sat com ppt

8/9/2019 sat com ppt

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By Rajendra

Kumawathttp://powerpointpresentationon.blogspot.com

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Satellite

Communication


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•What is satellite?

•Satellite is a repeater in thesky.

•Receives uplink re!uencies an" translates to

"ownlink

re!uencies an" transmits back to the earth station

ater

ampliication

•#he translation is "one to avoi" $ve ee"back.#rying to

receive an" transmit an ampliie" version o the same

uplink waveorm at the same satellite will cause

unwante" ee"back% or ring aroun"% rom the "ownlink

antenna back into the receiver


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What is a communications satellite and how does it

work?

& communications satellite is a ra"io relay station in orbit above the earth that

receives% ampliies% an" re"irects analog an" "igital signals carrie" on a speciic

ra"io re!uency.

'n a""ition to communications satellites.

'n satcom the satellite acts as a me"ia or the "ata transer between the source an"

"estination.

Between the source an" "estination we use a pair o re!uencies to communicate.

#he Satellite acts as a re!uency translator an" ampliier.


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What are the different kinds of orbits?

&n orbit is the path that a satellite ollows as it revolves aroun" (arth. 'n terms o

commercial satellites% there are three main categories o orbits:

•)**+,%*** km above the earth

•#hese orbits are much closer to the (arth% re!uiring satellites to travel at a veryhigh spee" in

or"er to avoi" being pulle" out o orbit by (arth-s gravity

• &t (% a satellite can circle the (arth in appro0imately one an" a hal hours

•LEO( Low Earth Orbit)


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•MEO( Medium EarthOrbit)

•1%***+,*%*** km above the earth•#hese orbits are primarily reserve" or communications satellites that cover the

2orth an"

South 3ole

•4(-s are place" in an elliptical 5oval+shape"6 orbit


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•GEO 5 GeosnchronousOrbit)•7)%819 km above the earth

•rbiting at the height o ,,%,1, miles above the e!uator 57)%819 km6% thesatellite

travels in the same "irection an" at the same spee" as the (arth-s rotation on its

a0is%

taking , hours to complete a ull trip aroun" the globe. #hus% as long as a

satellite is

positione" over the e!uator in an assigne" orbital location% it will appear to be

;stationary; with respect to a speciic location on the (arth.

• & single geostationary satellite can view appro0imately one thir" o the(arth-s surace.

' three satellites are place" at the proper longitu"e% the height o this orbit allows

almost all o the (arth-s surace to be covere" by the satellites.


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!olar Orbitin"

#atellite

•#hese satellites orbit the earth in such a way as to cover the north an" southpolar regions.

•#hese satellites i in a low earth orbit have to travel at a very high spee".

•#hese satellites can be kept in low earth orbit 51** +


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Geo$#nchronous

#atellite•rbit on the e!uatorial plane + appears stationary

• &ltitu"e o 79*** =ms.

•Circular orbit aroun" earth with perio" o , hours.

•Coverage o about >/7 o (arth.

•, "eg. apart. '"entiie" by ongitu"inal position with re. toreenwich.

%d&anta"e Of Geostationar

#atellite •Simple groun" station trackingre!uirements.

•Removes Satellite han"+overproblems.

•2egligible @oppler shit


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• & "isa"vantage o eostationary satellites is that points on (arthbeyon" about 1* "eg latitu"e are not visible.

• 'ncline" orbits% on the other han" can provi"e visibility to thehigher

northern an" southern latitu"es% although they re!uire earth stations

to continually track the satellite.

'nclined Orbit#atellite


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•eosynchronous

•#ranspon"er

•Aootprint

•Are!uency

•3olariation

•3ath 3ropagation

•#iming

•Satellite &ccess

•ink 3erormance

echnical

erm


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Geosnchronous

eosynchronous means that the satellite is synchronie" with the earth in time an"

"irection. 't means that is time taken by a satellite to complete its orbit aroun" earth is

e!ual to the time taken by to earth rotates aroun" its own a0is.

ransonder

Are!uency ban" on the satellite is "ivi"e" into several channels. (ach channels are

calle" transpon"er (ach transpon"er have * 4.

#atellite *ootrint

Coverage o entire surace o earth that is visible by the

satellite.


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*re+uenc

,and

Ran"e

+Ban" > to >.)

S+Ban" > to 7.<

C+Ban" 7.< to 1

D+Ban" 1 to >,.)

=u+Ban" >*.1

=+Ban" >1 to ,9.)

=a+Ban" ,9.) to *

*re+uenc ,ands use in #atellite

-ommunication


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%d&anta"es %nd .isad&anta"es of .ifferent *re+uenc

,and

-$,and

&"v. : Broa" Aootprint% little rain a"e

@isa"v. : Weak signals% intererence% large antenna sies

an" ampliiers

E/-$,and &"v.. : Broa" Aootprint% little rain a"e% less intererence

@isa"v. : Week signals% large antenna sies an" ampliiers

Ku$,and

&"v. : Aocuse" Aoot prints% no terrestrial intererence

small antenna an" ampliier @isa"v. : 'ntererence to rain.

Ka$,and

&"v. : Aocuse" Aoot prints% large unuse"

ban"wi"ths

@isa"v. : 'ntererence to rain.


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*RE01E

2-3

,%2.

1!L'2K .OW2L'

2K

C+Ban" )..**+

>.)*

>*.,.8)

=a+Ban" 7*.** ,*.**

#atellites 1link %nd .ownlink *re+uenc in .ifferent

,ands

EE all re!uencies are in.


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4#% echnolo" in #atellite -ommunication

•FS stan"s or Fery Small &perture #erminal

• 't is a two way satellite groun" station.

•FSs are most commonly use" to transmit narrowban" "ata orbroa"ban" "ata.

•FSs access satellites in geosynchronous orbit to relay "ata romsmall remote

earth stations 5terminals6 to other terminals or master earth station ;hubsG.


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Remote FS

> Remote FS

,

Earth #tation

(51,)

Hplink@ownlin

k

#atellit

e

#atellite

Link


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Mesh oolo"

•(ach FS terminal relays "ata via satellite to another terminal by acting asa hub% minimiing the nee" or a centralie" uplink site.

•FSs are comparatively larger as they have to communicate "irectly witheach other

•FSIs communicate "irectly with each other% ub will be involve" only orcall

setup an" then a"e out.5 ub will not be involve" in permanent Circuits6


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!arts Of

4#%s

• &ntenna

•Block Hp Converter 5BHC6

•ow 2oise Block Converter52B6

•rthomo"e #rans"ucer54#6

• 'nteracility ink Cable 5'A6

• 'n"oor Hnit 5'@H6


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es Of

%ntenna

!rime *ocus%ntenna

•Single Relector &ntenna.•Aee" horn is place" at the Aocal point

o the Relector.

• &ntenna (lectronics are place" on

Aee".

•4ore susceptible to 'ntererence romow elevation sources.

•4ore Blockage because ee".• &ntenna (iciency is in the range o

9*J.•ow Cost &ntenna.•3rimarily Hse" or Receive only

applications.


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-assa"rain

%ntenna

•4ain relector is 3araboloi"•Sub+Relector is hyperboloi" an"

place" at 3rime Aocus

•Aee" is Corrugate" orn an" is

place" at Center o the 4ainRelectors.

•#he paraboloi" converges towar"sthe Sub Relector 5 prime ocus6%

which is then relecte" by Sub+

Relector to orm a Spherical Wave

converging on the Aee".


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Gre"arion

%ntenna

•4ain relector is 3araboloi"•Sub+Relector is 3araboloi" an"

place" at 3rime Aocus

•Aee" is Corrugate" orn an" isplace" at Center o the 4ain

Relectors.

•#he paraboloi" converges towar"sthe Sub Relector 5 prime ocus6%

which is then relecte" by Sub+

Relector to orm a Spherical Wave

converging on the Aee".


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Offset *ed

%ntenna

•Hse" or Smaller (arth Stations.•4ain Relector is a section o

3arabolic% cuto above the a0is.

•Aee" is locate" below the a0is

giving a completely unblocke" &perture.

•igh &ntenna eiciency.


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• & BHC 5Block Hp+Converter6 takes an +Ban" input an" transmits it upstream to

the satellite on =a% =u% or C ban".

•BHC-s are rate" accor"ing to their output

power. & low power =a+Ban" BHC can

transmit with as little as , watts% while a

high power C+Ban" BHC can transmit with

as much as ,** watts.

,lock 1$-on&erter

(,1-)


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Low 2oise ,lock

-on&erter(L2,)

• 't is typically mounte" at the ocal point o thereceiving parabolic "ish.

• 't-s primarily use" to ampliy an" convertreceive"

satellite signals into re!uencies compatible with

the satellite receiver.


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Orthomode ransducer

(OM)

•4# is 7+port microwave wavegui"esystem that split input power into two

parts% allow the simultaneous operation o

two out"oor ra"io units

•4# can be "irectly mounte" on the

antennas that have circular wavegui"e

connector.


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'nterfacilit Link -able

('*L)

• 'nteracility ink 5'A6 @istributionCable is an in"oor rate"%

connectorie"

cable assembly that is use" within a

buil"ing to connect a iber ee"er

splice

point to an optical connector

"istribution panel.

•#he cable can be terminate" withconnectors at one or both en"s in

conKunction with various styles o an+

out kits at any breakout length.


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'ndoor 1nit

('.1)

• 'ts Satellite 4o"em consists o 4o"ulatoran"

@emo"ulator.

•#he '@H also "etermines the accessschemes

un"er which the FS woul" operate.

•#he '@H also interaces with various en"user

e!uipment% ranging rom stan" alone

computers%&2-s% routers% multiple0es% telephone

instruments% (3&BD as per the re!uirement.


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sat com ppt

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