ashish kumar pandit

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REPORT

ON

INDUSTRIAL TRAINING

AT

ALL INDIA RADIO & DOORDARSHAN

Submitted to the Department of Electronics and Communication Engineering

I n parti al fu lf ilment of the r equir ements

F or the degree of

BACHELOR IN TECHNOLOGY

INELECTRONICS & COMMUNICATION

By

ASHISH KUMAR PANDIT

Univ. roll no : 1009531023

Under the guidance of

Academic tutor Industrial tutor

MRS. ASHWINI DESHMUKH MR. A.K VERMA

ASST.PROFESSOR (E & C department) Project manager (AIR)

Mahatma Gandhi Missions College of Engineering and Technology, NOIDA

Aff il iated to

Mahamaya Technical University,

Aug 2013


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CERTIFICATE

This is to certify that seminar report on Direct to Home which is submitted by ASHISH

KUMAR PANDIT (1009531023) in partial fulfilment of the requirement of the award of

degree B.Tech in department of Electronics and Communication department of Mahamaya

Technical University is original and has not been submitted for the award of any other degree

Date: Supervisor: MRS.ASHWINI DESHMUKH

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DECLARATION

I hereby declare that this submission is my own work and that,to the best of my knowledge

and belief , it contains no material previously published or written by another person nor

material which to a substantial extent has been accepted for the award of any other degree or

diploma of the university or other institute of higher learning ,except where due

acknowledgment had been made in the text

Name:ASHISH KUMAR PANDIT

Roll no:1009531023

DATE:

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ACKNOWLEDGEMENT

It gives me a great sense of pleasure to present the report of the B. Tech industrial training. I owe special debt of gratitude to Professor MRS.ASHWINI DESHMUKH, Department of Electronics & communication Engineering, Mahatma Gandhi Missions College of Engineering and Technology, Noida for her constant support and guidance throughout thecourse of my work. Her sincerity, thoroughness and perseverance have been a constant

source of inspiration for me. It is only her cognizant efforts that my endeavors have seen light of the day.

I also take the opportunity to acknowledge the contribution of Professor MR A.K VERMA project manager at ALL INDIA RADIO for his full support and assistance during the

development of the project.

I also do not like to miss the opportunity to acknowledge the contribution of all facultymembers of the department for their kind assistance and cooperation during my training.

Last but not the least, I acknowledge my friends for their contribution in the completion of mytraning .

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ABOUT THE TRAINING

The training institute is the apex in-house training Institute of All India Radio &

Doordarshan, primarily catering to the training needs of engineering personnel of All India

Radio & Doordarshan. The Institute conducts about 120 courses every year and trains around

1,600 engineering personnel. Officials from broadcasting organizations of some neighboring

developing countries are regular participants in the Institutes training programmes

To mould raw recruits into broadcasting technology

To upgrade the skills of personnel in tune with emerging technology

To bring out training related material

To assist in career growth of the staff

Apart from the main functions of imparting training, the institute has the responsibility to

carry out the following activities:

Conducting Departmental Competitive Examinations

Conducting Direct Recruitment Examination

Preparing and updating Technical Manuals

Preparing Safety Manuals

Preparation of Technical Monographs

Publication of Newsletter

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Table of Contents

TOPIC/CHAPTER PAGENO.

Certificate ii

Declaration iii

Acknowledgement iv

About the training v

Table of contents vi

List of figure ix

Abstract 1

1. Introduction 2

1.1 All India Radio 2

1.2 History 2

1.3 External services 3

1.4 Other services 4

1.4.1 News-on-phone services 4

1.4.2 Documentaries 5

1.5 All India Radio specifications 6

2. Direct to Home 7 2.1 Introduction 7

2.2 A path towards DTH 8

2.3 The DTH 9

2.4 Need of study 9

2.5 Objectives of study 9

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3. Literature Survey 113.1 Future of DTH in Indian scenario 11

3.2 Research methodology 11

3.2.1

Descriptive research 123.2.2 Data collection method 12

3.3 Sampling plan 13

3.3.1 Sample size 13

3.3.2 Sampling techniques 13

3.3.3 Sampling media 13

3.4 Field work 13

3.4.1 Statistical tools used 13

3.5 Limitations 14

3.6 Scope of the study 14

4. Working of DTH 15 4.1 Difference between DTH and cable T.V 15

4.2 DTH rather than cable T.V 16

4.3 Will DTH be cheaper than cable or more expensive 17

4.4 The satellite T.V solution 18

5. Overview of DTH system 20 5.1 DD direct 20

5.2 Dish T.V 21

5.3 NSS 21

5.4 Satellite 21

5.4.1 Geostationary satellite 22

5.5 A look of geostationary satellite in its orbit KU band frequencies 25

5.6 The programming 25

5.7 Compression 26

5.8 Encryption and Transmission 27

5.9 The moving picture expert groupMPEG-2 compression technique 28

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5.10 MPEG-2 compression techniques 29

5.11 The broadcast centre 30

5.12 Communication channel and bandwidth 30

5.13 Receive terminals 31

5.14 Satellite reciving antenna 31

5.15 Dish material and construction 33

5.16 The low noise block down convertor 36

5.17 The set top box 38

5.18 DTH applications 39

5.19 DTH benifits 39

5.20 Conclusion 39

6. REFERENCES 41

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List of Figures

Figure no. Figure title Page no.

1. Geostationary satellite 22

2. Reciving satellite of DTH 24

3. Noise temp to noise figure conversion chart 36

4. Block diagram of KU band universal LNB 37

5. Set top Box 38

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ABSTRACT

DTH is a new technology and it has matured to its full potential in other parts of the world.

There are many application has been found everyday for exploitation of benefits of DTHThe word DTH is synonymous with transmission of digital video channel to home subscriber

using a small dish antenna. The DTH utilizes a technology which enables a home

to receive high speed internet broadband access data communication, voice over internet

protocol (IP) telephony and much more using an open standard Digital Video

Broadcasting (DVB) technology. The video channels are received with a suitable set top box.

Capable of demodulating Motion Picture Engineering Group (MPEG-2) standard videos. It

is for the return channel required for other services such as voice over internet protocol and

broadband access data communications, that a return channel is also required for the

home terminal. The return channel via the satellite is called RCS and is an open standard.

Hardware compatible with DVB-RCS technology are readily available in the market in both

Ku-band and C-band. DVB-RCS is an international open standard for multimedia satellite

network where the return data rates in access of 2 Mbps are possible using low cost user

terminals. The forward ink is usually at 40 Mbps. Today, most satellite TV customers in

developed television markets get their programming through a direct broadcast satellite

(DBS) provider, such as DISH TV or DTH platform. The provider selects programs and

broadcasts them to subscribers as a set package. Basically, the provider goal is to bring

dozens or even hundreds of channels to the customer television in a form that approximates

the competition from Cable TV. Unlike earlier programming, the provider. broadcast is

completely digital, which means it has high picture and stereo sound quality. Early satellite

television was broadcast in C-band - radio in the 3.4- gigahertz (GHz) to 7-GHz frequency

range. Digital broadcast satellite transmits programming in the Ku frequency range (10GHz

to 14 GHz). There are five major components involved in a

direct to home (DTH) satellite.

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CHAPTER 1

INTRODUCTION

1.1 All India Radio

(AIR), officially known since 1956 as Akashvani (Devanagari: , kshavn

literally Sky's Voice ), is the radio broadcaster of India and a division of Prasar Bharati.

Established in 1930. it is the sister service of Prasar Bharati's Doordarshan, the national

television broadcaster. All India Radio is one of the largest radio networks in the world. Its

headquarters is at the Akashvani Bhavan in New Delhi. Akashvani Bhavan houses the Drama

Section, the FM Section and the National Service. Doordarshan Kendra (Delhi) offices are

also located on the sixth floor at Akashvani Bhavan.

1.2 HISTORY

In British India, broadcasting began in July 1923 with programmes by the Radio Club of

Bombay and other radio clubs. According to an agreement of July 23, 1927, the private

Indian Broadcasting Company LTD (IBC) was authorized to operate two radio stations; theBombay station began on 23 July 1927, and the Calcutta station followed on 26 August 1927.

On 1 March 1930, however, the company went into liquidation. The government took over

the broadcasting facilities, beginning the Indian State Broadcasting Service (ISBS) on 1 April

1930 (on an experimental basis for two years, and permanently in May 1932). On June 8,

1936; the ISBS was renamed All India Radio.

On 1 October 1939 the External Service began with a broadcast in Pushtu; it was intended to

counter radio propaganda from Germany directed to Afghanistan, Iran and the Arab nations.

When India became independent in 1947 the AIR network had only six stations (in Delhi,

Bombay, Calcutta, Madras, Lucknow, and Tiruchi); the total number of radio sets at that time

was about 275,000. On 3 October 1957 the Vividh Bharati Service was launched, to compete

with Radio Ceylon. Television broadcasting began in Delhi in 1959 as part of AIR, but was

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French, Indonesian, Persian, Pushtu, Russian, Sinhala, Swahili, Thai, Tibetan and English

(General Overseas Service). The Indian languages are Bengali, Gujarati, Marathi, Kokani,

Kashmiri, Hindi, Kannada, Malayalam, Nepali, Punjabi, Saraiki, Sindhi, Tamil, Telugu and

Urdu.

The longest daily broadcast is the Urdu Service to Pakistan, around the clock on DTH and on

short- and mediumwave for 12 hrs. The English-language General Overseas Service are

broadcast 8 hours daily. During Hajj, there are special broadcasts beamed to Saudi Arabia

in Urdu. The external services of AIR are also broadcast to Europe in DRM (Digital Radio

Mondiale) on 9950 kHz between 1745-2230 UTC.

The transmissions are broadcast by high-power transmitters located at Aligarh, Bengaluru,Chennai, Delhi, Gorakhpur, Guwahati, Mumbai and Panaji on shortwave and from Jalandhar,

Kolkata, Nagpur, Rajkot and Tuticorin on mediumwave. Some of these transmitters are

1000 kW (1 MW) or 500 kW. Programs are beamed to different parts of the world except the

Americas and received in very good Reception Quality in the Target areas. In each language

service, the program consists of news, commentary, a press review, talks on matters of

general or cultural interest, feature programmes, documentaries and music from India and the

target region. Most programs originate at New Broadcasting House on Parliament Street in

New Delhi, with a few originating at SPT Bengaluru, Chennai, Hyderabad, Jalandhar,

Kolkata, HPT Malad Mumbai, Thiruvanthapuram and Tuticorin.

The External Services Division of AIR is a link between India and rest of the world,

especially in countries with Indian emigrants and people of Indian origin. It broadcasts the

Indian point of view on matters of national and international importance, and demonstrates

the Indian way of life through its programs. QSL cards (which are sought-after by

international radio hobbyists) are issued to radio hobbyists by AIR in New Delhi for

reception reports of their broadcasts.

1.4 OTHER SERVIES

1.4.1 News-on-phone service

All India Radio launched news-on-phone service on 25 February 1998 in New Delhi; it now

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has service in Chennai, Mumbai, Hyderabad, Indore, Patna and Bangalore. The service is

accessible through STD, ISD and local calls. There are plans to establish the service in 11

more cities: Ahmedabad, Bhopal, Guwahati, Gwalior, Jabalpur, Jaipur, Kolkata, Lucknow,

Ranchi, Simla and Thiruvanthapuram. English and Hindi hourly news bulletins may be heard

live. News in MP3 format may be directly played from the site, and filenames are time-

stamped. AIR news bulletins are available in nine regional languages (Tamil, Kannada,

Gujarati, Bengali, Marathi, North East, Punjabi, Telugu and Urdu).

1.4.2 Documentaries

There is a long tradition of documentary features on AIR. There is great interest in radio

documentaries, particularly in countries like India, Iran, South Korea and Malaysia. This

format has been revived because of its flexibility, cost-cutting capacity, messaging potential

and creative potential with producers such as Chitra Narain, R. G. Narula and Danish Iqbal.

Iqbal has brought his experience as a drama producer to the documentary field; his

documentary "Yeh Rishta Kya Kehlata Hai" makes effective use of narrative and ambient

sounds. The documentary is a heartfelt account of an unseen bridge between a Kashmiri,

Shikarah Wala, and his auto rickshaw-driver friend in Delhi. Although they never met, their

unseen bond transcends the barriers of political, religious and regional prejudice. Because

Narula, Chitra and Danish had a long tenure at Delhi and creative collaboration with media

institutes, their influence is seminal in shaping the thinking of their colleagues. Chitra and

Narula were rewarded for their work, and Danish twice received the Public Service

Broadcasting Award for his documentaries.

AIR's Central Drama Unit is responsible for the national broadcast of plays. Playwrights and

producers such as Chiranjeet, Satyendra Sharat, Nirmala Agarwal and Danish Iqbal has been

associated with the department. Plays produced by the CDU are translated and produced byregional stations. Since its inception in the 1960s the unit has produced more than 1,500

plays, and the CDU is a repository of old scripts and productions. The National Programme

of Plays is broadcast by the CDU of AIR the fourth Thursday of each month at 9.30 pm. On

the National Programme of Plays, the same play is produced in 22 Indian languages and

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broadcast at the same time by all regional and national network stations. The CDU also

produces Chain Plays, half-hour dramas broadcast in succession by a chain of stations.

1.5 All India Radio SPECIFICATIONS

10 KW (1+1) Digital compatible VHF FM Transmitter & Accessories

16 Panel VHF FM Antenna

Programme Receiving /Feed Facility

(A) RN Terminal- C-Band

(B) DTH Ku-Band

(c) Emergency Transmission Facility

Stereo & Digital Programme Input Cum Monitoring Rack

Measuring Equipment

SETC OF;

82.5 KVA DG SET (1+1) for transmitter

62.5 KVA DG SET (1+1) for ancillary

40 KVA UPS

80 KVA AVR

80 KVA ISOLATION TRANSFORMER

Ventilation Equipment

Power supply LT board & earthing system(A) Design, Supply,Errection,Testing and

Commissioning

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CHAPTER-2

DIRECT TO HOME

2.1 Introduction:-

In this world, the inventions were born because of need .To satisfy the peoples entertainment

and information need TELEVISION Is the primary instrument that came in the market

.Slowly, the satellite channels age came in. The growth of satellite channels revolutionized

the peoples life. The satellite channels growth also moved to the wonderful concept DTH .

''Television is one of the most wonderful and latest gifts of science to man for his profit and pleasure. Science has come with Aladdins lamp in its hand to help man with various gifts.

Television is a wonderful gift. The credit for the miraculous invention of television goes to

Mr. John L. Baird, a scientist of Scotland. Television is a greatly source of recreation,

entertainment and pastime. Television plays a great role in informing and educating the

masses about family planning, health, sanitation, nutrition, agriculture, etc. Besides,

television is a good means of advertisement and propaganda also. Television has great

potential as an instrument of education. It has made living better and added lustre to life.Doordarshan the Indian national television network, one of the largest broadcasting

organizations in the world. The experimental telecast started in Delhi in September 1959 with

a small transmitter and a make shift studio and the regular daily transmission in 1965.The

year 1982 witnessed the introduction of regular satellite link between Delhi and different

transmitters the start of the national programme and doordarshan switching to colour

transmission. Doordarshan has three tier primary programme service the national, the

regional and the local. In the national programme the focus is on national intergration,

communal harmony and programmes includes news, current affairs, science cultural

magazines, serials ,music, dance, drama, and feature films. The regional programmes

originating from the

capital of the states and relayed by all transmitted in the concerned states also deal with

similar programmes at the state level, but in the language and idiom of that particular

regional. The local programme are specific and cover local issues featuring local people.

Now more than 85% of the over the 900 million population of the country can receive

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doordarshan programmes through network of more than 700 terrestrial transmitters.

Doordarshan programmes have mix of education, information and entertainment.An

exclusive service of programme of culture, current affairs and business catering to the need of

the serious viewless has been recently started. Doordarshan has also entered into an

agreement with the cable news network and twenty-four hours news and current affairs is

also available for viewers in the country.

Opportunities for DTH in India look great. Since cable has penetrated the Indian market in a

big way with roughly 40 million C&S homes, it is imperative that in its first few years of

operations, paid service of DTH will be focused on a niche market. This niche would

basically constitute the rich segment from urban as well as rural areas due to the primary

reason of high initial costs for DTH and the associated psychology of people. DISH TV have

started the operations from October 2003. The power of digital signals being broadcasted

directly to your home. This means, you enjoy all your 17avourite programmes with true

digital picture quality and awesome stereophonic sound.

2.2 A path towards DTH

On June 25, 1967, for two hours 26 nations of the world were joined together by an invisible

electromagnetic grid utilizing four satellites. The London-based production, in glorious black

and white, was the first-ever use of satellites to simultaneously interconnect remote corners of

the world to a single program event. The program, appropriately entitled "Our World,"

included the Beatles debuting the song "All You Need Is Love" to an audience estimated at

more than 600 million.During the course of the telecast, live feeds were interconnected

through a pair of early design Intelsats, an American experimental satellite (ATS-1), and a

Russian Molniya class bird. The New York Times would write about the ground-breaking

telecast, "Our World was a compelling reaffirmation of the potential of the home

screen to unify the peoples of the world."Less than three decades later, or approximately the

period of one generation of mankind, more than 30 million homes in the world

are equipped with their own satellite dishes. The early Intelsat, ATS, and Molniya satellites

were capable of relaying one (or at most, two) simultaneous TV programs; each satellite of

the current generation easily can deliver as many as 200 program channels to dish antennas

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less than one-thirtieth of the size required for reception of the original "Our World" telecast.

Well before the turn of the century, virtually any location in Asia or the Pacific will have

direct access to hundreds of channels of TV, high-speed Internet links, and thousands of radio

program channels. It is not an exaggeration to suggest that satellites are redesigning the very

fabric of life by creating full-time universal access to "our world."

All of this technology creates virtually unlimited opportunities for new business enterprise

and personal development. You are holding in your hand a key that will unlock for you, your

family, and your business the "secrets" of the 21st century "Information Revolution." There

has never been a point in the history of the world when so much opportunity has presented

itself to mankind. Use what you learn here wisely and your life will forever be

changed.

2.3 The DTH

DTH stands for Direct-To-Home television. DTH is defined as the reception of satellite

programmes 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 the consumer. Only

cable operators can receive satellite programmes and they then distribute them to individual

homes.

2.4 Need Of Study:-

This project was carried for Cosmic Info System pvt. Ltd is one of the largest players in the

electronic industry. The company needed to know the consumers attitude and factors

influencing purchase of DISH TV. The project is taken up to know the consumers view

regarding the product.

2.5 Objectives Of Study:-

The objectives for the project are

1. To find the customers need for DTH

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2. To forecast the demand for DTH in India.

3. To study the factors influencing in purchase of DISH TV.

4. To analyses the brand awareness of DISH TV.

5. To find the consumer opinion about DTH.

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big way with roughly 40 million C&S homes, it is imperative that in its first few years of

operations, paid service of DTH will be focused on a niche market. This niche would

basically constitute the rich segment from urban as well as rural areas due to the primary

reason of high initial costs for DTH and the associated psychology of people. Since

Doordarshan will be starting its novel free-to-air service on Ku band, it is likely to give the

prospective private DTH operators tremors and nightmares. The most attractive part of the

Doordarshan platform is going to be its low initial cost and no recurring expenditure.

Many cable homes are likely to make a shift to its platform and the service is likely to show

its full impact in the rural areas where cable service is not possible.All in all, there exists a

tremendous potential for direct to home broadcast in Indian market and it is projected that

within three years, there would be around 2.5 million DTH subscribers in India. This figure is

likely to increase due to the increase in TV and Cable households and also the growing

multiple TV households, which would form a large percentage of the total subscriber base.

Since India s population crossed the one billion mark, it is no surprise that satellite operators

and programmers world-wide have set their eyes on the world s largest open market for DTH

satellite TV services. The growing popularity of TV as a communication medium has resulted

in the TV media sectors undergoing a rapid transformation.

3.2 RESEARCH METHODOLOGY

The following points are considered in carrying out the research .

A research design is purely ad simply the framework a plan for a study that guides the

collection and analysis of the data.The research design used in the project is:

3.2.1 Descriptive Research:-

To describe the characteristics of certain groups e.g. users of a product with different age, sex

etc., to determine whether certain variables are associated e.g., age and usage of a product.

3.2.2 Data Collection Method:-

The main source through which data is collected are:-

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1. Primary data

2. Secondary data

The data collected for this research is through primary data collection method.

3.3 Sampling Plan

Sampling is used to collected data from limited numbers whereas census is used for large

numbers. Since limited is considered sampling method is used .

3.3.1 Sample size :-

Dth user = 100

Non dth user =150

3.3.2 Sampling technique:-

Non probability (non random ) sampling method is used in this project. Convenience

sampling technique is those which do not provide every item in the universe with knownchance of being included in the sample.

3.3.3 Sampling media

Sampling media adopted in this survey is personal interview.

3.4 Field Work:-

Fieldwork carried on for administering questionnaire is at Chennai, Bangalore, and Cochin.

3.4.1 Statistical Tools Used :-

Statistical tools were used to find inference between the variables and analyzing the result.

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The following are the tools used.

1) Kalmogrov Sminrov Test

2) Ranking Method

3) Kendalls Coefficient of Concordance

4) Chi square Test

Considering the above points the research is carried out.

3.5 Limitations:-

1. Study is concentrated in Chennai, Bangalore & Cochin and the result cannot be

generalized.

2. Rural market is not concentrated.

3. It is observed by the researcher that some of the respondents were biased.

3.6 Scope Of The Study:-

The scope of the study is to find the opinion of consumer about the DTH. This study elicited

the attitude for dish TV, the factor influence purchase of DISH TV, attitude level of

consumer with regard to dish TV, awareness level of consumer on DISH TV. Further this

study would help in understanding the DTH, market and for those pursuing a study in area.

Primary data was collected from consumer the research work was concentrated in Chennai,

Bangalore and Cochin.

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CHAPTER -4

WORKING OF DTH

A DTH network consists of a broadcasting centre, satellites, encoders, multiplexers,

modulators and DTH receivers. A DTH service provider has to lease Ku-band transponders

from the satellite. The encoder converts the audio, video and data signals into the digital

format and the multiplexer mixes these signals. At the user end, there will be a small dish

antenna and set-top boxes to decode and view numerous channels. On the user's end,

receiving dishes can be as small as 45 cm in diameter. DTH is an encrypted transmission that

travels to the consumer directly through a satellite. DTH transmission is received

directly by the consumer at his end through the small dish antenna. A set top box, unlike the

regular cable connection, decodes the encrypted transmission.

4.1 Difference Between DTH and Cable TV :-

The way DTH reaches a consumer's home is different from the way cable TV does. 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

remotest of areas since it does away with the intermediate step of a cable operator and the

wires (cables) that come from the cable operator to your house. As we explained above, in

DTH signals directly come from the satellite to your DTH dish. Also, with DTH, a user can

scan nearly 700 channels Does one need to put two dish antennae and pay double

Subscription per month if one has two TVs For multiple connections in the same premises,

one can use the same connection. However, every television set will need to have

an individual STB. Also, DTH is a national service and the STBs enable a viewer to

change service providers without changing the STB, even if one moves from one city to

another .

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4.2 DTH Rather Than Cable TV

DTH offers better quality picture than cable TV. This is becausecable TV in India is analog.

Despite digital transmission and reception, the cable transmission is still analog. DTH offersstereophonic sound effects. It can also reach remote areas where terrestrial transmission and

cable TV have failed to penetrate. Apart from enhanced picture quality, DTH has also allows

for interactive TV services such as movie-on-demand, Internet access, video conferencing

and e-mail. But the thing that DTH has going for it is that the powerful broadcasting

companies like Star,Zee, etc are pushing for it.

In DTH, the payments will be made directly by the subscriber to the satellite company

offering the service.A big problem that broadcasters face in India is the issue of underreporting of subscribers by cable operators. Consider the cable operators pyramid. Right

at the top is the broadcaster. Next comes the Multi Service Cable Operator (MSOs)

like Siticable, InCable, etc. Below them are the Access Cable Operators (ACOs) or your local

cable guy who actually lays the wires to your house. The local cable operators or the ACOs

then allegedly under-report the number of subscribers they have bagged because they have

to pay the MSOs something like Rs 30-45 per household. Showing a lesser number of

households benefits ACOs.With no way to actually cross check, the MSOs and the

broadcasters lose a lot. Broadcasters do not earn much in subscription fees and are mostly

dependent on advertisement revenue to cover their costs, which is not sustainable and does

not offer high growth in revenues for broadcasters. The way out of this is to use a set-top box

so that it will be clear how many households are actually using cable or going for DTH

where broadcasters directly connect to consumers and can actually grow revenues with a

growth in the subscriber base. Today, broadcasters believe that the market is ripe for DTH.

The prices of the dish and the set-top box have come down significantly. Overall investments

required in putting up a DTH infrastructure has dropped and customers are also reaping the

benefits of more attractive tariffs.The major thing that DTH operators are betting on is that

the service is coming at a time when the government is pushing for CAS (conditional access

system), which will make cable television more expensive, narrowing the tariff gap between

DTH and cable.

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4.3 Will DTH Be Cheaper Than Cable Or More Expensive

DTH will be definitely more expensive than cable as it exists today. A set-top box is a must

for DTH. Earlier, when CAS made set-top box mandatory for households, the costs betweenDTH and cable would not have been too wide. But CAS on the backburner now -- which

means no set-top box (a must for DTH), the price gap between DTH and cable, will be

wide .In Oct 2002, Siti cable, which is owned by Zee, said that the cost of the installation

equipment, which includes the receiver dish and the set-top box, would be priced at around

Rs 3,900. Siticable is looking to rope in 1 million subscribers in 15 months. Other estimates

say that digital cable set-top box may cost Rs 4,000, a DTH decoder dish is unlikely to cost

less than Rs 7,000. DTH's minimum subscription could be priced around Rs 500 per month.

Some reports say that an entry level DTH STB will cost about Rs 7,000 (including taxes and

installation cost at consumers end). A more advanced STB with value added features like

PVR (Personal Video Recorder), PSTN connectivity, Gamming console, channel

management system, etc. may cost as much as Rs 15,000. HISTORY OF DTH IN INDIA

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. In 1997, the government

even imposed a ban when the Rupert Murdoch-owned Indian Sky Broadcasting (ISkyB) was

about to launch its DTH services inIndia.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. The

companies offering DTH service will have to have an Indian chief and foreign equity has

been capped at 49 per cent. There is no limit on the number of companies that can apply for

the DTH license. MARKET COMPARISON OF D TH AND CABLE TV The cable system

is well entrenched in India and is showing quite rapid growth. If DTH had come to India in

1996-97 (like Star had originally attempted), then it could have made a significant

breakthrough.Europe is an example of this. DTH developed there before cable and now

controls nearly 80 per cent of the total satellite television subscriber base. But in US, cable

rules because it came before DTH.DTH will definitely cut into the existing cable user base. It

will make the local cable operator less important and take business away from him. It will

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this is all there is to satellite television. But as we'll see in the next section, there are several

important steps between the original.programming source and your television.

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CHAPTER-4

OVERVIEW OF DTH SYSTEMS

Direct to Home are nothing but the Direct Broadcast Satellite Television and Radio Systems.

Geostationary satellites play an important role for DTH systems. In general, DTH service is

the one in which a large number of channels are digitally compressed, encrypted and beamed

from very high power Geostationary satellites. The programs can be directly received at

homes. Also,DTH transmission eliminates local cable operator completely,

since an individual user is directly connected to the service providers. An individual user has

a small dish usually 45 to 60cm in diameter and Low Noise Block Converter (LNBC) pointed

towards satellite. At home digital receiver i.e. Set top box is connected to TV which receives

digitally multiplexed channels from LNBC and gives RF output for TV .

The satellite transmission is usually in Ku-Band. The digital channels are first multiplexed

and then QPSK modulated before transmission. The small dish along with LNBC receives the

signals and LNBC converts these Ku band signals to Intermediate Frequency based on the

local IF which is typically 10.7GHz. Now, the set top box receives the down-converted

satellite signals and performs the demodulation and de-multiplexing and finally D to Aconversion before making signal competent to TV. The DTH receivers available in the

Market are affordable and the use of such systems is nowadays increasing dramatically in

urban as well as ruler areas.

5.1 DD Direct:

DD Direct is launched by Doordarshan. It operates from NSS-6 Satellite and gives 33 free to

air channels and 13 radio channels. The transmission covers most of the India. The cost of the

Dish,LNBC and Set top box is around Rs. 2500/-. With this setup only

free to air channels are visible.

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5.2 Dish TV:

Dish TV is launched by Essel Group. The Dish TV has different set top box with Smart card

facility to decode paid channels. The cost of the unit is around Rs. 4000/-. So user can watch paid as well as free channels and radio programs. The user has to pay monthly rental for paid

channels. The entire Zee Network channels are available on Dish TV. Dish TV

Transmission is also from NSS-6Satellite.

5.3 NSS:

NSS 6, Ku-band satellite with Ka band uplink capabilities, will provide fully interactiveaccess to high speed internet and other multimedia communications. Additionally, it will

provide direct to home broadcasting services a well AS THE full compliment of

traditional enterprise telecommunications services across the large coverage area stretching

from the eastern Mediterranean and southern Africa to Australia, Japan and Korea.

Access Cable Operators (ACOs) or your local cable guy who actually lays the wires to your

house. The local cable operators or the ACOs then allegedly underreport the number of

subscribers they have bagged because they have to pay the MSOs somethinglike Rs 30-45 per household. Showing a lesser number of households benefits ACOs. With no

way to actually cross check, the MSOs and the broadcasters lose a lot. Broadcasters do not

earn much in subscription fees and aremostly dependent on advertisement revenue to cover

their costs,which is not sustainable and does not offer high growth in

revenues for broadcasters.The way out of this is to use a set-top box so that it will be clear

how many households are actually using cable or going for DTH where broadcasters directly

connect to consumers and can actually grow revenues with a growth in the subscriber base.

Specifications of NSS-6 Satellite:

5.4 SATELLITEGeostationary satellites play an important role for DTH systems.

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5.4.1 GEO STATIONARY SATELLITE

Geostationary satellites are positioned at an exact height above the earth (about 36000 Km).

At this height they rotate around the earth at the same speed as the earth

rotates around its axis, so in effect remaining stationary above a point on

the earth (normally directly overhead the equator). As they remain stationary they are ideal

for use as communications satellites and also for remote imaging as they can repeatedly scan

the same points on the earth beneath them .

Polar Orbiting satellites by comparison have a much lower orbit, moving around the earth

fairly rapidly, and scanning different areas of the earth at relatively infrequent periods.

Motion of Geostationary Satellite around EARTH

Fig:-1-geostationary satellite

In above fig. , it is clear that geostationary satellite has circular orbit. In each orbit the time period remains same. Orbital plane is same as equator. Above 3 condition are necessary for a

satellite to be a geostationary satellite.

Otherwise it will become geo synchronous satellite, which appears oscillating to an observer

on the earth at fix location in sky. Focusing of a particular position on earth

Above fig. shows how geostationary satellite focuses a part of earth. We know that earth

rotates on its axis. Each such rotation has time period 24 hours. Fig. explains how the same

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while, if , the maximum value is

If the maximum is less than the radius of the central body, then the conic section is an ellipse

which is fully inside the central body and no part of it is a possible trajectory. If the

maximum is more, but the minimum is less than the radius, part of the trajectory is possible:

if the energy is non-negative (parabolic or hyperbolic orbit): the motion is either away

from the central body, or towards it.

if the energy is negative: the motion can be first away from the central body, up to

after which the object falls back.

If r becomes such that the orbiting body enters an atmosphere, then the standard assumptions

no longer apply, as in atmospheric reentry.

Above is mathematical calculation of radius of

geostationary satellite.

Fig:-2- reciving antenna of DTH

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Receiver which point to a geostationary satellite In above fig. receiving antenna of DTH is

shown located at the top of a house. Position of receivers at different location of earth

Above fig. is there to explain that within the focus there is a uplink station which transmits

programs to satellite. Satellite again broadcasts them to subscribers as a set

package. Basically, the provider goal is to bring dozens or even hundreds of channels to the

customer television.

5.5 A LOOK OF GEOSTATIONARY SATELLITE IN ITS ORBIT KU

BAND FREQUENCIES

Digital broadcast satellite transmits programming in the Ku frequency range (10 GHz to 14

GHz). Rain Fade Effects on Ku-band Transmissions There is one major drawback to satellitesdown linking signals at frequencies greater than 10 GHz: the signal wavelength is so

short that rain, snow, or even rain-filled clouds passing overhead can reduce the intensity of

the incoming signals. Atthese higher frequencies, the lengths of the falling rain droplets are

close to a resonant submultiples of the signal's wavelength; the droplets therefore are able to

absorb and depolarize the microwaves as they pass through the Earth's atmosphere.

5.6 THE PROGRAMMING

Satellite TV providers get programming from two major sources: national turn around

channels (such as HBO, ESPN and CNN) and various local channels (the NBC, CBS, ABC,

PBS and Fox affiliates in a particular area). Most of the turnaround channels also provide

programming for cable television, and the local channels typically broadcast their

programming over the airwaves.

Turn around channels usually have a distribution center that beams their programming to a

geostationary satellite. The broadcast center uses large satellite dishes to pick up these

analog and digital signals from several sources. Most local stations don't transmit their

programming to satellites, so the provider has to get it another way. If the provider includes

local programming in a particular area, it will have a small local facility consisting of a few

racks of communications equipment. The equipment receives local signals directly from the

broadcaster through fiber-optic cable or an antenna and then transmits them to the central

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broadcast center. The broadcast center converts all of this programming into a

high-quality, uncompressed digital stream. At this point, the stream contains a vast quantity

of data -- about 270 megabits per second (Mbps) for each channel. In order to transmit the

signal from there, the broadcast center has to compress it. Otherwise, it would be too big for

the satellite to handle. In the next section, we'll find out how the signal is compressed.

5.7 COMPRESSION

The two major providers in the United States use the MPEG-2 compressed video format --

the same format used to store movies on DVDs. With MPEG-2 compression, the provider can

reduce the 270- Mbps stream to about 5 or 10 Mbps (depending on the type of programming).

This is the crucial step that has made DBS service a success. With digital compression, a

typical satellite can transmit about 200 channels. Without digital compression, it can

transmit about 30 channels. At the broadcast center, the high-quality digital stream of video

goes through an MPEG-2 encoder, which converts the programming to MPEG-2 video of the

correct size and format for the satellite receiver in your house. The MPEG encoder analyzes

each frame and decides how to encode it. The encoder eliminates redundant or irrelevant

data, and extrapolates information from other frames to reduce the overall size of the file.

Each frame can be encoded in one of three ways:

As an intraframe - An intraframe contains the complete image data for that frame. This

method of encoding provides the least compression.

As a predicted frame - A predicted frame contains just enough information to tell the satellite.

Receiver how to display the frame based on the most recently displayed intra frame or

predicted frame. This means that the frame contains only the data that relates to how the

picture has changed from the previous frame.

As a bidirectional frame - To display a bidirectional frame,the receiver must have the

information from the surrounding intraframe or predicted frames. Using data from the closest

surrounding frames, the receiver interpolates the position and color of each pixel. This

process occasionally produces "artifacts" -- little glitches in the video image -- but for the

most part, it creates a clear, vivid picture.

The rate of compression depends on the nature of the programming. If the encoder is

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converting a newscast, it can use a lot more predicted frames because most of the scene stays

the same from one frame to the next. In other sorts of programming, such as action movies

and music videos, things change very quickly from one frame to the next, so the encoder has

to create more intraframes. As a result, something like a newscast generally compresses to a

much smaller size than something like an action movie.

5.8 ENCRYPTION AND TRANSMISSION

After the video is compressed, the provider needs to encrypt it in order to keep people from

accessing it for free. Encryption scrambles the digital data in such a way that it can only be

decrypted (converted back into usable data) if the receiver has the correct decryption

algorithm and security keys.

What is Encryption

Encryption is an electronic method of securing the video and audio of any TV program so

that satellite, cable, and broadcast TV services can maintain control over the distribution of

their signals.

To receive encrypted or "scrambled" TV services, cable and SMATV system operators, hotel

chains, private satellite networks, and home dish owners must possess a compatible decoder

that can sense the presence of the encrypted TV signal and then automatically decode the

pictures and sound Premium program services purchase the rights to movies from film

production companies with the understanding that every individual will pay for the right to

view them. Programmers also are very concerned about hotels, bars, and other commercial

establishments that derive monetary benefit from signal piracy. Within a particular region,

program producers may license more than one broadcast outlet for use of their programs. The

program producer may require that broadcasters encrypt their signals whenever the

broadcaster airs the producer's copyrighted material. This strictly limits reception of the

programming to the market for which each broadcaster is licensed. In some areas of

the world, satellite broadcasters periodically must switch from a free-to-air to an encrypted

transmission mode whenever required under their respective agreements with the program

copyright owners.

Each IRD contains a unique numerical address number that is installed at the factory. The

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satellite TV programmer's authorization center sends a coded conditional access message

over the satellite that includes this unique address. This authorization message can turn on an

individual IRD so that it can receive a particular service or group of services, or turn off an

IRD in the event that the subscriber fails to pay the required monthly subscription fee.

Moreover, the authorization center can use this addressable feature to selectively turn off and

on large groups of decoders. Group IRD control is used to selectively "black out" TV events,

such as a live championship boxing match, in certain countries for which the programmer

does not own the distribution rights. Once the signal is compressed and encrypted, the

broadcast center beams it directly to one of its satellites. The satellite picks up the signal with

an onboard dish, amplifies the signal and uses another dish to beam the signal back to Earth,

where viewers can pick it up. Bit Rate The amount of data information being transmitted in

one second of time is called the bit rate, expressed in bits per second (b/s). A bit rate of one

thousand bits per second is called a kilobit per second (kb/s); one million bits per second a

megabit per second (Mb/s); and one billion bits per second a gigabit per second

(Gb/s).

A bit rate of more than 200 Mb/s would be required to digitize a broadcast quality video

service without any signal impairment. This would require the use of several satellite

transponders to relay just one uncompressed digital video signal. It therefore is essential that

some form of signal compression be used to dramatically reduce the number of bits required

for digital TV transmissions.

5.9 THE MOVING PICTURES EXPERT GROUP

In 1988, the International Standards Organization (ISO) of the International

Telecommunication Union established the Moving Pictures Experts Group (MPEG) to agree

on an internationally recognized standard for the compressed representation of video,

film, graphic, and text materials. The committee's goal was to develop a relatively simple,

inexpensive, and flexible standard that put most of the complex functions at the transmitter

rather than the receiver. Representatives from more than 50 corporations and governmental

organizations worldwide took part in the MPEG committee's deliberations. In 1991, the

MPEG-1 standard was introduced to handle the compressed digital representation of non

video sources of multimedia at bit rates of 1.5 Mb/s or less. However, MPEG-1 can be

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5.11 THE BROADCAST CENTER

The broadcast center converts all of this programming into a high-quality, uncompressed

digital stream. At this point, the stream contains a vast quantity of data about 270

megabits per second (Mbps) for each channel. In order to transmit the signal from there, the broadcast center has to compress it. Otherwise, it would be too big for the satellite to handle.

The providers use the MPEG-2 c ompressed video format the same format used to store

movies on DVDs. With MPEG-2 compression, the provider can reduce the 270-Mbps stream

to about 3 or 10 Mbps (depending on the type of programming). This is the crucial step that

has made DTH service a success. With digital compression, a typical satellite can transmit

about 200 channels. Without digital compression, it can transmit about 30 channels. At

the broadcast center, the high-quality digital stream of video goes through an MPEG-2encoder, which converts the programming to MPEG-2 video of the correct size and format

for the satellite receiver in your house.

5.12 COMMUNICATION CHANNEL AND BAND-WIDTH

In a communications system, the part that connects a data source to a data sink is known as

channel. Bandwidth refers to the data transmission capacity of a communications channel.

The greater a channel's bandwidth, the more information it can carry per unit of time.The term technically refers to the range of frequencies that a channel can carry. The higher

the frequency, the higher the bandwidth and thus the greater the capacity of a channel. This

capacity might more appropriately be referred to as throughput.

For digital devices, the bandwidth is usually expressed in bits per second (bps), kilobits per

second (kbps) or megabits per second (mbps). For analog devices, the bandwidth is expressed

in cycles per second, or Hertz (Hz). The required bandwidth can vary greatly according to the

type of application. For example, the transmission of simple ASCII text messages requires

relatively little bandwidth, whereas the transmission of high resolution video images requires

a large amount of bandwidth. A major trend in networks at all levels (i.e., from LANs to the

Internet) has been increasing bandwidth. For example, the development of optical fiber cable

made possible a huge increase in bandwidth as compared with copper wire cable, and the

bandwidth of optical fiber cable continued to increase both as a result of improvements to the

optical fiber itself and to the transmitters and other devices used with it. Nevertheless,

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bandwidth is often insufficient. This is due to such factors as the continued increase in the

numbers of users (especially of the Internet), the growth in the demand for applications which

require more bandwidth and the high cost of upgrading some portions of networks

(particularly replacing copper wire connections to individual homes and offices with

optical fiber). Thus, an important principle in the design of network protocols continues to be

the conservation of bandwidth. For DTH system communication channel is air and Band-

Width is :

Ku Band Uplink : 13.75 to 14.5 GHz

Ku Band Down links : 10.95 to 11.2 GHz

11.45 to 11.70 GHz

12.50 to 12.75 GHz

5.13 RECEIVE TERMINALS

The receive terminals are basically for the reception of the signals being beamed from the

transmission station. The terminal consists of the following:

1. receive type solid offset antenna

2. LNB feed system

3. Interface cables &

4. Set top box

The terminal can be placed outside the window of a high rise building, on the ground or a

roof mount. The terminals can be used as per the contents being beam by the transmission

stations.

5.14 SATELLITE RECEIVING ANTENNAS

Antenna size considerations:

The selection of the appropriate antenna size helps in keep in the network up and healthy.

It is decided based on the following:

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1. Satellite EIRP at the particular location.

2. Rain attenuation at the location.

3. Adequate Eb/No for reception of excellent picture quality.

The satellite dish is a parabola of revolution, that is, a surface having the shape of a parabola

rotated about its axis of symmetry. The resulting paraboloid shares one key property of

optical lenses: it is able to form an image of whatever object is placed in front of it. The

largest optical and radio telescopes employ the parabolic reflector to gather and concentrate

electromagnetic radiation. Any antenna surface irregularities or any departure from the

precise parabolic shape will degrade the image resolution. As is more often the case,

however, low resolution performance is the result of the installer's failure to grasp the

importance of using good antenna assembly techniques.

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. The parabolic

reflector receives externally generated noise along with the desired signal. When the satellite

dish tilts up towards the "cold" sky, the antenna noise temperature is at its lowest

level. If the antenna must tilt downward to receive a low-elevation satellite, however, the

antenna's noise temperature will increase dramatically because it is now able to intercept the

"hot" noise temperature of the Earth. The actual amount of noise increase in this case is a

function of antenna f/D ratio and diameter. Minimum antenna elevation angles of 5 degrees,

for Cband, and 10 degrees, for Ku-band, above the site location's horizon usually are

recommended.

Antenna f/D Ratio The f/D ratio of the antenna is the ratio of focal length to dish

diameter, measured in the same units. A paraboloid reflector that is 3 m in diameter and with

a focal length of 1.26 m therefore will exhibit an f/D of 0.42. The f/D ratio selected by the

antenna designer also determines the depth of the dish itself, that is, the amount of contour or

"wraparound" of the paraboloid within its fixed diameter. A long-focus (high f/D) paraboloidreflector will have a shallow contour, while a short-focus paraboloid reflector resembles a

deep bowl. The deepest reflectors have a f/D ratio of 0.25. This places the focal point directly

in the plane of the antenna aperture. An antenna design with a large value of f/D requires a

feed horn that has a narrower beam width, so that the edge illumination of

the antenna can be maintained. This typically is between 10 and 15 dB below the value

produced at the center of the reflector. Conversely, a small value of f/D will require a feed

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horn with a wider beam width. Paraboloid antennas that are 3 m or less in diameter (at 4

GHz) commonly use a 12-dB feed illumination taper, while larger antennas will use a 15-dB

taper. The antenna designer must make a trade-off between antenna gain and noise

temperature, balancing the entry of random noise due to feed horn over

illumination or low antenna elevation angle with the noise contribution of the antenna side

lobes in the antenna radiation pattern.

Although the long focal length employed by the shallow dish design increases the

illumination of the reflector surface, there are distinct disadvantages to this design approach.

Moreover, antenna noise increases as antenna elevation increases. Shallow dishes are more

susceptible to intercepting Earth noise when pointing at low elevation angles. Finally, the

shallow dish is more susceptible to picking up terrestrial interference from terrestrial

microwave stations. The deep-dish design trades off gain in order to lower antenna

noise performance. The deep-dish design is an attractive alternative for locations that

potentially may experience terrestrial interference (TI) problems or at installations that

require low antenna elevation angles. The deep-dish design positions the feed horn relatively

close to the rim of the reflector. Therefore, the deep dish has a greater ability to shield the

feed horn from potential TI sources. However, the feed horn is so close to the reflector that it

cannot effectively illuminate the entire surface.

Antenna noise temperature is a function of the antenna f/D ratio and diameter as well as the

elevation angle of the dish as it points toward the geostationary satellite's location in the sky

5.15 DISH MATERIALS AND CONSTRUCTION

The reflector's surface material must be constructed out of metal in order to reflect the

incoming microwave signals. Some antenna reflectors appear to be manufactured out of

plastic or fiberglass; however, these dishes actually have an embedded metal mesh

material that reflects the incoming satellite signals to the front and center of the dish.

The solid one-piece metal antenna is most always the dish with the best performance

characteristics because there can be no assembly errors and the reflector normally will

maintain its precise shape over the lifetime of the system. Solid petal

antennas constructed out of four or more metal panels are generally the next best performance

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value, as potential assembly errors are limited to variations along the seams between panels.

The installer can visually inspect these seams during assembly to ensure that there are no

variations in the surface curve from one petal to the next. Installation errors almost never

occur when this type of antenna is assembled face-down on a flat, level surface.

Offset-feed Antennas

One oval dish design that is the antenna of choice for most digital DTH satellite TV service

providers is called the offset-fed antenna . Here the manufacturer uses a smaller subsection of

the same paraboloid used to produce prime focus antennas (see but with a major axis in the

north/south direction, and a smaller minor axis in the east/west direction. The offset

paraboloid eliminates aperture blockage, reduces antenna noise temperature, and resists the

accumulation of ice and snow by placing the feed below the reflector and angling it upwards.

In this case, the reflector acts as if it were a portion of a much larger paraboloid. But because

only a portion of this imaginary reflector exists, the feed is designed just to illuminate that

portion. The offset-fed antenna then performs just as it would as a part of the larger dish, and

directs its beam exactly the same way.

The offset-fed antenna design offers several distinct advantages over its prime focus

counterparts. There is no feedhorn blockage, an important consideration when the antenna

aperture is less than one meter in diameter. Moreover, antenna designers can reconfigure the

required antenna aperture as a flatter, more nearly vertical reflector, with the added advantage

of pointing the feed skywards, away from the hot-noise source of the Earth. Because of these

advantages, the offset-fed antenna can achieve higher efficiency levels than prime focus

antennas normally attain, usually in the 70 percent range. The point is the dish's feed horn,

which passes the signal onto the receiving equipment. In an ideal setup, there aren't any major

obstacles between the satellite and the dish, so the dish receives a clear signal. In some

systems, the dish needs to pick up signals from two or more satellites at the same time. Thesatellites may be close enough together that a regular dish with a single horn can pick up

signals from both. This compromises quality somewhat, because the dish isn't aimed directly

at one or more of the satellites. A new dish design uses two or more horns to pick up different

satellite signals. As the beams from different satellites hit the curved dish, they reflect at

different angles so that one beam hits one of the horns and another beam hits a different horn.

The central element in the feed horn is the low noise block down converter, or LNB. The

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LNB amplifies the radio signal bouncing off the dish and filters out the noise (radio signals

not carrying programming). The LNB passes the amplified, filtered signal to the satellite

receiver inside the viewer's house.

Antenna Specifications:

Reflector Size

65cm

Type

Offset Feed

Frequency

10.7 to 12.75GHz

Antenna Gain

> 36.75dBi @12.75GHz

3dB Beam width

< 3.2 degree

10dB Beam width

< 5.2 degree

Aperture efficiency

> 70%

Surface Accuracy

< 0.01"

Material

Steel! Aluminum

Elevation Angel Range 15 to 50 degree Cross Polar Discrimination on major axis.> 27dB

VSWR max 1.3

Noise Temperature


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5.16 THE LOW NOISE BLOCK DOWN CONVERTER ( LNB)

The incoming satellite signal propagates down the waveguide of the feed horn and exits into

a rectangular chamber mounted at the front of the low-noise block down converter (LNB), in

which a tiny resonant probe is located. This pickup probe, which has a wavelength thatresonates with the incoming microwave frequencies, conducts the signal onto the first stage

of electronic amplification.

In addition to amplifying the incoming signal, the first stage of electronic amplification also

generates thermal noise internally. The internal noise contribution of the LNB is amplified

along with the incoming signal and passed on to succeeding amplifier stages.

The LNB sets the noise floor for the satellite receiving system. Today's high-performance

LNB uses gallium arsenide semiconductor and high electron mobility transistor (HEMT)

technologies to minimize the internal noise contribution of the LNB.

The noise performance of any C-band LNB is quantified as a noise temperature measured in

Kelvin (K), while Ku -band LNB noise performance is expressed as a noise figure measured

in decibels . Today's C-band LNB commonly achieves a noise temperature of 40 K or less,

while Ku-band noise figures of less than 1 dB/K are commonly available. In either case, the

lower the noise performance rating of the LNB, the less noise introduced into the LNB by its

own circuitry.

Figure :-3- Noise temperature to noise figure conversion chart.

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Universal LNB

A wide band product called a "universal" Ku-band LNB is available that can switch

electronically between the 10.7-11.7 and 11.7-12.75 GHz frequency spectra to provide

complete coverage of the entire Ku-band frequency range. The receiver or IRD sends a

switching voltage (13 or 17 volts DC) to the LNB that automatically changes the LNB input

frequency range to the desired frequency spectrum (10.70-11.75 GHz or 11.7-12.75 GHz).

Keep in mind, however, that any universal LNB with an IF output frequency range of 950-

2,050 MHz can only be used effectively with a receiver or IRD that also has a comparable IF

input frequency range.

FIG-4- Block diagram of a Ku-band Universal LNB .

LNB Gain

Another important LNB specification is the amount of amplification or gain that each unit

provides. This also is measured in decibels. The consumer-grade LNB commonly produces

50-65 dB of gain. The gain specification for any LNB is important for ensuring that the signal

arriving at the IF input of the IRD is within a range of values in dBmV recommended by the

IRD manufacturer. For example, an LNB with a gain of 65 dB is the logical choice for an

installation where there is a long cable run between the outdoor and indoor units. The

installer uses an LNB with 65 dB of gain to overcome signal attenuation through the cable,

while an LNB with 50 dB of gain is preferred for installations with a short cable run between

the outdoor and indoor units.

LNB Specifications:

I/P Range 1O.7GHz to 12.75GHz

Local Oscillator 9.75GHz or 10.6GHz

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Noise Figure 0.5dB

Noise Temperature 35 Kelvin @ 290 degree

Gain 55dB 4

5.17 SET TOP BOX

Simplified Block Diagram

The typical block diagram of the Set top box is as shown in following figure ,

Fig-5: set top box

As per the diagram, the set top box accepts the entire down converted band and separates out

the individual transponder frequency. Then signals are first converted to fixed IF and then

QPSK demodulated. The bandwidth of QPSK signals is 27.5 MHz as the bit rate is 27.5

Mb/s. It is observed that 11 digital channels are multiplexed in 27.5 MHz bandwidth. The

power supply for LNB, polarization selection signals as well as LO setting signals

are send by the set top box itself by using the same cable between the LNB and set top box.

After the QPSK demodulation, the digital bit stream obtained contains several multiplexed

channels as well as error control bits. The bit stream is processed to correct and detect errors,

de interleaved, and decrypted. A digital demultiplexer then extracts the bits for wanted

channel, and sends them to MPEG decoder, and finally generates analog Audio and Video

signals with DIA converters to drive TV set. The paid channels are encrypted, and a smart

card having the correct key for decryption is required to view the paid channels.

The key is provided by the paying monthly rent by the user.

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5.18 DTH APPLICATIONS

a) To view pay & free-to-air TV channels of various DTH platform on your home TV.

b) Doordarshan free-to-air services providing 40 TV channels with no subscription fees is anattractive preposition to people in urban and rural areas. These channels comprises of DD

channels and popular channels of news , sports , information , entertainment etc.

c) One can scan the entire globe with a motorized dish using a CI set top box with CAM

modules and watch TV channels of several DTH platforms visible to the dish terminals.

d) A number has started IP broadcast with return channel on PSTN line and this would be for

education and other application.

5.19 DTH-BENEFITS

Benefits of DTH extends to all sections of the society since DTH has a reach in all areas

whether it is remote or urban , it provides equal benefits to everyone. Benefits of DTH are

listed below:

1. Cost effective communication, information and entertainment to all .

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

through a click of a button and thus brings world at least information, news,

entertainment to your home .

3. DTH services bypasses mediators and thus content provider comes with customer

directly.

4. DTH services are transparent providing digital quality video, audio, radio, and IP to

all at equal prices and other benefits with reliability.

5.20 CONCLUSION

DTH projects in India are just a beginning and we are taking the advantage of DTH

revolution. Direct to home connects urban, rural and remote areas of the country and provides

desire information communication, education and entertainment at the click of a button.

1. Broadband noise will have negligible effect on GMRT Observations, as the minimum

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separation distance is 90 meters with the assumption that there is no DTH system in 100

meter circle from any of the GMRT antennas. Care must be taken for arm antennas.

2. Narrow band noise can cause RFI, in spectral line observations below 400MHz, if located

at about 2 km from a GMRT antenna. Further Work

1. It is useful to be able to control LNB without set top box so as to understand the exact

spectrum at LNB o/p. Effort is to be put to make the circuit on page 18 (or some other

approach) work.

2. Effect of Narrow band noise on GMRT must be studied in detail. Towards this, a DTH

Receiver needs to be installed on an evaluation basis at the GMRT Guest Housel Recreation

Room and test observations in spectral line mode perfonned with different "poorly made"

coaxial cables to link the LNB and STB. Careful check for lines seen in nearby antennas like

C3, C4, and C9 etc in 235 and 325 MHz bands would help in getting a clearer picture

regarding the severity of the problem/s in a controlled manner.

3. Finally, to restrict possible RFI, one can design a Hair Pin Filter with provision of passing

DC and 22 KHz tone which can be added between the LNB and set top box. This will only

allow the required satellite signals and attenuate noise in the GMRT band. Depending on the

result of (2) above, we may have to plan a strategy of adding such units BEFORE THE STB

at installations in nearby villages.

4. We may find that a simpler solution might be to buy a good quality double shielded cable,

assemble connectors professionally and supply to the nearby villages, if the tests as in (2)

above does show interference to operation of GMRT.

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CHAPTER-6

REFERENCES

[1]. http://seminarprojects.com/Thread-direct-to-home-television-dth[2]. http://www.termpaperwarehouse.com/essay-on/Project-Report-On-Dth/32016[3].http://allindiaradio.gov.in/Information/Tenders/Documents/7aac6dcccfb34fdc9cc2509a1d19c7naushera_final_specs_1.pdf [4]. https://en.wikipedia.org/wiki/All_India_Radio[5]. http://www.allindiaradio.com.au/

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