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A 

INDUSTRIAL TRAINING REPORT 

ON

PRESENTED BY:HIMANSHU MAHAJAN

GIRISH KHAJURIARACHIT SHARMA 

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HISTORY : In its early stages of development, television

employed a combination of optical, mechanical andelectronic technologies to capture, transmit and

display a visual image. By the late 1920s, however, those employing only 

optical and electronic technologies were beingexplored.

Doordarshan is the public television broadcaster of India and a division of Prasar Bharti ,a public servicebroadcaster nominated by the govt. of India

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• It is one of the largest broadcasting organisations in the

world in terms of infrastructure of STUDIOS andTRANSMITTERS

More than 90 percent of the population receive doordarshan

programmes through a network of 1400 terrestrial

transmitters.

•The first practical use of television was in Germany.

•Regular television broadcasts began in Germany in 1929and in 1936 the Olympic Games in Berlin were broadcast to

television stations in Berlin and Leipzig where the public

could view the games live.

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BLOCK DIAGRAM OF T.V. STATION

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PROGRAMMER CONTROL ROOM

(PCR)  The programmer control room is one of the essential

blocks of TV transmission.

• It can be termed as recording Centre for the program.The live telecast of the programs such as news,interviews etc. also take place here.

• This is one among the major sections of transmissionand involves a number of technical and non-technical persons.

• Recording takes place according to a predetermined

schedule called programmed schedule.

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• TV STUDIO

•

  VIDEO TAPE RECODER 

•  AUDIO SECTION

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TELEVISON STUDIO[CAMERA

SECTION] • Studio floor  Studio is the room where a program is performed and

recorded using cameras. The studio floor is an open area, which contains the

television cameras, microphones, lighting equipments

sets and crew.

• Control room 

In control room there is program director, assistant

director, technical director, audio engineer and video

engineer workers.

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T.V. PICTURE • A picture can be considered to contain a number of 

small elementary areas of light or shade which arecalled picture element.

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

The photo electric properties of the pickup deviceconvert the optical image to a electric image charge

depending on the light & shade of the scene.   

To transmit this information, scanning isemployed.

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VIDEO CAMERA A video camera is a camera used for electronic motion

picture acquisition, initially developed by the television 

industry but now common in other applications as well. 

Cameras based on solid-state image sensors such asCCDs (and later CMOS active pixel sensors)

eliminated common problems with tube technologiessuch as burn-in and made digital video workflowpractical.

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Camera Control Unit (C.C.U) The camera control unit has the provision to control the

zoom lens action and brightness of camera tubes.

The C.C.U. engineer has the necessary facilities to adjust

parameters such as video gain , camera sensitivity.

The composite video signal received over the microwavelink is demodulated and processed in the usual manner by

the C.C.U. engineer for transmission on the channel

allocated to the station.

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CAMERA TUBE

VIDEO CAMERA

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• Main recording room having coordination with bothstudio as well as audio section

•Here the output of all cameras is controlled

•It consists of video console which is used for shot

selection using different control knobs on it

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VTR characteristics Linear speed: It is the speed at which tape runs. It decides

the tape length required/consumed for a particular duration.

Tape length for 30 Min. Cassette= 10.15x30x60 Cm.

Writing Speed: It is the speed at which signal information

is written on the tape by the Head.

W. Speed =3.14xDrum Diameter in m x Drum Speed in rpsFor Beta cam edit VCR, Drum Diameter = 74.4mm

Drum speed =25 rps

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Video tape Format

It defines the arrangement of magnetic information on the

tape. It specifies:

• 1. Tape width

• 2. No. of tracks for Video, Audio

• 3. Their electrical characteristic and orientation.

• 4. Track width.

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Material Used for recording 

• . FERRO MAGNETIC MATERIALS

•

(Fe2O3/Fe2O4) ARE USED• . THESE MATERIALS HAS SPECIAL

CHARACTERISTIC OF MAGNETIC

RETAINTIVITY

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TRANSMITTER

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TRANSMITTER

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FEATURE’S : 1. TYPE: -PCN-810 AL.

2. RATING: -10 KW.

3. STATUS: -VHF. CONSTRUCTION :

The transmitter consists of two frames as shown facing the

front. The left frame accommodates the s and P A panel

while the right frame accommodates Visual Last Stagepower amplifiers In addition plate voltage transformer,

silicon rectifier and blower are installed outside the frame.

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NTSC NTSC, named for the National Television System

Committee, is the analog television system used inmost of North America, most countries in South

 America and some Pacific island nations andterritories .

The NTSC selected 525 scan lines as a compromise thenumber of scan lines to between 605 and 800. Thestandard recommended a frame rate of 30 frames persecond, consisting of two interlaced fields per frame at262.5 lines per field and 60 fields per second.

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SECAM SECAM, also written ,as Sequential Colour with

Memory, is an analog color television system first usedin France.

SECAM uses frequency modulation to encodechrominance information on the sub carrier.

The red difference signal is transmitted on one line

then the blue difference signal is transmitted on theother line.

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PAL (Phase Alternate By Line): is an analogue television encoding system used in

broadcast television systems in many countries.

It is used for broadcast television systems and analogue

television for additional discussion of frame rates, image

resolution and audio modulation.

The basics of PAL and the NTSC system are very 

similar; a quadrature amplitude modulated subcarrier carrying the chrominance information is added to theluminance video signal to form a composite video baseband signal. 

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The frequency of this subcarrier is 4.43361875 MHz forPAL, compared to 3.579545 MHz for NTSC.

The name "Phase Alternating Line" describes the way that the phase of part of the colour information on the video signal is reversed with each line, whichautomatically corrects phase errors in thetransmission of the signal by cancelling them out.

The 4.43361875 MHz frequency of the colour carrier isa result of 283.75 colour clock cycles per line plus a 25

Hz offset to avoid interferences. Since the linefrequency is 15625 Hz, the colour carrier frequency calculates as follows: 4.43361875 MHz = 283.75 * 15625Hz + 25 Hz.

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 VESTIGIAL SIDE BAND TRANSMISSION

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 As PAL is interlaced, every two fields are summed tomake a complete picture frame.

Luminance, Y, is derived from red, green, and blue(R'G'B') signals.

 Y = 0.299R' + 0.587G' + 0.114B'

U and V are used to transmit chrominance. Each has atypical bandwidth of 1.3 MHz.

U = 0.492(B' − Y) 

 V = 0.877(R' − Y) 

Composite PAL signal = Y + Usin(ωt) + Vcos(ωt) +timing where ω = 2πFSC.

Subcarrier frequency FSC is 4.43361875 MHz (±5 Hz)for PAL-B/D/G/H/I/N.

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The original colour carrier is required by the colourdecoder to recreate the colour difference signals.

Since the carrier is not transmitted with the videoinformation it has to be generated locally in thereceiver.

In order that the phase of this locally generated signal

can match the transmitted information, a 10 cycleburst of colour subcarrier is added to the video signalshortly after the line sync pulse but before the pictureinformation, during the so called BACK PORCH.

 An interesting comparison can be made with the VGA signal, the most notable differences being the doublehorizontal sweep time and interlace mode.

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Video Formats MPEG : The ' Moving Picture Experts Group' (MPEG) is

a working group of experts that was formed by ISO and

IEC to set standards for audio and video compression and

transmission.

The MPEG compression methodology is consideredasymmetric as the encoder is more complex than thedecoder. The encoder needs to be algorithmic oradaptive whereas the decoder is 'dumb' and carries outfixed actions. 

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This is considered advantageous in applications suchas broadcasting where the number of expensivecomplex encoders is small but the number of simpleinexpensive decoders is large.

The MPEG's (ISO's) approach to standardization is

novel, because it is not the encoder that isstandardized, but the way a decoder interprets thebitstream. A decoder that can successfully interpretthe bit stream is said to be complaint.

The advantage of standardizing the decoder is thatover time encoding algorithms can improve, yetcompliant decoders continue to function with them.

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MPEG has standardized the following compressionformats and ancillary standards:

MPEG-1 (1993): Coding of moving pictures andassociated audio for digital storage media at up toabout 1.5 Mbit/s (ISO/IEC 11172).

The first MPEG compression standard for audio and video. It was basically designed to allow movingpictures and sound to be encoded into the bit rate of aCompact Disc.

It is used on Video CD, SVCD and can be used for low-

quality video on DVD Video. It was used in digitalsatellite/cable TV services before MPEG-2 became widespread.

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MPEG-2 (1995): Generic coding of moving pictures andassociated audio information. (ISO/IEC 13818) Transport,video and audio standards for broadcast-quality television.MPEG-2 standard was considerably broader in scope andof wider appeal – supporting interlacing and highdefinition.

MPEG-2 is considered important because it has beenchosen as the compression scheme for over-the-air digitaltelevision ATSC, DVB and ISDB, digital satellite TVservices like Dish Network , digital cable television 

signals, SVCD and DVD Video.

 

It is also used on Blu-ray Discs, but these normally useMPEG-4 Part 10 or SMPTE VC-1 for high-definitioncontent.

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MPEG-3: MPEG-3 dealt with standardizing scalableand multi-resolution compression and was intendedfor HDTV compression but was found to be redundantand was merged with MPEG-2, as a result there is noMPEG-3 standard.

MPEG-3 is not to be confused with MP3, which isMPEG-1 Audio Layer 3.

MPEG-4 (1998): Coding of audio-visual objects.(ISO/IEC 14496) MPEG-4 uses further coding tools

 with additional complexity to achieve highercompression factors than MPEG-2. 

In addition to more efficient coding of video, MPEG-4moves closer to computer graphics applications.

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MPEG-4 Part 2 (or Simple and Advanced SimpleProfile) and

MPEG-4 AVC (or MPEG-4 Part 10 or H.264). MPEG-4 AVC may be used on HD DVD and Blu-ray Discs,

along with VC-1 and MPEG-2.

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SATELLITE COMMUNICATION 

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Satellite: Satellite is a device that performs two functions atthe same time. One is that it receives the information originatedfrom a ground station (transmitter) and then secondly it sendsthis information to another ground station (receiver).

These satellites revolve around a fixed orbit.

“Satellite is a communicational device used for a high scalebroadcast and Monitoring purposes that may be stationary orrevolving in an orbit”. 

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  Following are two types of satellites that are used

generally. Low earth satellite Geo synchronous satellite (i) Low earth Satellite: This type of satellite

 which are within an altitude of 400kms from earthsurface are known as low earth satellite.

(ii) Geo Synchronous Satellite: The type of satellites which are above an altitude of 22,000 milesfrom earths surface are known as Geo - synchronoussatellite.

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NEAR-EARTH

MOST COMMON ORBIT: NEAR POLAR 

 ALTITUDE : 400kms LIFETIME: LESS THAN 1 YEAR 

MAJOR EFFECT ON LIFESPAN: ATMOSPHERIC DRAG

PERIOD: 90 MIN

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GEO-SYNCHRONOUS ORBIT

THREE SATELLITES IN NEAR-EQUATORIAL ORBITS CANPROVIDE CONTINUOUS GLOBAL COVERAGE...

...EXCEPT

FOR THE

POLES

GEO-SYNCHRONOUS SATCOM

BASIC BLOCK DIAGRAM

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BASIC BLOCK DIAGRAM

Uplink

Downlink

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SATELLITE TRANSPONDER

EARTH STATION

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EARTH STATION

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

• The signal is up-linked from the earth station and received by manydown link centers in TV broad casting. 

• It is a very important part of satellite communication system for

broadcasting of signals.  Earth Station classification 

• Analog Earth Station 

• Analog / Digital Simulcast 

• Digital Earth Station 

• C-band or Ku-band

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DIGITAL EARTH STATION

Why Digital ? • More programs per channel / Transponder i.e. spectrum efficient 

• Noise-Free Reception 

CD quality sound & better than DVD quality picture 

• Reduced transmission power. 

• 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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DIGITAL EARTH STATION REQUIREMENTS 

Up-converters 

• The up-conversion is required to raise the frequency of thesignal in desired band: C-band, Extended C-band or Ku-bandbefore transmission. 

• The input to up converter is 70 MHz (output of modulator) andoutput of Up-converter is fed to HPA. 

• The up-conversion may done in stages or in one stagedirectly. For example the 70 MHz signal is first converted into

L –

band and then L band signal raised to desired frequencyband. 

• Normally L-band monitoring point is also provided in Up-converters for monitoring purposes. 

DIGITAL EARTH STATION

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DIGITAL EARTH STATION

Antenna system 

• The most widely used narrow beam antennas are reflectorantennas. The shape is generally a paraboloid of revolution.

• For full earth coverage from a geostationary satellite, a hornantenna is used. Horns are also used as feeds for reflectorantennas.

• 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 convex with ahyperboloid surface, while in the Gregorian design it isconcave with an ellipsoidal surface.

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MICROWAVE ANTENNAE

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HIGH POWER AMPLIFIER

The high power amplifier is used for the final power amplificationof the digital RF signal in C-band/ Ku band that is fed to theantenna.

The important parameters of HPAs are: 

• Frequency range 

• Output power at flange 

• Bandwidth 

• Gain variation (1.0 db (max.) for 40 MHz (narrow band)

Types of HPAs are: 

• KHPA - Klystron High Power Amplifier • TWTA -Traveling Wave Tube Amplifier 

• SSPA- Solid state Power Amplifier 

DOORDARSHAN SAT SERVICE

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DOORDARSHAN SAT. SERVICE

sno

service mode satellite

Posn. transponder

D/Lfreq(MHz)

Symrate

1 DDNational

SCPC 3C 74E C-02 3778.5 6.25

2 DD Kashir MCPL 3A 93.5E C-02 3780.5 6.25

3 DDNational

MCPC 4B 93.5E C-01 3725 27.5

4 DD

 Jammu

SCPC 4B 93.5E C-02 3774 4.25

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• HIGH-DEFINITION VIDEO 

High-definition video or HD video refers to any video system of higher

resolution than standard-definition (SD) video, and most commonly

involves display resolutions of 1,280×720 pixels (720p) or 1,920×1,080

pixels (1080i/1080p).

FUTURE SCOPE

• High-definition image sources include terrestrial

broadcast, direct broadcast satellite, digital cable, highdefinition disc (BD), internet downloads and the latest

generation of video game consoles

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THANK YOU