TELEVISION BROADCAST SYSTEM

Presented By-NAME

OUTLINES

• Introduction• Overview• Requirements of a TV Studio• Colour Composite Video Signal• Colour Television• Television Transmission• Antenna System• Satellite Communication

INTRODUCTION

• One of India’s largest broadcasting organisation in terms of studio and transmitter infrastructure

Channels• Two all India channels DD National and DD News• 11 regional, four state, a sports, an international and two channels Rajya Sabha & Lok Sabha TV

INPUTS

• Studio Production

• Outdoor Recordings

• Outsourced Recordings

• Live Events

• Feed from other countries

EDITING/ ONLINE EDITING

• Non- linear editing

LINKS

• Studio Transmission Link (STL)

• Satellite Link

• Sending the programme through storage device

TRANSMISSION

• TV Transmitter

• High Power transmitter

• Low power transmitter

• Very low power transmitter

• Satellite transmission (Up-Linking)

OVERVIEW

REQUIREMENTS OF A TV STUDIO

• Camera• Lighting• Air conditioning• Video Tape Recorder• Editing• Audio Chain• Power Supply

CAMERA

• Optical instrument for recording images, which may be stored locally, transmitted to another location, or both

Controls Of a Camera• Focus• Iris• Zoom

AIR CONDITIONING

• Process of altering the properties of air (temperature and humidity) to more comfortable conditions

Refrigerant Cycle

Recorders/Players

Tape Based Disc Based

DVC PRO Beta CAM Mini DV XD CAM

(Panasonic) (Sony) (JVC) (Sony)

VIDEO TAPE RECORDERS

• Designed to record video material on magnetic tape

NON-LINEAR EDITING

• A video or audio editing digital audio workstation system that performs non-destructive editing on source material

• Enables direct access to any video frame in a digital video clip, without needing to play or scrub/shuttle through adjacent footage to reach it

COLOUR COMPOSITE VIDEO SIGNAL

• Based on persistence of vision = (1/16) sec.• Mixing of two signals is done = Video signal + Control Signal• Active Pulse (52microsec.) + Blank Pulse (12microsec.) = 64microsec.• Retrace is invisible (Blank Pulse)

COLOUR TELEVISION

• To obtain any desired colour by mixing three primary colours i.e. Red, Blue and green in a suitable proportion

• Visible spectrum is from 780 mm (Red) to 380 mm (Violet)

• The figure shows the effect of projecting red, green, blue beams of light so that they overlap on screen.

Y= 0.3 Red + 0.59 Green + 0.11 Blue

TELEVISION TRANSMISSION

• Exciter stage determines the quality of a transmitter• Contains pre-corrector units both at base band as well as at IF stage

ANTENNA SYSTEM

• Accepts RF Energy from transmitter and launches electromagnetic waves in space

It should fulfill the following requirements:

• Should have required gain and provide desired field strength at the point of reception

• Should have desired horizontal radiation pattern and directivity

• Should offer proper impedance to the main feeder cable

PARABOLIC DISH ANTENNA

• Very high gain (30-40 dB is common) and low cross polarization• Can operate in the VHF region (30-300 MHz)• Consists of a feed antenna pointed towards a parabolic reflector• At the frequency of operation, the reflecting dish must be much larger than a wavelength in size for very high gain dishes (>50 dB gain)•The distance between the feed antenna and the reflector is typically several wavelengths

SATELLITE COMMUNICATION

SATELLITE TRANSPONDER• Uplinked signal (6 GHz) at satellite is received, amplified and down converted to 4 GHz band and sent back through filter and power amplifier

RECEIVING SATELLITE SIGNAL• Down link signal can be received through Parabolic Dish Antenna using Trans-Receive Filter (TRF) and Low Noise Amplifier (LNA)•After down conversion to 70 MHz, it is demodulated to get audio and video

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