2. WHAT IS DTH?
‡ DTH stands for Direct-To-Home television.
‡ Defined as the reception of satellite programs
with a personal dish in an individual home.
3. HISTORY
‡ 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.
4. ELEMENTS OF DTH
‡ DTH network consists of a broadcasting
centre, satellites, encoders, multiplexers,
modulators and DTH receivers.
5. DIFFERENCE BETWEEN DTH AND CABLE TV
‡ 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
channels!
6. DTH RATHER THAN 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
7. BROADCAST TV PROBLEM
‡ 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 µline of sight¶ of the antenna.
‡ Small obstacles is not a problem but earth
reflect radio waves.
‡ Other limitation is, signals are often
distorted.
8. SATELLITE TV SOLUTION
‡ 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 µline of sight¶ range.
‡ The television satellites are all in geosynchronous
orbit.
9. COMPONENTS FOR DTH
‡ 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.
10. GEOSTATIONARY SATELLITE
‡ Positioned at exact height above the earth
(36000km)
‡ Rotate around the earth at the same speed
as the earth rotates
‡ Has circular orbit
11. FUNCTIONING OF DTH
‡ 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.
12. KU BAND FREQUENCIES
‡ 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.
13. SATELLITE RECEIVING ANTENNA
‡ 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.
14. ANTENNA FUNCTIONING
‡ 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.
15. DTH BENEFITS
‡ 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.
16. 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.
