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CHAPTER-1

INTRODUCTION TO SATELLITE TELEVISION

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1.1 INTRODUCTION TO SATELLITE TELEVISION

Satellite television is television delivered by the means ofcommunications satellite and

received by a satellite dish and set-top box. In many areas of the world it provides a wide range

of channels and services, often to areas that are not serviced by terrestrial orcable providers.

Satellite television or digital television (DTV) is the transmission of audio and video by

discrete (digital) signals, in contrast to the analog signals used by analog TV but are not trulyembedded systems, because they allow different applications to be loaded and peripherals to be

connected.

The first satellite television signal was relayed from Europe to the Telstarsatellite over

North America in 1962. The first geosynchronous communication satellite, Syncom 2, was

launched in 1963. The world's first commercial communication satellite, called Intelsat I

(nicknamed Early Bird), was launched into synchronous orbit on April 6, 1965. The first national

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networkof satellite television, called Orbita, was created in Soviet Union in 1967, and was based

on the principle of using the highly elliptical Molniya satellite for re-broadcasting and delivering

of TV signal to ground downlinkstations. The first domestic North American satellite to carry

television was Canadas geostationary Anik 1, which was launched in 1972.[1] ATS-6, the world's

first experimental educational and Direct Broadcast Satellite, was launched in 1974. The first

Soviet geostationary satellite to carry Direct-To-Home television, called Ekran, was launched in

1976.

1.2 OBJECTIVE

The main objective behind using a Satellite TV or Digital TV over Analogue TV is to reach the

modern day demands of picture quality and less cost. Until the advent of digital television, all

television was based on the transmission and reception ofanalog signals, displayed on a cathode-

ray tube. Although a number of differentbroadcast television systems were in use worldwide, thesame principles of operation apply.

While this low-quality analogue signals looked fine on the comparatively small, tube TVs, this is

no longer the case with modern flat-panels. Anyone who's tried to "admire" an analog TV signal

on a 50-inch plasma TV will know how pitiful it looks: a lackluster, low-resolution picture,

plagued by disturbances - in short, TV that'll turn you off. The video signal of analog television

was transmitted in AM, while the audio was transmitted in FM. Analog TV was subject to

interference, such as ghosting and snow, depending on the distance and geographical location of

the TV receiving the signal. In addition, the amount of bandwidth assigned to an analog TV

channel restricted the resolution and overall quality of the image. The analog TV transmissionstandard (in the U.S.) was referred to as NTSC.

Satellite TV or Digital TV, or DTV, on the other hand, is transmitted as data bits of information,

just as computer data is written or the way music is written on a CD. In this way, the signal is

basically "on" or "off". In other words, the intent of DTV technology is that the viewer eithersees an image or nothing at all. There is no gradual signal loss as distance from the transmitter

increases. If the viewer is too far from the transmitter or is in an undesirable location, there is

nothing to see. In addition, since the DTV signal is made up of "bits", the same bandwidth sizethat takes up a current analog TV signal, can accommodate not only a higher quality image in

digital form, but the extra space not used for the TV signal can be used for additional video,

audio, and text signals. In other words, broadcasters can supply more features, such as surroundsound, multiple language audio, text services, and more in the same space now occupied by a

standard analog TV signal. However, there is one more advantage to the ability of a Digital TV

channel's space; the ability to transmit a High Definition (HDTV) signal.

.

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1.3 CHARACTERISTICS

These are some characteristics of Satellite TV:

1) Satellite television uses the digital transmission technology in which images are

converted to digital data that is transferred to the television set. This is where the digital

television set changes the digital data into images and audio.

2) This way of transmitting image and audio can result in a picture that is extremely clear

and a sound quality that is unparalleled. There are no grains as there used to be earlier

and there are no breakages in the sound either.

3) Satellite television is also extremely convenient because it allows for a betteruser

interface. The listing of channels is digitized and therefore one does not have to randomlyflip through channels to find where the favourite channel is. In a digital channel you have

to just check out the list and choose the channel that you want to watch.

4) The Satellite television option also allows for a higher number of channel possibilities

because the data can be compressed into s smaller bandwidth. So using the same cable

options, a higher number of channels can be transmitted without investing in additional

infrastructure.

5) While all seems in favour of Satellite television, adopting this option also means that you

are in a 0-1 bit world. This means that you either get transmission or do not and there is

not middle path where you can at least watch some grainy image if the signal is not

perfect.

1.4 ORGANISATIONOFTHESIS

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1.4.1: INTRODUCTION TO SATELLITE TV RECEPTION:

There are a number of different ways to receive digital television. One of the oldest means of

receiving DTV (and TV in general) is using an antenna (known as an aerial in some countries).

This way is known as Digital Terrestrial Television (DTT). With DTT, viewers are limited to

whatever channels the antenna picks up. Signal quality will also vary.

Other ways have been devised to receive digital television. Among the most familiar to people

are digital cable and digital satellite. In some countries where transmissions of TV signals are

normally achieved by microwaves, digital MMDS is used. Other standards, such as DMB andDVB-H, have been devised to allow handheld devices such as mobile phones to receive TV

signals. Another way is IPTV, that is receiving TV via Internet Protocol, relying on DSL or

optical cable line. Finally, an alternative way is to receive digital TV signals via the openInternet. For example, there is P2P (peer-to-peer) Internet television software that can be used towatch TV on a computer.

Some signals carry encryption and specify use conditions (such as "may not be recorded" or

"may not be viewed on displays larger than 1 m in diagonal measure") backed up with the force

of law under the WIPO Copyright Treaty and national legislation implementing it, such as theU.S. Digital Millennium Copyright Act. Access to encrypted channels can be controlled by a

removable smart card, for example via the Common Interface (DVB-CI) standard for Europe and

via Point Of Deployment (POD) for IS or named differently CableCard.

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1.4.2: REDUCING EFFECTS OF POOR RECEPTION IN ANALOGUE

TECHNIQUE

Changes in signal reception from factors such as degrading antenna connections or changingweather conditions may gradually reduce the quality of analog TV. The nature of digital TVresults in a perfectly-decodable video initially, until the receiving equipment starts picking up

interference that overpowers the desired signal or if the signal is too weak to decode.

Some equipment will show a garbled picture with significant damage, while other devices may

go directly from perfectly-decodable video to no video at all or lock up. This phenomenon isknown as the digital cliff effect.

For remote locations, distant channels that, as analog signals, were previously usable in a snowy

and degraded state may, as digital signals, be perfectly decodable or may become completelyunavailable. In areas where transmitting antennas are located on mountains, viewers who are too

close to the transmitter may find reception difficult or impossible because the strongest part of

the broadcast signal passes above them.

The use of higher frequencies will add to these problems, especially in cases where a clear line-

of-sight from the receiving antenna to the transmitter is not available.

Dynamic multipath interference, in which the delay and magnitude of reflections are rapidly

changing, is particularly problematic for digital reception. While this just produces moving andchanging ghost images for analog TV, it can render a digital signal impossible to decode.

The 8VSB-based standards in use in North American ATSC broadcasts are particularly

vulnerable to problems from dynamic multipath; this has the potential to severely limit mobile orportable use of digital television receivers.

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The figure below shows an PCI based analog TV receiver:

PCI based Analogue Satellite TV receiver

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The figure below showing the block diagram of a PCI based Digital Satellite TV receiver:

PCI based Satellite TV receiver

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CHAPTER-2

DIGITAL TELEVISION

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2.1 WHATISDIGITAL TV?

Digital television (DTV) is the transmission of audio and video by discrete (digital)

signals, in contrast to the analog signals used by analog TV. Digital Television (DTV) is anadvanced broadcasting technology that has transformed the television viewing experience. DTV

has enable broadcasters to offer television with better picture and sound quality. It also offers

multiple programming choices, called multicasting, and interactive capabilities.

DTV uses MPEG-2 encoding just like the satellite systems do, but digital TV allows a

variety of new, larger screen formats. The formats include:

480p - 640x480 pixels progressive

720p - 1280x720 pixels progressive 1080i - 1920x1080 pixels interlaced

1080p - 1920x1080 pixels progressive

A digital TV decodes the MPEG-2 signal and displays it just like a computer monitor does,giving it incredible resolution and stability. There is also a wide range of set-top boxes that can

decode the digital signal and convert it to analog to display it on a normal TV.

Digital television supports many different picture formats defined by the combination of size,aspect ratio (width to height ratio) and interlacing. With digital terrestrial television broadcastingin the USA, the range of formats can be broadly divided into two categories: HDTV and SDTV.

These terms by themselves are not very precise, and many subtle intermediate cases exist.

High-definition television (HDTV), one of several different formats that can be transmitted over

DTV, uses different formats, amongst which: 1280 720 pixels in progressive scan mode(abbreviated 720p) or 1920 1080 pixels in interlace mode (1080i). Each of these utilizes a 16:9

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aspect ratio. (Some televisions are capable of receiving an HD resolution of 1920 1080 at a 60

Hz progressive scan frame rate known as 1080p.) HDTV cannot be transmitted over current

analog channels.

Standard definition TV (SDTV), by comparison, may use one of several different formats taking

the form of various aspect ratios depending on the technology used in the country of broadcast.For 4:3 aspect-ratio broadcasts, the 640 480 format is used in NTSC countries, while

720 576 is used in PAL countries. For16:9 broadcasts, the 704 480 format is used in NTSCcountries, while 720 576 is used in PAL countries. However, broadcasters may choose to

reduce these resolutions to save bandwidth (e.g., many DVB-T channels in the United Kingdom

use a horizontal resolution of 544 or 704 pixels per line).[1]

Each commercial terrestrial DTV channel in North America is permitted to be broadcast at a datarate up to 19 megabits per second, or 2.375 megabytes per second. However, the broadcaster

does not need to use this entire bandwidth for just one broadcast channel. Instead the broadcast

can be subdivided across several video subchannels (aka feeds) of varying quality and

compression rates, including non-video datacasting services that allow one-way high-bandwidthstreaming of data to computers.

The figure showing Advanced Television System Committee Digital Television system:

A simple digital-TV architecture would include a receiver section for digital-terrestrial signals.Digital-TV standards bodies have developed specifications, such as the ATSC (Advanced

Television Systems Committee) A/74, that receivers must meet to provide good reception of the

new digital-TV signals.

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A broadcaster may opt to use a standard-definition digital signal instead of an HDTV signal,

because current convention allows the bandwidth of a DTV channel (or "multiplex") to be

subdivided into multiple subchannels (similar to what most FM stations offer with HD Radio),providing multiple feeds of entirely different programming on the same channel. This ability to

provide either a single HDTV feed or multiple lower-resolution feeds is often referred to as

distributing one's "bit budget" or multicasting. This can sometimes be arranged automatically,using a statistical multiplexer (or "stat-mux"). With some implementations, image resolution

may be less directly limited by bandwidth; for example in DVB-T, broadcasters can choose from

several different modulation schemes, giving them the option to reduce the transmission bitrateand make reception easier for more distant or mobile viewers.

2.1.1 TRANSMISSION

DTTV is transmitted on radio frequencies through the airwaves that are similar to standard

analogue television, with the primary difference being the use of multiplex transmitters to allowreception of multiple channels on a single frequency range (such as a UHF orVHF channel).

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The amount ofdata that can be transmitted (and therefore the number of channels) is directly

affected by the modulation method of the channel. [2] The modulation method in DVB-T is

COFDM with either 64 or 16 state Quadrature Amplitude Modulation (QAM). In general a64QAM channel is capable of transmitting a greater bitrate, but is more susceptible to

interference. 16 and 64QAM constellations can be combined in a single multiplex, providing a

controllable degradation for more important programme streams. This is called hierarchicalmodulation.

New developments in compression have resulted in the MPEG-4/AVC standard which enable

three high definition services to be coded into a 24 Mbit/s European terrestrial transmission

channel.

The DVB-T standard is not used for terrestrial digital television in North America. Instead, the

ATSC standard calls for 8VSB modulation, which has similar characteristics to the vestigialsideband modulation used for analogue television. This provides considerably more immunity to

interference, but is not immune as DVB-T is to multipath distortion and also does not

provide for single-frequency network operation (which is in any case not relevant in the UnitedStates).

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Both systems use the MPEG transport stream and H.262/MPEG-2 Part 2 video codec specified

in MPEG-2; they differ significantly in how related services (such as multichannel audio,

captions, and program guides) are encoded.

2.2 Why Did We Switch to DTV?

An important benefit of the switch to all-digital broadcasting is that it freed up parts of the

valuable broadcast spectrum for public safety communications (such as police, fire departments,

and rescue squads). Also, some of the spectrum can now be auctioned to companies that will beable to provide consumers with more advanced wireless services (such as wireless broadband).

Consumers also benefited because digital broadcasting allows stations to offer improved picture

and sound quality, and digital is much more efficient than analog. For example, rather than being

limited to providing one analog program, a broadcaster is able to offer a super sharp High

Definition (HD) digital program or multiple Standard Definition (SD) digital programssimultaneously through a process called multicasting.

Multicasting allows broadcast stations to offer several channels of digital programming at thesame time, using the same amount of spectrum required for one analog program. So, for

example, while a station broadcasting in analog on channel 7 is only able to offer viewers one

program, a station broadcasting in digital on channel 7 can offer viewers one digital program on

channel 7-1, a second digital program on channel 7-2, a third digital program on channel 7-3, andso on. This means more programming choices for viewers. Further, DTV provides interactive

video and data services that were not possible with analog technology.

Nowadays, microcontrollers are so cheap and easily available that it is common to usethem instead of simple logic circuits like counters for the sole purpose of gaining some designflexibility and saving some space. Some machines and robots will even rely on a multitude of

microcontrollers, each one dedicated to a certain task. Most recent microcontrollers are 'In

System Programmable', meaning that you can modify the program being executed, withoutremoving the microcontroller from its place.

Today, microcontrollers are an indispensable tool for the robotics hobbyist as well as forthe engineer. Starting in this field can be a little difficult, because you usually can't understand

how everything works inside that integrated circuit, so you have to study the system gradually, a

small part at a time, until you can figure out the whole image and understand how the system

works.

2.3 HISTORY OF DTV

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History

The first satellite television signal was relayed from Europe to the Telstarsatellite overNorth

America in 1962. The first geosynchronous communication satellite, Syncom 2, was launched in1963. The world's first commercial communication satellite, called Intelsat I (nicknamed Early

Bird), was launched into synchronous orbit on April 6, 1965. The first national network ofsatellite television, called Orbita, was created in Soviet Union in 1967, and was based on the

principle of using the highly elliptical Molniya satellite for re-broadcasting and delivering of TVsignal to ground downlink stations. The first domestic North American satellite to carry

television was Canadas geostationary Anik 1, which was launched in 1972.[1] ATS-6, the world's

first experimental educational and Direct Broadcast Satellite, was launched in 1974. The firstSoviet geostationary satellite to carry Direct-To-Home television, called Ekran, was launched in

1976.

2.3.1 THE DTV TRANSITION

The switch from analog to digital broadcast television is referred to as the Digital TV (DTV)Transition. In 1996, the U.S. Congress authorized the distribution of an additional broadcast

channel to each broadcast TV station so that they could start a digital broadcast channel while

simultaneously continuing their analog broadcast channel.

DTV has several advantages over analog TV, the most significant being that digital channelstake up less bandwidth, and the bandwidth needs are continuously variable, at a corresponding

reduction in image quality depending on the level of compression as well as the resolution of the

transmitted image. This means that digital broadcasters can provide more digital channels in the

same space, provide high-definition television service, or provide other non-television servicessuch as multimedia or interactivity. DTV also permits special services such as multiplexing

(more than one program on the same channel), electronic program guides and additionallanguages (spoken or subtitled). The sale of non-television services may provide an additionalrevenue source.

Digital signals react differently to interference than analog signals. For example, common

problems with analog television include ghosting of images, noise from weak signals, and many

other potential problems which degrade the quality of the image and sound, although theprogram material may still be watchable. With digital television, the audio and video must be

synchronized digitally, so reception of the digital signal must be very nearly complete;

otherwise, neither audio nor video will be usable. Short of this complete failure, "blocky" videois seen when the digital signal experiences interference.

Analogue to digital transition by country

The broadcasting of digital terrestrial transmissions has led to many countries planning to phaseout existing analogue broadcasts. This table shows the launches of DTT and the closing down of

analogue television in several countries.

http://en.wikipedia.org/wiki/Europehttp://en.wikipedia.org/wiki/Telstarhttp://en.wikipedia.org/wiki/North_Americahttp://en.wikipedia.org/wiki/North_Americahttp://en.wikipedia.org/wiki/Geosynchronoushttp://en.wikipedia.org/wiki/Communication_satellitehttp://en.wikipedia.org/wiki/Syncomhttp://en.wikipedia.org/wiki/Intelsat_Ihttp://en.wikipedia.org/wiki/Television_networkhttp://en.wikipedia.org/wiki/Orbitahttp://en.wikipedia.org/wiki/Soviet_Unionhttp://en.wikipedia.org/wiki/Molniya_(satellite)http://en.wikipedia.org/wiki/Signalling_(telecommunication)http://en.wikipedia.org/wiki/Downlinkhttp://en.wikipedia.org/wiki/Canadahttp://en.wikipedia.org/wiki/Anik_1http://en.wikipedia.org/wiki/Satellite_television#cite_note-0http://en.wikipedia.org/wiki/Satellite_television#cite_note-0http://en.wikipedia.org/wiki/ATS-6http://en.wikipedia.org/wiki/Direct_Broadcast_Satellitehttp://en.wikipedia.org/wiki/Direct-To-Homehttp://en.wikipedia.org/wiki/Ekranhttp://en.wikipedia.org/wiki/High-definition_televisionhttp://en.wikipedia.org/wiki/Ghosting_(television)http://en.wikipedia.org/wiki/Europehttp://en.wikipedia.org/wiki/Telstarhttp://en.wikipedia.org/wiki/North_Americahttp://en.wikipedia.org/wiki/North_Americahttp://en.wikipedia.org/wiki/Geosynchronoushttp://en.wikipedia.org/wiki/Communication_satellitehttp://en.wikipedia.org/wiki/Syncomhttp://en.wikipedia.org/wiki/Intelsat_Ihttp://en.wikipedia.org/wiki/Television_networkhttp://en.wikipedia.org/wiki/Orbitahttp://en.wikipedia.org/wiki/Soviet_Unionhttp://en.wikipedia.org/wiki/Molniya_(satellite)http://en.wikipedia.org/wiki/Signalling_(telecommunication)http://en.wikipedia.org/wiki/Downlinkhttp://en.wikipedia.org/wiki/Canadahttp://en.wikipedia.org/wiki/Anik_1http://en.wikipedia.org/wiki/Satellite_television#cite_note-0http://en.wikipedia.org/wiki/ATS-6http://en.wikipedia.org/wiki/Direct_Broadcast_Satellitehttp://en.wikipedia.org/wiki/Direct-To-Homehttp://en.wikipedia.org/wiki/Ekranhttp://en.wikipedia.org/wiki/High-definition_televisionhttp://en.wikipedia.org/wiki/Ghosting_(television)

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Official launch: The official launch date of digital terrestrial television in the country, not

the start for trial broadcasts.

Start of closedown: The date for the first major closedown of analogue transmitters.

End of closedown: The date when analogue television is definitely closed down.

System: Transmission system, e. g. DVB-T, ATSC orISDB-T.

Interactive: System used for interactive services, such as MHP and MHEG-5. Compression: Video compression standard used. Most systems use MPEG-2, but the

more efficient H.264/MPEG-4 AVC has become increasingly popular among networks

launching later on. Some countries use both MPEG-2 and H.264, for example Francewhich uses MPEG-2 for standard definition free content but MPEG-4 for HD broadcasts

and pay services.

2.4 DTV RECEPTION

There are a number of different ways to receive digital television. One of the oldest means ofreceiving DTV (and TV in general) is using an antenna (known as an aerial in some countries).

This way is known as Digital Terrestrial Television (DTT). With DTT, viewers are limited to

whatever channels the antenna picks up. Signal quality will also vary.

Other ways have been devised to receive digital television. Among the most familiar to peopleare digital cable and digital satellite. In some countries where transmissions of TV signals are

normally achieved by microwaves, digital MMDS is used. Other standards, such as DMB and

DVB-H, have been devised to allow handheld devices such as mobile phones to receive TV

signals. Another way is IPTV, that is receiving TV via Internet Protocol, relying on DSL oroptical cable line. Finally, an alternative way is to receive digital TV signals via the open

Internet. For example, there is P2P (peer-to-peer) Internet television software that can be used towatch TV on a computer.

Figure showing the reception of Digital signal by antenna dishes:

http://en.wikipedia.org/wiki/DVB-Thttp://en.wikipedia.org/wiki/ATSC_Standardshttp://en.wikipedia.org/wiki/ISDB-Thttp://en.wikipedia.org/wiki/Multimedia_Home_Platformhttp://en.wikipedia.org/wiki/MHEG-5http://en.wikipedia.org/wiki/MPEG-2http://en.wikipedia.org/wiki/H.264/MPEG-4_AVChttp://en.wikipedia.org/wiki/Antenna_(radio)http://en.wikipedia.org/wiki/Digital_terrestrial_televisionhttp://en.wikipedia.org/wiki/Digital_cablehttp://en.wikipedia.org/wiki/Digital_satellitehttp://en.wikipedia.org/wiki/Microwaveshttp://en.wikipedia.org/wiki/MMDShttp://en.wikipedia.org/wiki/Digital_multimedia_broadcastinghttp://en.wikipedia.org/wiki/DVB-Hhttp://en.wikipedia.org/wiki/Mobile_phoneshttp://en.wikipedia.org/wiki/IPTVhttp://en.wikipedia.org/wiki/Digital_Subscriber_Linehttp://en.wikipedia.org/wiki/DVB-Thttp://en.wikipedia.org/wiki/ATSC_Standardshttp://en.wikipedia.org/wiki/ISDB-Thttp://en.wikipedia.org/wiki/Multimedia_Home_Platformhttp://en.wikipedia.org/wiki/MHEG-5http://en.wikipedia.org/wiki/MPEG-2http://en.wikipedia.org/wiki/H.264/MPEG-4_AVChttp://en.wikipedia.org/wiki/Antenna_(radio)http://en.wikipedia.org/wiki/Digital_terrestrial_televisionhttp://en.wikipedia.org/wiki/Digital_cablehttp://en.wikipedia.org/wiki/Digital_satellitehttp://en.wikipedia.org/wiki/Microwaveshttp://en.wikipedia.org/wiki/MMDShttp://en.wikipedia.org/wiki/Digital_multimedia_broadcastinghttp://en.wikipedia.org/wiki/DVB-Hhttp://en.wikipedia.org/wiki/Mobile_phoneshttp://en.wikipedia.org/wiki/IPTVhttp://en.wikipedia.org/wiki/Digital_Subscriber_Line

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Some signals carry encryption and specify use conditions (such as "may not be recorded" or"may not be viewed on displays larger than 1 m in diagonal measure") backed up with the force

of law under the WIPO Copyright Treaty and national legislation implementing it, such as the

U.S. Digital Millennium Copyright Act. Access to encrypted channels can be controlled by aremovable smart card, for example via the Common Interface (DVB-CI) standard for Europe and

via Point Of Deployment (POD) for IS or named differently CableCard.

2.5 ADVANTAGES AND DISADVANTAGES OF DTV

http://en.wikipedia.org/wiki/Encryptionhttp://en.wikipedia.org/wiki/WIPO_Copyright_Treatyhttp://en.wikipedia.org/wiki/Legislationhttp://en.wikipedia.org/wiki/Digital_Millennium_Copyright_Acthttp://en.wikipedia.org/wiki/Smart_cardhttp://en.wikipedia.org/wiki/DVB-CIhttp://en.wikipedia.org/w/index.php?title=Point_Of_Deployment&action=edit&redlink=1http://en.wikipedia.org/wiki/CableCardhttp://en.wikipedia.org/wiki/Encryptionhttp://en.wikipedia.org/wiki/WIPO_Copyright_Treatyhttp://en.wikipedia.org/wiki/Legislationhttp://en.wikipedia.org/wiki/Digital_Millennium_Copyright_Acthttp://en.wikipedia.org/wiki/Smart_cardhttp://en.wikipedia.org/wiki/DVB-CIhttp://en.wikipedia.org/w/index.php?title=Point_Of_Deployment&action=edit&redlink=1http://en.wikipedia.org/wiki/CableCard

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2.5.1 Advantages

Digital reception tends to be better overall, particularly with a good signal. With a

weaker signal there is little perceptible difference, in fact analogue can be better.

It is easier to obtain the optimum digital picture than the optimum analogue picture.

Many more channels can fit on the digital transmission.

Interactive (red button) services can be provided.

2.5.2 Disadvantages

It can be quite difficult to adjust the antenna, because of the lack of feedback that

would be provided by a gradually degraded analog picture. The picture is usually

either totally on or totally off, providing no information about which direction to

move the antenna. A signal meter provided on most tuners helps considerably withthis problem, but some televisions (such as the very popular Vizio branded ones) lack

a signal meter. The same problem can also make it very difficult to select and test

antennas.

New equipment (Set-top box) may be required.

Increased electricity consumption by the digital receiving equipment if both TV andadditional set-top box is plugged.

An upgraded antenna installation may be required.

http://en.wikipedia.org/wiki/Set_top_boxhttp://en.wikipedia.org/wiki/Set_top_box

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Analogue requires lower signal strength to get a viewable picture. By extension,

digital does not degrade as gracefully as analogue. For example, with low signalstrength an analogue picture gets fuzzy (but is still viewable) while a digital picture

freezes and stops updating.

Switching channels is slower because of the time delays in decoding digital signals.

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CHAPTER-3

C-BAND DIGITAL SATELLITE TV RECEIVER

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3.1 C-BAND SATELLITE TV RECEIVER: AN INTRODUCTION

As we all know that Satellite TV reception has gained much popularity in India over thelast three decades, specially after the live telecasting of Gulfwar by CNN. Both the S-Band and

C-Band satellite signals are available to India. C-band signals are beamed from various satellites

like Asiasat, Aralisat, and Insat 2B.

In India, the C-band reception is much more popular than the S-band. The popular satellite

programmes which can be received on C-band include Star-TV, Zee TV, PTV2, CNN, ATN,

Sun TV, and Doordarshan. Besides programmes from Russia, China, Saudi Arabia are also

available on C-band channels, although their language is a barrier.

3.2 ELECTROMAGNETIC SPECTRUM

The electromagnetic spectrum is the range of all possible frequencies of electromagnetic

radiation. The "electromagnetic spectrum" of an object is the characteristic distribution of

electromagnetic radiation emitted or absorbed by that particular object.

EM waves are typically described by any of the following three physical properties: the

frequencyf, wavelength , orphoton energy E. Frequencies range from 2.41023 Hz (1 GeV

gamma rays) down to the local plasma frequency of the ionized interstellar medium (~1 kHz).

Wavelength is inversely proportional to the wave frequency, so gamma rays have very short

wavelengths that are fractions of the size ofatoms, whereas wavelengths can be as long as theuniverse.

The electromagnetic spectrum extends from low frequencies used for modern radio to gamma

radiation at the short-wavelength end, covering wavelengths from thousands of kilometers down

to a fraction of the size of an atom. The long wavelength limit is the size of the universe itself,

while it is thought that the short wavelength limit is in the vicinity of the Planck length, although

in principle the spectrum is infinite and continuous.

3.2.1 TYPES OF RADIATION

http://en.wikipedia.org/wiki/Electromagnetic_radiationhttp://en.wikipedia.org/wiki/Electromagnetic_radiationhttp://en.wikipedia.org/wiki/Frequencyhttp://en.wikipedia.org/wiki/Wavelengthhttp://en.wikipedia.org/wiki/Photonhttp://en.wikipedia.org/wiki/GeVhttp://en.wikipedia.org/wiki/Plasma_frequencyhttp://en.wikipedia.org/wiki/Atomhttp://en.wikipedia.org/wiki/Atomhttp://en.wikipedia.org/wiki/Wavelengthhttp://en.wikipedia.org/wiki/Universehttp://en.wikipedia.org/wiki/Planck_lengthhttp://en.wikipedia.org/wiki/Infinityhttp://en.wikipedia.org/wiki/Continuum_(theory)http://en.wikipedia.org/wiki/Electromagnetic_radiationhttp://en.wikipedia.org/wiki/Electromagnetic_radiationhttp://en.wikipedia.org/wiki/Frequencyhttp://en.wikipedia.org/wiki/Wavelengthhttp://en.wikipedia.org/wiki/Photonhttp://en.wikipedia.org/wiki/GeVhttp://en.wikipedia.org/wiki/Plasma_frequencyhttp://en.wikipedia.org/wiki/Atomhttp://en.wikipedia.org/wiki/Atomhttp://en.wikipedia.org/wiki/Wavelengthhttp://en.wikipedia.org/wiki/Universehttp://en.wikipedia.org/wiki/Planck_lengthhttp://en.wikipedia.org/wiki/Infinityhttp://en.wikipedia.org/wiki/Continuum_(theory)

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EM radiation is classified by wavelength into radio wave, microwave,infrared, the visible region

we perceive as light, ultraviolet, X-rays and gamma rays. The brief types of EM radiation are on

the basis of region in the EM spectrum, as mentioned below:

1) Radio

2) Microwave

3) Infrared

4) Visible

5) Ultraviolet

6) X-rays

7) Gamma rays

The region classification is shown in the figure below:

http://en.wikipedia.org/wiki/Radio_wavehttp://en.wikipedia.org/wiki/Microwavehttp://en.wikipedia.org/wiki/Infraredhttp://en.wikipedia.org/wiki/Visible_regionhttp://en.wikipedia.org/wiki/Ultraviolethttp://en.wikipedia.org/wiki/X-rayhttp://en.wikipedia.org/wiki/Gamma_rayshttp://en.wikipedia.org/wiki/Radio_wavehttp://en.wikipedia.org/wiki/Microwavehttp://en.wikipedia.org/wiki/Infraredhttp://en.wikipedia.org/wiki/Visible_regionhttp://en.wikipedia.org/wiki/Ultraviolethttp://en.wikipedia.org/wiki/X-rayhttp://en.wikipedia.org/wiki/Gamma_rays

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3.3 MICROWAVES

Microwaves are electromagnetic waves with wavelengths ranging from as long as one meter to

as short as one millimeter, or equivalently, with frequencies between 300 MHz (0.3 GHz) and

300 GHz. This broad definition includes both UHF and EHF (millimeter waves), and varioussources use different boundaries. In all cases, microwave includes the entire SHF band (3 to

30 GHz, or 10 to 1 cm) at minimum, with RF engineering often putting the lower boundary at

1 GHz (30 cm), and the upper around 100 GHz (3mm).Here we have a program to ADDInstruction.

Typically, microwaves are used in television news to transmit a signal from a remote location to

a television station from a specially equipped van. Seebroadcast auxiliary service (BAS), remote

pickup unit (RPU), and studio/transmitter link(STL).

Most satellite communications systems operate in the C, X, Ka, or Ku bands of the microwave

spectrum. These frequencies allow large bandwidth while avoiding the crowded UHF

frequencies and staying below the atmospheric absorption of EHF frequencies.

Satellite TV either operates in the C band for the traditional large dishfixed satellite service or

Ku band fordirect-broadcast satellite. Military communications run primarily over X or Ku-band

links, with Ka band being used forMilstar.

http://en.wikipedia.org/wiki/Electromagnetic_radiationhttp://en.wikipedia.org/wiki/Wavelengthhttp://en.wikipedia.org/wiki/Frequencyhttp://en.wikipedia.org/wiki/Hertzhttp://en.wikipedia.org/wiki/UHFhttp://en.wikipedia.org/wiki/Extremely_high_frequencyhttp://en.wikipedia.org/wiki/Millimeter_wavehttp://en.wikipedia.org/wiki/Super_high_frequencyhttp://en.wikipedia.org/wiki/RF_engineeringhttp://en.wikipedia.org/wiki/Television_newshttp://en.wikipedia.org/wiki/Broadcast_auxiliary_servicehttp://en.wikipedia.org/wiki/Remote_pickup_unithttp://en.wikipedia.org/wiki/Remote_pickup_unithttp://en.wikipedia.org/wiki/Studio/transmitter_linkhttp://en.wikipedia.org/wiki/Satellite_communicationshttp://en.wikipedia.org/wiki/Satellite_TVhttp://en.wikipedia.org/wiki/TVROhttp://en.wikipedia.org/wiki/Fixed_satellite_servicehttp://en.wikipedia.org/wiki/Direct-broadcast_satellitehttp://en.wikipedia.org/wiki/Milstarhttp://en.wikipedia.org/wiki/Electromagnetic_radiationhttp://en.wikipedia.org/wiki/Wavelengthhttp://en.wikipedia.org/wiki/Frequencyhttp://en.wikipedia.org/wiki/Hertzhttp://en.wikipedia.org/wiki/UHFhttp://en.wikipedia.org/wiki/Extremely_high_frequencyhttp://en.wikipedia.org/wiki/Millimeter_wavehttp://en.wikipedia.org/wiki/Super_high_frequencyhttp://en.wikipedia.org/wiki/RF_engineeringhttp://en.wikipedia.org/wiki/Television_newshttp://en.wikipedia.org/wiki/Broadcast_auxiliary_servicehttp://en.wikipedia.org/wiki/Remote_pickup_unithttp://en.wikipedia.org/wiki/Remote_pickup_unithttp://en.wikipedia.org/wiki/Studio/transmitter_linkhttp://en.wikipedia.org/wiki/Satellite_communicationshttp://en.wikipedia.org/wiki/Satellite_TVhttp://en.wikipedia.org/wiki/TVROhttp://en.wikipedia.org/wiki/Fixed_satellite_servicehttp://en.wikipedia.org/wiki/Direct-broadcast_satellitehttp://en.wikipedia.org/wiki/Milstar

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3.3.2 MICROWAVE FREQUENCY BANDS

The microwave spectrum is usually defined as the electromagnetic spectrum that ranges from

1.0 GHz to 30 GHz in frequency, but some antiquated usages includes lower frequencies. Mostcommon applications are within the 1.0 to 30 GHz range. Microwave frequency bands, as

defined by the Radio Society of Great Britain (RSGB), are shown in the table below. Note thatfrequencies above 30 GHz are typically said to be in the "millimeter wave" because their

wavelengths can be conveniently measured in millimeters (mm). The frequency of 30 GHzcorresponds quite closely to a wavelength of 10 mm, or 1.0 centimeter.

The table below showing the different Microwave frequency bands:

Band Frequency range

L band 1 to 2 GHz

S band 2 to 4 GHzC band 4 to 8 GHz

X band 8 to12 GHz

KU band 12 to 18 GHz

K band 18 to 26.5 GHz

KA band 26.5 to 40 GHz

Q band 30 to 50 GHz

U band 40 to 60 GHz

V band 50 to 75 GHz

E band 60 to 90 GHz

W band 75 to 110 GHz

F band 90 to 140 GHz

D band 110 to 170 GHz

3.4 C BAND

The C band is a name given to certain portions of the electromagnetic spectrum, as well as a

range ofwavelengths ofmicrowaves that are used for long-distance radio telecommunications.

The IEEE C-band - and its slight variations - contains frequency ranges that are used for manysatellite communications transmissions; by some Wi-Fi devices; by some cordless telephones;

and by some weather radar systems. For satellite communications, the microwave frequencies of

http://en.wikipedia.org/wiki/Electromagnetic_spectrumhttp://en.wikipedia.org/wiki/Radio_Society_of_Great_Britainhttp://en.wikipedia.org/wiki/Millimeter_wavehttp://en.wikipedia.org/wiki/Millimeterhttp://en.wikipedia.org/wiki/Centimeterhttp://en.wikipedia.org/wiki/Electromagnetic_spectrumhttp://en.wikipedia.org/wiki/Wavelengthhttp://en.wikipedia.org/wiki/Microwavehttp://en.wikipedia.org/wiki/Telecommunicationshttp://en.wikipedia.org/wiki/IEEEhttp://en.wikipedia.org/wiki/Satellite_communicationshttp://en.wikipedia.org/wiki/Wi-Fihttp://en.wikipedia.org/wiki/Mobile_phonehttp://en.wikipedia.org/wiki/Weather_radarhttp://en.wikipedia.org/wiki/Electromagnetic_spectrumhttp://en.wikipedia.org/wiki/Radio_Society_of_Great_Britainhttp://en.wikipedia.org/wiki/Millimeter_wavehttp://en.wikipedia.org/wiki/Millimeterhttp://en.wikipedia.org/wiki/Centimeterhttp://en.wikipedia.org/wiki/Electromagnetic_spectrumhttp://en.wikipedia.org/wiki/Wavelengthhttp://en.wikipedia.org/wiki/Microwavehttp://en.wikipedia.org/wiki/Telecommunicationshttp://en.wikipedia.org/wiki/IEEEhttp://en.wikipedia.org/wiki/Satellite_communicationshttp://en.wikipedia.org/wiki/Wi-Fihttp://en.wikipedia.org/wiki/Mobile_phonehttp://en.wikipedia.org/wiki/Weather_radar

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the C-band perform better in comparison with Ku band (11.2 GHz to 14.5 GHz) microwave

frequencies, under adverse weather conditions, which are used by another large set of

communication satellites.[1] The adverse weather conditions all have to do with moisture in theair, such as during rainfalls, thunderstorms, sleet storms, and snowstorms.

3.4.1 C-BAND CLASSIFICATIONS

The NATO C-band

The NATO C-band is that portion of the radio spectrum between 500 megahertz (MHz) and

1000 MHz, but this terminology is rarely used in the two very large NATO members that arelocated inNorth America.

The IEEE C-band

The IEEE C-band is a portion of the electromagnetic spectrum in the microwave range of

frequencies ranging from 4.0 to 8.0 gigahertz (GHz).[2], but this definition is the one that is

followed by radar manufacturers and users, but not necessarily by microwave radiotelecommunications users.

The communications C-band was the first frequency band that was allocated for commercial

telecommunications via satellites. Nearly all C-band communication satellites use the band of

frequencies from 3.7 to 4.2 GHz for their downlinks, and the band of frequencies from5.925 GHz to 6.425 GHz for theiruplinks. Note that by using the band from 3.7 to 4.0 GHz, this

C-band overlaps somewhat into the IEEE S-band for radars.

The C-band communication satellites typically have 24 radio transponders spaced 20 MHz apart,

but with the adjacent transponders on opposite polarizations. Hence, the transponders on thesame polarization are always 40 MHz apart. Of this 40 MHz, each transponder utilizes about

36 MHz. (The unused 8.0 MHz between the pairs of transponders acts as "guard bands" for the

likely case of imperfections in the microwave electronics.)

The C-band is primarily used for open satellite communications, whether for full-time satellite

TV networks or raw satellite feeds, although subscription programming also exists. This use

contrasts with direct broadcast satellite, which is a completely closed system used to deliver

subscription programming to small satellite dishes that are connected with proprietary receivingequipment.

The satellite communications portion of the C-band is highly associated with television receive-

only satellite reception systems, commonly called "big dish" systems, since small receiving

antennas are not optimal for C-band systems. Typical antenna sizes on C-band capable systemsranges from 7.5 to 12 feet (2.5 to 3.5 meters) on consumer satellite dishes, although larger ones

also can be used.

http://en.wikipedia.org/wiki/Ku_bandhttp://en.wikipedia.org/wiki/Ku_bandhttp://en.wikipedia.org/wiki/Ku_bandhttp://en.wikipedia.org/wiki/GHzhttp://en.wikipedia.org/wiki/Communication_satellitehttp://en.wikipedia.org/wiki/C_band#cite_note-0http://en.wikipedia.org/wiki/Thunderstormhttp://en.wikipedia.org/wiki/Radio_spectrumhttp://en.wikipedia.org/wiki/Megahertzhttp://en.wikipedia.org/wiki/North_Americahttp://en.wikipedia.org/wiki/IEEEhttp://en.wikipedia.org/wiki/Microwavehttp://en.wikipedia.org/wiki/Gigahertzhttp://en.wikipedia.org/wiki/C_band#cite_note-1http://en.wikipedia.org/wiki/Radarhttp://en.wikipedia.org/wiki/Telecommunicationshttp://en.wikipedia.org/wiki/GHzhttp://en.wikipedia.org/wiki/Downlinkhttp://en.wikipedia.org/wiki/Uplinkhttp://en.wikipedia.org/wiki/Transpondershttp://en.wikipedia.org/wiki/Polarizationhttp://en.wikipedia.org/wiki/Electronicshttp://en.wikipedia.org/wiki/Cable_televisionhttp://en.wikipedia.org/wiki/Direct_broadcast_satellitehttp://en.wikipedia.org/wiki/Television_receive-onlyhttp://en.wikipedia.org/wiki/Television_receive-onlyhttp://en.wikipedia.org/wiki/Ku_bandhttp://en.wikipedia.org/wiki/GHzhttp://en.wikipedia.org/wiki/Communication_satellitehttp://en.wikipedia.org/wiki/C_band#cite_note-0http://en.wikipedia.org/wiki/Thunderstormhttp://en.wikipedia.org/wiki/Radio_spectrumhttp://en.wikipedia.org/wiki/Megahertzhttp://en.wikipedia.org/wiki/North_Americahttp://en.wikipedia.org/wiki/IEEEhttp://en.wikipedia.org/wiki/Microwavehttp://en.wikipedia.org/wiki/Gigahertzhttp://en.wikipedia.org/wiki/C_band#cite_note-1http://en.wikipedia.org/wiki/Radarhttp://en.wikipedia.org/wiki/Telecommunicationshttp://en.wikipedia.org/wiki/GHzhttp://en.wikipedia.org/wiki/Downlinkhttp://en.wikipedia.org/wiki/Uplinkhttp://en.wikipedia.org/wiki/Transpondershttp://en.wikipedia.org/wiki/Polarizationhttp://en.wikipedia.org/wiki/Electronicshttp://en.wikipedia.org/wiki/Cable_televisionhttp://en.wikipedia.org/wiki/Direct_broadcast_satellitehttp://en.wikipedia.org/wiki/Television_receive-onlyhttp://en.wikipedia.org/wiki/Television_receive-only

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The C-band frequencies of 5.4 GHz band [5.15 to 5.35 GHz, or 5.47 to 5.725 GHz, or 5.725 to

5.875 GHz, depending on the region of the world] is used for IEEE 802.11a Wi-Fi and cordless

telephone applications, leading to occasional interference with some weather radars that are alsoallocated to the C-band.

3.4.2 C-BAND VARIATIONS

Slight variations in the assignments of C-band frequencies have been approved for use in various

parts of the world, depending on their locations in the three International TelecommunicationsUnion radio regions. Note that one region includes all of the Americas; a second includes all of

Europe and Africa, plus all ofRussia, and the third region includes all of Asia outside of Russia,

plus Australia and New Zealand. This latter region is the most populous one, since it includes thePeople's Republic of China, India, Pakistan, Japan, and Southeast Asia.

The Table below shows the variations in C band across various countries of the world

Band Transmit Frequency (GHz) Receive Frequency (GHz)

Standard C-Band 5.8506.425 3.6254.200

Extended C-Band 5.8506.725 3.4004.200

INSAT/Super-Extended C-Band 6.7257.025 4.5004.800

Russian C-Band 5.9756.475 3.6504.150

LMI C-Band 5.72506.025 3.7004.000

3.5 PRINCIPLE OF C-BAND SATELLITE TV RECEPTION

Principle: Satellite television, like other communications relayed by satellite, starts witha transmitting antenna located at an uplink facility. Uplink satellite dishes are very large, asmuch as 9 to 12 meters (30 to 40 feet) in diameter. The increased diameter results in more

accurate aiming and increased signal strength at the satellite. The uplink dish is pointed toward a

http://en.wikipedia.org/wiki/Wi-Fihttp://en.wikipedia.org/wiki/Telephonehttp://en.wikipedia.org/wiki/International_Telecommunications_Unionhttp://en.wikipedia.org/wiki/International_Telecommunications_Unionhttp://en.wikipedia.org/wiki/Europehttp://en.wikipedia.org/wiki/Africahttp://en.wikipedia.org/wiki/Russiahttp://en.wikipedia.org/wiki/Australiahttp://en.wikipedia.org/wiki/New_Zealandhttp://en.wikipedia.org/wiki/People's_Republic_of_Chinahttp://en.wikipedia.org/wiki/Indiahttp://en.wikipedia.org/wiki/Pakistanhttp://en.wikipedia.org/wiki/Japanhttp://en.wikipedia.org/wiki/Southeast_Asiahttp://en.wikipedia.org/wiki/INSAThttp://en.wikipedia.org/wiki/Uplinkhttp://en.wikipedia.org/wiki/Wi-Fihttp://en.wikipedia.org/wiki/Telephonehttp://en.wikipedia.org/wiki/International_Telecommunications_Unionhttp://en.wikipedia.org/wiki/International_Telecommunications_Unionhttp://en.wikipedia.org/wiki/Europehttp://en.wikipedia.org/wiki/Africahttp://en.wikipedia.org/wiki/Russiahttp://en.wikipedia.org/wiki/Australiahttp://en.wikipedia.org/wiki/New_Zealandhttp://en.wikipedia.org/wiki/People's_Republic_of_Chinahttp://en.wikipedia.org/wiki/Indiahttp://en.wikipedia.org/wiki/Pakistanhttp://en.wikipedia.org/wiki/Japanhttp://en.wikipedia.org/wiki/Southeast_Asiahttp://en.wikipedia.org/wiki/INSAThttp://en.wikipedia.org/wiki/Uplink

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specific satellite and the uplinked signals are transmitted within a specific frequency range, so as

to be received by one of the transponders tuned to that frequency range aboard that satellite.

The transponder 'retransmits' the signals back to Earth but at a different frequency band(a process known as translation, used to avoid interference with the uplink signal), typically in

the C-band (48 GHz) or Ku-band (1218 GHz) or both. The leg of the signal path from the

satellite to the receiving Earth station is called the downlink.

The downlinked satellite signal, quite weak after traveling the great distance (see inverse-

square law), is collected by a parabolic receiving dish, which reflects the weak signal to the

dishs focal point. Mounted on brackets at the dish's focal point is a device called a feed horn.

This feed horn is essentially the flared front-end of a section of waveguide that gathers the

signals at or near the focal point and 'conducts' them to a probe or pickup connected to a low-noise block down converteror LNB. The LNB amplifies the relatively weak signals, filters the

block of frequencies in which the satellite TV signals are transmitted, and converts the block offrequencies to a lower frequency range in the L-band range. The evolution of LNBs was one of

necessity and invention. The advantages of using an LNB are that cheaper cable could be used to

connect the indoor receiver with the satellite TV dish and LNB, and that the technology forhandling the signal at L-Band and UHF was far cheaper than that for handling the signal at C-

Band frequencies.

The satellite receiver or [Set-top box] demodulates and converts the signals to the desiredform (outputs for television, audio, data, etc.). Sometimes, the receiver includes the capability tounscramble or decrypt the received signal; the receiver is then called an Integrated

receiver/decoderor IRD.

3.6 C-BAND SATELLITE TV RECEIVER:

The direct C-band reception system compromises of the following:

1) Dish antenna

2) LNB (low-noise block converter)

3) Satellite receiver

http://en.wikipedia.org/wiki/Transponderhttp://en.wikipedia.org/wiki/C_bandhttp://en.wikipedia.org/wiki/Ku_bandhttp://en.wikipedia.org/wiki/Ku_bandhttp://en.wikipedia.org/wiki/Ku_bandhttp://en.wikipedia.org/wiki/Inverse-square_lawhttp://en.wikipedia.org/wiki/Inverse-square_lawhttp://en.wikipedia.org/wiki/Parabolic_reflectorhttp://en.wikipedia.org/wiki/Feedhornhttp://en.wikipedia.org/wiki/Waveguidehttp://en.wikipedia.org/wiki/Low-noise_block_converterhttp://en.wikipedia.org/wiki/Low-noise_block_converterhttp://en.wikipedia.org/wiki/L_bandhttp://en.wikipedia.org/wiki/Scramblerhttp://en.wikipedia.org/wiki/Encryptionhttp://en.wikipedia.org/wiki/Integrated_receiver/decoderhttp://en.wikipedia.org/wiki/Integrated_receiver/decoderhttp://en.wikipedia.org/wiki/Transponderhttp://en.wikipedia.org/wiki/C_bandhttp://en.wikipedia.org/wiki/Ku_bandhttp://en.wikipedia.org/wiki/Inverse-square_lawhttp://en.wikipedia.org/wiki/Inverse-square_lawhttp://en.wikipedia.org/wiki/Parabolic_reflectorhttp://en.wikipedia.org/wiki/Feedhornhttp://en.wikipedia.org/wiki/Waveguidehttp://en.wikipedia.org/wiki/Low-noise_block_converterhttp://en.wikipedia.org/wiki/Low-noise_block_converterhttp://en.wikipedia.org/wiki/L_bandhttp://en.wikipedia.org/wiki/Scramblerhttp://en.wikipedia.org/wiki/Encryptionhttp://en.wikipedia.org/wiki/Integrated_receiver/decoderhttp://en.wikipedia.org/wiki/Integrated_receiver/decoder

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Dish antenna:

A satellite dish is a dish-shaped type ofparabolic antenna designed to receive

microwaves from communications satellites, which transmit data transmissions orbroadcasts, such as satellite television.

There are different types of Dish antenna available in various sizes ranging from 1.8

metres to 4.8 metres. The size of the dish depend on the size of distribution network

and the strength of the signal.

The area where the signal is weak requires a large dish, and vice-versa.

A dish consists of the following parts:

a) The stand or the base structure which supports the entire dish.

b) The parabolic reflector.

c) The electromechanical arrangement to move dish in horizontal and vertical planesto track the satellite.

d) LNB mounting arrangement.

The base structure should be strong enough to withstand the entire load of the

dish. To withstand the windloads during heavy winds or storms, the base structureshould be firmly grounded in the concrete.

The parabolic reflector receives the signals from the satellite and focuses them to

the focal point where the feed horn is positioned. The focused signal picked up by

the feed horn is fed into the LNB, which is mounted on the feed horn itself.

http://en.wikipedia.org/wiki/Dishhttp://en.wikipedia.org/wiki/Parabolic_antennahttp://en.wikipedia.org/wiki/Microwavehttp://en.wikipedia.org/wiki/Communications_satellitehttp://en.wikipedia.org/wiki/Data_transmissionhttp://en.wikipedia.org/wiki/Broadcastinghttp://en.wikipedia.org/wiki/Satellite_televisionhttp://en.wikipedia.org/wiki/Dishhttp://en.wikipedia.org/wiki/Parabolic_antennahttp://en.wikipedia.org/wiki/Microwavehttp://en.wikipedia.org/wiki/Communications_satellitehttp://en.wikipedia.org/wiki/Data_transmissionhttp://en.wikipedia.org/wiki/Broadcastinghttp://en.wikipedia.org/wiki/Satellite_television

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LNB assembly:

The LNB assembly consists of the following three parts: the scalar ring, polarator,

and LNB.

a) The scalar ring: There are 2 types of scalar rings, namely, adjustable andfixed.

(i) Adjustable scalar ring: In this the adjustable ring slides on the feed

horn and can be positioned to suit the focal distance to diameter ratio

(F/d) of the dish.(ii) Fixed scalar ring: Here, the scalar ring is the integral part of the feed

horn and the distance X is fixed.

b) Polarator: Inside the feed horn, there is a probe, which is required to moveaccording to the polarization of the satellite signals.

For large dish assemblies, a motorized polarator is preferred. The motor used

in polarator has 3 terminals: +5V, ground, and pulse.

The motor responds to the width of the pulse supplied by the receiver.

The pulsewidth can be varied from 0.8 to 2.8ms with the help of the trimcontrols in the receiver and the position of the V/H switch. In H position, the

probe can be rotate by almost 140.

c) LNB. The LNB stands for low-noise block converter. LNB comprises asamplifier and a frequency converter. The signals in C-band (3.7 GHz to4.7GHz), which are received and reflected by the dish, are fed to the amplifier

inside LNB via the feed horn probe, as mentioned earlier. The signal to noise

ratio of the amplifier has to be rather good because the received signals arevery weak. The lower the noise, the better will be the picture quality.

3.6.1 C-band receiver

The main function of the receiver is to select a particular channel from theconverted block of frequencies (between 950 and 1450 MHz) and retrieve the

audio and video signal information. The audio and video output signals are finally

fed into the TV monitors audio and video input terminals, respectively.

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If the TV does not have separate audio and video input points, the feed the audio

and video output signals from receiver to an RF modulator which modulates the

RF and provides a modulated VHF RF output (corresponding to anyone of thechannels in the VHF band from channel 2 to channel 12) to operate the domestic

receiver directly.

The block diagram of a satellite receiver is shown in Figure below:

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The coaxial cable from LNB is connected to the tuner (which contains RF and IF modules)

through F socket. To simplify the design for an average constructor, the Mitsumi TSU2-EOIP

tuner is used in the circuit. Pin-out of the tuner are shown in figure below:

The specifications of the tuner are shown in the table II. It is a readymade tuner withtunable range from 950 MHz to 1450 MHz, giving baseband output directly with audio sub-

carrier.

The tuner module is tuned with a voltage (VT) between 0 and 20V and requires no

high/low band switch. It has a terminal for applying the supply voltage for LNB via the downlead, coaxial cable type RG-8 or RG-11. The module itself is fed +12V and +5V DC for its

operation. The complete circuit diagram of the receiver is shown in Figure below:

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The baseband output from the tuner module is fed to the audio stage, video stage, and

signal-strength indication circuit.

Audio section: It consists of three stages: sound intermediate frequency (SIF) stage,sound driver stage, and sound output stage. The audio signal from the baseband output of the

tuner module is separated with the help of an LC tuned wave-trap circuit compromisingcapacitors C1 through C4 and inductors L1 through L3. SIF signal is fed to pin 6 (limiter section)

of IC1 (NE564). The positive DC voltage is fed to pins 1, 3, 9, and 10 of IC1.

Audio IF frequency can be varied by varying the voltage of VCO of the IC. The VCO

voltage is controlled with the help of potmeter VR2, which is connected to pin 13 of IC1 and acts

as an audio IF frequency-controller. Varactor diode D1 (MV2109) is connected across pins 12

and 13 through capacitors C9 and C13.

Audio bandwidth can also be adjusted with the help of potmeter by changing the voltage

at pin 2 (phase comparator section) of IC. Potmeter VR1 generally changes the phase of the

audio signal.

After processing of the audio IF signal, including its amplification and rectification, anAF output is available at pin 14. The audio output is further amplified by transistor amplifiers

built around transistors T1 and T2 (2SC2458), which develop 1V peak to peak audio output

across resistor R16. Potmeter VR3 acts as an audio gain control.

Video section: This is divided into four stages, namely, video amplifier, video detector,video driver, and video-output stage.

Signal from the baseband output of the tuner module is fed via resistor R17 (2.2 K-ohm)

to the base of video amplifier compromising transistor T3 (2SC2458). Capacitor C17 and resistorR19 used to suppress the interference. R20 (1k) id used for emitter bias.

Video signal is taken from the emitter of the transistor T3 and fed to video detector IC2

(NE592) through an LC network comprising of the capacitors C18 through C20 and inductor L4

(a video take-off coil). Pin 1 of IC is takes as reference input and pin 14 is taken as signal input.

A suitable positive bias is given to pin 1 and pin 14 through resistors R22 to R24.

The output is taken from pin 8 of IC (positive video) and fed to the video driver as well

as the output stage comprising transistors T4 and T5. After amplification of video signal, 1V

peak to peak video output is taken from the emitter of transistor T5 through capacitor C25 and

resistor R29. Potmeter VR4 (4.7k) is a video gain control, which is used to adjust the contrast ofthe picture.

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CHAPTER-4

CONCLUSION AND FUTURE SCOPE

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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 desireinformation communication, education and entertainment at the

click of a button.

1. Broadband noise will have negligible effect on GMRT

Observations, as the minimum 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 GMR

Also the DBS-TV systems operate with small antennas and low cost receiving systems, and offer

a very large number of video and audio channels, making them attractive to customers.

Delivery of bit stream through direct broadcast satellite could be adapted to allow to serve

Internet users who requires to download larger blocks of data.

A simple digital-TV architecture would include a receiver section for digital-terrestrial signals.

Digital-TV standards bodies have developed specifications, such as the ATSC (AdvancedTelevision Systems Committee) A/74, that receivers must meet to provide good reception of the

new digital-TV signals. Generally, the digital-terrestrial-TV receivers have a better noise figure,

overall gain, selectivity, linearity, and AGC range and response than their analog counterparts.Digital-tuner modules offer these specifications.

However, most early hybrid analog/digital-TV designs used two tuner modulesone for

receiving analog signals and the other for receiving digital signals. This approach increased the

cost, size, and power consumption of the designs. On the other hand, it also allowed designers to

include additional filtering, amplification, or both to either the digital or the analog tuner to

further increase performance.

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Most digital TVs also included two threaded, F-type RF connectors with analog, digital,

air, and cable labels. To keep up with flat-panel TV screens, TV developers must work withconstantly shrinking PCBs (printed-circuitboards). A hybrid tuner and RF switch provide dual

inputs with a single tuner module. More recently, designers have developed hybrid

analog/digital-capable tuner modules.

These new designs provide the performance for DTV and meet the demanding requirements of

TV manufacturers for analog-terrestrial and cable reception. New TV designs employ thesemodules, sometimes with an RF switch so that dual input connectors could still be available at

the back of the TV.

In some cases, the TV manufacturer adds application-specific gain or filtering between the tunermodule and the connector to enhance the receiver performance.

These types of designs frequently include low-noise amplifiers that provide additional gain to

achieve better sensitivity when the system is operating in digital mode.

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References:

The digital satellite TV handbook by Mark E Long.

Satellite Technology: Principles and Applications by Anil.K.Maini, Varsha Agrawal

Consumer Electronics by J.S Chitode

http://books.google.com/books?id=L4yQ0iztvQEC&pg=PA140&dq=c-band+satellite+tv+receiver&hl=en&ei=TxHmTInzOY-MvQPy9vXCCA&sa=X&oi=book_result&ct=result&resnum=2&ved=0CDYQ6AEwAQhttp://books.google.com/books?id=L4yQ0iztvQEC&pg=PA140&dq=c-band+satellite+tv+receiver&hl=en&ei=TxHmTInzOY-MvQPy9vXCCA&sa=X&oi=book_result&ct=result&resnum=2&ved=0CDYQ6AEwAQhttp://books.google.com/books?id=L4yQ0iztvQEC&pg=PA140&dq=c-band+satellite+tv+receiver&hl=en&ei=TxHmTInzOY-MvQPy9vXCCA&sa=X&oi=book_result&ct=result&resnum=2&ved=0CDYQ6AEwAQhttp://books.google.com/books?id=gUHJoAgcncUC&pg=PA392&dq=c-band+satellite+tv+receiver&hl=en&ei=TxHmTInzOY-MvQPy9vXCCA&sa=X&oi=book_result&ct=result&resnum=5&ved=0CEUQ6AEwBAhttp://books.google.com/books?id=gUHJoAgcncUC&pg=PA392&dq=c-band+satellite+tv+receiver&hl=en&ei=TxHmTInzOY-MvQPy9vXCCA&sa=X&oi=book_result&ct=result&resnum=5&ved=0CEUQ6AEwBAhttp://books.google.com/books?id=1UPYEpzTnuoC&pg=PA106&dq=c-band+satellite+tv+receiver&hl=en&ei=4RHmTJWsJ466vwPj1eTCCA&sa=X&oi=book_result&ct=result&resnum=1&ved=0CCoQ6AEwADgUhttp://books.google.com/books?id=L4yQ0iztvQEC&pg=PA140&dq=c-band+satellite+tv+receiver&hl=en&ei=TxHmTInzOY-MvQPy9vXCCA&sa=X&oi=book_result&ct=result&resnum=2&ved=0CDYQ6AEwAQhttp://books.google.com/books?id=gUHJoAgcncUC&pg=PA392&dq=c-band+satellite+tv+receiver&hl=en&ei=TxHmTInzOY-MvQPy9vXCCA&sa=X&oi=book_result&ct=result&resnum=5&ved=0CEUQ6AEwBAhttp://books.google.com/books?id=1UPYEpzTnuoC&pg=PA106&dq=c-band+satellite+tv+receiver&hl=en&ei=4RHmTJWsJ466vwPj1eTCCA&sa=X&oi=book_result&ct=result&resnum=1&ved=0CCoQ6AEwADgU