STUDY PROJECT IN DOORDARSHAN RELAY CENTRE, KAKINADA

DOORDARSHAN

INDIA’S NATIONAL ROADCASTER

LOW POWER TV TRANSMITTER

Report Submitted by the Students of

KAKINADA INSTITUTE OF ENGINEERING AND TECHNOLOGY FOR WOMEN,

YANAM ROAD, KORANGI

A Mini Project Report on

LOW POWER TV TRANSMITTER

PRESENTED

BY

1

Department of Electronics & Communication Engineering

(Affiliated to JNTUK & Approved By AICTE)

INTRODUCTION

DoorDarshan is the public TeleVision broadcaster of India & It is one of the largest broadcasting organisations in the world .

DoorDarshan was first started in Delhi on 15th september,1959 on a small transmitter and makeshift studio

Till 1975,seven Indian states had television services &

DoorDarshan remained only the TeleVision channel in

India.

TeleVision services were seperated from radio in 1976.

CHANNELS LIST

DD Direct Plus DD National DD News DD Bharathi DD Chennai DD Sports DD Madurai DD Urdu DD Pudhucherry DD North-East DD Bihar DD Bangla DD Jharkhand DD Gujarati DD chattisgarh DD Chandana DD Madhya Pradesh DD Kashir DD Utaar Pradesh DD Malayalam DD Haryana DD sahyadri DD Uttarkhand DD Oriya DD Himachal Pradesh DD Punjabi DD Rajastan DD Saptagiri DD Mijoram DD India DD Tripura DD Podhigai TV

2.BASIC TRANSMISSION SYSTEM

TV transmission is basically divided into 3 types.

1.Through Cable TV

2.DTH Service

3.Local Area Transmission

VIA COAXIAL CABLE

CABLE TV TRANSMISSION

LOCAL ORGNIGATION

(STUDIO)

HEAD END

TRUNK AMPLIFIER

TRUNK AMPLIFIER

BRIDGING

AMPLIFIER

LINE-EXTENDE

R AMPLIFIE

R

SATELLITE RECIEVER

TRUNK

Receiving antenna

Co-axial cable

Directional coupler

Birding amplifier

Subscriber tapSubscriber

Subscriber

Flexible cable

BLOCK DIAGRAM OF CABLE TV DISTRIBUTION SYSTEM

8

DTH stands for DIRECT-TO-HOME television.

DTH is defined as:

The reception of satellite programmers with a

personal dish in an individual home.

DTH does away with the need for the local

cable operator and puts the broadcaster

directly in touch with consumer .

HISTORY

DTH was first invented by sir ARTHURE CHARLES CLARKE,a british inventor in late 1946.

DTH services were first proposed in INDIA in 1996. But was not approved due to the concerns over national security.

Finally, in 2000 DTH was allowed and it was Doordarshan which made it possible to provide its facilities to consumers from 1st April 2000.

Broadcasters like STAR and ZEE are pushing hard for DTH services in INDIA.

The operators were required to setup earth stations in INDIA within 12 month for getting license of broadcasting whose cost was $2.14 million and will be valid for 10 years.

BLOCK DIAGRAM OF DTH

DISH FEED LNBCVIDEO RECEVI

ER

TVRECEVIE

R

LOCAL AREA TRANSMISSION It covers a distance of 21 kms. The transmitters that are present in INDIAN DD Network are

HPT (Located in Rajahmundry)

1.Transmitted power is 10KW

2.Distance covered is 60Km-100Km

LPT (Located in Kakinada)

1 .Transmitter power is 100W-500W

2.Distance covered is around 21Kms

VLPT (Located in Yanam)

1.Transmitted power is 10W

2. Distance covered is around 5-10Kms

BLOCK DIAGRAM OF LPT

MONITORING RACK INPUT RACK TRANSMITTER RACK

  T.V   WAVE FROM MONITORING     DEMODULATION  

T.V

WAVE FROM MONITORING

DEMODULATION

RECEIVER -1

RECEIVER -2

RECEIVER-3

V.C.R

P.G

SWITCHER

EXCITER

DRIVER AMPLIFIER

DIVIDER

COMBINER

TRANSMITTER RACK

TYPES OF LOW POWER TRANSMITTERS

There are two types of low power transmitters.

They are:

1.Very high frequency transmitter(VHF)

2. Ultra high frequency transmitter(UHF)

In this transmitter the frequency ranges from 224MHz-231Mhz. It requires 100W power. DD is presented by this transmitter in channel no.11.

VIDEO SIGNAL

LPFVIDEO

PROCESSOR

VISION MODULAT

OR

POWER CONTROL

LER

VESTIGIAL SIDEBAND

FILTER

IF OSCILLATO

R

AURAL MODULATO

R

CONTROL OSSCILLAT

OR

DRIVER

AUDIO SIGNAL

VHF Transmitter

SECTIONS IN AURAL MODULATOR

AUDIO AMPLIFIER VOLTAGE CONTROL OSCILLATOR(VCO) MIXER AUTOMATIC PHASE CONTROL(APC)

UHF TRANSMITTER

In this transmitter frequency range from 564-574MHz. It requires 500W power. DD news is broadcasted in channel 33. This transmitter is manufactured by BHARAT ELECTRONICS(BEL).

Linearity corrector

Base band corrector

EXCITERUp-

convertor

Video signal

Spiltter & PA

:

SPLITTER

PA

PA

PA

PA

COMBINER

INPUT FROM EXCITER

ANTEENA

BLOCK DIAGRAM OF AMPLIFIER

500W UHF TV TRANSMITTER TYPE MUV 199

RECEIVING SECTION

It consists of mainly four types of sections, they are

The parabolic dish antenna is metal structure with a shape of half cycle, and

a part that at distance a feed arm is held with support ,in air.

To which a low noise amplifier in addition to the low noise block Convertor and internal relay station there is a digital broadcast receiver.

Later on re-transmission of the signal is down in the transmitting section.

Parabolic dish

antenna

Low power

amplifier

Low noise block

convertor

Digital video

broadcast receiver

PARABOLIC DISH ANTENNA

TRANSMITTER SECTION

ANTENNA SECTION

For the propagation the electrical energy is converted into electro-magnetic wave.

where the VHF and UHF transmissions are different.

VHF ANTENNA UHF ANTENNA

YAGI-UDA ANTENNA

DIFFERENT TYPES OF PROPAGATION

1.Sky wave propagation [2 to 30KHz]: This is used for long radio communication at medium and high frequencies This is used to long distance, point to point communication is possible.

2.Space wave propagation[>30MHz]: Height of the this is 16KMs from atmosphere is known as troposphere.

3.Ground wave propagation: As two antennas are with in the line of sight of each propagation of such space

wave is called line of propagation.

Here there are 2 types of Antennas.,

They are : 1.Self Supporting Mast.

2.Guided Wire Mast.

SELF SUPPORTING MAST:

It is general broadcasting purpose antenna here the antenna here the transmission of the signals would be without any obstacles it generally almost used in all media using sector.

GUIDED WIRE MAST:

THE MAST IS SUSPENDED FROM THE GROUND AND SUPPORTED BY

SOME WIRES.

conclusi

on