-Satellite Communication - 6

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Satellite CommunicationSatellite CommunicationLecture 6Lecture 6

Direct-to-Home Satellite Television

Broadcasting and S-DARS

http://web.uettaxila.edu.pk/CMS/teSCms/http://web.uettaxila.edu.pk/CMS/teSCms/


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OverviewOverview I

ntroduction DTH Systems

DTH Systems Architecture Basic Elements of DTH System and Signal FlowBasic Elements of DTH System and Signal Flow Compression System ArrangementCompression System Arrangement DTH ConsiderationsDTH Considerations

DTH Systems around the worldDTH Systems around the world DTH Service SatellitesDTH Service Satellites

Satellite Digital Audio Radio Service Satellite Radio Broadcast Concept SS--DARS ArchitectureDARS Architecture

WorldSpace Sirius Satellite RadioSirius Satellite Radio XM Satellite RadioXM Satellite Radio Issues and Opportunities related to SIssues and Opportunities related to S--DARSDARS


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IntroductionIntroduction

DTH systems are designed to transmitentertainment TV programming to home-receivingEarth terminals (or, simply, home receivers).

This is a natural extension of TV distribution by

satellite, utilizing the area-coverage and singleservice provider features of the technology.

DTH systems, also called Direct BroadcastSatellite, employ either the BSS allocations, whichare intended for this use, or the FSS allocations as

one of a number of possible applications. This choice has some important implications, yet

the end result is the same to the user


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Introduction (contd.)Introduction (contd.)

We focus on the nature of DTH services and the variousfactors that must be addressed to assure a successfulintroduction of these services: The programming mix, for example, the quantity, variety,

language options, and degree of interactivity, must competewith other DTH systems and delivery mechanisms (e.g., cable

TV, AM and FM radio, audio CDs, Internet delivered MP3 files,cassette and DVD rental);

Receiving equipment - its affordability, convenience ofinstallation and use, integration with other video and audiodevices, and aesthetics;

Acceptability of the service price and an effective means tocollect payment;

Incompatibilities with the other DTH, radio, and cable TVsystems, which are dependent on the nature of the businessplan;

Conditional access and scrambling in order to deal withcopyrights, privacy, collection, regulations, and content rules(which may exist in the country markets of interest);

Uplinking system, including redundancy, strength, programdevelopment and contribution facilities.


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DTH SystemsDTH Systems

Experience with DTH systems has shownthat the service must be attractive ascompared to other forms of videodistribution;

and access to the programming by theconsumer must be properly controlled. The competition between delivery media is

highly variable between countries. e.g.there is more intense competition in US

while much lesser in UK and Japan The major elements of a DTH system are

shown in Figure 6.1.


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DTH Systems ArchitectureDTH Systems Architecture


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DTH System ArchitectureDTH System Architecture

We briefly summarize the overallarchitecture of a DTH program deliverysystem such as that used for commercialpurposes.

It encompasses the uplink systems fordigitizing, compressing, and transmittingmultiple television programs using theDVB-S standard, for example.

Other elements are required for thecontribution of the programs, storage andswitching of video signals, and themanagement of DTH as a customer service.


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Basic Elements ofDTH System andBasic Elements ofDTH System andSignal FlowSignal Flow

The major elements of DTH system arelisted as follows as indicated in Figure 6.1: DTH satellites in GEO (one or more):

Spacecraft construction;

Launch services; Launch and on-orbit insurance.

TT&C: Controls the space segment and monitors spacecraft

health; Verifies that transmissions to satellite do not cause

interference; Provided by satellite operator (usually a separate

company); Limited communication required between DTH network

operator and satellite operator.


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Broadcast center: Originates, acquires, and transmits program

material;

Generally centralized, with no or limitedbackup;

Part of conditional access system.

Customer service:

Billing and customer turn-on-off; Customer assistance.


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These are the major elements, and thereare many vital components and functionshidden within each.

For example, customer service is involved

with connecting and controlling individualsubscribers. However, how they obtain their equipment

in the first place and have it installed hasturned into an industry all its own.

Ownership and operation of the satellitescan be internal or taken as a service from aprofessional satellite operator.


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A more detailed configuration of the operatingcomponents is presented in Figure 6.3.

At the top of the diagram we find the servicemanagement functions of the network.

These manage the interaction with the customerover the telephone and Internet, and provide themeans to download PPV movie selections on amonthly basis.

It also ties into the CA segment, which authorizesindividual IRDs over the space segment.

The technical functions at the bottom of thediagram show the physical production andtransmission facilities, from content input throughbaseband processing and on up to the satellite.


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The basic arrangement of the uplinkcompression-encoding-modulationchain and downlink demodulation-

decoding-decompression chain ispresented in Figure 6.4.


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Basic Elements ofDTH System and SignalBasic Elements ofDTH System and SignalFlow:Flow: Compression System Arrangement


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The uplink compression elements arecontained within the broadcast center Earthstation such as that shown in Figure 6.5 forDIRECTV.

This includes equipment that digitizes andtime division multiplexes the video, audio,and data information.

In large networks, between 5 and 12 video

channels and their associated audio anddata are combined using TDM onto a singlecarrier that would occupy the entiretransponder bandwidth.


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The compression systems themselvesfall into two categories: (1) those that comply with a standard,

particularly MPEG 2 or DVB-S (whichincludes MPEG 2 as a component); or

(2) those that use a proprietaryalgorithm and multiplexing scheme.

Systems that started out in category(2) are quickly moving to MPEG 2because of the rapidly decreasing costof the receiving equipment.


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DTH ConsiderationsDTH Considerations

DTH is a delivery vehicle forprogramming, where the receiver islocated with and probably owned by

the end user. In the ideal case, specifics like the

type of receiver, size of antenna,

signal format, and satellite design aresecondary.


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The emphasis should be on making it easyand relatively inexpensive for thesubscriber, since their interest is in the

programming and the cost of gettingaccess to it.

The quality of satellite-delivered digitalvideo is as good as or superior to cable or

over-the-air broadcasting; hence, thepicture quality will probably not be adifferentiating factor.


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The area where quality is seen as anegative is at C-band where users have tocontend with terrestrial interference.

Ku-band systems, while generally free fromterrestrial interference, are subject to rainfade, which produces occasional outages.

Once this problem is solved through

adequate link design and margin,subscribers will next be drawn by adesirable array of programming.


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The Asian environment has many opportunitiesbecause of the primitive nature of the DTHindustry in the region.

Cable TV is a viable business in developedcountries and city-states; China, India, and

Indonesia have large populations that are hungryfor more and better entertainment. China now has a DTH platform operating on

Sinosat. Importantly, money flows easily into major

projects and business ventures. This has fueled the creation of several new

satellite operators and the development of thelargest satellite market in the world.


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DTH Systems around the worldDTH Systems around the world


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DTH Service SatellitesDTH Service Satellites


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Satellite Digital Audio Radio Service

S-DARS systems deliver a multiplexedcombination of several audio programchannels transmitted directly to automobile

receivers, portable radios, and homes usingspecial frequency allocations in the regionof L- and S-bands.

S-DARS overcomes the range limitation of

terrestrial FM radio broadcasting andprovides quality of sound comparable toother digital formats such as MP3 andpossibly CD.


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Satellite Digital Audio Radio Service

Satellites have been used to deliver audio programming fordecades, but these systems were directed toward fixedinstallations at radio stations and commercial buildings.

Additionally, DTH systems typically include a package ofmusic channels that can be played through the TV set.

What sets the new S-DARS apart is that it provides coverageto automobiles and portable radios, and offers some uniqueprogram formats not popular enough to sustain themselvesas commercial operations.

Thus, we have a new generation of direct broadcastingservices to provide universal coverage of radio-like servicesto the general public.

Begun in Africa as a free, advertiser-supported service byWorldSpace, S-DARS has been propelled into a potentiallymajor satellite business for subscribers who are willing topay a monthly fee (e.g., pay radio) akin to what is alreadystandard for cable and DTH TV (e.g., pay TV).


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Satellite Radio Broadcast Concept

Satellite radio broadcasting is not so different from TVprogram distribution and in fact shares many of the sameprinciples and components.

First use of dedicated satellite audio was by Muzak, acompany that delivered elevator music in the 1970s andmoved from tape to satellite.

Subsequently, all DTH TV operators included digital versionsof such service as part of their programming content throughthe facilities of Music Choice.

Another form was the private radio broadcast to chains ofretail stores, pioneered by Supermarket Radio Network.

But it was not until Noah Samara created WorldSpace that S-

DARS really got its start. The concept is indicated in Figure 7.1, where a broadcast

center obtains audio content from a variety of sources: tape,local studio, audio CD, and existing radio stations andnetworks.


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SS--DARS ArchitectureDARS Architecture


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SS--DARS ArchitectureDARS Architecture

The actual broadcast transmission isfairly standard, as in TV, usinganalog-to-digital conversion,

compression appropriate to thecontent, forward error correction,modulation, and RF amplification.

The satellite to be used may be a

bent-pipe design with sufficient EIRPto allow the use of portable orvehicular receivers.


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First Introduction of S-DARSWorldSpace

WorldSpace was founded in 1990 and represents aninteresting startup venture in the commercial satelliteindustry.

Initial financial support made it possible for WorldSpace tobuild and launch satellites under contracts placed with Alcateland other major companies.

The WorldSpace system was the first S-DARS system andtherefore was the innovator in applying L-band spectrum toaudio broadcasting.

Of critical importance are the size of the coverage areas inrelation to the cost of the satellites, advanced low bit rateaudio coding, and simple satellite uplinking arrangements.

However, WorldSpace is less suitable for mobile receptionthan XM or Sirius because of low elevation angles in someareas served.

Without any form of diversity, signal fades and dropoutsmake reception extremely problematic in moving vehicles.


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Sirius Satellite RadioSirius Satellite Radio

Sirius Satellite Radio is a commercial radio broadcastingcompany, publicly traded and headquartered in the heart ofNew York City.

Both Sirius and XM provide a programming package within atotal of about 5 Mbps comprising 100 total audio channels,half of which are music formats and half of which are talk

radio. Using advanced digital recording systems, the music may be

assembled off-line for later playback and without advertising.

The talk formats include standard services like Fox NewsChannel and CNN along with a variety of shows to appealacross a spectrum of interests.

Talk channels that are taken from existing program sourcesmay include advertising.

Sirius has assembled a large suite of studios and editingfacilities in New York to allow them to originate a substantialnumber of the audio channels.


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XM Satellite RadioXM Satellite Radio

XM Satellite Radio was first to market in the United States,providing a comparable programming package to Sirius butusing the standard GEO satellite approach.

The two high-power Boeing 702 S-DARS satellites, namedRock and Roll, were launched on March 18, 2001, and May 8,2001, by Boeing.

Positioned at 115 W and 85 W, respectively, Rock and Rolleach transmit two carriers (total of four for the system) thatcontain half of the channels each.

Due to elevation angle constraints of using GEO, there are amultitude of terrestrial repeaters throughout the UnitedStates.

Unlike Sirius, delivery of the broadcast channels to therepeaters is accomplished using the X-band downlink fromRock and Roll.

The exact same content is transmitted three times in threedifferent signals: once on each of two satellites and a thirdtime by repeaters.


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Issues and Opportunities related toIssues and Opportunities related toSS--DARSDARS

Satellite-based S-DARS has many advantages inthe market, some of which are apparent and someof which are underlying.

From a practical perspective, services like XM andSirius offer more audio programming options than

one can possibly receive by AM/FM radio at anygiven time. Coupled with this is the added feature that the

same channel complement is available throughoutthe country according to a constant name andnumber assignment.

Audio quality is comparable to clear FM receptionand the radios have the added feature ofdisplaying the channel number and specific piecebeing played.

Perhaps the biggest issue in front of S-DARS is

that a subscription fee seems to be needed tooffset the costs of operation and programming.


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There are risks in this market, asmany such projects failed.

Becoming a mainstream service takenby millions of paying subscribers isstill only an expectation at best ordream at worst.

Today, there are about 20 million DTHService subscribers in the UnitedStates.


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The true potential of S-DARS lies in the need to change theattitude of the radio listener, who is now accustomed to freeservice (supported through a continuous stream ofadvertising or requests for donations).

Being able to get the specific channels that interest you,possibly without commercial interruption, represents a new

kind of market that at times seems a luxury. Consider, for example, that people in the United States are

willing to pay more for bottled water than for gasoline.

The nominal $10 per month charge for S-DARS would not setmany people back and in fact is well below the threshold of$50 one associates with new services like DSL and thepricey subscription packages on DTH.

If equipment costs are to be reduced to around $100 (orprovided nearly free as an already installed feature in newautomobiles), the subscriber take-up would accelerate.


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DTH stands for DIRECT-TO-HOMEtelevision.DTH is defined as:Thereception of satellite programmers

with a personal dish inan individualhome.DTH does away with the needfor the local cable operator andputsthe broadcaster directly in touch withconsumer .


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