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Project Report on Summer

Training at Doordarshan Kendra,Patna

TOPIC:

STUDY OF TELEVISIONTRANSMISSION AND BROADCASTING

SYSTEM

INSTRUCTOR:SUBMITTED BY:1. Mr. N.K.SINGH DILEEP KR.RAJJAK (BE/5543/08)2. Md. KHALID AHMED CHANDRASHEKHARBEHERA (BE/5581/08)

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DOORDARSHAN KENDRA SHREEKANTKUMAR (BE/5592/08)PATNA (BIHAR)MRITUNJAY KUMAR (BE/5610/08)

SUNIL KUMAR

SHAW (BE/5723/08) ELECTRONICS &

COMMUNICATION ENGINEERRING

BIT MESRA,

PATNA CAMPUS

ACKNOWLEDGEMENT

The above project has been a great working experience for us.

We learnt about the various aspects of working ofDOORDARSHAN. Topic of project Study of TelevisionTransmission and Broadcasting System helped us to knowthe steps involved from inception of the video signal fromsource to transmission medium toits reception at televisionsets.

First of all, we would like to show our deepest gratitude to Mr.S.K.F. YUSUF, Assistant Station Engineer (Doordarshan Kendra,Patna), who provided us this opportunity to work with

Doordarshan.

We are grateful to Mr. N.K.Singh and Mr. Khalid Ahmed whothrough their deep knowledge of the topic helped us inunderstanding it in a simple and better way.

We are also thankful to all the employees of DOORDARSHANKENDRA, Patna without whose support in providing thenecessary materials this project report would not have been

possible.

At last we are thankful to Training and Placement Cell of ourcollege which gave us the opportunity to pursue summerinternship at Doordarshan Kendra, Patna.

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DOORDARSHAN: A BRIEF DESCRIPTION:

Doordarshan is the public television broadcaster of India and a

division ofPrasar Bharati, a public service broadcaster nominated by

the Government of India. It is one of the largest broadcasting

organizations in the world in terms of the infrastructure of studiosand transmitters. Recently, it has also started Digital Terrestrial

Transmitters. Doordarshan had a modest beginning with the

experimental telecast starting in Delhi on 15 September 1959 with a

small transmitter and a makeshift studio. The regular daily

transmission started in 1965 as a part of All India Radio. The

television service was extended to Bombay (now Mumbai) and

Amritsar in 1972. Up until 1975, only seven Indian cities had a

television service and Doordarshan remained the sole provider of

television in India.

Presently, Doordarshan operates 21 channels two All Indiachannels-DD National and DD News, 11 Regional languagesSatellite Channels (RLSC), four State Networks (SN), an Internationalchannel, a Sports Channel DD Sports and two channels RajaySabha TV & DD-Lock Sabha for live broadcast of parliamentaryproceedings.

On DD National(DD-1), Regional programmes and LocalProgrammes are carried on time-sharing basis. DD News channel,launched on 3 November 2003, which replaced the DD Metro(DD-2) Entertainment channel, provides 24-Hour news service.

The Regional Languages Satellite channels have two components The Regional service for the particular state relayed by all terrestrialtransmitters in the state and additional programmes in the RegionalLanguage in prime time and non-prime time available only throughcable operators. DD-Sports Channel is exclusively devoted to the

broadcasting of sporting events of national and internationalimportance.
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INTRODUCTION:

Television (TV) is a telecommunicationmedium for transmitting andreceiving moving images that can be monochromatic (shades ofgrey) or multi-coloured. Images are usually accompanied by sound.

The etymology of the word is derived from mixed Latin and Greekorigin, meaning "far sight": Greek tele ( ), far, and Latin visio,sight (from video, vis- to see, or to view in the first person.

Broadcast TV is typically disseminated via radio transmissions ondesignated channels in the 54890 MHz frequency band.[1] Signalsare now often transmitted with stereo and/or surround sound inmany countries. Until the 2000s broadcast TV programs weregenerally transmitted as an analogue television signal, but in recentyears public and commercial broadcasters have been progressivelyintroducing digital television broadcasting technology.

Analog television systems:

All but one analog television system began as monochromesystems. Each country, faced with local political, technical, andeconomic issues, adopted a color system which was grafted onto anexisting monochrome system, using gaps in the video spectrum(explained below) to allow color transmission information to fit in theexisting channels allotted. The grafting of the color transmissionstandards onto existing monochrome systems permitted existingmonochrome television receivers predating the change over to color

television to continue to be operate as monochrome television.Because of this compatibility requirement, color standards added asecond signal to the basic monochrome signal, which carries thecolor information. The color information is called chrominance or Cfor short, while the black and white information is called theluminance or Y for short. Monochrome television receivers onlydisplay the luminance, while color receivers process both signals.

Though in theory any monochrome system could be adopted to acolor system, in practice some of the original monochrome systemsproved impractical to adapt to color and were abandoned when theswitch to color broadcasting was made. All countries now use one of
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three color systems: NTSC, PAL, or SECAM.In India PAL technique isused for television broadcasting:

PHASE ALTERNATING LINE (PAL):

PAL, short for Phase Alternating Line, is an analog colortelevision encoding system used in broadcast television systems inmany countries. Other common analogue television systems areSECAM and NTSC.

The basics of PAL and the NTSC system are very similar; aquadrature amplitude modulated subcarrier carrying thechrominance information is added to the luminance video signal toform a composite video baseband signal. The frequency of thissubcarrier is 4.43361875 MHz for PAL, compared to 3.579545 MHzfor NTSC. The SECAM system, on the other hand, uses a frequencymodulation scheme on its two line alternate colour subcarriers4.25000 and 4.40625 MHz.

The name "Phase Alternating Line" describes the way that the phaseof part of the colour information on the video signal is reversed witheach line, which automatically corrects phase errors in thetransmission of the signal by cancelling them out, at the expense ofvertical frame colour resolution. Lines where the colour phase isreversed compared to NTSC are often called PAL or phase-alternation lines, which justifies one of the expansions of theacronym, while the other lines are called NTSC lines. Early PALreceivers relied on the imperfections of the human eye to do that

cancelling; however, this resulted in a comblike effect known asHanover bars on larger phase errors. Thus, most receivers now use achrominance delay line, which stores the received colourinformation on each line of display; an average of the colourinformation from the previous line and the current line is then usedto drive the picture tube. The effect is that phase errors result insaturation changes, which are less objectionable than the equivalenthue changes of NTSC. A minor drawback is that the vertical colourresolution is poorer than the NTSC system's, but since the humaneye also has a colour resolution that is much lower than its

brightness resolution, this effect is not visible. In any case, NTSC,
http://en.wikipedia.org/wiki/NTSChttp://en.wikipedia.org/wiki/PALhttp://en.wikipedia.org/wiki/SECAMhttp://en.wikipedia.org/wiki/Analog_televisionhttp://en.wikipedia.org/wiki/Analog_televisionhttp://en.wikipedia.org/wiki/Broadcast_television_systemshttp://en.wikipedia.org/wiki/Analog_televisionhttp://en.wikipedia.org/wiki/SECAMhttp://en.wikipedia.org/wiki/NTSChttp://en.wikipedia.org/wiki/Quadrature_amplitude_modulationhttp://en.wikipedia.org/wiki/Subcarrierhttp://en.wikipedia.org/wiki/Composite_videohttp://en.wikipedia.org/wiki/Megahertzhttp://en.wikipedia.org/wiki/Hanover_barshttp://en.wikipedia.org/wiki/Delay_linehttp://en.wikipedia.org/wiki/Saturation_(color_theory)http://en.wikipedia.org/wiki/NTSChttp://en.wikipedia.org/wiki/PALhttp://en.wikipedia.org/wiki/SECAMhttp://en.wikipedia.org/wiki/Analog_televisionhttp://en.wikipedia.org/wiki/Analog_televisionhttp://en.wikipedia.org/wiki/Broadcast_television_systemshttp://en.wikipedia.org/wiki/Analog_televisionhttp://en.wikipedia.org/wiki/SECAMhttp://en.wikipedia.org/wiki/NTSChttp://en.wikipedia.org/wiki/Quadrature_amplitude_modulationhttp://en.wikipedia.org/wiki/Subcarrierhttp://en.wikipedia.org/wiki/Composite_videohttp://en.wikipedia.org/wiki/Megahertzhttp://en.wikipedia.org/wiki/Hanover_barshttp://en.wikipedia.org/wiki/Delay_linehttp://en.wikipedia.org/wiki/Saturation_(color_theory)

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PAL, and SECAM all have chrominance bandwidth (horizontal colourdetail) reduced greatly compared to the luminance signal.

Fig: Spectrum of a System I television channel with PALcolour.

DISPLAYING AN IMAGE

A CRT television displays an image by scanning a beam ofelectronsacross the screen in a pattern of horizontal lines known as a raster.At the end of each line the beam returns to the start of the next line;at the end of the last line it returns to the top of the screen. As itpasses each point the intensity of the beam is varied, varying the

luminance of that point. A color television system is identical exceptthat an additional signal known as chrominance controls the color ofthe spot.
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Fig: Raster scanning is shown in a slightly simplifiedform.

When analog television was developed, no affordable technology forstoring any video signals existed; the luminance signal has to begenerated and transmitted at the same time at which it is displayed

on the CRT. It is therefore essential to keep the raster scanning inthe camera (or other device for producing the signal) in exactsynchronization with the scanning in the television.

The physics of the CRT require that a finite time interval is allowedfor the spot to move back to the start of the next line (horizontalretrace) or the start of the screen (vertical retrace). The timing ofthe luminance signal must allow for this.

MPEG-2:

MPEG-2 is a standard for "the generic coding of moving pictures

and associated audio information".[1] It describes a combination of

lossyvideo compression and lossy audio data compression methods

which permit storage and transmission of movies using currently

available storage media and transmission bandwidth.

Main characteristics:

MPEG-2 is widely used as the format ofdigital television signals thatare broadcast by terrestrial (over-the-air), cable, and directbroadcast satelliteTV systems. It also specifies the format of moviesand other programs that are distributed on DVD and similar discs. Assuch,TV stations, TV receivers, DVD players, and other equipmentare often designed to this standard. MPEG-2 was the second ofseveral standards developed by the Moving Pictures Expert Group(MPEG) and is an international standard (ISO/IEC 13818). Parts 1 and

2 of MPEG-2 were developed in a joint collaborative team with ITU-T,and they have a respective catalog number in the ITU-TRecommendation Series.

While MPEG-2 is the core of most digital television and DVD formats,it does not completely specify them. Regional institutions can adaptit to their needs by restricting and augmenting aspects of thestandard. See Video profiles and levels.

STRUCTURE OF VIDEO SIGNAL
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The video carrier is demodulated to give a composite video signal;this contains luminance (brightness), chrominance (color) andsynchronization signals; this is identical to the video signal formatused by analog video devices such as VCRs or CCTV cameras. Notethat the RF signal modulation is inverted compared to theconventional AM: the minimum video signal level corresponds to

maximum carrier amplitude, and vice versa. The carrier is nevershut off altogether; this is to ensure that inter carrier sounddemodulation can still occur.

Each line of the displayed image is transmitted using a signal asshown above. The same basic format (with minor differences mainlyrelated to timing and the encoding of color) is used for PAL, NTSCand SECAM television systems. A monochrome signal is identical toa color one, with the exception that the elements shown in color inthe diagram (the color burst, and the chrominance signal) are notpresent.

FRAMES:

Ignoring color, all television systems work in essentially the samemanner. The monochrome image seen by a camera (now, theluminance component of a color image) is divided into horizontalscan lines, some number of which make up a single image or frame.A monochrome image is theoretically continuous, and thus unlimitedin horizontal resolution, but to make television practical, a limit hadto be placed on the bandwidth of the television signal, which puts anultimate limit on the horizontal resolution possible. When color wasintroduced, this limit of necessity became fixed. All current analogtelevision systems are interlaced; alternate rows of the frame are

transmitted in sequence, followed by the remaining rows in theirsequence. Each half of the frame is called a field, and the rate at
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PRINCIPLES OF TELEVISION COLOR:

This is a spectrum of energy that starts with low frequency radio

waves, moves through VHF-TV, FM radio, UHF-TV (which nowincludes the new digital TV band of frequencies), all the way throughx-rays.

The visible light portion of the electromagnetic spectrum consists ofall the colors of the rainbow (as shown in the enlarged segmentabove), which combine to produce white light.

The fact that white light consists of all colors of light added togethercan be demonstrated with the help of a prism.

Additive Color

Thus far we have been talking about the subtractive colorprocess -- the effect of mixing paints or pigments that in variousways absorb or subtract colors of light.

When colored lights are mixed (added) together, the result isadditive rather than subtractive. Thus, when the additive primaries(red, green and blue light) are mixed together in the rightproportions, the result is white.

This can easily be demonstrated with three slide projectors.

Let's assume that a colored filter is placed over each of the threeprojector lenses -- one red, one green, and one blue.

When all three primary colors overlap (are added together) on awhite screen, the result is white light. Note in this illustration thatthe overlap of two primary colors (for example, red and green)creates a secondary color (in this case, yellow).

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Y= 0.59G+0.3R+0.11B(1)

R-Y= R-(0.59G+0.3R+0.11B) = 0.7R-0.59G-0.11B(2)

B-Y= B-(0.59G+0.3R+0.11B) = 0.89B-0.59G-0.3R. (3)

Chrominance Signal = {(R-Y)2 + (B-Y)2}1/2

.. (4)

tan = (R-Y)/(B-Y)..(5)

In analog television, chrominance is encoded into a video signal

using a special Subscriber frequency, which, depending on thestandard can be either quadrature- amplitude (NTSC & PAL) or

frequency (SECAM) modulated. In PAL system, the color subcarrier is

4.43 MHz above video carrier.

COLORTYPE

WHITE

YELLOW

CYAN GREEN

MAGENTA

RED BLUE BLACK

Y 1.0 0.89 0.7 0.59 0.41 0.3 0.15 0

B-Y 0 -0.89 0.3 -0.59 0.59 -0.3 0.89 0

R-Y 0 0.11 -0.7 -0.59 0.59 0.7 -0.11 0

G-Y 0 0.11 0.3 0.41 -0.41 -0.3 -0.11 a

U 0 -0.439 0.146 -0.291

0.291 -0.148

0.439 0

V 0 0.097 -

0.614

-

0.517

0.517 -

0.614

-

0.097

0

Table: Relative Value of Luminance and Chrominance for 100%Saturated Colors

The 4.43361875 MHz frequency of the colour carrier is a result of283.75 colour clock cycles per line plus a 25 Hz offset to avoidinterferences. Since the line frequency (number of lines per second)is 15625 Hz (625 lines x 50 Hz / 2), the colour carrier frequencycalculates as follows: 4.43361875 MHz = 283.75 * 15625 Hz +

25 Hz.

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The presence of chrominancein a video signal is signalled by a

color burst signal transmitted on the back porch, just after

horizontal synchronisation and before each line of video starts.

COMPOSITE VIDEO SIGNAL:

Composite video is the format of an analog television (pictureonly) signal before it is combined with a sound signal and modulatedonto an RF carrier. In contrast to component video (YPbPr) itcontains all required video information, including colors in a singleline-level signal. Like component video, composite-video cables donot carry audio and are often paired with audio cables (see RCAconnector).

Composite video is often designated by the CVBS initialism,meaning "Composite Video, Blanking, and Sync."

It is usually in standard formats such as NTSC, PAL, and SECAM.

SIGNAL COMPONENTS

It is a composite of three source signals called Y, U and V (togetherreferred to asYUV) with sync pulses. Y represents the brightness or

luminance of the picture and includes synchronizing pulses, so thatby itself it could be displayed as a monochrome picture. U and Vrepresent hue and saturation or chrominance; between them theycarry the color information. They are first modulated on twoorthogonal phases of a color carrier signal to form a signal called thechrominance. Y and UV are then combined. Since Y is a basebandsignal and UV has been mixed with a carrier, this addition isequivalent to frequency-division multiplexing.

SIGNAL MODULATION

Composite video can easily be directed to any broadcast channelsimply by modulating the proper RF carrier frequency with it. Mostanalog home video equipment record a signal in (roughly) compositeformat: LaserDiscs store a true composite signal, while VHS tapesuse a slightly modified composite signal. These devices then givethe user the option of outputting the raw signal, or modulating itonto a VHF or UHF frequency to appear on a selected TV channel.
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COLOR BURST:

In composite video, colorburst is a signal used to keep thechrominance subcarrier synchronized in a color television signal. By

synchronizing an oscillator with the colorburst at the back porch

(beginning) of each scan line, a television receiver is able to restore

the suppressed carrier of the chrominance signals, and in turn

decode the color information. PAL uses a frequency of exactly

4.43361875 MHz, with its phase alternating between 135 and 225

from line to line.

TELEVISION BROADCAST CHANNEL:

For television broadcasting, channels have been assigned in the VHF

and UHF ranges. The allocated frequencies are:

RANGE BAND FREQUENCY

Lower VHF Range Band I 41-68 MHz

Upper VHF Range Band III 174-230 MHz

Lower UHF Range Band IV 470-582 MHz

Upper UHF Range Band V 606-790 MHz

*NOTE: Band II (88-108 MHz) is allotted for FM broadcasting.

VESTIGIAL SIDEBAND TRANSMISSION:

In the video signal, very low frequency modulating components

exist along with rest of the signal
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These components give rise to sidebands very close to the carrier

frequency difficult to remove by physically realizable filters

Again the low video frequencies contain the most important

information of the picture

Complete suppression of the lower sideband would result in

phase distortion at these frequencies

Therefore we cannot fully suppress one complete sideband

As a compromise only a part of the LSB is suppressed

Radiated signal consist of :

Full USB + Carrier + Vestige of the partially suppressed LSB

This pattern of transmission is known as

Vestigial Side Band Transmission or A5C transmission

Frequencies up to 0.75 MHz of the LSB are fully radiated

Attenuation slope of 0.5 MHz at either end

FM sound signal occupies a frequency spectrum of about 75

KHz around the sound carrier

Guard band of 0.25 MHz allowed on the sound carrier side

for interchannel separation

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VIDEO CAMERA TUBE:

In older video cameras, before the mid to late 1980s, a video

camera tube or pickup tube was used instead of a charge-

coupled device (CCD) for converting an optical image into an

electrical signal. Several types were in use from the 1930s to the

1980s. The most commercially successful of these tubes were

various types ofcathode ray tubes or "CRTs".

TYPES:

Image dissector The iconoscope Vidicon Plumbicon Saticon Pasecon Newvicon Trinicon
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VIDICO

N:

A vidicon tube is a video camera tube design in which the target

material is a photoconductor. The Vidicon was developed in the1950s at RCA by P. K. Weimer, S. V. Forgue and R. R. Goodrich as asimple alternative to the structurally and electrically complex ImageOrthicon.[citation needed] While the initial photoconductor used wasselenium, other targetsincluding silicon diode arrayshave beenused.[citation needed]

Fig: Schematic View of vidicon tube.

The vidicon is a storage-type camera tube in which a charge-densitypattern is formed by the imaged scene radiation on aphotoconductive surface which is then scanned by a beam of low-velocity electrons. The fluctuating voltage coupled out to a videoamplifier can be used to reproduce the scene being imaged. Theelectrical charge produced by an image will remain in the face plateuntil it is scanned or until the charge dissipates. Pyroelectricphotocathodes can be used to produce a vidicon sensitive over a

broad portion of the infrared spectrum.
http://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/Photoconductorhttp://en.wikipedia.org/wiki/Electronhttp://en.wikipedia.org/wiki/Amplifierhttp://en.wikipedia.org/wiki/Pyroelectrichttp://en.wikipedia.org/wiki/Photocathodehttp://en.wikipedia.org/wiki/Infraredhttp://en.wikipedia.org/wiki/File:Vidicon.pnghttp://en.wikipedia.org/wiki/File:Vidicon.pnghttp://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/Photoconductorhttp://en.wikipedia.org/wiki/Electronhttp://en.wikipedia.org/wiki/Amplifierhttp://en.wikipedia.org/wiki/Pyroelectrichttp://en.wikipedia.org/wiki/Photocathodehttp://en.wikipedia.org/wiki/Infrared

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TELEVISION STUDIO:

A television studio is an installation in which television or videoproductions take place, either for live television, for recording live to

tape, or for the acquisition of raw footage for post-production. The

design of a studio is similar to, and derived from, movie studios, with

a few amendments for the special requirements of television

production. A professional television studio generally has several

rooms, which are kept separate for noise and practicality reasons.

These rooms are connected via intercom, and personnel will be

divided among these workplaces.

STUDIO FLOOR

Fig: Studio Room of a news channel in making

The studio floor is the actual stage on which the actions that will berecorded take place. A studio floor has the following characteristicsand installations:

decoration and/or sets cameras (sometimes one, usually several) on pedestals microphones lighting rigs and the associated controlling equipment. several video monitors for visual feedback from the production

control room a small public address system for communication A glass window between production control room (PCR) and

studio floor for direct visual contact is usually desired, but notalways possible
http://en.wikipedia.org/wiki/Televisionhttp://en.wikipedia.org/wiki/Videohttp://en.wikipedia.org/wiki/Live_televisionhttp://en.wikipedia.org/w/index.php?title=Live_to_tape&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Live_to_tape&action=edit&redlink=1http://en.wikipedia.org/wiki/Footagehttp://en.wikipedia.org/wiki/Post-productionhttp://en.wikipedia.org/wiki/Movie_studiohttp://en.wikipedia.org/wiki/Intercomhttp://en.wikipedia.org/wiki/Set_constructionhttp://en.wikipedia.org/wiki/Professional_video_camerahttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Stage_lightinghttp://en.wikipedia.org/wiki/Video_monitorhttp://en.wikipedia.org/wiki/Public_addresshttp://en.wikipedia.org/wiki/File:Al_Jazeera_mews_room_under_construction_by_ashour_jsc.jpghttp://en.wikipedia.org/wiki/Televisionhttp://en.wikipedia.org/wiki/Videohttp://en.wikipedia.org/wiki/Live_televisionhttp://en.wikipedia.org/w/index.php?title=Live_to_tape&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Live_to_tape&action=edit&redlink=1http://en.wikipedia.org/wiki/Footagehttp://en.wikipedia.org/wiki/Post-productionhttp://en.wikipedia.org/wiki/Movie_studiohttp://en.wikipedia.org/wiki/Intercomhttp://en.wikipedia.org/wiki/Set_constructionhttp://en.wikipedia.org/wiki/Professional_video_camerahttp://en.wikipedia.org/wiki/Microphonehttp://en.wikipedia.org/wiki/Stage_lightinghttp://en.wikipedia.org/wiki/Video_monitorhttp://en.wikipedia.org/wiki/Public_address

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While a production is in progress, the following people work in thestudio floor.

The on-screen "talent" themselves, and any guests - thesubjects of the show.

A floor director or floor manager, who has overall charge of the

studio area, and who relays timing and other information fromthe director.

One or more camera operators who operate the televisioncameras, though in some instances these can also be operatedfrom PCR using remote heads.

Possibly a teleprompter operator, especially if this is a newsbroadcast

PRODUCTION-CONTROL ROOM:

The production control room (PCR), also known as the "gallery" orStudio Control Room (SCR), is the place in a television studio inwhich the composition of the outgoing program takes place.Facilities in a PCR include:

A video monitor wall, with monitors for program, preview,VTRs, cameras, graphics and other video sources. In somefacilities, the monitor wall is a series of racks containingphysical television and computer monitors; in others, themonitor wall has been replaced with a virtual monitor wall(sometimes called a "glass cockpit"), one or more large videoscreens, each capable of displaying multiple sources in asimulation of a monitor wall.

A vision mixer, a large control panel used to select the videosources to be seen on air and, in many cases, in any monitorson the set. The term 'vision mixer' is primarily used in Europe,while the term 'switcher' is usually used in North America.

An audio mixing console and other audio equipment such aseffects devices.

A character generator, which creates the majority of thenames and full screen graphics that are inserted into theprogram

Digital video effects, or DVE, for manipulation of video sources.In newer vision mixers, the DVE is integrated into the visionmixer; older models without built-in DVE's can often controlexternal DVE devices, or an external DVE can be manually runby an operator.

A still store, or still frame, device for storage of graphics orother images. While the name suggests that the device is only

capable of storing still images, newer still stores can storemoving video clips.
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The technical director's station, with waveform monitors,vectorscopes and the CCUs or remote control panels for theCCUs.

In some facilities, VTRs may also be located in the PCR, but arealso often found in the central machine room

Intercom and IFB equipment for communication with talent and

crew

Fig: A Production Control Room

MASTER-CONTROL ROOM

The master control room houses equipment that is too noisy or runstoo hot for the production control room. It also makes sure that wirelengths and installation requirements keep within manageablelengths, since most high-quality wiring runs only between devices inthis room. This can include:

The actual circuitry and connection boxes of the vision mixer,DVE and character generator devices

camera control units VTRs patch panels for reconfiguration of the wiring between the

various pieces of equipment.

In a broadcast station in the US, master control room or "MCR" is theplace where the on-air signal is controlled. It may include controls toplay back programs and commercials, switch local or network feeds,record satellite feeds and monitor the transmitter(s), or these itemsmay be in an adjacent equipment rack room. The term "studio"usually refers to a place where a particular local program isoriginated. If the program is broadcast live, the signal goes from theproduction control room to MCR and then out to the transmitter.
http://en.wikipedia.org/wiki/Technical_directorhttp://en.wikipedia.org/wiki/Waveform_monitorhttp://en.wikipedia.org/wiki/Vectorscopehttp://en.wikipedia.org/wiki/Camera_control_unithttp://en.wikipedia.org/wiki/Interruptible_feedbackhttp://en.wikipedia.org/wiki/Master_controlhttp://en.wikipedia.org/wiki/Vision_mixerhttp://en.wikipedia.org/wiki/Digital_video_effectshttp://en.wikipedia.org/wiki/Character_generatorhttp://en.wikipedia.org/wiki/Camera_control_unithttp://en.wikipedia.org/wiki/VTRhttp://en.wikipedia.org/wiki/Patch_panelhttp://en.wikipedia.org/wiki/Master_controlhttp://en.wikipedia.org/w/index.php?title=Satellite_feed&action=edit&redlink=1http://en.wikipedia.org/wiki/Technical_directorhttp://en.wikipedia.org/wiki/Waveform_monitorhttp://en.wikipedia.org/wiki/Vectorscopehttp://en.wikipedia.org/wiki/Camera_control_unithttp://en.wikipedia.org/wiki/Interruptible_feedbackhttp://en.wikipedia.org/wiki/Master_controlhttp://en.wikipedia.org/wiki/Vision_mixerhttp://en.wikipedia.org/wiki/Digital_video_effectshttp://en.wikipedia.org/wiki/Character_generatorhttp://en.wikipedia.org/wiki/Camera_control_unithttp://en.wikipedia.org/wiki/VTRhttp://en.wikipedia.org/wiki/Patch_panelhttp://en.wikipedia.org/wiki/Master_controlhttp://en.wikipedia.org/w/index.php?title=Satellite_feed&action=edit&redlink=1

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OTHER FACILITIES:

A television studio usually has other rooms with no technicalrequirements beyond program and audio monitors. Among themare:

one or more make-up and changing rooms a reception area for crew, talent, and visitors, commonly called

the green room.

VISION MIXER:

A vision mixer (also called video switcher, video mixer or

production switcher) is a device used to select between several

different video sources and in some cases composite (mix) video

sources together and add special effects. This is similar to what amixing console does for audio.

CAPABILITIES AND USAGE IN TV PRODUCTION:

Besides hard cuts (switching directly between two input signals),mixers can also generate a variety of transitions, from simpledissolves to pattern wipes. Additionally, most vision mixers canperform keying operations and generate color signals (called mattes

in this context). Most vision mixers are targeted at the professionalmarket, with newer analog models having component videoconnections and digital ones using SDI. They are used in live andvideo tapedtelevision productions and for linear video editing, eventhough the use of vision mixers in video editing has been largelysupplanted by computer based non-linear editing.

Fig: A Sony BVS-3200CP vision mixer.

OPERATION:
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The main concept of a professional vision mixer is the bus, basicallya row of buttons with each button representing a video source.Pressing such a button will select the video out of that bus. Oldervideo mixers had two equivalent buses (called the A and B bus; sucha mixer is known as an A/B mixer). One of these buses could beselected as the main out (or program) bus. Most modern mixers,

however, have one bus that is always the program bus, the secondmain bus being the preview (sometimes called preset) bus. Thesemixers are called flip-flop mixers, since the selected source of thepreview and program buses can be exchanged. Both preview andprogram bus usually have their own video monitor.

Another main feature of a vision mixer is the transition lever, alsocalled a T-bar or Fader Bar. This lever, similar to an audio fader,creates a smooth transition between two buses. Note that in a flip-flop mixer, the position of the main transition lever does not indicatewhich bus is active, since the program bus is always the active orhotbus. Instead of moving the lever by hand, a button (commonlylabeled "mix", "auto" or "auto trans") can be used, which performsthe transition over a user-defined period of time. Another button,usually labeled "cut" or "take", directly swaps the buses without anytransition. The type of transition used can be selected in thetransition section. Common transitions include dissolves (similar toan audio crossfade) and pattern wipes.

The third bus on a vision mixer is the key bus. A mixer can actuallyhave more than one of these, but they usually share only one set ofbuttons. Here, a signal can be selected for keying into the program.

The image that will be seen in the program is called the fill, whilethe mask used to create the key's translucence is called the source.

This source, e.g. chrominance, luminance, pattern (the internalpattern generator is used) or split (an additional video signal similarto an alpha channel is used) and can be selected in the keyingsection of the mixer. Note that instead of the key bus, other videosources can be selected for the fill signal, but the key bus is usually

the most convenient method for selecting a key fill. Usually, a key isturned on and off the same way a transition is. For this, thetransition section can be switched from program (or background)mode to key mode. Often, the transition section allows backgroundvideo and one or more keyers to be transitioned separately or in anycombination with one push of the "auto" button.

CHARACTER GENERATOR:
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A character generator, often abbreviated as CG, is a device orsoftware that produces static or animated text (such as crawls androlls) for keying into a video stream. Modern character generatorsare computer-based, and can generate graphics as well as text. (Theintegrated circuit, usually in the form of a PROM, that decodes akeystroke in a keyboard, and outputs a corresponding character, is

also referred to as a "character generator.")

Character generators are primarily used in the broadcast areas oflive sports or news presentations, given that the modern charactergenerator can rapidly (i.e., "on the fly") generate high-resolution,animated graphics for use when an unforeseen situation in the gameor newscast dictates an opportunity for broadcast coverageforexample, when, in a football game, a previously unknown playerbegins to have what looks to become an outstanding day, thecharacter generator operator can rapidly, using the "shell" of asimilarly-designed graphic composed for another player, build a newgraphic for the previously unanticipated performance of the lesserknown player. The character generator, then, is but one of manytechnologies used in the remarkably diverse and challenging work oflive television, where events on the field or in the newsroom dictatethe direction of the coverage. In such an environment, the quality ofthe broadcast is only as good as its weakest link, both in terms ofpersonnel and technology. Hence, character generator developmentnever ends, and the distinction between hardware and software

generators begins to blur as new platforms and operating systemsevolve to meet the live television consumer's expectations.

Two types of Character Generators:

HARDWARE CHARACTER GENERATORS

Hardware character generators are used in television studios andvideo editing suites. A desktop publishing-like interface can be usedto generate static and moving text or graphics, which the device

then encodes into some high-quality video signal, like digital SDI oranalog component video, high definition or even RGB video. Inaddition, they also provide a key signal, which the compositingvision mixer can use an alpha channel to determine which areas ofthe CG video are translucent.

Chyron Corporation developed the character generator specificallyfor broadcast use. The term lower third was developed to describethe chyron machine font that was predominately on the lower partof the TV screen. The original chyron was the only hardware that all

professionals in the industry used for 2D and 3D graphics.
http://en.wikipedia.org/wiki/News_crawlhttp://en.wikipedia.org/wiki/Credits_rollhttp://en.wikipedia.org/wiki/Keying_(graphics)http://en.wikipedia.org/wiki/Videohttp://en.wikipedia.org/wiki/Integrated_circuithttp://en.wikipedia.org/wiki/Programmable_read-only_memoryhttp://en.wikipedia.org/wiki/Keystrokehttp://en.wikipedia.org/wiki/Keyboard_(computing)http://en.wikipedia.org/wiki/Television_studiohttp://en.wikipedia.org/wiki/Video_editinghttp://en.wikipedia.org/wiki/Desktop_publishinghttp://en.wikipedia.org/wiki/Serial_Digital_Interfacehttp://en.wikipedia.org/wiki/Component_videohttp://en.wikipedia.org/wiki/High-definition_televisionhttp://en.wikipedia.org/wiki/RGBhttp://en.wikipedia.org/wiki/Keying_(graphics)http://en.wikipedia.org/wiki/Vision_mixerhttp://en.wikipedia.org/wiki/Alpha_channelhttp://www.chyron.com/http://en.wikipedia.org/wiki/News_crawlhttp://en.wikipedia.org/wiki/Credits_rollhttp://en.wikipedia.org/wiki/Keying_(graphics)http://en.wikipedia.org/wiki/Videohttp://en.wikipedia.org/wiki/Integrated_circuithttp://en.wikipedia.org/wiki/Programmable_read-only_memoryhttp://en.wikipedia.org/wiki/Keystrokehttp://en.wikipedia.org/wiki/Keyboard_(computing)http://en.wikipedia.org/wiki/Television_studiohttp://en.wikipedia.org/wiki/Video_editinghttp://en.wikipedia.org/wiki/Desktop_publishinghttp://en.wikipedia.org/wiki/Serial_Digital_Interfacehttp://en.wikipedia.org/wiki/Component_videohttp://en.wikipedia.org/wiki/High-definition_televisionhttp://en.wikipedia.org/wiki/RGBhttp://en.wikipedia.org/wiki/Keying_(graphics)http://en.wikipedia.org/wiki/Vision_mixerhttp://en.wikipedia.org/wiki/Alpha_channelhttp://www.chyron.com/

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SOFTWARE CHARACTER GENERATORS

Software CGs run on standard off-the-shelf hardware and are oftenintegrated into video editing software such as nonlinear videoediting applications. Some stand-alone products are available,however, for applications that do not even attempt to offer text

generation on their own, as high-end video editing software oftendoes, or whose internal CG effects are not flexible and powerfulenough. Some software CGs can be used in live production withspecial software and computer video interface cards. In that case,they are equivalent to hardware generators.

CAMERA CONTROL UNIT:

DESCRIPTION:

The Camera Control Unitis typically part of a live broadcast camera"chain". It is responsible for powering the camera, handling signalssent over the camera cable (multicore, triax or fiber) to and from thecamera, and can be used control various camera parameters suchas iris remotely.

Broadcast cameras typically carry several signals over the camera

cable in addition to the camera output itself.

Typically, RGB signals are transmitted over the camera cable. TheCCU will usually convert these to SDI, YUV or composite forinterfacing to other video equipment.

Fig: Equipment CCU

Advantages over using independent cameras withautomatic settings

In a system with multiple cameras, the cameras canbe "matched" - made to look the same in terms of colour
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balance and picture intensity without having to ask thecamera operator to

The camera operators are freed from the control ofiris and black level - leaving them free to concentrate onother aspects of camerawork such as blocking and image

composition

All camera signals are carried in one cable.

Scope of CCU functions

A CCU is typically able to control the following camera parametersremotely:

Iris (see aperture) Color temperature filters ND filters Master Black (pedestal). Black level trim (for red, green and bluecomponents) Gain trim (for red, green and blue components) Master gain

In addition to these, there are usually options for switching in acable test filter.

VIDEO TAPE RECORDER:

A video tape recorder (VTR) is a tape recorder that can record

video material, usually on a magnetic tape. VTRs originated as

individual tape reels, serving as a replacement for motion picture

film stock, and making recording for television applications cheaper

and quicker. An improved form included the tape within avideocassette which were used with video cassette recorders (VCR).

VCRs soon found their way onto the consumer market, however

there have been a wide variety of VTR technologies, many produced

primarily for the professional market.

VIDEO CASSETTE RECORDER (VCR):

The videocassette recorder (or VCR, also known as the video

recorder), is a type of electro-mechanical device that uses

removable videotape cassettes that contain magnetic tape forrecording audio and video from television broadcasts so that the
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images and sound can be played back at a more convenient time.

This facility afforded by a VCR machine is commonly referred to as

television program Timeshift. Most domestic VCRs are equipped with

a television broadast receiver (tuner) for TV reception, and a

programmable clock (timer) for unattended recording of a certain

channel at a particular time. These features began as simplemechanical counter-based single event timers, but were later

replaced by multiple event digital clock timers that afforded greater

flexibility to the user.

VTR FORMATS:

S.N

o.

FORM RECORDING TAPE

SIZE

A/D

COMPRESSION

MANUFACTU

RER

1. D1 Component(Y, Cb, Cr)

4:2:2(mpeg-2, 8bit)

Sony, BTS,Ampex

2. D2 Composite(CVS)

Uncompressed(17.7 MHz,8 bit)

Sony, BTS,Ampex

3. D3 Composite(CVS)

Uncompressed(17.7 MHz,8 bit)

BTS,Panasonic

4. D5 Component(Y, Cb, Cr)

4:2:2(mpeg-2, 8bit)

BTS,Panasonic

5. D6(HD)

Component(Y, Cb, Cr)

4:2:2(mpeg-2, 10bit)

BTS,Panasonic

6. D7 Component(Y, Cb, Cr) 4:2:2(mpeg-2, 8

bit)

BTS,Panasonic,Hitachi

7. D8(Betacam

SX)


4:2:2(mpeg-2, 10bit)

AMPEX, Sony

8. D9(Digital-S)


4:2:2(mpeg-2, 8bit)

JVC

9. DVC

(Cam)

Component

(Y, Cb, Cr)

4:2:2

(mpeg-2, 8bit)

Sony
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10. Betacam-SX


4:2:2(mpeg-2, 8bit)

Sony

PATCH PANEL:

A patch panel or patch bay is a panel, typically rackmounted, that

houses cable connections. One typically shorter patch cable will plug

into the front side, whereas the back holds the connection of a much

longer and more permanent cable. The assembly of hardware is

arranged so that a number ofcircuits, usually of the same or similar

type, appear on jacks for monitoring, interconnecting, and testing

circuits in a convenient, flexible manner.

Fig: A Patch Panel

MIXING CONSOLE:

In professional audio, a mixing console, or audio mixer, alsocalled a sound board, mixing desk, or mixer is an electronicdevice for combining (also called "mixing"), routing, and changingthe level, timbre and/or dynamics of audio signals. A mixer can mixanalog or digital signals, depending on the type of mixer. The

modified signals (voltages or digital samples) are summed toproduce the combined output signals.

Mixing consoles are used in many applications, including recordingstudios, public address systems, sound reinforcement systems,broadcasting, television, and filmpost-production.

STRUCTURE

A typical analog mixing board has three sections:

Channel inputs
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Master controls Audio level metering

The channel inputs are replicated monaural or stereo input channelswith pre-amp controls, channel fader and pan, sub-groupassignment, equalization and auxiliary mixing bus level controls. The

master control section has sub-group faders, master faders, masterauxiliary mixing bus level controls and auxiliary return level controls.In addition it may have solo monitoring controls, a stage talk-backmicrophone control, muting controls and an output matrix mixer.

The audio level meters may be above the input and master sectionsor they may be integrated into the input and master sectionsthemselves

Fig: Yamaha 2403 audio mixing console in a 'live' mixing

application

SYNC PULSE GENERATORS (SPG):

A sync pulse generator is a special type of generator which producessynchronization signals, with a high level of stability and accuracy.

These devices are used to provide a master timing source for avideo facility. The output of an SPG will typically be in one of severalforms, depending on the needs of the facility:

A continuous wave signal

In standard-definition applications, a bi-level sync signal, oftenwith a colorburst signal in facilities that have analogequipment. Typically, this is either in NTSC or PAL format. Asthe resulting signal is usually indistinguishable from an all-black television signal of the same format, this sort ofreference is commonly known as black or black burst.

In some high-definition applications, a tri-level sync signal isused instead. This signal is virtually identical to thesynchronization signal used in component analogue video(CAV); and is similar to the synchronization signals used in VGA

(the main difference being, in VGA the horizontal and vertical
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syncs are carried on different wires; whereas TLS signalsinclude both H and V syncs).

STUDIO LIGHTING:

Lighting has two purposes in television. It allows the camera tomake a picture and it makes the picture interesting. Flat, evenlighting gives the video engineer the least amount of trouble, but italso renders the least interesting picture. The most basic lightingset-up is called "3-point" lighting. Lighting is always planned relativeto the camera angles. Advanced students are expected to practicebasic 3-point lighting.Since lighting can be a very subjective medium, there are no realhard and fast rules about lighting ratios and lighting setups. Talkshows tend to be lit evenly and flat. The particular lighting set updepends on mood, purpose, or style of lighting needed. There aremany different ways to achieve this.

Fresnel spotlight: so named for its ring-stepped lens. In our studio,most of the fresnel spots contain 500-1000 watt lamps. A 1000 wattinstrument is called a one-k. The instrument has a spot/flood controlon the side or rear which allows the light to be changed from anarrow, highly focused beam of light, to a wider, less intense spread.

This range is actually produced by the movement of a reflectorinside the instrument which moves closer to, or farther away fromthe Fresnel lens. On the other side of each fresnel spot is a knobcalled the "tilt lock". When tight, the up andDown motion of the instrument is locked.when loosened, theinstrument may be tilted up or down to any position. The tilt controlis usually set tight enough to maintain the tilt position, yet looseenough to allow the operator to move the light up or down. "barn-

doors" are metal flags attached to a spotlight to confine the light toa given area, often to keep light off the background. Scoop

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floodlight: a deep open-faced (no lens) floodlight with a diffused,generally elliptical Contoured reflector. Often used as a fill light.

.Key light: the key light is defined as the apparent, main source oflight. The position of the key light can greatly impact the positioning

of all the other lights. The key light is the modelling light. A harsh,shadow producing instrument such as a fresnel spotlight, is usuallyused as the key light.

Fill light: the fill light is the instrument used to soften the dark, welldefined shadow produced by the key light. Ideally, the fill lightshould not produce a shadow of its own. Therefore, an instrumentwhich produces a softer, more diffused type of light is usually used.

Back light: back light is illumination from behind the subject. Itsmain purpose is to show the separation between the subject and thebackground. Since the television screen is a two dimensional object,it is necessary to imply the third dimension with light. Without thebacklight, the subject and the background tend to blend together,but when correctly applied, the back light subtly rims the subjectwith light, which visually separates the subject from the background.

The back light is set at about a 45 degree angle. It must be usedwith care,since its intensity should vary according to the relativequality of the hair, etc. Blonds and bald people get less back lighting

than those having dark hair.

Side light: side light is sometimes used as an alternative to thestandard three point lighting set up. It is helpful to light this way forpeople with glasses because there are no reflections of the lights inthe glasses. It still involves a main, key source, and a soft fill, exceptthe lights are aimed almost directly from the side.

Background light: the purpose of the background light is toestablish a "base level of overall lighting" on the set, and to

illuminate the set pieces. These lights are usually considerablydimmer than the lights on the performers. Background lights aresimilar to back lights in that they are both used to create a feeling ofdepth and dimension in a two dimensional medium. "slashing" thedrapes is to light them with an oblique beam of light that creates ahighlight line or "slash" across them.

Barndoors - the flaps attached to the front of the instrument, theyare manipulated to prevent light from striking unwanted areas.

Flags - a device which can also block out light. Flags can bemounted on a light stand or in the lighting grid. Flags create harder

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edges where the light is cut off, than barndoors do, and can alsoblock off unwanted light.

Scrims - a wire screen used to cut down the amount of lightemulating from an instrument. It is inserted between the lens andthe barndoors. They do not significantly alter the shadow pattern or

color temperature produced by a light.

Gels - the generic nickname for a vast array of colored tough, heatresistant, polyester, film-like products used in front of lights. Theirpurpose is to alter the color characteristics of the lights to whichthey are attached. Gels are mounted in a "gel frame" or attached tothe instruments barndoors with clothes pins.

Footcandle - refers to the amount of light falling on a one-footsquare surface from a candle placed one foot away.

Light meter - a device used to measure the quantity of light (infoot candles). The camera requires a minimum amount of light torender an acceptable image.

Color temperature - color temperature refers to the redness orblue-white quality of light, certain color temperatures are requiredfor color tv. Cameras are calibrated for a specific color temperature,the lighting should remain reasonably close to that temperature

range. You should also know that when you dim a light, its colortemperature drops, becoming more red based.

GENLOCK TECHNOLOGY:

Genlock (for generator lock) is a common technique where thevideo output of one source, or a specific reference signal, is used tosynchronize other television picture sources together. The aim invideo and digital audio applications is to ensure the coincidence of

signals in time at a combining or mixing or switching point. Whenvideo instruments are synchronized in this way, they are said to begenlocked.[1] When two video signals are generated or output bygenlocked instruments the signals are said to be synchronized orsynchronous. Synchronized video signals will be precisely frequencylocked but because of delays caused by the unequal transmissionpath lengths the synchronized signals will exhibit differing phases atvarious points in the television system. Modern video equipmentsuch as production switchers that have multiple video inputs willoften include a variable delay on each input to compensate for the

phase differences and time all the input signals to precise phasecoincidence.
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Where two or more video signals are combined or being switchedbetween, the horizontal and vertical timing of the picture sourcesshould be coincident with each other. If they are not, the picture willappear to jump when switching between the sources whilst thedisplay device (television set) re-adjusts the horizontal and/orvertical scan to correctly reframe the image.

Where composite video is in use, the phase of the chrominancesubcarrier of each source being combined or switched should alsobe coincident. This is to avoid changes in colour hue and/orsaturation during a transition between sources.

Genlock can be used to synchronize as few as two isolated sources(e.g. a television camera and a videotape machine feeding a visionmixer (production switcher)), or in a wider facility where all thevideo sources are locked to a single synchronizing pulse generator

(e.g. a fast paced sporting event featuring multiple cameras andrecording devices).

Natlockrefers to a picture source synchronizing system using audiotone signals to describe the timing discrepancies betweencomposite video signals, whilst Icelock uses digital informationconveyed in the vertical blanking interval of a composite videosignal.

Genlock is also used to synchronize two cameras for Stereoscopic3D video recording.

THE CAMERA IMAGING DEVICE:

The principal elements of a typical black-and-white television cameraare the lens and the camera imaging device. This used to be acamera tube (with its associated scanning and focusing coils), butnow is a CCD. The lens focuses the scene on the front end of theimaging device.

CHARGE COUPLED DEVICE:Broadcasters have used charge-coupleddevices (CCDs) for ENG camerassince the early 1980s. Their light

weight, low cost and high reliabilityallowed CCDs to gain rapid acceptance.
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Manufacturers now produce thesedevices for use in professional andconsumer video camcorders.

The first step in creating a camera image is to gather light. CCDs arerigidly and permanently mounted, usually to the prism itself. There isno possibility for adjusting the scanning process. Lens

manufacturers, in turn, standardize their product to work understringent conditions.

How CCDs Work:

There are three sections in your average CCD. An array of photodiodes is positioned at the output of the prism. As varying amountsof light strike the diodes, those that are illuminated become "forwardbiased", and a current flows that is proportional to the intensity of

the light.

Fig: Layers of a CCD

The shift gate acts as a switch. This permits the current from eachdiode to be stored in a solid state capacitor in the CCD. As we know,capacitors store voltages, and these little guys are no exception.

The actual transfer of the voltages out to the real world is the key towhy CCDs are so ingenious. The CCD unit can transfer the voltagefrom cell to cell without any loss. This is called charge coupling,which is how the CCD gets its name: Charge Coupled Device.

When the transfer gate of a CCD image sensor is activated, theCCD's clocking circuitry moves the contents of each picture cell to

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the adjacent cell. Clocking the shift registers in this mannertransfers the light input value of each cell to the output, one valueat a time. The CCD chips provide their own scanning circuitry, in away. The last cell in the chain sends its voltage, in turn, to theoutput circuit of the chip. As an added bonus, cycling through all ofthe cells this way will not only send out all of the stored voltages,

but also discharges all of the cells, too. Everything goes back tonormal and the cells are ready to take in a new analog voltagevalue.

The CCD analog shift register deals with the charges coming fromthe capacitors. Each of these registers has an address decoderthatallows each portion of the image to be individually addressed. Anaddress encodercycles through the field of photosensitive registers,and reads out the analog voltages for each pixel. The speed ofoperation of this decoder is synchronized to the scan rate oftelevision.

COLOUR CAMERAS

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THREE CHIP CAMERAS:

Fig: Colour camera head end

A three-CCD camera is a camera whose imaging system uses threeseparate charge-coupled devices (CCDs), each one taking aseparate measurement of red, green, or blue light. Light coming into

the lens is split by a trichroic prism assembly, which directs theappropriate wavelength ranges of light to their respective CCDs. Thesystem is employed by some still cameras, video cameras, telecinesystems and camcorders.

Compared to cameras with only one CCD, three-CCD camerasgenerally provide superior image quality and resolution. By takingseparate readings of red, green, and blue values for each pixel,three-CCD cameras achieve much better precision than single-CCDcameras. By contrast, almost all single-CCD cameras use a Bayer

filter, which allows them to detect only one-third of the colorinformation for each pixel. The three electrical signals that controlthe respective beams in the picture tube are produced in the colourtelevision camera by three CCD (Charge Coupled Device) integratedcircuit chips. The camera has a single lens, behind which a prism ora set of dichroic mirrors produces three images of the scene. Theseare focused on the three CCDs. In front of each CCD is a colour filter;the filters pass respectively only the red, green, or blue componentsof the light in the scene to the chips. The three signals produced bythe camera are transmitted (via colour encoding) to the respective

electron guns in the picture tube, where they re-create the scene.
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The combination of the three sensors can be done in the followingways:

Composite sampling, where the three sensors are perfectly

aligned to avoid any color artifact when recombining theinformation from the three color planes Pixel shifting, where the three sensors are shifted by a fraction

of a pixel. After recombining the information from the threesensors, higher spatial resolution can be achieved.[2] Pixelshifting can be horizontal only to provide higher horizontalresolution in standard resolution camera, or horizontal andvertical to provide high resolution image using standardresolution imager for example. The alignment of the threesensors can be achieved by micro mechanical movements of

the sensors relative to each other. Arbitrary alignment, where the random alignment errors due to

the optics are comparable to or larger than the pixel size.

MAIN PARTS OF CAMERA:

LENS:

The lens is the first component in the light path. The camcorder'soptics generally have one or more of the following adjustments:

aperture or iris to regulate the exposure and to control depthof field;

zoom to control the focal length and angle of view; shutter speed to regulate the exposure and to maintain

desired motion portrayal; gain to amplify signal strength in low-light conditions; neutral density filterto regulate the exposure.
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IMAGER:

The imager converts light into electric signal. The camera lensprojects an image onto the imager surface, exposing thephotosensitive array to light. The light exposure is converted intoelectrical charge. At the end of the timed exposure, the imagerconverts the accumulated charge into a continuous analog voltageat the imager's output terminals. After scan-out is complete, thephotosites are reset to start the exposure-process for the next videoframe.

RECORDER:

The recorder is responsible for writing the video-signal onto arecording medium (such as magnetic videotape.) The recordfunction involves many signal-processing steps, and historically, therecording-process introduced some distortion and noise into thestored video, such that playback of the stored-signal may not retainthe same characteristics/detail as the live video feed.

STUDIO CAMERAS:

Most studio cameras stand on the floor, usually with pneumatic orhydraulic mechanisms called pedestals to adjust the height, and areusually on wheels. Any video camera when used along with other

video cameras in a studio setup is controlled by a device known asCCU (camera control unit), to which they are connected via aTriax,Fibre Optic or the almost obsolete Multicore cable. The cameracontrol unit along with other equipment is installed in the productioncontrol room often known as the Gallery of the television studio.When used outside a studio, they are often on tripods that may ormay not have wheels (depending on the model of the tripod). Initialmodels used analog technology, but are now obsolete, supplantedby digital models. Studio cameras are light and small enough to betaken off the pedestal and the lens changed to a smaller size to be

used on a cameraman's shoulder, but they still have no recorder oftheir own and are cable-bound. Cameras can be mounted on atripod, a dolly or a crane, thus making the cameras much moreversatile than previous generations of studio cameras.

ENG CAMERA:

Though by definition, ENG (Electronic News Gathering) videocameras were originally designed for use by news camera operators,these have become the dominant style of professional video camera

for most productions, from dramas to documentaries, from music
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videos to corporate training. While they have some similarities tothe smaller consumer camcorder, they differ in several regards:

ENG cameras are larger and heavier, and usually supported bya shoulder stock on the cameraman's shoulder, taking theweight off the hand, which is freed to operate the lens zoom

control. The weight of the cameras also helps dampen smallmovements.

3 CCDs are used instead of one, one for each primary color They have interchangeable lenses. All settings, white balance, focus, and iris can be manually

adjusted, and automatics can be completely disabled. The lens is focused manually and directly, without

intermediate servo controls. However the lens zoom and focuscan be operated with remote controls in a studio configuration.

Professional BNC connectors for video and at least two XLRinput connectors for audio are included.

A complete time code section is available, allowing time codepresets; and multiple cameras can be timecode-synchronizedwith a cable.

"Bars and tone" are available in-camera (the color bars areSMPTE (Society of Motion Picture and Television Engineers)Bars, a reference signal that simplifies calibration of monitorsand setting levels when duplicating and transmitting thepicture.)

EFP CAMERAS:

Electronic Field Production cameras are similar to studio cameras inthat they are used primarily in multiple camera switchedconfigurations, but outside the studio environment, for concerts,sports and live news coverage of special events. These versatilecameras can be carried on the shoulder, or mounted on camerapedestals and cranes, with the large, very long focal length zoomlenses made for studio camera mounting. These cameras have no

recording ability on their

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