WELCOME

ARYAN INSTITUTE OF TECHNOLOGY GHAZIABAD

SEMINAR

DTH

DTH can be defined as :

The reception of satellite programmers with a personal dish

at individual home.

DTH does not require the local cable operator and put the

broadcaster directly in touch with the consumer.

WHAT IS DTH

DTH Stand’s for Direct to home television .

HISTORYThe first person who invented the technology for DTH was sir ARTHURE CLARLES CLARKE , a british inventor in late 1946.The DTH service was first proposed in INDIA in 1996 , but was not approved due to concern over national security.Finally , 2000 DTH service was allowded and Doordarshan was first to

To provide the service to the consumers from 1st of April ,2000.

After this other DTH service provider like ZEE and STAR starded

pushing hard for DTH service in INDIA and setup earth station whose cost was 2.15 million and was valid

for 10 years in INDIA.

MAIN PARAMETER OF DTH DTH network consist of

Broadcasting center .Satellite encodes.

Multiplexer.Modulator.

DTH receiver.

DTH NETWORK

UPLINK ANTENNAUplink satellite dishes are large in size which provides accurate

aiming and increase signal strength

The y are pointed toward specific satellite and the frequency used

is specific so that satellite transponder can receive the signal.

The EIRP (Effective isotropically radiated power) for the uplink

antenna

EIRP = Pt – Lc + Ga

Where Pt = Power of transmitter (dbm)

Lc = Line loss(db)Ga = Gain of antenna(dbi)

SATELLITEA typical satellite can have 32

transponder for Ku band (10 Ghz to 18 Ghz) and 24 transponder for

C band( 4 Ghz to 8 Ghz).A typical transponder can

have bandwidth between 27 Mhz to 50 Mhz.

The satellite retransmits the signal back to earth in Ku band

and C band frequency.

MINIDISH ANTENNA It is parabolic reflector it receives the signal and fed to the LNBF(low noise band down converter) ,which works as a receiver for signal transmitted by satellite. LNBF

Parabolic reflector

( 60 to 120 cm )

SIGNAL RECEIVED BY MINIDISH

LOW NOISE BLOCK DOWN CONVERTER(LNBF)

It collect the signal from minidish.

It receive the signal from Ku band and down convert to radio frequency

signal.It amplify and remove the distortion

from the received signal.

BLOCK DIAGRAM OF DTH SYSTEM

Low noise amplifier

Down Converter

Amplifier

Down Converter

Tunable Local Oscillator

Filter

Demodulator

TV SET

Video baseband

Channel selector

Low noise block down converter

COAXIAL CABLE The coaxial cable connect LNBF to

set top box.A transmission cable consist of

outer metal condutor

enclosing and insulated from a

central conduting core.

Impedance provided by the coaxial cable

can be calculated by the formulaZ0 =( 1/2∏)√μ/ ε ln(D/d)

Where μ = relative permeability of

inisulator ε = dielectric constant

D =outer diameter of the coaxial cable

d = inner diameter of coaxial cable.

A settop box can demodulate

the received signal and can convert these

signal into audio and

video signal.

SETTOP BOX

SET TOP BOX

TUNER DEMODULATOR

DECODER

AMPLIFIER

MICROCONTROLLER

DISH ANTENNA

CAS SYSTEM

A

V

GENERAL BLOCK DIAGRAM OF SETTOP BOX

TUNNERIt select particular channel range

from 48 Mhz to 840 MhzDEMODULATOR

Selected channel demodulated and fed to decoder

DECODERIt is a D to A converter which

provide audio and video signal as output.

MICROCONTROLLERIt control all the process performed

by each block.

HOW DOES DTH DIFFER FROM CABLE TVIn DTH , TV channel are directly

transmitted from satellite to a small dish antenna at the

subscriber home.The broadcaster directly

connect to the subscriber ,the middlemen like local cable

operator are not there in the picture , hence provide better picture quality directly from

satellite to the user.

The cable TV was limited to the urban area ,but the DTH followed

cable TV in urban as well as in rural area.

DTH technology is more resistive to the weather condition ,it can work in

any type of environment.Since coaxial cable connection are

used in DTH technology less distortion of the signal take place ,

which ultimately provides better picture quality and better signal.

FUTUTRE PROSPECT OF DTHThe DTH market in

INDIA is relatively incresing day by day

and in next 5 years (by 2014 ) we will be able

to add another 30 million subscriber.

In the next 5 years ..,we have manage to overtake JAPAN as

the largest DTH market in ASIA.

DTH SERVICE PROVIDER

CONCLUSIONDTH has made the hopes for

people of the rural area to come true.

It help to develop the economy condition of our country

It provide the wide thinking of rural people which helps to

develop the culture of society.