources.

The sum of two video sources is always 1 volt p-p.

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A VIDEO B VIDEO

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WIPING

This is a non additive combination of two sources. A switching

occurs during the active video at specific points on the raster toproduces a pattern, between two video sources. Switching iscontrolled by an internal wipe pattern generator which can providethe waveform either saw tooth or parabola at H,V or both H and Vrates. The very simple to very complex waveform can be

generated by the wipe pattern generator.Simple patterns can begenerated by logical combination of different waveforms Howeverthe production of more complex patterns is better handled by amicroprocessor.

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WIPING




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WIPINGThis is a non additive combination of two sources. A switching



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WIPING




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WIPING




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WIPING




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WIPING




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WIPING




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This is also a non additive combination of two videosources. In keying operation, part of the picture(Background) is replaced by another picture(foreground) according to the limits set by a third signal

called key or alpha signal which can be derived eitherfrom the picture itself being keyed (self key or internalkey), or from a third video signal from camera or CG orDVE etc.(Auto select or external key) .

HARRYPOTTER

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Digital video effects are created by digitizing thevideo effects signal so that it can be stored,retrieved, and manipulated in digital format.

These effects are generated by digital video effects

device which can be a separate standalone unit orcan be an integral part of production switcher.

A typical digital video effects system consists ofthe control panel, controller electronics to generate

the required control signals to define the effect,and the digital video processor which uses thecontrol signals to control the video signal in thedigital domain producing the desired effect.

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Types Of DIGITAL VIDEO EFFECTS 3D CREATIVITY IMAGING EFFECTS

CURVILINEAR EFFECTS PAINTERLY AND PARTICLE EFFECTS SLABS BORDER EFFECTS

LIGHTING EFFECTS SHADOWS DYNAMIC RECURSIVE EFFECTS

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Digital EarthStation

.

Modes of Distribution of TV

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Modes of Distribution of TVProgrammes

Terrestrial Satellite Cable

All the above three modes can be eitherin Analog or in digital domain.

Satellite Transmission

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Earth station

DownlinkUplink

Satellite Transmission

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Earth Station is a uplink center from which the signals are fedto Satellite for distribution in a specified area covered by theSatellite.

The signal is up-linked from the earth station and received bymany down link centers in TV broad casting.

It is a very important part of satellite communication system forbroadcasting of signals.

Earth Station classification Analog Earth Station Analog / Digital Simulcast

Digital Earth Station ASNG DSNG C-band or Ku-band

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Why Digital ? More programs 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 planningNew services like Pay TV, VOD,Teletext, Data, Surround sound, Multimedia etc.

Interactive services like e-commerce, e-banking, tele-quiz, tele-games etc.

Automated operation in broadcast plan Non availability of analog systems in near future Future of TV transmission DTH, DTT & Digital Cable

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REQUIREMENTS

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 ofmodulator) and output of Up-converter is fed toHPA.

The up-conversion may done in stages or in onestage directly. For example the 70 MHz signal isfirst converted into Lband and then L band signalraised to desired frequency band.

Normally L-band monitoring point is also provided

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REQUIREMENTS

Antenna system

PDAs The most widely used narrow beam antennas are

reflector antennas. The shape is generally a paraboloidof revolution.

For full earth coverage from a geostationary satellite, ahorn 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 Cass grain design, the sub reflector is

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REQUIREMENTS Antenna system(PDA)

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REQUIREMENTS

Antenna system

DSNG Antenna case: Antenna segment case, Antenna mount

case, Antenna hub case, Antenna feed horn case;1.9meter antenna (C band) & 1.2 meter antenna ( Ku-band)

HPA case: 400 W TWTA ( C band) & 125 W TWTA (

Ku-band) Base band unit : Test and monitoring case Digital case : Encoder, Modulator, Up convertor(L band) HPA control and Up convertor case: Up convertor(C

band / Ku-band ),HPA controller

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REQUIREMENTS Antenna system

DSNG

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REQUIREMENTS

High Power Amplifier 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: Frequency range Output power at flange Bandwidth Gain variation (1.0 db (max.) for 40 MHz (narrow band) 2.50 db for full bandwidth)

The different types of HPAs are: KHPA - Klystron High Power Amplifier

TWTA -Traveling Wave Tube Amplifier SSPA- Solid state Power Amplifier

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Microphone

In all microphones, sound waves (sound pressure) aretranslated into mechanical vibrations in a thin, flexiblediaphragm. These sound vibrations are then convertedby various methods into an electrical signal which varies

in voltage amplitude and frequency in an analog of theoriginal sound. For this reason, a microphone is anacoustic wave to voltage modulation transducer.

Mi h i i
http://en.wikipedia.org/wiki/Sound_pressurehttp://en.wikipedia.org/wiki/Diaphragm_(acoustics)http://en.wikipedia.org/wiki/Analog_(signal)http://en.wikipedia.org/wiki/Transducerhttp://en.wikipedia.org/wiki/Transducerhttp://en.wikipedia.org/wiki/Analog_(signal)http://en.wikipedia.org/wiki/Diaphragm_(acoustics)http://en.wikipedia.org/wiki/Sound_pressurehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Microphone

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Microphone varieties

1 Capacitor or Condenser microphones 2 Electret condenser microphones 3 Dynamic microphones

4 Ribbon microphones 5 Carbon microphones 6 Piezo microphones 7 Laser microphones

Sunday, July, 18, 2010

Capacitor or Condenser
http://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Microphone

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Capacitor or Condensermicrophones

In a capacitor microphone, also known as a condenser

microphone, the diaphragm acts as one plate of acapacitor, and the vibrations produce changes in thedistance between the plates. Since the plates arebiased with a fixed charge (Q), the voltage maintained

across the capacitor plates changes with the vibrationsin the air., according to the capacitance equation:Q=C.V

where Q = charge in coulombs, C = capacitance in

farads and V = potential difference in volts. Thecapacitance of the plates is inversely proportional tothe distance between them for a parallel-platecapacitor.

Capacitor microphones can be expensive and require

El d i h
http://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Capacitorhttp://en.wikipedia.org/wiki/Biashttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Biashttp://en.wikipedia.org/wiki/Capacitorhttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Microphone

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Electret condenser microphones

applicatioA foil electret microphone is a relatively new type ofcondenser microphone invented at Bell laboratories in 1962 byGerhard Sesslerand Jim West[1], and often simply called an electretmicrophone. An electret is a dielectric material that has beenpermanently electrically charged orpolarised. Electret microphones

have existed since the 1920s but were considered impractical, but theyhave now become the most common type of all, used in manyapplications from high-quality recording and lavalieruse to built-inmicrophones in small sound recording devices. Though electret micswere once considered low-cost and low quality, the best ones can now

rival capacitor mics in every respect apart from low noise and evenhave the long-term stability and ultra-flat response needed for ameasuring microphone. Unlike other condenser microphones theyrequire no polarising voltage, but normally contain an integratedpreamplifierwhich does require power (often incorrectly called

polarizing power or bias). The integral preamp usually forms part of the

D i i h
http://en.wikipedia.org/wiki/Faradhttp://en.wikipedia.org/wiki/Volthttp://en.wikipedia.org/wiki/Power_supplyhttp://en.wikipedia.org/wiki/Phantom_powerhttp://en.wikipedia.org/wiki/Bell_laboratorieshttp://en.wikipedia.org/wiki/1962http://en.wikipedia.org/wiki/Gerhard_Sesslerhttp://en.wikipedia.org/wiki/Gerhard_Sesslerhttp://en.wikipedia.org/wiki/James_Edward_Maceo_Westhttp://www.lucent.com/news_events/articles/020916.htmlhttp://en.wikipedia.org/wiki/Electrethttp://en.wikipedia.org/wiki/Electrethttp://www.lucent.com/news_events/articles/020916.htmlhttp://en.wikipedia.org/wiki/James_Edward_Maceo_Westhttp://en.wikipedia.org/wiki/Gerhard_Sesslerhttp://en.wikipedia.org/wiki/Gerhard_Sesslerhttp://en.wikipedia.org/wiki/1962http://en.wikipedia.org/wiki/Bell_laboratorieshttp://en.wikipedia.org/wiki/Phantom_powerhttp://en.wikipedia.org/wiki/Power_supplyhttp://en.wikipedia.org/wiki/Volthttp://en.wikipedia.org/wiki/Farad

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Dynamic microphones

In a dynamic microphone a small movable induction

coil, positioned in the magnetic field of a permanentmagnet, is attached to the diaphragm. When thediaphragm vibrates, the coil moves in the magneticfield, producing a varying current in the coil (See

electromagnetic induction). The principle is exactly thesame as in a loudspeaker, only reversed. Dynamicmicrophones are robust, relatively inexpensive, andresistant to moisture, and for this reason they arewidely used on-stage by singers. They tend to havea poor low-frequency response, which is advantageousfor reducing handling noise as a vocal mic, but tends toexclude them from other uses.

Ribb i h
http://en.wikipedia.org/wiki/Electric_chargehttp://en.wikipedia.org/wiki/Electric_chargehttp://en.wikipedia.org/wiki/Lavalierhttp://en.wikipedia.org/wiki/Sound_recordinghttp://en.wikipedia.org/wiki/Sound_recordinghttp://en.wikipedia.org/wiki/Preamplifierhttp://en.wikipedia.org/wiki/Phantom_powerhttp://en.wikipedia.org/wiki/Induction_coilhttp://en.wikipedia.org/wiki/Magnetic_fieldhttp://en.wikipedia.org/wiki/Magnetic_fieldhttp://en.wikipedia.org/wiki/Induction_coilhttp://en.wikipedia.org/wiki/Phantom_powerhttp://en.wikipedia.org/wiki/Preamplifierhttp://en.wikipedia.org/wiki/Sound_recordinghttp://en.wikipedia.org/wiki/Sound_recordinghttp://en.wikipedia.org/wiki/Lavalierhttp://en.wikipedia.org/wiki/Electric_chargehttp://en.wikipedia.org/wiki/Electric_charge

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Ribbon microphones In ribbon microphones a thin, usually corrugated metal ribbon

is suspended in a magnetic field: vibration of the ribbon in themagnetic field generates a changing current. Basic ribbonmicrophones detect sound in a bidirectional (also called afigure-of-eight) pattern because the ribbon, which is open tosound both front and back, responds to the pressure gradient

rather than the sound pressure. Though the symmetrical frontand rear pickup can be a nuisance in normal stereo recording,the high side rejection can be used to advantage by positioninga ribbon mic horizontally, for example above cymbals, so that

the rear lobe picks up only sound from the ceiling. Otherdirectional patterns are produced by enclosing one side of theribbon in an acoustic trap or baffle, allowing sound to reachonly one side. Ribbon mics can give very high quality, andwere once valued for this reason, but a good low-frequency

response can only be obtained if the ribbon is suspended very

Ribb i h
http://en.wikipedia.org/wiki/Permanent_magnethttp://en.wikipedia.org/wiki/Diaphragmhttp://en.wikipedia.org/wiki/Diaphragmhttp://en.wikipedia.org/wiki/Permanent_magnet

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Audio Basics By R.K.Jain

Ribbon microphones

Carbon microphones

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Carbon microphones

A carbon microphone, formerly used in telephonehandsets, is a capsule containing carbon granulespressed between two metal plates. A voltage is appliedacross the metal plates, causing a current to flow

through the carbon. One of the plates, the diaphragm,vibrates in sympathy with incident sound waves,applying a varying pressure to the carbon. Thechanging pressure deforms the granules, causing the

contact area between each pair of adjacent granules tochange, and this causes the electrical resistance of themass of granules to change (lose contact). Since thevoltage across a conductor is proportional to its

resistance the volta e across the ca sule varies

Piezo microphones
http://en.wikipedia.org/wiki/Current_(electricity)http://en.wikipedia.org/wiki/Electromagnetic_inductionhttp://en.wikipedia.org/wiki/Loudspeakerhttp://en.wikipedia.org/wiki/Loudspeakerhttp://en.wikipedia.org/wiki/Electromagnetic_inductionhttp://en.wikipedia.org/wiki/Current_(electricity)

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Piezo microphones

A piezo microphone uses the phenomenon ofpiezoelectricity the tendency of some materials toproduce a voltage when subjected to pressure toconvert vibrations into an electrical signal. This type of

microphone is often used to mic acoustic instrumentsfor live performance, or to record sounds in unusualenvironments (underwater, for instance.)

An example of this is Rochelle Salt, Potassium SodiumTartrate, which is a piezo crystal and works both waysand is in common use as a slimline loudspeakercomponent.

Laser microphones
http://en.wikipedia.org/wiki/Ribbon_microphonehttp://en.wikipedia.org/wiki/Ribbon_microphone

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Laser microphones

A laser microphone is an exotic application oflasertechnology. It consists of a laser beamthat must be reflected off a glass window or

any rigid surface that vibrates in sympathy withnearby sounds. The mic essentially measuresthe distance between itself and the surfacevery accurately in order to turn any resonantsurface into a microphone. Laser microphonesare new, very rare and expensive, and aremost commonly portrayed in the movies as

spying devices
http://en.wikipedia.org/wiki/Current_(electricity)http://en.wikipedia.org/wiki/Telephonehttp://en.wikipedia.org/wiki/Telephonehttp://en.wikipedia.org/wiki/Current_(electricity)

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