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ACKNOWLEDGEMENT

ABSTRACT

Satellites are one of the greatest achievements of manind! They

have been used for various applications lie communication" military

application" #eather forecasting and so on! They play a big role in the case

of television channels and other entertainment net#ors! One of the latest

applications of satellites is the satellite radio!

Satellite radio is a subscriber based radio service that broadcast

directly from satellites! It is an advanced form of mobile radio service #here

one can receive compact disc quality music and other entertainmentchannels! Even if the person is miles a#ay from the radio station" the quality

of the program is not affected! The paper deals #ith the basic structure of the

satellite radio and its transmission and reception procedures!

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CONTENTS

$! I%TRO'CTIO% $

(! B)SIC CO*+O%E%TS O, S)TE--ITE R)IO .

(!$! S)TE--ITES /

(!$$ 0* Satellite radio /

(!$( Sirius Satellite radio 1

(!$. 2orld space Satellite radio 3

(!(! 4RO'% RE+E)TERS 5

(!.! R)IO RECEI6ETRS 7

. TR)%S*ISSIO% )% RECE+TIO% $(

.!$ 4eneration of )B signal $.

.!( Reception of )B signal $/

.!. ,requency of operation $1

.!/ *ultipath interference $1

/ S)TE--ITE R)IO 6S! OT8ER ,OR*)TS $3

1 )6)%T)4ES O6ER )%)-O4 R)IO $7

3 CO%C-'SIO% (9

: BIB-IO4R)+8; ($S)TE--ITE R)IO $

1. INTRODUCTION

2e all have our favorite radio stations that #e preset into our car

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radios" flipping bet#een them as #e

drive to and from #or" on errands

and around to#n! But #hen travel too

far a#ay from the source station" thesignal breas up and fades into static!

*ost radio signals can only travel

about .9 or /9 miles from their source!

On long trips that find you passing

through different cities" you might

have to change radio stations every

hour or so as the signals fade in and

out!

%o#" imagine a radio station

that can broadcast its signal from more

than (("999 miles

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selected marets! follo#ed by full nation#ide service in %ovember! Sirius

lagged slightly" #ith a gradual rollout beginning n ,ebruary" including a

quiet launch in the Bay )rea on Dune $1! The nation#ide launch comes Duly $!

To the average user" these systems #ill loo very similar to

conventional )*,* !radio systems" #hether they are used in the home"

office" or on the road! 8o#ever! the real difference is in #hat the listener

#onFt see! Rather than receiving a signal from a to#er antenna of a local radio

station" these ne# radios #ill receive signals from a set of satellites in

geosynchronous orbit! +rogramming #ill be up lined from ground stations to

the satellites and then broadcast bac to large geographic areas!

The programming #ill be up lined to the three geostationary orbit

satellites and then rebroadcast directly to radios in the vehicles of C Radio

subscribers! 4round based repeaters #ill be used in urban areas to provide a

clear and uninterrupted radio signal!

,ig! $ The satellite station

S)TE--ITE R)IO .

2. BASIC COMPONENTS O SATELLITE RADIO

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Each company has a different plan for its broadcasting system" but the

systems do share similarities! 8ere are the ey components of the three

satellite radio systemsG

SATELLITES

GROUND REPEATERS

RADIO RECEI!ERS

)t this time" there are three space@based radio broadcasters in variousstages of developmentG

XM Satellite Radio launched commercial service in limited areas of the

'nitedStates on September (1" (99$!

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radio companiesF systems! In the neAt three sections" #e #ill profile each of

the companies offering satellite radio services!

2.1 SATELLITES

2.1.1 XM SATELLITE RADIO

0* Radio uses t#o Boeing 8S :9( satellites" appropriately dubbed

>Roc> and >Roll"> placed in parallel geostationary orbit" one at 51 degrees

#est longitude and the other at $$1 degrees #est longitude! 4eostationary

Earth orbit (GED)is about ((!((. miles #as launched on *arch 18.(99$" #ith >Roll> follo#ing on

*ay 5! 0* Radio has a third 8S@:9( satellite on the ground ready to be

launched in case one of the t#o orbiting satellites fails!

0* RadioFs ground station transmits a signal to its t#o 4E satellites!2hich bounce the signals bac do#n to radio receiver son the ground! and the

do#nlin #ill be in the (!..@(!./ 48? frequency range! ) spare satellite #ill

be ept on the ground for emergencies! The radio receivers are programmed to

receive and unscramble the digital data signal" #hich contains up to $99

channels of digital audio! In addition to the encoded sound" the signal contains

additional information about the broadcast! The song title" artist and genre of

music are all displayed on the radio! In urban areas" #here buildings can bloc

out the satellite signal" ground transmitters supplement 0*Fs broadcasting

system!

S)TE--ITE R)IO 1

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2.1.2 SIRIUS SATELLITE RADIO

'nlie 0*" Sirius does not use OE satellites! Instead" its three SS-@

$.99 satellites form an inclined elliptical satellite constellation! Sirius says the

elliptical path of its satellite constellation ensures that each satellite spends

about $3 hours a day over the continental 'nited States " #ith at least one

satellite over the country at all times! Sirius completed its three@satellite

constellation on %ovember .9" 2000.) fourth satellite #ill remain on the

ground" ready to be launched if any of the three active satellites encounter

transmission problems!

The Sirius system is similar to that of 0*! +rograms are beamed to one

of the three Sirius satellites" #hich then transmit the signal to the ground

#here the radio receiver pics up one of the channels #ithin the signal!

Signals are also be beamed to ground repeaters for listeners in urban areas

wherethe satellite signal@can be interrupted!

2hile 0* offers both car and portable radios" Sirius is concentrating

on the car radio maret! The Sirius receiver includes t#o parts @@ the antenna

module and the receiver module! The antenna module pics up signals from

the ground repeaters or the satellite! )mplifies the signal and filters out any

interference! The signal is then passed on to the receiver module! Inside the

receiver module is a chipset consisting of eight chips! The chip set converts

the signals from (!. gigahert?

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S)TE--ITE R)IO 3

2.1.3 WORLDSPACE

So far" 2orldSpace has been the leader in the satellite radio industry! It

put t#o or its three satellites" )friStar and )siaStar" in geostationary orbit

before either of the other t#o companies launched one! )friStar and )siaStar

#ere launched in October $775 and *arch (999" respectively! )meriStar"

#hich #ill offer service to South )merica and parts of *eAico" is not yet

scheduled for launch! Each satellite transmits three signal beams carrying

more than /9 channels of programming" to three overlapping coverage areas

or about 1!/ million square miles

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2orIdSpace broadcasters uplin their signal to one of the three satellites

through a centrali?ed hub site or an individual feeder lin station located #ithin

the global uplin beam! The satellite then transmits the signal in one" t#o or all

three beams on each satellite! Receivers on the ground then pic up the signal

S)TE--ITE R)IO 5

and provide C@quality sound through a detachable antenna!

,ig! . 2orld space integrated solution

2.2 GROUND REPEATERS

Satellite radio reception" poses threatsfrom#eather" tall building and

mountains that can potentially interfere #ith broadcasts!

To avoid the interference caused by tall structures" both Sirius and 0*

Radio are supplementing their satellite coverage #ith terrestrial transmitters"

called ground repeaters! If the satellite radio antenna is bloced by a

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fist@si?ed antenna that sits on the roof or trun lid!

The receiving end is virtually the same for both companies" but the

satellite configurations are differentG 0* Radio #ill use t#o satellites" and

Sirius #ill use a combination three! These receivers" some#hat ain to

)*,* tuners" are made up of t#o partsG an >active> antenna and a receiving

module!

S)TE--ITE R)IO $9

0* and Sirius Radio #ill #or similarly! Each #ill beam a

combination of original and syndicated programming to orbiting

communications and terrestrial satellites #hich #ill send out signals to the

satellite radio receivers! These receivers" some#hat ain to )*,* tuners"

are made up of t#o partsG an >active> antenna and a receiving module!

The antenna is active because it basically loos for available signals topic up from! Satellites it recogni?es! 2hen it finds them" it amplifies them"

filters out any accompanying noise and interference" and then sends them to

the receiver" #here most of the real #or is done! En route to the receiver" the

signals are converted from analog to digital! Once in the digital realm" they

are analy?ed for quality" and then processed and combined to produce the best

digital >image> of the sound! The receiver also decrypts the signals and finally

converts them bac to analog audio" #hich can be sent to the radioF s speaers

so one can hear it!

The receiver connects to your eAisting car radio through a device called

an ,* modulator that puts the signal on an unused portion of the ,* band!

Or you can buy a car radio @@ called a >head unit> by industry insiders @@ thatFs

>satellite ready> to mae a direct #ired connection for maAimum audio

quality!

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On the open road" the receivers pic up a signal from orbiting

satellites! Sirius and 0* have also built repeater stations on the ground in

maor metropolitan areas to maintain reception #hen the satellites are bloced

by buildings or other large structures!

S)TE--ITE R)IO $$

One receiver utili?es a vehicles eAisting ,* radio! ) small flat (> dis

antenna is attached to the outside of the vehicle" a processing unit is placed in

the trun or dashboard and a display and control screen mounted neAt to the

vehicleFs ,* radio! The display screen indicates the selected channel number"

channel name" song title and artist!

Each receiver contains a proprietary chipset! 0* began delivering

chipsets to its 0* radio@manufacturing partners in October (999! The chipset

consists of t#o custom integrated circuits designed by ST *icroelectronics!

0* has partnered #ith +ioneer! )lpine" Clarion" elphi eleo" Sony and

*otorola to manufacture 0* car radios! Each satellite radio receiver uses a

small" car@phone@si?ed antenna to receive the 0* signal! 4eneral *otors has

invested about $100million in 0*" and 8onda has also signed an agreement

to use 0* radios in its cars! O* began installing 0* satellite radio receivers

in selected models in early (99$!

2orldSpace satellite receivers are capable of receiving data at a rate of

$(5 ilobits per second

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S)TE--ITE R)IO $(

". TRANSMISSION AND RECEPTION

igital radio #ors by combining t#o digital technologies to produce

an efficient and reliable radio broadcast system!

,irstly" an audio compression system" called *+E4" reduces the vast

amount of digital information required to be broadcast! It does this by

discarding sounds that #ill not be perceived by the listener @ for eAample"

very quiet sounds that are mased by other louder sounds @ and hence not

required to be broadcast" and efficiently pacages together the remaining

information!

The second technology" CO,*

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disturbed for a short period of time" the receiver is still able to recover the

original sound!

The interference #hich disturbs ,* reception" caused by radio signals

>bouncing> off buildings and hills

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,igure .!( demonstrates a )B receiver! The )B ensemble is

selected in the analogue tuner" the digiti?ed output of #hich is fed to the

O,* demodulator and channel decoder to eliminate transmission errors!

The information contained in the ,IC is passed to the user interface forservice selection and is used to setup the receiver appropriately! The *SC

data is further processed in an audio decoder to produce the left and right

audio signals or in a data decoder

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igital radio is operated in a frequency range of bet#een ($1 @ (.9

*8?

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channels are #ill have Ds!advertisement@ 'sually no

free because of advertisementsthe paid

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%onprofit stations and public radio net#ors such as CBCRadio@

Canada" %+R" and +RI@affiliated stations and the BBC are commercial@free!

In the 'S" all stations are required to have periodic station identifications and

public service announcements!

In the 'nited States" the ,CC regulates technical broadcast spectrum

only! +rogram content is unregulated! 8o#ever" the ,CC has tried in the past

to eApand its reach to regulate content to satellite radio and cable television"

and its options are still open to attempt such in the future! The ,CC does issue

licenses to both satellite radio providers

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broadcast!

)s #ell -unlie )* and ,* @ digital radio reception is virtually

immune to interference" #hich means there are no static gro#ls or Fmulti pathF

echoes

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,or the listener" digital radio #ill be more than ust Fthe best sound on

the air#avesF" it #ill be an intelligent communications device that #ill offer

more services and conveniences than can be provided by conventional analog

technology!

,or the broadcaster" digital radio is not ust a #ay to stay competitive

#ith other forms of digital sound" but one that offers numerous ne# business

opportunities as #ell!

It is a bright future for listeners and broadcasters alieG a future thattruly promises to provide Fthe best sound on the air#avesF for the #orld!

S)TE--ITE R)IO ($

7. BIBLIOGRAP#%

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1. ! +rabaaran" N2OR- S+)CE@ Satellite digital audio broadcast

service! Electronics ,or ;ou! %ov (99$" 6olume .." %oG$$!