DIRECT TO HOME (DTH)G. Akhila Yadav (06D21A0461)

• DTH stands for Direct-To-Home television. • Defined as the reception of satellite programs

with a personal dish in an individual home.

WHAT IS DTH?

• DTH services were first proposed in India in 1996. But they did not pass approval because there were concerns over national security and a cultural invasion.

• Finally in 2000, DTH was allowed. The new policy requires all operators to set up earth stations in India within 12 months of getting a license. DTH licenses in India will cost $2.14 million and will be valid for 10 years.

HISTORY

• DTH network consists of a broadcasting centre, satellites, encoders, multiplexers, modulators and DTH receivers.

ELEMENTS OF DTH

• In DTH, TV channels would be transmitted from the satellite to a small dish antenna mounted on the window or rooftop of the subscriber's home. So the broadcaster directly connects to the user. The middlemen like local cable operators are not there in the picture.

• DTH can also reach the remote areas.• With DTH, a user can scan nearly 700 chan

nels!

DIFFERENCE BETWEEN DTH AND CABLE TV

DTH offers,• Better quality picture• Stereophonic sound effects• Can reach remote areas• Allows interactive TV services like

Movie on demand Internet access Video conferencing Email

DTH RATHER THAN CABLE TV

• Satellite television is not like a broadcast television. It’s a wireless system but both transmit via a radio signal.

• Main limitation is range.• In order to receive signals, one must be in

the direct ‘line of sight’ of the antenna.• Small obstacles is not a problem but earth

reflect radio waves.• Other limitation is, signals are often

distorted.

BROADCAST TV PROBLEM

• Satellite television system transmit and receive radio signals using special antennas called satellite dishes.

• Satellites are higher in the sky than TV antennas so they have much larger ‘line of sight’ range.

• The television satellites are all in geosynchronous orbit.

SATELLITE TV SOLUTION

• Programming sources are simply the channels that provide programming for broadcasting.

• Broadcast center is the central hub of the system.

• Satellites receive the signals from broadcast station and rebroadcast them to ground.

• Dish picks up the signal from the satellite and passes it on to the receiver in the viewers house.

• Receiver processes the signal and passes it on to standard television.

COMPONENTS FOR DTH

• Positioned at exact height above the earth (36000km)

• Rotate around the earth at the same speed as the earth rotates

• Has circular orbit

GEOSTATIONARY SATELLITE

• Channels are first multiplexed• QPSK modulated before transmission• Dish receives the signal• LNBC converts KU band signals to

intermediate frequency based on the local IF

• Set top box receives signals and performs demodulation and D to A conversion and gives the RF output to TV.

FUNCTIONING OF DTH

• Digital broadcast satellite transmits programming in the KU frequency range (10GHz-14GHz)

• Frequencies above 10GHz are affected by rain and snow.

• Compressing and encryption are done during transmission

• Bit rate of more than 200Mb/s would be required to digitize video.

KU BAND FREQUENCIES

• The parabolic curve has the property of reflecting all incident rays arriving along the antenna reflector’s axis of symmetry to a common focus located to the front and centre.

SATELLITE RECEIVING ANTENNA

• The dish’s feed horn passes the signal on to the receiving equipment.

• The central element in the feed horn is the LNB (Low Noise Block down converter.

ANTENNA FUNCTIONING

• Cost effective communication, information and entertainment.

• Small size terminals can provide up to 4000 TV channels and 2000 radio channels.

• Services bypass mediators and comes to customers directly.

• Transparent providing digital quality video, audio, radio and IP to all at equal amount.

DTH BENEFITS

CONCLUSION

• DTH has made the hopes of the people of rural areas to come true. It helps to develop and explore the ignited mind of people of India to think beyond the scope of imagination.

• It also helps to develop the economic conditions of a country.