A seminar report on

DTH Technology

K.JAYA PRAKASH 10MT0817

DTH TechnologyAbstract

Direct to home technology (DTH) refers to the satellite television broadcasting process which is actually intended for home reception. This technology is originally referred to as direct broadcast satellite (DBS) technology. The technology was developed for competing with the local cable TV distribution services by providing higher quality satellite signals with more number of channels.

In short, DTH refers to the reception of satellite signals on a TV with a personal dish in an individual home. The satellites that are used for this purpose is geostationary satellites. The satellites compress the signals digitally, encrypt them and then are beamed from high powered geostationary satellites. They are received by dishes that are given to the DTH consumers by DTH providers.

Though DBS and DTH present the same services to the consumers, there are some differences in the technical specifications. While DBS is used for transmitting signals from satellites at a particular frequency band [the band differs in each country], DTH is used for transmitting signals over a wide range of frequencies [normal frequencies including the KU and KA band]. The satellites used for the transmission of the DTH signals are not part of any international planned frequency band. DBS has changed its plans over the past few years so as to include new countries and also modify their mode of transmission from analog to digital. But DTH is more famous for its services in both the analog and digital services which includes both audio and video signals. The dishes used for this service is also very small in size. When it comes to commercial use, DBS is known for its service providing a group of free channels that are allowed for its targeted country.

In broadcasting center consist all the channels antenna which authorized by their own channel, and we will receive the single from that channel provider. Collection of all the signal transferring to the DTH service provider ,then DTH providers are collect the those signal converts into the Digital signals with in range of bandwidth transfer the signal to satellite and Satellite amplifies signals

Introduction

India is one of the biggest DTH service providers in the world. The requirement is very high because of the high population and the increased number of viewers. The low cost of DTH when compared to other local cable providers is also one main reason for this substantial growth.

In India the DTH requirement is more than in any country as the population of viewers is at very high rate.DTH is defined as the reception of satellite programmes with a personal dish in an individual home.

Cable TV is through cable networks and DTH is wireless, reaching direct to the consumer through a

small dish and a set-top box. Although the government has ensured that free-to-air channels on cable

are delivered to the consumer without a set-top box, DTH signals cannot be received without the set-

top box.

India currently has 6 major DTH service providers and a total of over 20 million subscriber

households in 2010. Dish TV(a ZEE TV subsidiary), Tata Sky, Tata Sky +, South India Media Giant Sun

Network owned 'Sundirect DTH',Reliance owned BIG TV,Bharti Airtel's DTH Service 'Airtel Digital TV'

and the public sector DD Direct Plus.As of 2010, India has the most competitive Direct-broadcast

satellite market with 7 operators vying for more than 110 million TV homes. India is set to overtake

the USA as the world's largest Direct-broadcast satellite market,The rapid growth of DTH in India

has propelled an exodus from cabled homes, the need to measure viewership in this space is more

than ever;  the overnight ratings agency, has mounted a people meter panel to measure viewership

and interactive engagement in DTH homes in India

The idea of DTH was first provided to India in 1996. But it was not approved then as there were concerns about national security. But the laws were changed by the year 2000 and thus DTH was allowed. According to the new rule, DTH providers are required to set up new stations within 12 months of getting the license. The cost of the license is almost $2.15 million in India with a validity of 10 years for renewal. The latest reports suggest that almost 25% of the total Indian population use this facility while others use local TV connections.Some of the common DTH providers in India are

1. TATA Sky

2. BIG TV

3. Sun Direct DTH

4. Dish TV

5. Airtel DTH

Working of DTH

For a DTH network to be transmitted and received, the following components are needed.

• Broadcasting center

• Direct Broadcasting Satellite

• DTH Receivers

Broadcasting center

In broadcasting center consist all the channels anntea which authorized by their own channel, and we will receive the single from that channel provider. Collection of all the signal transferring to the DTH service provider ,then DTH providers are collect the those signal converts into the Digital signals with in range of bandwidth transfer the signal to satellite and Satellite amplifies signals.

Direct Broadcasting Satellite

It must be noted the channels that are broadcasted from the broadcasting centre hare not created by the DTH providers. The DTH providers pay other companies like HBO, Sony MAX and so on for the right to broadcast their channel to the DTH consumers through satellite. Thus the DTH provider acts as a mediator r broker between the consumers and the programme channels. In dth we use this protocol Internet Protocol Television (IPTV)

The broadcast centre is the main part of the whole system. It is from the broadcast station that the signals are sent to the satellites to be broadcasted. The broadcast station receives the signals from various program channels.

The satellite receives the signal from the broadcast centre and compresses the signals and makes them suitable for re-transmission to the ground.

The DTH providers give dish receivers for the viewers to receive the signal from the satellites. There may be one or multiple satellites that send the signals at the same time. The receiver receives the signal from them and is passed on to the Set Top Box [STB] receiver in the viewer’s house.

The STB receiver changes the signal in a form suitable for our television and then passes it on to our TV.

Direct Broadcasting Satellite (DBS) Reception

Antenna shall be positioned with line of sight to the satellite.

Antenna shall be mounted on a proper foundation.

LNB is remotely supplied by RX.

Cable with a length of up to 50m mechanically protected.

Be aware of lightning protection.

Connectors at LNB shall be water-resistant by using shrink or rubber sleeves.

Broadcasting Satellite Working :-

Coverage INTELSAT 707

Coverage INTELSAT 707 FEC ½ Coverage INTELSAT 707 FEC 3/4

Coverage AsiaSat 2

Coverage AsiaSat 2

Coverage PAS-5

Coverage PAS-5

Coverage Eutelsat HOTBIRD 5

Coverage Eutelsat HOTBIRD 5

Coverage Astra 1A

Coverage Astra 1A

DTH Receivers

Antenna Principles

Satellite Broadcasting operates mainly on C-Band and KU-Band

Typical Antenna Types are Parabolic Antennas

On KU-Band also TVRO Panel Antennas (Dipole Arrays) are used

Efficiency of Antenna is important and depends mainly on surface roughness

Besides fixed Position Antennas also turning Antennas are used

Above a certain size/aperture tracking becomes necessary

Mechanical Stability is a expensive but guarantees long availability

LNB/Feedhorn/Polariser is normally part of TVRO Antenna (Outdoor Unit)

Prime Focus Satellite Antenna

Prime-Focus Antenna Prime-Focus Antenna

Offset Satellite Antenna

Offset-Antenna

Offset-Antenna

Feedhorn and Polariser

Feedhorn collects microwaves and feeds it into the LNB.

Feedhorn

LNB = Low Noise Block converter

Signal from Feedhorn

C-Band 3.800-4.200GHz Ku-Band 10.700-12.750GHz

fRX = fosc - fSAT fRX = fSAT - fosc

LNB-Practical Layouts and Specs

Typical Specification:

Input Frequency (GHz)

L.O. Frequency

Output Frequency

Noise Figure/Noise Temperature

L.O. Stability

L.O. Phase Noise

Conversion Gain

C-Band W 275

Output Level

Power Requirements (H/V)

Relation of Noise Temp. and Figure:

Ku-Band W 75

Outdoor-Unit consists of mechanically and electrically proper mounted satellite dish with LNB and feeder directed without obstacles (line of sight) towards satellite. A sufficant Figure of Merit (G/T) is important especially under bad weather conditions.

The Figure of Merit (G/T) depends on:

size of dish (diameter)

antenna efficiency ( surface of dish)

proper mechanical alignment of LNA/LNB.

LNA/LNB with noise figure (< 1DB) OR NOISE TEMPERATURE (< 75°K)

Reliability and long lifetime are achieved by using heavy duty materials to withstand high windload and aggressive environment.

Larger dishes need concrete foundation.

electrical connections outside have to be protected against water and dust.

Digital Satellite Receiver (IRD)

IRD (Integrated Receiver Decoder) also called Set Top Box (STB)

Receives and decodes signals compliant to DVB-MPEG-2 Standard.

Front-end: Tuner, ADC, Demodulator and FEC for DVB-S, -C, -T.

Back-end: MPEG-2 TS-demultiplexer, Audio/Video-decoder, Video-encoder.

LNB-Supply

IRD - Connections Consumer

In this set of box we have a circuit chip which is called the Digicard in set of box the digicard provides the author stream, similar to sim card provide strict according to cost plan of the digicard provide the channel to you. Will do recharge of that card similar as we do recharge as mobile phone

Conclusion

This technology is equally beneficial to everyone. As the process is wireless, this system can be used in all remote or urban areas.

High quality audio and video which are cost effective due to absence of mediators.

Almost 4000 channels can be viewed along with 2000 radio channels. Thus the world’s entire information including news and entertainment is available to you at home.

As there are no mediators, a complaint can be directly expressed to the provider.

With a single DTH service you will be able to use digital quality audio, video and also high speed broadband.

REFERENCES

1. Gagliardi R.M satellite communication CSB publisher

2. Rosie A.M information and communication theory Van Nostrand

3. Raja Roa K.N. satellite communication PHI 2004

4. Wikipedia http://en.wikipedia.org/wiki/Satellite_television

5. ̂  Robertson, Lloyd (1972-11-09). "Anik A1 launching: bridging the gap". CBC English TV. Retrieved 2007-01-25.

6. Bruce R. Elbert Introduction to satellite communication

7. S. Paul Bunea Dth : The New Cosmic Constant

8. http://pratyush.instablogs.com/entry/india-to-launch-insat-4b-tomorrow-from-french-guyana- countdown-to-start-now/

9. http://www.indiandth.in/Thread-Cable-networks-to-get-digital-edge-countrywide-reach-with- HITS

10. http://www.indiantelevision.com/perspectives/y2k4/dth_main.htm

11. http://www.watblog.com/2009/08/12/mnp-like-solution-for-dth-subscribers-may-finally-get- inter-operable-boxes/